Smithsonian Institution - United States National Museum - Bulletin 240 (part 3)

The throttle valve is a simple slide valve and must have been primitive for the time, for the balance-poppet throttle valve was in use in this country previous to 1851. It is located directly below the steam dome even though it was common practice to place the throttle valve at the front of the boiler in the smokebox. Considering the cramped condition inside the smokebox, there would seem to be little space for the addition of the throttle valve; hence its present location. The dry pipe projects up into the steam dome to gather the hottest, driest steam for the cylinders. The inverted, funnel-like cap on the top of the dry pipe is to prevent priming, as drops of water may travel up the sides of the pipe and then to the cylinders, with the possibility of great damage. After the steam enters the throttle valve it passes through the front end of the valve, through the top of the boiler via the dry pipe (fig. 18), through the front tube sheet, and then to the cylinders via the petticoat pipes. The throttle lever is a simple arrangement readily understood from the drawings. It has no latch and the throttle lever is held in any desired setting by the wingnut and quadrant shown in figure 18. The water level in the boiler is indicated by the three brass cocks located on the backhead. No gauge glass is used; they were not employed in this country until the 1870’s, although they were commonly used in England at the time the Pioneer was built.

While two safety valves were commonly required, only one was used on the Pioneer. The safety valve is located on top of the steam dome. Pressure is exerted on the lever by a spring balance, fixed at the forward end by a knife-blade bearing. The pressure can be adjusted by the thumbscrew on the balance. The graduated scale on the balance gave a general but uncertain indication of the boiler pressure. The valve itself is a poppet held against the face of the valve seat by a second knife blade attached to the lever. The ornamental column forming the stand of the safety valve is cast iron and does much to decorate the interior of the cab. The pipe carrying the escaping steam projects through the cab roof. It is made of copper with a decorative brass band. This entire mechanism was replaced by a modern safety valve for use at the Chicago Railroad Fair (1949). Fortunately, the old valve was preserved and has since been replaced on the engine.

The steam gauge is a later addition, but could have been put on as early as the 1860’s, since the most recent patent date that it bears is 1859. It is an Ashcroft gauge having a handsome 4—4—0 locomotive engraved on its silver face.

The steam jet (item 3, fig. 18) is one of the simplest yet most notable boiler fitting of the Pioneer, being nothing more than a valve tapped into the base of the steam dome with a line running under the boiler jacket to the smokestack. When the valve is opened a jet of steam goes up the stack, creating a draft useful for starting the fire or enlivening it as necessary. This device was the invention of Alba F. Smith in 1852, according to the eminent 19th-century technical writer and engineer Zerah Colburn.

The two feedwater pumps (fig. 20) are located beneath the cab deck (1, fig. 17). They are cast-iron construction and are driven by an eccentric on the driving-wheel axle (fig. 27). The airchamber or dome (1, fig. 27) imparts a more steady flow of the water to the boiler by equalizing the surges of water from the reciprocating pump plunger. A steam line (3, fig. 18), which heats the pump and prevents freezing in cold weather, is regulated by a valve in the cab (figs. , ). Note that the line on the right side of the cab has been disconnected and plugged.

The eccentric drive for the pumps is unusual, and the author knows of no other American locomotive so equipped. Eastwick and Harrison, it is true, favored an eccentric drive for feed pumps, but they mounted the eccentric on the crankpin of the rear driving wheel and thus produced in effect a half-stroke pump. This was not an unusual arrangement, though a small crank was usually employed in place of the eccentric. The full-stroke crosshead pump with which the Jenny Lind (fig. 22) is equipped, was of course the most common style of feed pump used in this country in the 19th century.

Of all the mechanisms on a 19th-century locomotive, the feed pump was the most troublesome. If an engineer could think of nothing else to complain about, he could usually call attention to a defective pump and not be found a liar. Because of this, injectors were adopted after their introduction in 1860. It is surprising that the Pioneer, which was in regular service as late as 1880 and has been under steam many times since for numerous exhibitions, was never fitted with one of these devices. Because its stroke is short and the plunger is in less rapid motion, the present eccentric arrangement is more complex but less prone to disorder than the simpler but faster crosshead pump.

Seth Wilmarth

Little is known of the builder of the Pioneer, Seth Wilmarth, and nothing in the way of a satisfactory history of his business is available. For the reader’s general interest the following information is noted.

Seth Wilmarth was born in Brattleboro, Vermont, on September 8, 1810. He is thought to have learned the machinist trade in Pawtucket, Rhode Island, before coming to Boston and working for the Boston Locomotive Works, Hinkley and Drury proprietors. In about 1836 he opened a machine shop and, encouraged by an expanding business, in 1841 he built a new shop in South Boston which became known as the Union Works. Wilmarth was in the general machine business but his reputation was made in the manufacture of machine tools, notably lathes. He is believed to have built his first locomotive in 1842, but locomotive building never became his main line of work. Wilmarth patterned his engines after those of Hinkley and undoubtedly, in common with the other New England builders of this period, favored the steady-riding, inside-connection engines. The “Shanghais,” so-called because of their great height, built for the Boston and Worcester Railroad by Wilmarth in 1849, were among the best known inside-connection engines operated in this country (fig. 14). While the greater part of Wilmarth’s engines was built for New England roads, many were constructed for lines outside that area, including the Pennsylvania Railroad, Ohio and Pennsylvania Railroad, and the Erie.

A comparison of the surviving illustrations of Hinkley and Wilmarth engines of the 1850’s reveals a remarkable similarity in their details (figs. and ). Notice particularly the straight boiler, riveted frame, closely set truck wheels, feedwater pump driven by a pin on the crank of the driving wheel, and details of the dome cover. All of the features are duplicated exactly by both builders. This is not surprising considering the proximity of the plants and the fact that Wilmarth had been previously employed by Hinkley.

In 1854 Wilmarth was engaged by the New York and Erie Railroad to build fifty 6-foot gauge engines. After work had been started on these engines, and a large store of material had been purchased for their construction, Wilmarth was informed that the railroad could not pay cash but that he would have to take notes in payment. There was at this time a mild economic panic and notes could be sold only at a heavy discount. This crisis closed the Union Works. The next year, 1855, Seth Wilmarth was appointed master mechanic of the Charlestown Navy Yard, Boston, where he worked for twenty years. He died in Malden, Massachusetts, on November 5, 1886.

[BOILER FITTINGS continued]

Figure 20.—Feedwater pump of the Pioneer. (Smithsonian photo 63344.)

The check valves are placed slightly below the centerline of the boiler (fig. 18). These valves are an unfinished bronze casting and appear to be of a recent pattern, probably dating from the 1901 renovation. At the time the engine was built, it was usual to house these valves in an ornamental spun-brass casing. The smokestack is of the bonnet type commonly used on wood-burning locomotives in this country between about 1845 and 1870. The exhaust steam from the cylinders is directed up the straight stack (shown in phantom in fig. 27) by the blast pipe. This creates a partial vacuum in the smokebox that draws the fire, gases, ash, and smoke through the boiler tubes from the firebox. The force of the exhausting steam blows them out the stack. At the top of the straight stack is a deflecting cone which slows the velocity of the exhaust and changes its direction causing it to go down into the funnel-shaped outer casing of the stack. Here, the heavy embers and cinders are collected and prevented from directly discharging into the countryside as dangerous firebrands. Wire netting is stretched overtop of the deflecting cone to catch the lighter, more volatile embers which may defy the action of the cone. The term “bonnet stack” results from the fact that this netting is similar in shape to a lady’s bonnet. The cinders thus accumulated in the stack’s hopper could be emptied by opening a plug at the base of the stack.

While the deflecting cone was regarded highly as a spark arrester and used practically to the exclusion of any other arrangement, it had the basic defect of keeping the smoke low and close to the train. This was a great nuisance to passengers, as the low trailing smoke blew into the cars. If the exhaust had been allowed to blast straight out the stack high into the air, most of the sparks would have burned out before touching the ground.

Figure 21.—“Pioneer” on exhibit in old Arts and Industries building of the Smithsonian Institution. In this view can be seen the bonnet screen of the stack and arrangement of the boiler-frame braces and other details not visible from the floor. (Smithsonian photo 48069A.)

Figure 22.—“Jenny Lind,” sister engine of the Pioneer, shown here as rebuilt in 1878 for use as an inspection engine. It was scrapped in March 1905. (Photo courtesy of E. P. Alexander.)

Figure 23.—Cylinder head with valve box removed.

Figure 24.—Bottom of valve box with slide valve removed.

Figures 25 and 26.—Cylinder with valve box removed, showing valve face.

FRAME

The frame of the Pioneer defies an exact classification but it more closely resembles the riveted- or sandwich-type frame than any other (figs. , ). While the simple bar frame enjoyed the greatest popularity in the last century, riveted frames were widely used in this country, particularly by the New England builders between about 1840 and 1860. The riveted frame was fabricated from two plates of iron, about /8-inch thick, cut to the shape of the top rail and the pedestal. A bar about 2 inches square was riveted between the two plates. A careful study of photographs of Hinkley and other New England-built engines of the period will reveal this style of construction. The frame of the Pioneer differs from the usual riveted frame in that the top rail is 1/4 inches thick by 4/8 inches deep and runs the length of the locomotive. The pedestals are made of two /8-inch plates flush-riveted to each side of the top rail. The cast-iron shoes which serve as guides for the journal boxes also act as spacers between the pedestal plates.

The bottom rail of the frame is a 1/8-inch diameter rod which is forged square at the pedestals and forms the pedestal cap. The frame is further stiffened by two diagonal rods running from the top of each truck-wheel pedestal to the base of the driving-wheel pedestal, forming a truss. Six rods, riveted to the boiler shell and bolted to the frame’s top rail, strengthen the frame laterally. Four of these rods can be seen easily as they run from the frame to the middle of the boiler; the other two are riveted to the underside of the boiler. The attachment of these rods to the boiler was an undesirable practice, for the boiler shell was thus subjected to the additional strain of the locomotive’s vibrations as it passed over the road. In later years, as locomotives grew in size, this practice was avoided and frames were made sufficiently strong to hold the engine’s machinery in line without using the boiler shell.

The front and rear frame beams are of flat iron plate bolted to the frame. The rear beam had been pushed in during an accident, and instead of its being replaced, another plate was riveted on and bent out in the opposite direction to form a pocket for the rear coupling pin. Note that there is no drawbar and that the coupler is merely bolted to the beams. Since the engine only pulled light trains, the arrangement was sufficiently strong.

RUNNING GEAR

The running gear is simply sprung with individual leaf springs for each axle; it is not connected by equalizing levers. To find an American locomotive not equipped with equalizers is surprising since they were almost a necessity to produce a reasonably smooth ride on the rough tracks of American railroads. Equalizers steadied the motion of the engine by distributing the shock received by any one wheel or axle to all the other wheels and axles so connected, thus minimizing the effects of an uneven roadbed. The author believes that the Pioneer is a hard-riding engine.

The springs of the main drives are mounted in the usual fashion. The rear boiler bracket (fig. 18) is slotted so that the spring hanger may pass through for its connection with the frame. The spring of the leading wheels is set at right angles to the frame (fig. 27) and bears on a beam, fabricated of iron plate, which in turn bears on the journal boxes. The springs of the trailing wheels are set parallel with the frame and are mounted between the pedestal plates (fig. 18).

The center of the driving wheel is cast iron and has spokes of the old rib pattern, which is a T in cross section, and was used previous to the adoption of the hollow spoke wheel. In the mid-1830’s Baldwin and others used this rib-pattern style of wheel, except that the rib faced inside. The present driving-wheel centers are unquestionably original. The sister engine Jenny Lind (fig. 22) was equipped with identical driving wheels. The present tires are very thin and beyond their last turning. They are wrought iron and shrunk to fit the wheel centers. Flush rivets are used for further security. The left wheel, shown in figure 17, is cracked at the hub and is fitted with an iron ring to prevent its breaking.

The truck wheels, of the hollow spoke pattern, are cast iron with chilled treads. They were made by Asa Whitney, one of the leading car-wheel manufacturers in this country, whose extensive plant was located in Philadelphia. Made under Whitney’s patent of 1866, these wheels may well have been added to the Pioneer during the 1871 rebuilding. Railroad wheels were not cast from ordinary cast iron, which was too weak and brittle to stand the severe service for which they were intended, but from a high-quality cast iron similar to that used for cannons. Its tensile strength, which ranged from 31,000 to 36,000 psi, was remarkably high and very nearly approached that of the best wrought-iron plate.

The cylinders are cast iron with an 8/2-inch bore about half the size of the cylinders of a standard 8-wheel engine. The cylinders are bolted to the frame but not to the saddle, and are set at a 9° angle to clear the leading wheels and at the same time to line up with the center of the driving-wheel axle. The wood lagging is covered with a decorative brass jacket. Ornamental brass jacketing was extensively used on mid-19th-century American locomotives to cover not only the cylinders but steam and sand boxes, check valves, and valve boxes. The greater expense for brass (Russia iron or painted sheet iron were a cheaper substitute) was justified by the argument that brass lasted the life of the engine, and could be reclaimed for scrap at a price approaching the original cost; and also that when brightly polished it reflected the heat, preventing loss by radiation, and its bright surface could be seen a great distance, thus helping to prevent accidents at grade crossings. The reader should be careful not to misconstrue the above arguments simply as rationalization on the part of master mechanics more intent on highly decorative machines than on the practical considerations involved.

The valve box, a separate casting, is fastened to the cylinder casting by six bolts. The side cover plates when removed show only a small opening suitable for inspection and adjustment of the valve. The valve box must be removed to permit repair or removal of the valve. A better understanding of this mechanism and the layout of the parts can be gained from a study of figures 23-26, 28 (8, 8A, and 8B).

Figure 27.—“Pioneer” locomotive. (1) Air chamber, (2) reversing lever, (3) counterweight, (4) reversing shaft, (5) link hanger, (6) rocker, (7) feedwater line to boiler, (8) link block, (9) link, (10) eccentric, (11) pump plunger, (12) pump steamheater line, (13) feedwater pump, (14) wire netting [bonnet], (15) deflecting cone, (16) stack, (17) stack hopper. (Drawing by J. H. White.)

Click on image to view larger sized.

Figure 28.—Rear elevation of Pioneer and detail of valve shifter; valve face and valve. (Drawing by J. H. White.)

Click on image to view larger sized.

Both crossheads were originally of cast iron but one of these has been replaced and is of steel. They run into steel guides, bolted at the forward end to the rear cylinder head and supported in the rear by a yoke. The yoke is one of the more finished and better made pieces on the entire engine (fig. 27). The main rod is of the old pattern, round in cross section, and only 1/2 inches in diameter at the largest point.

VALVE GEAR

The valve gear is of the Stephenson shifting-link pattern (see fig. 27), a simple and dependable motion used extensively in this country between about 1850 and 1900. The author believes that this is the original valve gear of the Pioneer, since the first mention (1854) in the Annual Report of the Cumberland Valley Railroad of the style of valve gear used by each engine, states that the Pioneer was equipped with a shifting-link motion. Assuming this to be the original valve gear of the Pioneer, it must be regarded as an early application, because the Stephenson motion was just being introduced into American locomotive practice in the early 1850’s. Four eccentrics drive the motion; two are for forward motion and two for reverse. The link is split and made of two curved pieces. The rocker is fabricated of several forged pieces keyed and bolted together. On better made engines the rocker would be a one-piece forging. The lower arm of each rocker is curiously shaped, made with a slot so that the link block may be adjusted. Generally, the only adjustment possible was effected by varying the length of the valve stem by the adjusting nuts provided. A simple weight and lever attached to the reversing shaft serve as a counterbalance for the links and thus assist the engineer in shifting the valve motion. There are eight positions on the quadrant of the reversing lever.

Figure 29.—“Pioneer” on exhibit in old Arts and Industries building, showing the tank and backhead. (Smithsonian photo 48069E.)

MISCELLANEOUS NOTES

The cab is solid walnut with a natural finish. It is very possible that the second cab was added to the locomotive after the 1862 fire. A brass gong used by the conductor to signal the engineer is fastened to the underside of the cab roof. This style of gong was in use in the 1850’s and may well be original equipment.

The water tank is in two sections, one part extending below the deck, between the frame. The tank holds 600 gallons of water. The tender holds one cord of wood.

The small pedestal-mounted sandbox was used on several Cumberland Valley engines including the Pioneer. This box was removed from the engine sometime between 1901 and 1904. It was on the engine at the time of the Carlisle sesquicentennial but disappeared by the time of the St. Louis exposition. Two small sandboxes, mounted on the driving-wheel splash guards, replaced the original box. The large headlamp (fig. 3) apparently disappeared at the same time and was replaced by a crudely made lamp formerly mounted on the cab roof as a backup light. Headlamps of commercial manufacture were carefully finished and made with parabolic reflectors, elaborate burners, and handsomely fitted cases. Such a lamp could throw a beam of light for 1000 feet. The present lamp has a flat cone-shaped piece of tin for a reflector.

The brushes attached to the pilot were used in the winter to brush snow and loose ice off the rail and thus improve traction. In good weather the brushes were set up to clear the tracks.

Figure 30.—Reconstructed sandbox replaced on the locomotive, August 1962. (Drawing by J. H. White.)

After the Pioneer had come to the National Museum, it was decided that some refinishing was required to return it as nearly as possible to the state of the original engine. Replacing the sandbox was an obvious change. The brass cylinder jackets were also replaced. The cab was stripped and carefully refinished as natural wood. The old safety valve was replaced, as already mentioned. Rejacketing the boiler with simulated Russia iron produced a most pleasing effect, adding not only to the authenticity of the display but making the engine appear lighter and relieving the somber blackness which was not characteristic of a locomotive of the 1850’s. Several minor replacements are yet to be done; chiefly among these are the cylinder-cock linkage and a proper headlamp.

The question arises, has the engine survived as a true and accurate representation of the original machine built in 1851? In answer, it can be said that although the Pioneer was damaged en route to the Cumberland Valley Railroad, modified on receipt, burned in 1862, and operated for altogether nearly 40 years, surprisingly few new appliances have been added, nor has the general arrangement been changed. Undoubtedly, the main reason the engine is so little changed is that its small size and odd framing did not invite any large investment for extensive alteration for other uses. But there can be no positive answer as to its present variance from the original appearance as represented in the oldest known illustration of it—the Hull drawing of 1871 (fig. 8). There are few, if any, surviving 19th-century locomotives that have not suffered numerous rebuildings and are not greatly altered from the original. The John Bull, also in the U.S. National Museum collection, is a good example of a machine many times rebuilt in its 30 years of service. Unless other information is uncovered to the contrary, it can be stated that the Pioneer is a true representation of a light passenger locomotive of 1851.

P. : ‘1880 and has been under steam’—was ‘1880 and has been under stream.’

P. : ‘made with parabolic reflectors’—was ‘made with parobolic reflectors.’

Transcription of Advertisement on Pg. 254

UNION WORKS, SOUTH BOSTON, SETH WILMARTH, Proprietor,
MANUFACTURER OF LOCOMOTIVES, STATIONARY STEAM ENGINES AND STEAM
BOILERS, OF THE VARIOUS SIZES REQUIRED, Parts connected with
Railroads, including Frogs, Switches, Chairs and Hand
Cars.MACHINISTS' TOOLS, of all descriptions, including TURNING
LATHES, of sizes varying from 6 feet to 50 feet in length, and
weighing from 500 pounds to 40 tons each; the latter capable of
turning a wheel or pulley, thirty feet in diameter. PLANING
MACHINES, Varying from 2 feet to 60 feet in length, and weighing
from 200 lbs. to 70 tons each, and will plane up to 55 feet long
and 7 feet square. Boring Mills, Vertical and Horizontal Drills,
Slotting Machines, Punching Presses, Gear and Screw Cutting
Machines, &c. &c. Also, Mill Gearing and Shafting.
JOBBING AND REPAIRS, and any kind of work usually done in Machine
Shops, executed at short notice.

Contributions from
The Museum of History and Technology:
Paper 43

History of the Division of Medical Sciences

Sami Hamarneh

SECTION OF MATERIA MEDICA (1881-1898) 272

DIVISION OF MEDICINE (1898-1939) 276

DIVISION OF MEDICINE AND PUBLIC HEALTH (1939-1957) 281

DIVISION OF MEDICAL SCIENCES (1957 TO PRESENT) 290

A NEW DIMENSION FOR THE HEALING ARTS 292

BIBLIOGRAPHY 297

FOOTNOTES

INDEX

Figure 1.—Early View of the United States National Museum, known for the last quarter of a century as the Arts and Industries building. Completed in 1881, it housed the Division of Medical Sciences from its establishment in 1881 as a Section of Materia Medica to the time of the writing of this paper. While the medical collection remained in the Department of Arts and Industries, by the end of June 1912 practically all other collections belonging to the fields of natural history and anthropology were transferred to the then new Natural History building.

Sami Hamarneh

HISTORY of the DIVISION of MEDICAL SCIENCES
In The Museum of History and Technology

This paper traces, for the first time, the history of the Division of Medical Sciences in the Museum of History and Technology from its small beginnings as a section of materia medica in 1881 to its present broad scope. The original collection of a few hundred specimens of crude drugs which had been exhibited at the centennial exhibition of 1876 at Philadelphia, has now developed into the largest collection in the Western Hemisphere of historical objects related to the healing arts.

The Author: Sami Hamarneh is the curator of the Division of Medical Sciences in the Smithsonian Institution’s Museum of History and Technology.

By the early 1870’s, leading figures from both the health professions and the general public had begun to realize the necessity for having the medical sciences represented in the Smithsonian Institution. The impetus behind this new feeling resulted from the action of a distinguished American physician, philanthropist, and author, Joseph Meredith Toner (1825-1896), and came almost a decade before the integration of a new section concerned with research and the historical and educational aspects of the healing arts in the Smithsonian Institution.

In 1872, Dr. Toner established the “Toner Lectures” to encourage efforts towards discovering new truths “for the advancement of medical science … for the benefit of mankind.” To finance these lectures, he provided a fund worth approximately $3,000 to be administered by a board of trustees consisting of the Secretary of the Smithsonian Institution, the Surgeon General of the U.S. Navy, the Surgeon General of the U.S. Army (only in some years), and the president of the Medical Society of the District of Columbia. The interest from this fund was to compensate physicians and scholars who were to deliver “at least two annual memoirs or essays” based on original research on some branch of the medical sciences and containing information which had been verified “by experiments or observations.”

The Secretary of the Smithsonian Institution agreed to have these lectures published by the Institution in its Miscellaneous Collections. The first lecture given by the Assistant Surgeon of the U.S. Army, “On the Structure of Cancerous Tumors and the Mode in which Adjacent parts are Invaded,” deserves credit even by current standards of scientific research. Only 10 lectures were given between 1873 and 1890 (see bibliography), despite the recommendation for at least two every year.

Figure 2.—Dr. Joseph M. Toner, a leading physician in Washington, D.C., and founder of the “Toner Lectures” for the promotion and advancement of medical education and research. In 1873, Dr. Toner became president of the American Medical Association and, in 1874, he became president of the American Public Health Association. He was a physician to St. Joseph’s Male Orphan Asylum and St. Ann’s Infants’ Asylum in Washington, D.C. In addition, he was instrumental in establishing Providence Hospital in the District of Columbia. He also provided a workable plan for the American Medical Association’s library in Washington, D.C. (1868-1871). Among his several publications are: Contributions to the Annals of Medical Progress and Medical Education in the United States before and during the War of Independence (Washington: Government Printing Office, 1874) and Medical Men of the Revolution (1876). In 1882, he donated his large library, consisting of 44,000 books and pamphlets on topics related mainly to medicine and history, to the Library of Congress. (Photo courtesy of National Library of Medicine.)

A more direct factor, which not only contributed to the establishment of a section on the healing arts, but also had a greater effect upon the Smithsonian Institution than any other event since its founding, was the 1876 centennial exhibition in Philadelphia.

This magnificent international fair commemorated the hundredth anniversary of the adoption of the Declaration of Independence. The finest exhibits of 30 foreign countries and various States of the Union participating in the fair were finally donated to the Smithsonian Institution as the official depository of historical and archeological objects for this country. As a result, the Institution’s collections increased to an extent far beyond the capacity of the first Smithsonian building. This led to the erection of the National Museum, known for the last two decades and until date of publication as the Arts and Industries building, which was completed on March 4, 1881, and was used that evening for the inaugural reception of incoming President James A. Garfield.

Section of Materia Medica (1881-1898)

Throughout the 19th century, the study of materia medica (dealing with the nature and properties of drugs of various kinds and origins, their collection and mode of administration for the treatment of diseases, and the medicinal utilization of animal products) held an increasingly important place among the medical sciences. In the United States, as in other civilized countries, this topic was greatly emphasized in the curriculum of almost every school teaching the health professions. Today, the subject matter contained in this branch of science is taught under the heading of several specialized fields, such as pharmacology, pharmacognosy, and drug analysis of various types. However, when the decision was made in 1881 to promote greater knowledge and interest in the healing arts by creating a section devoted to such pursuits in the U.S. National Museum, the title of Section of Materia Medica was adopted. Added to this, was the fact that the bulk of the first collections received in the Section was a great variety of crude drugs, which constituted much of the material then taught in the academic courses of materia medica.

The new Section was included in the Department of Arts and Industries, then under the curatorship of Assistant Director G. Brown Goode. From its beginning and for two decades, however, the Section of Materia Medica was sponsored and supervised by the U.S. Navy in cooperation with the Smithsonian Institution. For this reason, the Navy decided not to establish a similar bureau for a health museum as did the Army in starting the Medical Museum (of the Armed Forces Institute of Pathology) in 1862 through the efforts of Dr. William Alexander Hammond. The Smithsonian did, however, provide a clerk to relieve the curator of much of the routine work. The Section’s early vigorous activities were the result of the ingenuity of the first honorary curator, Dr. James Milton Flint (1838-1919), an Assistant Surgeon of the U.S. Navy. From the establishment of the Section, in 1881, to 1912, Dr. Flint was curator during separate periods for a total of nearly 25 years. For three of his tenures (1881-1884; 1887-1891; 1895-1900), he was detailed to the Smithsonian Institution by the Surgeon General of the U.S. Navy. During the interim periods, other naval doctors were detailed as curators. Finally, in 1900, Dr. Flint retired from the Navy with the rank of Rear Admiral and volunteered to continue his services to the National Museum. The proposal was gladly accepted and he continued as a curator until his retirement from the Smithsonian Institution in 1912.

Figure 3.—Rear Admiral James M. Flint, U.S. Navy surgeon and first honorary curator of the Section of Materia Medica. (Photo courtesy of the Library of Congress.)

The Section commenced with a wealth of material. After the close of the 1876 centennial exhibition, its materia medica collection had been stored with the other collections in a warehouse, awaiting an appropriation by Congress for transfer and installation. This collection was gradually brought into the new National Museum after that building’s completion in 1881. Many other materia medica specimens were transferred from the Department of Agriculture. In addition to these large collections of crude drugs, generous contributions came from several prominent pharmaceutical firms such as Parke, Davis & Company of Detroit, Michigan; Wallace Brothers of Statesville, North Carolina; and Schieffelin and Company of New York City. These manufacturing houses are mentioned here because they and their agents abroad were the first to take interest and donate to the Section, complete assortments of contemporary remedial agents then in common use throughout the United States and Europe, besides many hundreds of “rare and curious drugs.” Thus, in spite of difficulties encountered from bringing several collections into the building at one time, the materia medica exhibition got off to a good start.

It was Dr. Flint, the first curator, who stated in 1883 that remedial agents used by a nation or a community are as indicative of the degree of their cultural development and standard of living as is the nature of their food, the character of their dwellings, and their social and religious traditions. Therefore, he felt that collections of drugs and medical, surgical and pharmaceutical instruments and appliances should not be thought of or designed as instructive to the specialist only, but should also possess a general interest for the public. Because of these objectives, Dr. Flint added, this section was conceived as a departmental division for the collecting and exhibiting of objects related to medicine, surgery, pharmacology, hygiene, and all material related to the health field at large.

During his first term of curatorship (1881-1884), Dr. Flint devoted much of his time to sorting, examining, identifying, and classifying the materia medica specimens. In 1881, he issued a memorandum of instructions to be followed by collectors of drugs and urged them to give detailed and accurate information regarding acquired specimens so that they might be “more than mere museum curiosities.” In addition, in 1883, he prepared a brief manual of classification of the materia medica collection in the Museum as well as a useful, detailed catalog of informational labels of the individual objects on exhibition. The unpublished catalog is still the property of the Smithsonian Institution Archives, Division of Medical Sciences’ Library.

It was Dr. Flint’s ambition to obtain a comprehensive, worldwide collection of all substances used as remedies. Then, in order to identify drugs from foreign countries, he tried to collect illustrated works on medical botany and printed pharmacopoeias of all nations having them. He rightly defined an official pharmacopoeia as “a book containing directions for the identification and preparation of medicines prepared and issued with the sanction of a government or organized and authorized medical and pharmaceutical societies. Its purpose is to establish uniformity in the nomenclature of remedies and in the character and potency of the pharmaceutical preparations. It is enacted by legislation, and thus becomes binding on all who prepare drugs or sell them for medication.” By soliciting the help of various American consuls and Navy officers abroad, about 16 such official pharmacopoeias were collected, making an almost complete international representation of all available, official, drug standards. With these sources of information, Dr. Flint compiled and arranged an international list of materia medica specimens, indicating the authorized preparations of each. By so doing, the first curator of this Section took the initiative at least in proposing and, to some extent acting, on the preparation of an international pharmacopoeia of drugs used in existing authorized formularies giving “official synonyms, and tables showing the constituents and comparative strength of all preparations.” This undertaking is of special importance in the history of American pharmacy, since it was probably the first attempt of its kind in the United States. In addition, colored plates and photographs of medicinal plants were collected, forming the nucleus of the Division’s current collection of pictorial and photographic material related to the history of the health field.

Dr. Flint also put on exhibition 630 Chinese materia medica specimens from the 1876 Philadelphia centennial. These had been collected originally by the Chinese Imperial Customs Commission for the centennial and were subsequently given to this country.

In 1881, the numbered objects in the Section’s register amounted to 1,574 entries. In the following year, 1,590 more specimens were added, most of them drugs in their crude state. By the end of 1883, the total collection had reached 4,037, out of which 3,240 individual drugs in good condition were classified and put on display. Of these, about 500 specimens with beautiful illustrations of parts of their original plants had been mounted for exhibition. The drug exhibitions also included materials transferred from the Department of Agriculture in 1881, which originally had been brought from Central America and South America for the 1876 centennial exhibition, a variety of opium specimens from Turkey, and a number of rare drugs listed in the official formulary which were acquired from the Museum of Karachi in what was then India.

Dr. Flint commented in the Smithsonian Annual Report for 1883 that the collection of cinchona barks was especially complete. It was comprised of specimens of nearly all the natural cinchona barks of South America and every known variety of the cultivated product from the British government plantations in India. In addition, there were specimens from Java, Ceylon, Mexico, and Jamaica. The Indian and Jamaican barks were accompanied by herbarium specimens of the leaf and flower (and, in some cases, the fruit) of each variety of tree from which the bark was obtained.

In an attempt to protect specimens liable to attack by insects, a small piece of blotting paper moistened with chloroform was inserted underneath the stopper in each bottle. Later on, bichloride of mercury was found to be a better insecticide.

These early collections of the Section were brought into admirable condition and received compliments for their organization and completeness. In the Smithsonian Annual Report for 1883, the collections were praised as “superior to any other in the United States and scarcely excelled by any in Europe.”

Figure 4.—Dr. Henry Gustav Beyer, the second honorary curator of the Section of Materia Medica (1884-1887). (Photo courtesy of American Physiological Society.)

In spite of the apparent emphasis on the displaying of drugs, the first curator of the Section had envisioned that the exhibits eventually would embrace the entire field of the healing arts. In the Smithsonian Annual Report for 1883, Dr. Flint noted that “in the establishment of a museum designed to illustrate man and his environment, it is proper that the materials and methods used for the prevention and cure of disease should have a place.” However, his plans were temporarily interrupted when his first term as honorary curator ended in 1884.

On June 4, 1884, Dr. Henry Gustav Beyer was detailed by the Department of the Navy to become the second honorary curator of the Section of Materia Medica. As a young man, Dr. Beyer (1850-1918) had come from Saxony, Germany, to the United States and, in due course, became a naturalized citizen. He was graduated from the Bellevue Hospital Medical College of New York City in 1876.

Because of his interest in physiological experimental research, Dr. Beyer enrolled at the Johns Hopkins University, where he was awarded a Ph. D. degree in 1887. Unlike his predecessor, Dr. Beyer was primarily interested in carrying on research on the physiological action of certain drugs and in pharmacology. This was evident from the original scientific papers mentioned in the Smithsonian Annual Reports and published by him during the period of his curatorship from 1884 to 1887.

Despite the pressure of his postgraduate studies at Johns Hopkins University, Dr. Beyer helped in arranging and classifying the materia medica collection without trying to extend materially the scope of the Section.

After the term of Dr. Beyer expired in 1887, Dr. Flint returned to take charge of the Section. Surprisingly, at this time, it seems that he showed less enthusiasm and devotion to the work of the Museum which he had previously served so well. It could have been a disappointment resulting from a lack of evidence of any real progress in the Section since he had left it three years before. Whatever the reasons may have been, the Smithsonian Annual Reports show that only a few hundred specimens were added to the materia medica collections between 1887 and 1890, bringing the total to 5,915 preserved in good condition. Further curtailment of the Section’s activities began in November 1891 when Dr. Flint was again transferred to other duties for the U.S. Navy. From November 1891 to May 24, 1895, curatorship of the Section was charged to five physicians of the U.S. Navy: Drs. John C. Boyd (from November 1891 to April 6, 1892); William S. Dixon (April 1892 to January 5, 1893); C. H. White (January 1893 to July 15, 1893); C. U. Gravatt (July 1893 to January 22, 1894); R. A. Marmion (January 22, 1894 to June 15, 1894); and to Medical Inspector Daniel McMurtrie (June 1894 to May 24, 1895). During this interim of nearly three and a half years, there were neither literary contributions nor additions made to the collections of the Section that were of any significance. The reason is obvious, for all of these curators averaged less than seven months of service which is not enough time, even for a well-trained individual, to accomplish very much in a museum. Therefore, it is easy to imagine that when the Secretary of the Navy detailed Dr. Flint for a third time to take charge of the Section, he was rather discouraged. Nevertheless, at the Cotton States and International Exposition in Atlanta, Georgia, from September 18 to December 31, 1895, the materia medica was represented by two displays: one on mineral waters and amounts of solid constituents in pure state; and another showing the quantities of minerals after analysis of the composition of the human body.

A similar project was undertaken in 1897 at the Tennessee Centennial Exposition (May 1 to October 31) in Nashville, where there were two displays of materia medica. One showed several kinds of the cinchona barks and the medicinal preparations made from them, and another containing the commercial varieties of the alkaloids of opium.

At this time, Dr. Flint’s attention turned to a new phase of medical exhibition. He felt the need for a program of exhibits on the practice and the historical development of the healing arts. A change of the Section’s name was deemed necessary and, thus, in 1898 the more comprehensive title of Division of Medicine was adopted.

Division of Medicine (1898-1939)

The statement by L. Emmett Holt of the Rockefeller Institute for Medical Research, that before 1906, the Smithsonian Institution was never a beneficiary to medicine in any form, is not entirely applicable. The previous discussion has clearly shown that the U.S. National Museum’s cooperation with the Navy contributed materially towards encouraging and promoting medical knowledge. Furthermore, Dr. Flint tried to bring many of his plans for this medical division of the Museum to a practical fulfillment. He devised a program for presenting medical history in a way which would be of interest both to the public and to the profession. In order to best illustrate the history of the healing art, he divided his subject matter into five provisional classifications according to the Report upon the Condition and Progress of the U.S. National Museum during 1898:

1. Magical medicine including exorcism, amulets, talismans, fetishes and incantation;

2. Psychical medicine including faith cures, and hypnotism;

3. Physical and external medicine including baths, exercise, electricity, massage, surgery, cautery, and blood-letting;

4. Internal medicine including medications and treatment used by the ancient Egyptians, Greeks, Hindus, Arabians, and Chinese; and

5. Preventive medicine including beverages, food, soil, clothing and habitation.

It is certainly to Dr. Flint’s credit that from its early conception, first as Section of Materia Medica and thereafter as Division of Medicine, he planned for an all-embracing exhibition and reference collection of the medical sciences. Until the end of the 19th century and the early years of the 20th century, crude drugs as well as primitive and magic medicine held a more prominent place than medical instruments in the exhibits and collections. In 1905, Flint issued his last, known, literary contribution, “Directions for Collecting Information and Objects Illustrating the History of Medicine,” in Part S of Bulletin of the U.S. National Museum, no. 39. The emphasis he put upon this shows Dr. Flint’s interest in collecting medical and pharmaceutical objects and equipment of historical value. Consequently, he arranged new exhibits including one on American Indian medicine. A medical historian, Fielding H. Garrison, inspected these about 1910 and, in his “An Introduction to the History of Medicine,” wrote of their novelty and appeal. “In the interesting exhibit of folk medicine in the National Museum at Washington,” he commented, “a buckeye or horse chestnut (Aesculus flavus), an Irish potato, a rabbit’s foot, a leather strap previously worn by a horse, and a carbon from an arc light are shown as sovereign charms against rheumatism. Other amulets in the Washington exhibit,” he added, “are the patella of a sheep and a ring made out of a coffin nail (dug out of a graveyard) for cramps and epilepsy, a peony root to be carried in the pocket against insanity, and rare and precious stones for all and sundry diseases.” It had been Dr. Flint’s intention, besides presenting an educational display on the history of the medical arts, to warn the public against the perils of quackery and the faults of folk medicine, as well as to expose evils in drug adulteration. Today, we can see actual fulfillment of these intentions in the present exhibit at the medical gallery which has been executed recently on the basis of scientific, historical research.

After Dr. Flint’s retirement from the Smithsonian Institution in 1912, there was no replacement for over five years. Therefore, the Division of Medicine was placed, for administrative purposes, under the supervision of the curator of the newly reestablished (1912) Division of Textiles, Frederick L. Lewton. During these years, he fought against the dispersal of the medical and materia medica collections. Thus, for lack of a curator of its own, almost all new activities in the Division of Medicine were curtailed until 1917.

On January 31, 1917, Lewton addressed members of the American Pharmaceutical Association inviting them to cooperate in gathering up and preserving at the National Museum the “many unique and irreplaceable objects” connected with the early history of pharmacy in this country which could still be saved. Then, on March 14, 1917, an examination was announced by the Civil Service (held May 2) for an assistant curator for the Division of Medicine, and the position was filled by Joseph Donner on August 16, 1917. Donner was the first full-time employee paid by the Smithsonian Institution for the curatorship of this Division. He held the post until January 31, 1918, when he was inducted into the Sanitary Corps of the United States Army. No significant activities in the Division of Medicine were reported during these few months.

Mr. Donner was followed by a second, full-time, museum officer who promoted a great amount of good will towards the Division during his curatorship of a little over 30 years. Dr. Charles Whitebread (1877-1963), the first pharmacist to head the Division, joined the Smithsonian in 1918 and remained until his retirement in 1948, the longest service, thus far, of any individual in the Division.

Dr. Whitebread received his degree of Doctor of Pharmacy from the School of Pharmacy at George Washington University in Washington, D.C., in 1911. He entered government service late in 1915, but it was not until April 2, 1918, that he agreed to become assistant curator of the Division of Medicine.

Curator Whitebread’s first year was an active and challenging one, for in this new position he began to develop a deep interest in the history of the healing arts. He made a number of important acquisitions, most of them pertaining to pharmaceutical products, synthetic chemicals and crude drugs. He found that many specimens from the older drug collections had deteriorated to such an extent as to be worthless, and he began replacing them with freshly marketed drugs.

Figure 5.—Curator Charles Whitebread inspecting, with admiration, five drug containers from the Squibb collection (1945). (Photo courtesy of the American Pharmaceutical Association.)

Plans were completed for the opening of new medical exhibits and adopting, with some modifications and additions, earlier classifications set by Dr. Flint. Dr. Whitebread grouped these into the following classes: the evaluation of the healing arts; a picture display of medical men prominent in American history; a materia medica display including the history of pharmacy; and an exhibition on Sanitation and Public Hygiene which was later to evolve into the Hall of Health.

In 1920, Dr. Whitebread added a number of specimens of medical-dosage forms and pharmaceutical preparations to the Division’s collections. He also acquired other gifts to complete existing exhibits illustrating the basic principles of the various schools of medicine, such as homeopathy and osteopathy—their methods, tools, and ways of thought.

In 1921, a tablet machine by the Arthur Colton Company of Detroit, Michigan, was acquired, and an exhibit illustrating vaccine and serum therapy was installed in the medical gallery. This was followed, in 1922, by a collection arranged to tell the story of the prevention and cure of specific diseases by means of biological remedies.

During the following two years, two more exhibits related to hospital supplies and sanitation were added to the rapidly developing Hall of Health exhibition which was opened in 1924. A third exhibit in 1925 consisted of 96 mounted color transparencies illustrating services provided by hospitals to promote public health. Plans for the further development of the Hall of Health continued during 1926, and contacts were made with organizations interested in the educational aspects of the healing arts. As a result, several new exhibits were added. In 1926, the American Optometric Association helped in the installation of an exhibit on conservation of vision or the care of the eyes under the slogan “Save your vision,” as a phase of health work. Other exhibits in the Hall at this time were: what parasites are; water pollution and how to obtain pure water; waste disposal; ventilation and healthy housing, and the importance of recreation; purification of milk and how to obtain pure milk; transmission of diseases by insects and animals; how life begins; prenatal and postnatal care and preschool care; duties of the public health nurse; and social, oral and mental hygiene.

With the acquiring of more medical appliances and the widening of the scope of the exhibits, more and more space was needed, and attention was turned to the area of the medical gallery which had been occupied by the materia medica collection for almost four decades. To gain more exhibit space, it was decided that the greater part of the crude drugs should be removed from the exhibits and be kept as a reference collection and for research.

Figure 6.—Exhibit on Egyptian and Hebrew medicine, installed about 1924, which was illustrated by graphs and drugs mentioned in extant records of this ancient period. (Smithsonian photo 30796-C.)

Figure 7.—Exhibit on medical history during the Greco-Roman period. (Smithsonian photo 30796-D.)

Figure 8.—Exhibit on remedies derived from drugs of vegetable origin, displayed about mid-1930’s. (Smithsonian photo 30439.)

In 1926, original patent models including those related to pharmacy, medicine, and dentistry, were transferred from the U.S. Patent Office to the National Museum. These patent models, together with other apothecary tools and the machines used in drug production took up most of the available space. This unfortunate situation led Dr. Whitebread to turn down significant medical and pharmaceutical collections offered the Museum between 1927 and 1930. Since the patent models were devised for inventions designed to simplify the practice of the health professions, three cases of these models were displayed in the medical gallery in the early 1930’s. Other exhibits shown during this decade included the deception of folk medicine with warnings against superstitions, and an exhibition on osteopathy, as well as dioramas on the manufacture of medicines and their use in scientific medical treatment.

In the meantime, Dr. Whitebread was an active contributor to the literature of the health field in various periodicals, as well as in pamphlets issued by the Museum and other governmental agencies (see bibliography). His literary contributions, guided by the exhibits he designed and the collections he acquired, were focused on the Division’s collections, such as primitive and psychic medicine and warnings against reliance on magic and superstitions in treatment, medical oddities, and the utilization of drugs of animal origin, both past and present.

Division of Medicine and Public Health (1939-1957)

After taking charge of the Division of Medicine in 1918, Dr. Whitebread gave special attention to public health displays. His activities in this area were accelerated after 1924 when the health exhibit at the Smithsonian Institution was inaugurated. As the exhibits in this field increased, the Division, in 1939, took the more comprehensive title of Division of Medicine and Public Health. Also, in 1939, Dr. Whitebread was promoted to the rank of associate curator.

Figure 9.—Exhibit on methods of treatment of diseases through mental impressions and psychic conditions as displayed about 1925. (Smithsonian photo 30796-B.)

Figure 10.—An exhibit on superstitions, empiricism, magic, and faith healing in the light of scientific medicine, completed in 1962, is in sharp contrast with that shown in figure 9.

He continued his efforts to collect more specimens of interest to medical history and to contribute to the literature. Among exhibited specimens in 1941 were a powder paper-crimping machine, a portable drug crusher, an odd device for spreading plaster on cloth, a pill-coating apparatus, various suppository molds, a lozenge cutter, and an ingenious Seidlitz powder machine. The derivation of medicinal drugs from animal, vegetable, and mineral sources was also depicted, as were synthetic materials and their intermediates. Basic prescription materials were displayed, and rows of glass-enclosed cases held samples of crude botanical drugs from almost every part of the globe with explanatory cards giving brief, concise descriptions. The exhibition provided medical and pharmaceutical students about to take state-board examinations, the opportunity to study the subject in detail, especially the enormous collection of materia medica samples. Also in 1941, Eli Lilly and Company donated an exhibit on the medical treatment of various types of anemia. In the same year, a diorama including a hypochlorinator for purification of water on a farm was installed in the gallery. In 1942, the first Emerson iron lung (developed in 1931 by John Haven Emerson) for artificial respiration was acquired by the Division. The Division acquired, in 1944, the first portable x-ray machine known to have been operated successfully on the battlefield, as well as other x-ray equipment and early medicine chests.

Figure 11.—Old public health exhibition installed in the gallery about 1924. (Smithsonian photo 19952.)

Figure 12.—The Hall of Health, reestablished and opened in November 1957. (Smithsonian photo 44931.)

Figure 13.—Early exhibit on homeopathy showing its history, methods and remedies which was installed about 1929. (Smithsonian photo 27049.)

Without a doubt, the most outstanding accession in the field of pharmaceutical history during Dr. Whitebread’s years of service was the acquisition of the E. R. Squibb and Sons old apothecary shop. Most of the baroque fixtures, including the stained-glass windows with Hessian-Nassau coats of arms and wrought-iron frames, were part of the mid-18th-century cathedral pharmacy “Münster Apotheke” in Freiburg im Breisgau, Germany. It was offered for sale in September 1930 by Dr. Jo Mayer of Wiesbaden, Germany, who was an enthusiastic collector of antiques, especially those related to the health professions. Earlier that year, a historian of pharmacy and chemistry, Fritz Ferchl of Mittenwald, Germany, had published a series of scholarly and informative articles on the Meyer collection in which the outstanding specimens were beautifully portrayed and thoroughly described (see bibliography).

As a result of Dr. Mayer’s efforts to sell his collection, the impact of Ferchl’s illustrated articles, and the uniqueness of the collection, E. R. Squibb and Sons purchased it in 1932 and brought it to the United States “with the thought that it would provide for American pharmacy, its teachers and students, a museum illuminating the history, growth, and development of pharmacy, its interesting background and struggle through the ages.” It was displayed at the Century of Progress exposition held in Chicago during 1933 and 1934; subsequently, it was assembled in the Squibb Building in New York City as a private museum where, for about 10 years, it was visited by many interested in pharmacy, ceramics, and art. Charles H. LaWall, who was originally engaged to prepare a descriptive catalog on the exhibit, gave it the title “The Squibb Ancient Pharmacy.”

Late in 1943, E. R. Squibb and Sons offered the collection as a gift to the American Pharmaceutical Association if the latter would provide museum space for it. The offer was accepted, but the Association finally found it difficult to spare the needed space for the collection and decided to take up the matter with the U.S. National Museum.

Figure 14.—This early exhibit on osteopathy was renovated several times prior to the early 1940’s. (Smithsonian photo 19250.)

At this point, it should be stated that since 1883 the members of the American Pharmaceutical Association have been keenly interested in having the National Museum serve as the custodian for all collected objects and records of historical interest to pharmacy. In 1944, the Association officially offered to deposit on permanent loan, the Squibb’s pharmacy collection in the Smithsonian Institution with the understanding that a suitable place would be provided for prompt and permanent display. The offer was accepted, and during April and May of 1945, the entire collection was transferred to the Smithsonian Institution, and construction to recreate the original two rooms for the old, 18th-century, European “Apotheke” was underway.

By August 1946, the exhibit was completed. In the large room where the pharmacist met his customers, the shelves were filled with 15th- to 19th-century, European pharmaceutical antiques. These included Renaissance mortars; 16th- and 17th-century nested weights; beautiful Italian, French, Swiss, and German majolica and faience drug jars; Dutch and English delft; drug containers made of flint or opal glass with fused-enamel labels with alchemical symbols; rare, 16th-century, wooden drug containers, each with the coat of arms of the city in which each was made; and two glass-topped, display tables contained franchises issued and signed by Popes or state rulers, medical edicts, dispensatories, herbals, pharmacopoeias, and pharmaceutical utensils.

On the walls in the small laboratory room, which also had been used as a workshop and a study, were a stuffed crocodile, shark’s head, tortoise, fish, and salamander, parts of which were utilized as remedial agents. Their presence provided tangible evidence that the pharmacy dispensed genuine drugs and not substitutes.

The pharmaceutical profession in this country hailed the outstanding exhibition, and the November 1946 issue of the Journal of the American Pharmaceutical Association, Practical Pharmacy Edition, devoted its front cover to depicting one corner of the study and laboratory room of the shop. Also, in a letter dated January 2, 1947, addressed to Dr. Alexander Wetmore, then Secretary of the Smithsonian Institution, Dr. Robert P. Fischelis, the secretary of the American Pharmaceutical Association, considered the completion of the deposited exhibition a triumph and “as one of the highlights of the accomplishments of the Association in 1946.”

From 1946 to 1948, the Division’s collection was further enriched with a number of historical specimens, among which was a “grosse Flamme” x-ray machine with induction-coil tube and stand developed by Albert B. Koett. It is one of the earliest American-made machines of its kind, producing a 12-inch spark, the largest usable at that time with 180,000-volt capacity, and a forerunner of later autotransformers. Other accessions included two 19th-century drug mills, an electric belt used in quackery, two medicine chests, three sets of Hessian crucibles used in a pioneer drugstore in Colorado, a drunkometer, mineral ores, and purely produced chemical elements.

Figure 15.—Late 16th-century, wooden drug container with coat-of-arms, in the Squibb collection. The inscription Ungula Alcis (the hoof of the elk) suggests a superstitious attitude in medical practice and the wide use of animal organs in medical treatment. (Courtesy of the American Pharmaceutical Association.)

Figure 16.—A Rare, Antwerp, 16th-century drug jar in the Squibb collection deposited by the American Pharmaceutical Association.

In the spring of 1948, Associate Curator Whitebread retired after 30 years of service with the U.S. National Museum. He was a pioneer in the field of health museums and during his curatorship had developed a moribund section into a Division of field-wide importance. Dr. Whitebread was succeeded by George S. Thomas, also a pharmacist, who served as associate curator from August 1948 until early 1952.

Figure 17.—The Apothecary Shop as seen in the Arts and Industries building (1946-1964). (Courtesy of the American Pharmaceutical Association.)

Figure 18.—View of the laboratory and study room of the apothecary shop. On the left, the German-Swiss bronze mortar and pestle (1686) sign and above it an 18th-century German painting on canvas of Christ, “the apothecary of the soul.” The drug containers represent “the fruits of the spirit,” faith, patience, charity, etc., and the scales represent justice. Underneath is the verse from Matthew, 11:28, “Come unto me, all ye that labour and are heavy laden, and I will give you rest.” (Courtesy of the American Pharmaceutical Association.)

During his almost-three and a half years of service, Thomas acquired hearing-aid appliances from which he designed an exhibit on the development of these aids, surgical sutures, early samples of Aureomycin, and a static-electricity machine made by Henkel about 1840. He also published three short articles under the title, “Now and Then,” in the National Capital Pharmacist (1950), no. 1, pp. 8-9; no. 2, pp. 18-19, 29; and no. 3, pp. 15-16. In early 1952, Dr. Arthur O. Morton presented to the Division, a Swiss-made keratometer which he had purchased in 1907, and it is believed to be one of the first used in the United States to measure the curves of the cornea.

The achievements of the Division reached their highest point, thus far, in significantly increasing the national collection, as well as in contributing to the scientific, historical, and professional literature, under the curatorships of George B. Griffenhagen (December 8, 1952, to June 27, 1959) and John B. Blake (July 1, 1957, to September 2, 1961). Their reorganization of exhibits and collections, their competence and industry, fulfilled the hopes, plans, and purposes laid down by earlier curators for the Division.

Immediately after assuming the responsibilities of the Division and throughout 1953, Mr. Griffenhagen (M.S. in pharmaceutical chemistry from the University of Southern California) undertook to develop the collections still further. He increased the emphasis not only on historical pharmacy, but also on medicine, surgery, and dentistry. He also renovated the exhibits in the medical gallery.

In 1954, several antibiotics were donated to the Division including a mold of Penicillium notatum prepared and presented to the Smithsonian Institution by Sir Alexander Fleming (1881-1955), the discoverer of penicillium (1929), and a few Petri dishes used by botanist Benjamin M. Daggar who, while working for Lederle Laboratories, developed Aureomycin (chlortetracycline) in 1948. The Forest D. Dodrill—G.M.R. mechanical heart (1952), the first machine reported to be used successfully for the complete bypass of one side of the human heart during a surgical operation, was presented to the Smithsonian Institution.

The following year, 1955, the Division acquired one of the earliest Einthoven string galvanometers (named after the Dutch physiologist Willem Einthoven, 1860-1927) made in the United States in 1914 by Charles F. Hindle for an electrocardiograph. Also added to the Division’s collections was the electrocardiograph used by Dr. Frank E. Wilson of the United States, a pioneer educator in this field. Two temporary exhibits on allergy and surgical dressings were installed in the gallery. In the same year, Curator Griffenhagen published Early American Pharmacies, a catalog on 28 pharmacy restorations in this country.

In 1956, among many publications of interest in the fields of medical and pharmaceutical history, was Curator Griffenhagen’s Pharmacy Museum, with a foreword by Laurence V. Coleman, who termed it a useful catalog and “a good reflection of the history of the museum movement at large.” A third x-ray tube of Wilhelm Konrad Roentgen (1845-1922) was added to the collection in 1957 as well as a complete set of hospital-ward fixtures of about 1900 from the Massachusetts General Hospital, rare patent medicines, 18th-century microscopes, and a 13th-century mortar and pestle made in Persia.

In 1957, Mr. Griffenhagen published a series of illustrated articles in the Journal of the American Pharmaceutical Association, Practical Pharmacy Edition, which were later reprinted by the Association in a booklet entitled, Tools of the Apothecary. In it, he described several pharmaceutical specimens in the collection and their place in history.

Division of Medical Sciences (1957 to Present)

The U.S. National Museum was reorganized on July 1, 1957, into two units, the Natural History Museum and the Museum of History and Technology. At the same time, and in view of the widening scope of the Division, its more scientifically based planning, and the constantly increasing collection with equal emphasis on all branches of the healing arts, the Division’s title was changed to the Division of Medical Sciences—the title it still bears in 1964. With the reorganization, the Department of Engineering and Industries, under which the Division fell administratively, was renamed the Department of Science and Technology of the Museum of History and Technology. It was also the first time since its establishment in 1881 that the Division had two curators, for on July 1, 1957, Dr. John B. Blake joined the staff.

Figure 19.—Curators John B. Blake and George Griffenhagen examine the newly acquired (1957) electromagnetic, Morton-Wimshurst-Holz Influence Machine. It was manufactured by the Bowen Company of Providence, Rhode Island (1889). With the discovery of x-ray, it was used for making x-ray photographs until early in the 20th century.

As a result of these changes, the Division was subdivided into a Section of Pharmaceutical History and Health and a Section of Medical and Dental History. The former was planned to encompass the collections of materia medica, pharmaceutical equipment, and all material related to the history of pharmacy, toxicology, pharmacology, and biochemistry, as well as the Hall of Health which was opened November 2, 1957, and which emphasizes man’s progressing knowledge of his body and the functions of its major organs. The latter Section was planned to include all that belongs to the development of surgery, medicine, dentistry, and nursing, especially in relation to hospitals.

In October 1957, the Division acquired a collection of rare, ceramic, drug jars which included two, 13th-century, North Syrian and Persian, albarello-shaped, majolica jars; a 15th-century, Hispano-Moresque drug container; and a 16th-century, Italian faience, dragon-spout ewer. During the following two years, Curator Griffenhagen periodically toured museums and medical and pharmaceutical institutions in this country, South America, and Europe gathering specimens and information for the Division and for publication, respectively. However, on June 27, 1959, he resigned his curatorship to join the staff of the American Pharmaceutical Association in Washington, D.C. Dr. Blake became the curator in charge of the Division and Mr. Griffenhagen was succeeded on September 24, 1959, by the author of this paper as associate curator in charge of the Section of Pharmaceutical History and Health.

Dr. Blake, as curator of the Section of Medical and Dental History, acquired a large number of valuable and varied specimens for the Division’s collections. They included optometric refracting instruments, an early 1920’s General Electric, portable, x-ray machine, the Charles A. Lindbergh and Alexis Carrel pump (designed in 1935 to perfuse life-sustaining fluids to the organs of the body), the Sewell heart pump (1950) to control delivery of air pressure and suction to the pumping mechanism, and a large and valuable collection of dental equipment formerly at the universities of Pennsylvania and Illinois. Dr. Blake wrote the explanatory material and supervised the design and production of the majority of exhibits in the renovated hall of medical and dental history. He also contributed several scholarly articles and a book (see bibliography) on the history of the healing arts and public health in particular. He resigned on September 2, 1961, to join the staff of the National Library of Medicine as chief of the History of Medicine Division, and was succeeded by the author as curator of the Division. From the summer of 1962 to April 1964, the Division benefited from the expert advice of Dr. Alfred R. Henderson as consultant in the preparation and designing of the surgical and medical exhibits of the Museum of History and Technology.

During the period from 1961 to May 1964, the Division’s collections expanded greatly through its medical, dental, and pharmaceutical acquisitions. Specimens of antiques acquired from 1961 through 1963 numbered up to 1,539 and included gifts from leading institutions and individual philanthropists. The scope of these gifts and acquisitions ranges from electronic resuscitators, microscopes, x-ray equipment, and spectacles, to patent medicines, amulets, apothecary tools, dental instruments, and office material of practitioners.

Figure 20.—Exhibit on spectacles, lorgnettes, optometers, and refraction, completed in 1960. It features a cross section of the Division’s large collection of eyeglasses. (Smithsonian photo 47943-D.)

In the last decade, the interest in the national endeavor for promoting research and scholarship in the history of medicine has increased greatly. It was most appropriate, therefore, for the Smithsonian Institution to play host on May 2 for two sessions of the 37th annual meeting of the American Association for the History of Medicine held in the Washington, D.C., area from April 30 through May 2, 1964. In welcoming the members to the morning session in the auditorium of the new Museum of History and Technology, Frank A. Taylor, director of the United States National Museum, expressed the feeling that the meeting of the Association was, in a sense, a dedication of the new auditorium and an opportunity for the Smithsonian to reaffirm its deep interest and commitment in fostering research and furthering the appreciation of scholarly endeavor in the history of the healing arts.

A New Dimension For the Healing Arts

“One day the United States will have a National Museum of science, engineering, and industry, as most large nations have.” This was the prediction made in 1946 by the director of the U.S. National Museum, Mr. Frank A. Taylor, then curator of the Division of Engineering. It was in 1963, that the new $36,000,000 building of the Museum of History and Technology was completed, and opened to the public in 1964. The offices of the Division of Medical Sciences as well as the reference and study collections were moved to the fifth floor of the new building. The exhibits, however, will be displayed in the gallery at the southwest corner of the first floor. These exhibits, it is hoped, will show a new dimension and an unprecedented approach in displaying the development of the healing arts throughout the ages and the instruments and equipment associated with health professions. They also present the expanding objectives and plans of the Division’s growth as an integral part of the Smithsonian Institution. Conveniently, the exhibits form four, closely connected halls in one large gallery which will be open to the public in the summers of 1965 to 1966.

Figure 21.—Exhibit on the development of blood-pressure instruments and the early 20th-century sphygmomanometers which was completed in 1960. (Smithsonian photo 47943-M.)

1. The Hall of Health displays models and graphic and historical exhibit materials to demonstrate the function of the various healthy organs of the human body. The main topics emphasized are: embryology and childbirth; tooth structure; the heart and blood circulation; respiration; the endocrine glands; kidneys and the urinary-excretory system; the brain and the nervous system; the ear; and vision and the use of eyeglasses.

The most appreciated exhibit of all in this Hall is the “transparent woman” figure which rotates, automatically, every 15 minutes with a recorded message describing the function of each major organ of the body at the same time that the organ is electronically lighted, so that the viewer can see its place in the body.

Figure 22.—Hearing-aid exhibit designed in 1962. It includes otologist Julius Lempert’s personal memorabilia and original surgical instruments used in the fenestration operation for restoring hearing. (Smithsonian photo 49345-C.)

2. The Hall of Medicine and Dentistry will depict the history of these two sciences with exhibits of the equipment used through the centuries. In the medical field, early trephining and other surgical instruments will be displayed along with a diorama of an 1805 surgical operation performed by Dr. Philip Syng Physick in the amphitheater of the Pennsylvania Hospital. Diagnostic instruments such as stethoscopes, endoscopes, speculums, and blood-pressure measuring devices will be exhibited with a series of microscopes illustrating the development of these instruments. Exhibits of original galvanometers and other apparatus will trace the development of cardiography. The early use of anesthesia will be shown by apparatus of William Morton and Crawford W. Long, American pioneers in this field. The development of the devices of modern medicine and surgery will be shown by exhibits of the iron lung and x-ray tubes, including a tube used by W. K. Roentgen. Medicine chests and surgical kits of different periods will graphically summarize the state of medical science in the period each represents.

Exhibits on the development of dentistry and dental surgery will display examples of tooth-filling and extracting tools, drilling apparatus from the early hand and foot engines to the first ultrasonic cutting instrument (1954), and the original contra-angle, hydraulic and air-turbine handpiece model which revolutionized the field of instrumentation for dental surgery (with speeds of 200,000 to 400,000 rpm). This hydraulic turbine of Dr. Robert J. Nelson and associates of the National Bureau of Standards set the design pattern for the remarkable and successful high-speed, air-turbine handpiece developed by Paul H. Tanner and Oscar P. Nagel of the U.S. Naval Dental School in 1956. Also underway is the reconstruction of the offices of famous dentists such as G. V. Black and the father of American orthodontia, Edward H. Angle, using their original equipment and instruments. In addition, an exhibit is planned to include x-ray tubes and the electric dental engine, the first to be operated in a human mouth by the pioneer dentist on dental skiagraphy, Charles E. Kells (1856-1928).

Figure 23.—Exhibit on nursing bottles and measures to promote child health to counteract the once-common diseases of childhood. This display was completed in 1962. (Smithsonian photo 49345-G.)

3. The Hall of Pharmaceutical History will feature exhibits on the reconstruction of two pharmacy shops: an 18th-century apothecary shop, originally from Germany, with a very elegant collection of drug jars, decorated medicinal bottles, balances, mortars and pestles, and other tools and documents pertaining to the apothecary art, and a late 19th-century American drugstore with shelves filled with patent medicines and drug containers of various sizes and shapes. The window will also feature symbols of pharmacy and beautiful show globes. Displays will show the development of antibiotics and the early tools used in the manufacture of the so-called “miracle drugs,” including a mold from Sir Alexander Fleming, the discoverer of penicillin. In addition, a platform will be reconstructed to display a variety of pharmaceutical apparatus used in the preparation and manufacture of drugs, such as tablet and capsule machines and drug mills and percolators. Recently, with the assistance of Professor Glenn Sonnedecker, the Division acquired a fine collection of pharmaceutical equipment and devices from the School of Pharmacy of the University of Wisconsin.

Figure 24.—The origins of drugs from the three natural kingdoms, drug synthesis, and the increase in the manufacture of vitamins. This display was completed in 1962 and is now on display at the Museum of History and Technology. (Smithsonian photo P6316.)

Since the Division houses the largest collection of materia medica in the country, a representative cross section of crude drugs will be displayed in alphabetical order as well as a display illustrating the role of cinchona and antimalarial drugs in the fight against disease. An exhibit will portray the “origin of drugs” from the three natural kingdoms, animal, vegetable, and mineral, together with synthetic drugs including the manufacture of vitamins.

Plans are being made for an elaborate exhibit of weights and balances used in many countries throughout the centuries, their impact on accuracy of dosage and weighing of drugs, and their use in the apothecary art.

The Division will also display pictorial and printed materials, as well as artifacts from all periods and all countries. These collections are intended to help in presenting a more complete picture of the story of the medical sciences for educational purposes and research, and to increase man’s knowledge in fighting disease and promoting health.

Thus, from a few hundred specimens of crude drugs in the Section of Materia Medica of 83 years ago, there has developed a Museum Division today which embraces the evolution of the health professions through the ages. This Division now has the largest collection in the Western Hemisphere of historical objects which are related to the healing arts. The reference collections are available to the researcher and scholar, and the exhibits are intended for pleasure and educational purposes in these fields. The plans for expansion have no limitation as we keep pace with man’s progress in the medical sciences and continue to collect materials that contributed to the historical development in the fight against diseases and the attempts to secure better health for everyone.

BIBLIOGRAPHY

The Annual report of the Board of Regents of the Smithsonian Institution from 1872 to date and the Proceedings of the United States National Museum from 1881 to date were used extensively as sources in this survey. In the latter, see in particular, the year 1881, pp. 545-546; 1882, pp. 1-2; and 1884, pp. 431-475.

Atkinson, William B. The physicians and surgeons of the United States. Philadelphia, 1878. [On Dr. Toner.]

Blake, John B. Dental history and the Smithsonian Institution. Journal of the American College of Dentists (1961), vol. 28, pp. 125-127.

—— Public health in the town of Boston, 1630-1822. Cambridge, Mass.: Harvard University Press, 1959.

[Braisted, William C.] The biography of Dr. Beyer. Page 94 in Dictionary of American medical biography, by Howard A. Kelly and Walter L. Burrage; New York: D. Appleton and Co., 1928.

Clark, Leila F. The library of the Smithsonian Institution. Science (1946), vol. 104, p. 143.

Coleman, Laurence Vail. The museum in America: A critical study. 3 vols. Baltimore: Waverly Press, 1939. [Printed for the American Association of Museums, Washington, D.C.] See vol. 1, pp. 3, 11-12, 32-33, 143-146, 222, 318; vol. 3, p. 471.

Daukes, S. H. The medical museum: modern developments, organization and technical methods based on a new system of visual teaching. London: Wellcome Foundation Ltd., 1929.

Dodrill, Forest D., and others. Pulmonary volvuloplasty under direct vision using the mechanical heart for a complete bypass of the right heart in a patient with congenital pulmonary stenosis. Journal of Thoracic Surgery (1953), vol. 26, pp. 584-595.

—— Temporary mechanical substitution for the left ventricle in man. Journal of the American Medical Association (1952), vol. 150, pp. 642-644.

Dunglison, Robley. A dictionary of medical science. Rev. ed. Pp. 629-630. Philadelphia: Lea, 1874.

Edwards, J. J., and Edwards, M. J. Medical museum technology. London: Oxford University Press, 1959. [See in particular, pp. 33-62, 142-159.]

Ferchl, Fritz. Die Mörser der Sammlung Jo Mayer—Wiesbaden; Libri rari et curiosi der Sammlung Dr. Jo Mayer—Wiesbaden; Bildnisse und Bilder der Sammlung Jo Mayer—Wiesbaden; Kuriositäten und Antiquitäten der Sammlung Jo Mayer—Wiesbaden; and Gläser, Majoliken und Faensen der Sammlung Jo Mayer—Wiesbaden. Pharmazeutische Zeitung (Berlin, 1930), vol. 75: January 4, no. 2, pp. 19-24; February 15, no. 14, pp. 219-223; March 8, no. 20, pp. 309-314; April 19, no. 32, pp. 487-489; and June 21, no. 50, pp. 735-740.

Flint, James M. Classification and arrangement of the materia medica collection. Proceedings of the United States National Museum (1881), vol. 4, app. no. 6.

—— Classification of the materia medica collection of the United States National Museum, and catalogue of specimens. Proceedings of the United States National Museum (1883), vol. 6, app. 19, pp. 431-475.

—— Directions for collecting information and objects illustrating the history of medicine. Part S of Bulletin of the United States National Museum (1905). No. 39.

—— Memoranda for collectors of drugs for the materia medica section of the National Museum. Proceedings of the United States National Museum (1881), vol. 4, app. 8.

Foley, Matthew O. Smithsonian Institution devotes much space to hospital exhibit. Hospital Management (April 1929), pp. 271-287.

Galdston, Iago. Research in the United States. Ciba Symposia (June-July 1946), vol. 8, nos. 3 and 4, p. 366.

Garrison, Fielding H. An introduction to the history of medicine. 2d ed. p. 38. Philadelphia: Saunders, 1917.

Gebhard, Bruno. From medicine show to health museum. Ciba Symposia (March 1947), vol. 8, no. 12, p. 579.

Goode, George Brown. The Smithsonian Institution (1846-1896): The history of its first half century. Pp. 325-329, 362-363. Washington, 1897.

Griffenhagen, George. Pharmacy museums. Madison, Wis.: American Institute of the History of Pharmacy, 1956.

—— and Hughes, Calvin H. The history of the mechanical heart. Annual report of the Board of Regents of the Smithsonian Institution for the year ended June 30, 1955 (Washington, 1956), pp. 339-356.

Hamarneh, Sami. At the Smithsonian … exhibits on pharmaceutical dosage forms. Journal of the American Pharmaceutical Association (1962), new ser., vol. 2, pp. 478-479.

—— For the collector, facts and artifacts. Pharmacy in History (1961), vol. 6, p. 48.

—— Historical and educational exhibits on dentistry at the Smithsonian Institution. Journal of the American-Dental Association (July 1962), vol. 65, pp. 111-114.

—— New dental exhibits at the Smithsonian Institution. Journal of the American Dental Association (May 1963), vol. 66, pp. 676-678.

Haynes, William. Out of alchemy into chemistry. The Scientific Monthly (November 1952), vol. 75, p. 268.

Holt, L. Emmett. A sketch of the development of the Rockefeller Institute for Medical Research. Science (July 6, 1906), new ser., vol. 24, no. 601, p. 1.

Howell, William H. The American Physiological Society during its first twenty-five years. Pp. 21-22 [biography of Dr. Beyer] in History of the American Physiological Society semicentennial, 1881-1937; Baltimore, 1938.

[Klein, Allen.] He directs pharmacy exhibits at the Smithsonian Institution. Modern Pharmacy (July 1941), vol. 25, pp. 20-21.

LaWall, Charles H. Ancient pharmacy on display. Pacific Drug Review (1933), vol. 45, p. 18.

—— The curious lore of drugs and medicines. Garden City, N.Y.: Garden City Publishing Co., Inc., 1927. [See p. 453 on Division of Medical Sciences’ collection.]

Lewton, Frederick L. A national pharmaceutical collection. Journal of the American Pharmaceutical Association (1919), vol. 8, pp. 45-46.

—— The opportunity for developing historical pharmacy collections at the National Museum. Journal of the American Pharmaceutical Association (1917), vol. 6, pp. 259-262.

Long, Esmond R. The Army Medical Museum. Military Medicine (May 1963), vol. 128, pp. 367-369.

Monell, S. H. “Dental Skiagraphy” (pp. 313-336 in A system in x-ray methods and medical uses of light hot-air, vibration and high-frequency currents by Monell; New York: Pelton, 1902).

Murray, David. Museums, their history and their use. Glasgow: MacLehose, 1904. [See vol. 1, pp. 13-77.]

Nelson, Robert J.; Pelander, Carl E.; and Kumpula, John W. Hydraulic turbine, contra-angle handpiece. Journal of the American Dental Association (September 1953), vol. 47, pp. 324-329.

Official Catalogue of the Cotton States and International Exposition: Atlanta, Georgia, September 18 to December 31, 1895. Atlanta: Claflin and Mellichamp, 1895. [See p. 204.]

Packard, Frances R. History of medicine in the United States. New York, 1931. [See vol. 1, pp. 5-6, 37-51, 168-176, 602-607 on Dr. Toner.]

Pickard, Madge E. Government and science in the United States: Historical background. Journal of the History of Medicine and Allied Sciences (1946), vol. 1, nos. 2 and 3, pp. 265-266, 289, 446-447, 478.

Purtle, Helen R. Notes on the Medical Museum of the Armed Forces Institute of Pathology. Bulletin of the Medical Library Association (1956), vol. 44, no. 3, pp. 300-305.

Rathbun, Richard. A descriptive account of the building recently erected for the Departments of Natural History of the United States National Museum. (U.S. National Museum Bulletin 80.) Washington, 1913. [See pp. 7-15.]

Rhees, William J. The Smithsonian Institution; documents relative to its origin and history, 1835-1899. 2 vols. (Smithsonian Miscellaneous Collections: vol. 42, 1835-1881; vol. 43, 1881-1899.) Washington, 1901.

Shufeldt, R. W. Suggestions for a national museum of medicine. Medical Record (March 22, 1919), pp. 4-5. [Also reprinted, 1919, by William Wood and Co., New York.]

Sigerist, Henry E. Primitive and archaic medicine. (Vol. 1 of A history of medicine, by Sigerist.) New York: Oxford University Press, 1951. [See pp. 525-531.]

Silver, Edwin H. Description of the exhibit on conservation of vision placed in the United States Museum at Washington, D.C. The Optical Journal and Review of Optometry (February 3, 1927), vol. 59, no. 5, pp. 39-40.

[Sonnedecker, Glenn.] Apothecary shop nears completion. Journal of the American Pharmaceutical Association, Practical Pharmacy Edition (1946), vol. 7, pp. 157.

—— Dr. Charles Whitebread, pharmacist and museum curator. Journal of the American Pharmaceutical Association, Practical Pharmacy Edition (1946), vol. 7, p. 203.

—— Old apothecary shop. Journal of the American Pharmaceutical Association, Practical Pharmacy Edition (1945), vol. 6, pp. 184-187.

—— Old apothecary shop opened. Journal of the American Pharmaceutical Association, Practical Pharmacy Edition (1946), vol. 7, p. 427.

Taylor, Frank A. A national museum of science, engineering and industry. The Scientific Monthly (1946), vol. 63, pp. 359.

—— The background of the Smithsonian’s Museum of Engineering and Industries. Science (1946), vol. 104, no. 2693, pp. 130-132.

Toner Lectures:

1. J. J. Woodward. On the structure of cancerous tumors and the mode in which adjacent parts are invaded. No. 266 in Smithsonian Miscellaneous Collections, vol. 15; Washington, 1878. [Lecture given on March 28, 1873.]

2. C. E. Brown-Séquard. Dual character of the brain. No. 291 in Smithsonian Miscellaneous Collections, vol. 15; Washington, 1878. [Lecture given on April 22, 1874.]

3. J. M. Da Costa. On strain and over-action of the heart. No. 279 in Smithsonian Miscellaneous Collections, vol. 15; Washington, 1878. [Lecture given on May 14, 1874.]

4. H. C. Wood. A study of the nature and mechanism of fever. No. 282 in Smithsonian Miscellaneous Collections, vol. 15; Washington, 1878. [Lecture given on January 20, 1875.]

5. William W. Keen. On the surgical complications and sequels of the continued fevers. No. 300 in Smithsonian Miscellaneous Collections, vol. 15; Washington, 1878. [Lecture given on February 17, 1876.]

6. William Adams. Subcutaneous surgery: Its principles, and its recent extension in practice. No. 302 in Smithsonian Miscellaneous Collections, vol. 15; Washington, 1878. [Lecture given on September 13, 1876.]

7. Edward O. Shakespeare. The nature of reparatory inflammation in arteries after ligatures, acupressure, and torsion. No. 321 in Smithsonian Miscellaneous Collections, vol. 16; Washington, 1880. [Lecture given on June 27, 1878.]

8. George E. Waring. Suggestions for the sanitary drainage of Washington City. No. 349 in Smithsonian Miscellaneous Collections, vol. 26; Washington, 1883. [Lecture given on May 26, 1880.]

9. Charles K. Mills. Mental over-work and premature disease among public and professional men. No. 594 in Smithsonian Miscellaneous Collections, vol. 34; Washington, 1893. [Lecture given on March 19, 1884.]

10. Harrison Allen. A clinical study of the skull. No. 708 in Smithsonian Miscellaneous Collections, vol. 34; Washington, 1893. [Lecture given on May 29, 1889.]

True, Webster P. The Smithsonian Institution. (Vol. 1 of the Smithsonian Scientific Series.) Washington, 1929.

Urdang, George, and Nitardy, F. W. The Squibb ancient pharmacy. New York, 1940. [Out of print, but remaining catalogs were given to the Division of Medicine to “be reserved for pharmaceutical educators, foreign dignitaries, pharmacists of national and international reputation, and pharmaceutical historians,” according to a letter from Mr. Nitardy in 1945.]

Whitebread, Charles. Animal pharmaceuticals of the past and present. Journal of the American Pharmaceutical Association (1933), vol. 22, pp. 431-437.

—— An old apothecary shop of 1750. National Capital Pharmacist (September 1946), vol. 8, pp. 11-13, 35.

—— Early American pharmaceutical inventions. Journal of the American Pharmaceutical Association (1937), vol. 26, pp. 918-928.

—— Handbook of the health exhibits of the United States National Museum. Baltimore: Lord Baltimore Press [1924].

—— Health superstitions. Journal of the American Pharmaceutical Association, Practical Pharmacy Edition (1942), vol. 3, pp. 268-274.

—— Medicine making as depicted by museum dioramas. Journal of the American Pharmaceutical Association (January 1936), vol. 25, pp. 40-46.

—— Superstition, credulity and skepticism. Journal of the American Pharmaceutical Association (1933), vol. 22, pp. 1140-1145.

—— The Indian medical exhibit of the Division of Medicine in the United States National Museum. Article 10 in vol. 67 of Proceedings of the U.S. National Museum; Washington, 1926.

—— The magic, psychic, ancient Egyptian, Greek, and Roman medical collections of the Division of Medicine in the United States National Museum. Article 15 in vol. 65 of Proceedings of the U.S. National Museum; Washington, 1925.

—— The odd origin of medical discoveries. Journal of the American Pharmaceutical Association, Practical Pharmacy Edition (1943), vol. 4, p. 321.

—— The United States National Museum pharmaceutical collection, its aims, problems, and accomplishments. Journal of the American Pharmaceutical Association (1930), vol. 19, pp. 1125-1126.

Winters, S. R. Magic medicine. Hygeia (July 1937), vol. 15, pp. 630-633.

P. ‘the basis of scientific, historical’—was ‘the bases of scientific, historical’

Contributions from
The Museum of History and Technology:
Paper 44

Development of Gravity Pendulums in the 19th Century

Victor F. Lenzen and Robert P. Multhauf

GALILEO, HUYGENS, AND NEWTON

FIGURE OF THE EARTH

EARLY TYPES OF PENDULUMS

KATER’S CONVERTIBLE AND INVARIABLE PENDULUMS

REPSOLD-BESSEL REVERSIBLE PENDULUM

PEIRCE AND DEFFORGES INVARIABLE, REVERSIBLE PENDULUMS

VON STERNECK AND MENDENHALL PENDULUMS

ABSOLUTE VALUE OF GRAVITY AT POTSDAM

APPLICATION OF GRAVITY SURVEYS

SUMMARY

Victor F. Lenzen and
Robert P. Multhauf

DEVELOPMENT OF GRAVITY PENDULUMS
IN THE 19th CENTURY

Figure 1.—A study of the figure of the earth was one of the earliest projects of the French Academy of Sciences. In order to test the effect of the earth’s rotation on its gravitational force, the Academy in 1672 sent Jean Richer to the equatorial island of Cayenne to compare the rate of a clock which was known to have kept accurate time in Paris. Richer found that the clock lost 2 minutes and 28 seconds at Cayenne, indicating a substantial decrease in the force of gravity on the pendulum. Subsequent pendulum experiments revealed that the period of a pendulum varied not only with the latitude but also regionally, under the influence of topographical features such as mountains. It became clear that the measurement of gravity should be made a part of the work of the geodetic surveyor.

The history of gravity pendulums dates back to the time of Galileo. After the discovery of the variation of the force of gravity over the surface of the earth, gravity measurement became a major concern of physics and geodesy. This article traces the history of the development of instruments for this purpose.

THE AUTHORS: Victor F. Lenzen is Professor of Physics, Emeritus, at the University of California at Berkeley and Robert P. Multhauf is Chairman of the Department of Science and Technology in the Smithsonian Institution’s Museum of History and Technology.

The intensity of gravity, or the acceleration of a freely falling body, is an important physical quantity for the several physical sciences. The intensity of gravity determines the weight of a standard pound or kilogram as a standard or unit of force. In physical experiments, the force on a body may be measured by determining the weight of a known mass which serves to establish equilibrium against it. Thus, in the absolute determination of the ampere with a current balance, the force between two coils carrying current is balanced by the earth’s gravitational force upon a body of determinable mass. The intensity of gravity enters into determinations of the size of the earth from the angular velocity of the moon, its distance from the earth, and Newton’s inverse square law of gravitation and the laws of motion. Prediction of the motion of an artificial satellite requires an accurate knowledge of gravity for this astronomical problem.

The gravity field of the earth also provides data for a determination of the figure of the earth, or geoid, but for this problem of geodesy relative values of gravity are sufficient. If g is the intensity of gravity at some reference station, and Δg is the difference between intensities at two stations, the values of gravity in geodetic calculations enter as ratios (Δg)/g over the surface of the earth. Gravimetric investigations in conjunction with other forms of geophysical investigation, such as seismology, furnish data to test hypotheses concerning the internal structure of the earth.

Whether the intensity of gravity is sought in absolute or relative measure, the most widely used instrument for its determination since the creation of classical mechanics has been the pendulum. In recent decades, there have been invented gravity meters based upon the principle of the spring, and these instruments have made possible the rapid determination of relative values of gravity to a high degree of accuracy. The gravity meter, however, must be calibrated at stations where the absolute value of gravity has been determined by other means if absolute values are sought. For absolute determinations of gravity, the pendulum historically has been the principal instrument employed. Although alternative methods of determining absolute values of gravity are now in use, the pendulum retains its value for absolute determinations, and even retains it for relative determinations, as is exemplified by the Cambridge Pendulum Apparatus and that of the Dominion Observatory at Ottawa, Ontario.

The pendulums employed for absolute or relative determinations of gravity have been of two basic types. The first form of pendulum used as a physical instrument consisted of a weight suspended by a fiber, cord, or fine wire, the upper end of which was attached to a fixed support. Such a pendulum may be called a “simple” pendulum; the enclosure of the word simple by quotation marks is to indicate that such a pendulum is an approximation to a simple, or mathematical pendulum, a conceptual object which consists of a mass-point suspended by a weightless inextensible cord. If l is the length of the simple pendulum, the time of swing (half-period in the sense of physics) for vibrations of infinitely small amplitude, as derived from Newton’s laws of motion and the hypothesis that weight is proportional to mass, is T = π√(l/g).

The second form of pendulum is the compound, or physical, pendulum. It consists of an extended solid body which vibrates about a fixed axis under the action of the weight of the body. A compound pendulum may be constituted to oscillate about one axis only, in which case it is nonreversible and applicable only for relative measurements. Or a compound pendulum may be constituted to oscillate about two axes, in which case it is reversible (or “convertible”) and may be used to determine absolute values of gravity. Capt. Henry Kater, F.R.S., during the years 1817-1818 was the first to design, construct, and use a compound pendulum for the absolute determination of gravity. He constructed a convertible pendulum with two knife edges and with it determined the absolute value of gravity at the house of Henry Browne, F.R.S., in Portland Place, London. He then constructed a similar compound pendulum with only one knife edge, and swung it to determine relative values of gravity at a number of stations in the British Isles. The 19th century witnessed the development of the theory and practice of observations with pendulums for the determination of absolute and relative values of gravity.

Galileo, Huygens, and Newton

The pendulum has been both an objective and an instrument of physical investigation since the foundations of classical mechanics were fashioned in the 17th century. It is tradition that the youthful Galileo discovered that the period of oscillation of a pendulum is constant by observations of the swings of the great lamp suspended from the ceiling in the cathedral of Pisa. The lamp was only a rough approximation to a simple pendulum, but Galileo later performed more accurate experiments with a “simple” pendulum which consisted of a heavy ball suspended by a cord. In an experiment designed to confirm his laws of falling bodies, Galileo lifted the ball to the level of a given altitude and released it. The ball ascended to the same level on the other side of the vertical equilibrium position and thereby confirmed a prediction from the laws. Galileo also discovered that the period of vibration of a “simple” pendulum varies as the square root of its length, a result which is expressed by the formula for the time of swing of the ideal simple pendulum. He also used a pendulum to measure lapse of time, and he designed a pendulum clock. Galileo’s experimental results are important historically, but have required correction in the light of subsequent measurements of greater precision.

Mersenne in 1644 made the first determination of the length of the seconds pendulum, that is, the length of a simple pendulum that beats seconds (half-period in the sense of physics). Subsequently, he proposed the problem to determine the length of the simple pendulum equivalent in period to a given compound pendulum. This problem was solved by Huygens, who in his famous work Horologium oscillatorium … (1673) set forth the theory of the compound pendulum.

Huygens derived a theorem which has provided the basis for the employment of the reversible compound pendulum for the absolute determination of the intensity of gravity. The theorem is that a given compound pendulum possesses conjugate points on opposite sides of the center of gravity; about these points, the periods of oscillation are the same. For each of these points as center of suspension the other point is the center of oscillation, and the distance between them is the length of the equivalent simple pendulum. Earlier, in 1657, Huygens independently had invented and patented the pendulum clock, which rapidly came into use for the measurement of time. Huygens also created the theory of centripetal force which made it possible to calculate the effect of the rotation of the earth upon the observed value of gravity.

The theory of the gravity field of the earth was founded upon the laws of motion and the law of gravitation by Isaac Newton in his famous Principia (1687). It follows from the Newtonian theory of gravitation that the acceleration of gravity as determined on the surface of the earth is the resultant of two factors: the principal factor is the gravitational attraction of the earth upon bodies, and the subsidiary factor is the effect of the rotation of the earth. A body at rest on the surface of the earth requires some of the gravitational attraction for the centripetal acceleration of the body as it is carried in a circle with constant speed by the rotation of the earth about its axis. If the rotating earth is used as a frame of reference, the effect of the rotation is expressed as a centrifugal force which acts to diminish the observed intensity of gravity.

Glossary of Gravity Terminology

ABSOLUTE GRAVITY: the value of the acceleration of gravity, also expressed by the length of the seconds pendulum.

RELATIVE GRAVITY: the value of the acceleration of gravity relative to the value at some standard point.

SIMPLE PENDULUM: see theoretical pendulum.

THEORETICAL PENDULUM: a heavy bob (point-mass) at the end of a weightless rod.

SECONDS PENDULUM: a theoretical or simple pendulum of such length that its time of swing (half-period) is one second. (This length is about one meter.)

GRAVITY PENDULUM: a precisely made pendulum used for the measurement of gravity.

COMPOUND PENDULUM: a pendulum in which the supporting rod is not weightless; in other words, any actual pendulum.

CONVERTIBLE PENDULUM: a compound pendulum having knife edges at different distances from the center of gravity. Huygens demonstrated (1673) that if such a pendulum were to swing with equal periods from either knife edge, the distance between those knife edges would be equal to the length of a theoretical or simple pendulum of the same period.

REVERSIBLE PENDULUM: a convertible pendulum which is also symmetrical in form.

INVARIABLE PENDULUM: a compound pendulum with only one knife edge, used for relative measurement of gravity.

From Newton’s laws of motion and the hypothesis that weight is proportional to mass, the formula for the half-period of a simple pendulum is given by T = π√(l/g). If a simple pendulum beats seconds, 1 = π√(λ/g), where λ is the length of the seconds pendulum. From T = π√(l/g) and 1 = π√(λ/g), it follows that λ = l/T. Then g = πλ. Thus, the intensity of gravity can be expressed in terms of the length of the seconds pendulum, as well as by the acceleration of a freely falling body. During the 19th century, gravity usually was expressed in terms of the length of the seconds pendulum, but present practice is to express gravity in terms of g, for which the unit is the gal, or one centimeter per second per second.

Figure 2.—This drawing, from Richer’s Observations astronomiques et physiques faites en l’isle de Caïenne (Paris, 1679), shows most of the astronomical instruments used by Richer, namely, one of the two pendulum clocks made by Thuret, the 20-foot and the 5-foot telescopes and the large quadrant. The figure may be intended as a portrait of Richer. This drawing was done by Sebastian Le Clerc, a young illustrator who made many illustrations of the early work of the Paris Academy.

Figure of the Earth

A principal contribution of the pendulum as a physical instrument has been the determination of the figure of the earth. That the earth is spherical in form was accepted doctrine among the ancient Greeks. Pythagoras is said to have been the first to describe the earth as a sphere, and this view was adopted by Eudoxus and Aristotle.

The Alexandrian scientist Eratosthenes made the first estimate of the diameter and circumference of a supposedly spherical earth by an astronomical-geodetic method. He measured the angle between the directions of the rays of the sun at Alexandria and Syene (Aswan), Egypt, and estimated the distance between these places from the length of time required by a caravan of camels to travel between them. From the central angle corresponding to the arc on the surface, he calculated the radius and hence the circumference of the earth. A second measurement was undertaken by Posidonius, who measured the altitudes of stars at Alexandria and Rhodes and estimated the distance between them from the time required to sail from one place to the other.

With the decline of classical antiquity, the doctrine of the spherical shape of the earth was lost, and only one investigation, that by the Arabs under Calif Al-Mamun in A.D. 827, is recorded until the 16th century. In 1525, the French mathematician Fernel measured the length of a degree of latitude between Paris and Amiens by the revolutions of the wheels of his carriage, the circumference of which he had determined. In England, Norwood in 1635 measured the length of an arc between London and York with a chain. An important forward step in geodesy was the measurement of distance by triangulation, first by Tycho Brahe, in Denmark, and later, in 1615, by Willebrord Snell, in Holland.

Of historic importance, was the use of telescopes in the triangulation for the measurement of a degree of arc by the Abbé Jean Picard in 1669. He had been commissioned by the newly established Academy of Sciences to measure an arc corresponding to an angle of 1°, 22′, 55″ of the meridian between Amiens and Malvoisine, near Paris. Picard proposed to the Academy the measurement of the meridian of Paris through all of France, and this project was supported by Colbert, who obtained the approval of the King. In 1684, Giovanni-Domenico Cassini and De la Hire commenced a trigonometrical measure of an arc south of Paris; subsequently, Jacques Cassini, the son of Giovanni-Domenico, added the arc to the north of Paris. The project was completed in 1718. The length of a degree of arc south of Paris was found to be greater than the length north of Paris. From the difference, 57,097 toises minus 56,960 toises, it was concluded that the polar diameter of the earth is larger than the equatorial diameter, i.e., that the earth is a prolate spheroid (fig. 3).

Figure 3.—Measurements of the length of a degree of latitude which were completed in different parts of France in 1669 and 1718 gave differing results which suggested that the shape of the earth is not a sphere but a prolate spheroid (1). But Richer’s pendulum observation of 1672, as explained by Huygens and Newton, indicated that its shape is that of an oblate spheroid (2). The disagreement is reflected in this drawing. In the 1730’s it was resolved in favor of the latter view by two French geodetic expeditions for the measurement of degrees of latitude in the equatorial and polar regions (Ecuador—then part of Peru—and Lapland).

Meanwhile, Richer in 1672 had been sent to Cayenne, French Guiana, to make astronomical observations and to measure the length of the seconds pendulum. He took with him a pendulum clock which had been adjusted to keep accurate time in Paris. At Cayenne, however, Richer found that the clock was retarded by 2 minutes and 28 seconds per day (fig. 1). He also fitted up a “simple” pendulum to vibrate in seconds and measured the length of this seconds pendulum several times every week for 10 months. Upon his return to Paris, he found that the length of the “simple” pendulum which beat seconds at Cayenne was 1/4 Paris lines shorter than the length of the seconds pendulum at Paris. Huygens explained the reduction in the length of the seconds pendulum—and, therefore, the lesser intensity of gravity at the equator with respect to the value at Paris—in terms of his theory of centripetal force as applied to the rotation of the earth and pendulum.

A more complete theory was given by Newton in the Principia. Newton showed that if the earth is assumed to be a homogeneous, mutually gravitating fluid globe, its rotation will result in a bulging at the equator. The earth will then have the form of an oblate spheroid, and the intensity of gravity as a form of universal gravitation will vary with position on the surface of the earth. Newton took into account gravitational attraction and centrifugal action, and he calculated the ratio of the axes of the spheroid to be 230:229. He calculated and prepared a table of the lengths of a degree of latitude and of the seconds pendulum for every 5° of latitude from the equator to the pole. A discrepancy between his predicted length of the seconds pendulum at the equator and Richer’s measured length was explained by Newton in terms of the expansion of the scale with higher temperatures near the equator.

Newton’s theory that the earth is an oblate spheroid was confirmed by the measurements of Richer, but was rejected by the Paris Academy of Sciences, for it contradicted the results of the Cassinis, father and son, whose measurements of arcs to the south and north of Paris had led to the conclusion that the earth is a prolate spheroid. Thus, a controversy arose between the English scientists and the Paris Academy. The conflict was finally resolved by the results of expeditions sent by the Academy to Peru and Sweden. The first expedition, under Bouguer, La Condamine, and Godin in 1735, went to a region in Peru, and, with the help of the Spaniard Ullo, measured a meridian arc of about 3°7′ near Quito, now in Ecuador. The second expedition, with Maupertuis and Clairaut in 1736, went to Lapland within the Arctic Circle and measured an arc of about 1° in length. The northern arc of 1° was found to be longer than the Peruvian arc of 1°, and thus it was confirmed that the earth is an oblate spheroid, that is, flattened at the poles, as predicted by the theory of Newton.

Figure 4.—The direct use of a clock to measure the force of gravity was found to be limited in accuracy by the necessary mechanical connection of the pendulum to the clock, and by the unavoidable difference between the characteristics of a clock pendulum and those of a theoretical (usually called “simple”) pendulum, in which the mass is concentrated in the bob, and the supporting rod is weightless.

After 1735, the clock was used only to time the swing of a detached pendulum, by the method of “coincidences.” In this method, invented by J. J. Mairan, the length of the detached pendulum is first accurately measured, and the clock is corrected by astronomical observation. The detached pendulum is then swung before the clock pendulum as shown here. The two pendulums swing more or less out of phase, coming into coincidence each time one has gained a vibration. By counting the number of coincidences over several hours, the period of the detached pendulum can be very accurately determined. The length and period of the detached pendulum are the data required for the calculation of the force of gravity.

The period from Eratosthenes to Picard has been called the spherical era of geodesy; the period from Picard to the end of the 19th century has been called the ellipsoidal period. During the latter period the earth was conceived to be an ellipsoid, and the determination of its ellipticity, that is, the difference of equatorial radius and polar radius divided by the equatorial radius, became an important geodetic problem. A significant contribution to the solution of this problem was made by determinations of gravity by the pendulum.

An epoch-making work during the ellipsoidal era of geodesy was Clairaut’s treatise, Théorie de la figure de la terre. On the hypothesis that the earth is a spheroid of equilibrium, that is, such that a layer of water would spread all over it, and that the internal density varies so that layers of equal density are coaxial spheroids, Clairaut derived a historic theorem: If γE, γP are the values of gravity at the equator and pole, respectively, and c the centrifugal force at the equator divided by γE, then the ellipticity α = (/2)c - (γP - γE)/γE.

Laplace showed that the surfaces of equal density might have any nearly spherical form, and Stokes showed that it is unnecessary to assume any law of density as long as the external surface is a spheroid of equilibrium. It follows from Clairaut’s theorem that if the earth is an oblate spheroid, its ellipticity can be determined from relative values of gravity and the absolute value at the equator involved in c. Observations with nonreversible, invariable compound pendulums have contributed to the application of Clairaut’s theorem in its original and contemporary extended form for the determination of the figure and gravity field of the earth.

Early Types of Pendulums

The pendulum employed in observations of gravity prior to the 19th century usually consisted of a small weight suspended by a filament (figs. -). The pioneer experimenters with “simple” pendulums changed the length of the suspension until the pendulum beat seconds. Picard in 1669 determined the length of the seconds pendulum at Paris with a “simple” pendulum which consisted of a copper ball an inch in diameter suspended by a fiber of pite from jaws (pite was a preparation of the leaf of a species of aloe and was not affected appreciably by moisture).

A celebrated set of experiments with a “simple” pendulum was conducted by Bouguer in 1737 in the Andes, as part of the expedition to measure the Peruvian arc. The bob of the pendulum was a double truncated cone, and the length was measured from the jaw suspension to the center of oscillation of the thread and bob. Bouguer allowed for change of length of his measuring rod with temperature and also for the buoyancy of the air. He determined the time of swing by an elementary form of the method of coincidences. The thread of the pendulum was swung in front of a scale and Bouguer observed how long it took the pendulum to lose a number of vibrations on the seconds clock. For this purpose, he noted the time when the beat of the clock was heard and, simultaneously, the thread moved past the center of the scale. A historic aspect of Bouguer’s method was that he employed an “invariable” pendulum, that is, the length was maintained the same at the various stations of observation, a procedure that has been described as having been invented by Bouguer.

Since T = π√(l/g), it follows that T1/T2 = g2/g1. Thus, if the absolute value of gravity is known at one station, the value at any other station can be determined from the ratio of the squares of times of swing of an invariable pendulum at the two stations. From the above equation, if T1 is the time of swing at a station where the intensity of gravity is g, and T2 is the time at a station where the intensity is g + Δg, then (Δg)/g = (T1/T2) - 1.

Bouguer’s investigations with his invariable pendulum yielded methods for the determination of the internal structure of the earth. On the Peruvian expedition, he determined the length of the seconds pendulum at three stations, including one at Quito, at varying distances above sea level. If values of gravity at stations of different elevation are to be compared, they must be reduced to the same level, usually to sea level. Since gravity decreases with height above sea level in accordance with the law of gravitation, a free-air reduction must be applied to values of gravity determined above the level of the sea. Bouguer originated the additional reduction for the increase in gravity on a mountain or plateau caused by the attraction of the matter in a plate. From the relative values of gravity at elevated stations in Peru and at sea level, Bouguer calculated that the mean density of the earth was 4.7 times greater than that of the cordilleras. For greater accuracy in the study of the internal structure of the earth, in the 19th century the Bouguer plate reduction came to be supplemented by corrections for irregularities of terrain and by different types of isostatic reduction.

La Condamine, who like Bouguer was a member of the Peruvian expedition, conducted his own pendulum experiments (fig. 4). He experimented in 1735 at Santo Domingo en route to South America, then at various stations in South America, and again at Paris upon his return to France. His pendulum consisted of a copper ball suspended by a thread of pite. For experimentation the length initially was about 12 feet, and the time of swing 2 seconds, but then the length was reduced to about 3 feet with time of swing 1 second. Earlier, when it was believed that gravity was constant over the earth, Picard and others had proposed that the length of the seconds pendulum be chosen as the standard. La Condamine in 1747 revived the proposal in the form that the length of the seconds pendulum at the equator be adopted as the standard of length. Subsequently, he investigated the expansion of a toise of iron from the variation in the period of his pendulum. In 1755, he observed the pendulum at Rome with Boscovich. La Condamine’s pendulum was used by other observers and finally was lost at sea on an expedition around the world. The knowledge of the pendulum acquired by the end of the 18th century was summarized in 1785 in a memoir by Boscovich.

Figure 5.—An apparatus for the practice measurement of the length of the pendulum devised on the basis of a series of preliminary experiments by C. M. de la Condamine who, in the course of the French geodetic expedition to Peru in 1735, devoted a 3-month sojourn on the island of Santo Domingo to pendulum observations by Mairan’s Method. In this arrangement, shown here, a vertical rod of ironwood is used both as the scale and as the support for the apparatus, having at its top the brass pendulum support (A) and, below, a horizontal mirror (O) which serves to align the apparatus vertically through visual observation of the reflection of the pointer projecting from A. The pendulum, about 37 inches long, consists of a thread of pite (a humidity-resistant, natural fiber) and a copper ball of about 6 ounces. Its exact length is determined by adjusting the micrometer (S) so that the ball nearly touches the mirror. It will be noted that the clock pendulum would be obscured by the scale. La Condamine seems to have determined the times of coincidence by visual observation of the occasions on which “the pendulums swing parallel.” (Portion of plate 1, Mémoires publiés par la Société française de Physique, vol. 4.)

Figure 6.—The result of early pendulum experiments was often expressed in terms of the length of a pendulum which would have a period of one second and was called “the seconds pendulum.” In 1792, J. C. Borda and J. D. Cassini determined the length of the seconds pendulum at Paris with this apparatus. The pendulum consists of a platinum ball about 1/2 inches in diameter, suspended by a fine iron wire. The length, about 12 feet, was such that its period would be nearly twice as long as that of the pendulum of the clock (A). The interval between coincidences was determined by observing, through the telescope at the left, the times when the two pendulums emerge together from behind the screen (M). The exact length of the pendulum was measured by a platinum scale (not shown) equipped with a vernier and an auxiliary copper scale for temperature correction.

When, at the end of the 18th century, the French revolutionary government established the metric system of weights and measures, the length of the seconds pendulum at Paris was considered, but not adopted, as the unit of length. (Plate 2, Mémoires publiés par la Société française de Physique, vol. 4.)

The practice with the “simple” pendulum on the part of Picard, Bouguer, La Condamine and others in France culminated in the work of Borda and Cassini in 1792 at the observatory in Paris (fig. 6). The experiments were undertaken to determine whether or not the length of the seconds pendulum should be adopted as the standard of length by the new government of France. The bob consisted of a platinum ball 16/6 Paris lines in diameter, and 9,911 grains (slightly more than 17 ounces) in weight. The bob was held to a brass cup covering about one-fifth of its surface by the interposition of a small quantity of grease. The cup with ball was hung by a fine iron wire about 12 Paris feet long. The upper end of the wire was attached to a cylinder which was part of a wedge-shaped knife edge, on the upper surface of which was a stem on which a small adjustable weight was held by a screw thread. The knife edge rested on a steel plate. The weight on the knife-edge apparatus was adjusted so that the apparatus would vibrate with the same period as the pendulum. Thus, the mass of the suspending apparatus could be neglected in the theory of motion of the pendulum about the knife edge.

Figure 7.—Results of experiments in the determination of the length of the seconds pendulum at Königsberg by a new method were reported by F. W. Bessel in 1826 and published in 1828. With this apparatus, he obtained two sets of data from the same pendulum, by using two different points of suspension. The pendulum was about 10 feet long. The distance between the two points of suspension (a and b) was 1 toise (about six feet). A micrometric balance (c) below the bob was used to determine the increase in length due to the weight of the bob. He projected the image of the clock pendulum (not shown) onto the gravity pendulum by means of a lens, thus placing the clock some distance away and eliminating the disturbing effect of its motion. (Portion of plate 6, Mémoires publiés par la Société française de Physique, vol. 4.)

In the earlier suspension from jaws there was uncertainty as to the point about which the pendulum oscillated. Borda and Cassini hung their pendulum in front of a seconds clock and determined the time of swing by the method of coincidences. The times on the clock were observed when the clock gained or lost one complete vibration (two swings) on the pendulum. Suppose that the wire pendulum makes n swings while the clock makes 2n + 2. If the clock beats seconds exactly, the time of one complete vibration is 2 seconds, and the time of swing of the wire pendulum is T = (2n + 2)/n = 2(1 + 1/n). An error in the time caused by uncertainty in determining the coincidence of clock and wire pendulum is reduced by employing a long interval of observation 2n. The whole apparatus was enclosed in a box, in order to exclude disturbances from currents of air. Corrections were made for buoyancy, for amplitude of swing and for variations in length of the wire with temperature. The final result was that the length of the seconds pendulum at the observatory in Paris was determined to be 440.5593 Paris lines, or 993.53 mm., reduced to sea level 993.85 mm. Some years later the methods of Borda were used by other French investigators, among whom was Biot who used the platinum ball of Borda suspended by a copper wire 60 cm. long.

Another historic “simple” pendulum was the one swung by Bessel (fig. 7) for the determination of gravity at Königsberg 1825-1827. The pendulum consisted of a ball of brass, copper, or ivory that was suspended by a fine wire, the upper end of which was wrapped and unwrapped on a horizontal cylinder as support. The pendulum was swung first from one point and then from another, exactly a “toise de Peru” higher up, the bob being at the same level in each case (fig. 7). Bessel found the period of vibration of the pendulum by the method of coincidences; and in order to avoid disturbances from the comparison clock, it was placed at some distance from the pendulum under observation.

Bessel’s experiments were significant in view of the care with which he determined the corrections. He corrected for the stiffness of the wire and for the lack of rigidity of connection between the bob and wire. The necessity for the latter correction had been pointed out by Laplace, who showed that through the circumstance that the pull of the wire is now on one side and now on the other side of the center of gravity, the bob acquires angular momentum about its center of gravity, which cannot be accounted for if the line of the wire, and therefore the force that it exerts, always passed through the center. In addition to a correction for buoyancy of the air considered by his predecessors, Bessel also took account of the inertia of the air set in motion by the pendulum.

Figure 8.—Mode of suspension of Bessel’s pendulum is shown here. The iron wire is supported by the thumbscrew and clamp at the left, but passes over a pin at the center, which is actually the upper terminal of the pendulum. Bessel found this “cylinder of unrolling” superior to the clamps and knife edges of earlier pendulums. The counterweight at the right is part of a system for supporting the scale in such a way that it is not elongated by its own weight.

With this apparatus, Bessel determined the ratio of the lengths of the two pendulums and their times of vibration. From this the length of the seconds pendulum was calculated. His method eliminated the need to take into account such sources of inaccuracy as flexure of the pendulum wire and imperfections in the shape of the bob. (Portion of plate 7, Mémoires publiés par la Société française de Physique, vol. 4.)

Figure 9.—Friedrich Wilhelm Bessel (1784-1846), German mathematician and astronomer. He became the first superintendent of the Prussian observatory established at Königsberg in 1810, and remained there during the remainder of his life. So important were his many contributions to precise measurement and calculation in astronomy that he is often considered the founder of the “modern” age in that science. This characteristic also shows in his venture into geodesy, 1826-1830, one product of which was the pendulum experiment reported in this article.

The latter effect had been discovered by Du Buat in 1786, but his work was unknown to Bessel. The length of the seconds pendulum at Königsberg, reduced to sea level, was found by Bessel to be 440.8179 lines. In 1835, Bessel determined the intensity of gravity at a site in Berlin where observations later were conducted in the Imperial Office of Weights and Measures by Charles S. Peirce of the U.S. Coast Survey.

Kater’s Convertible and Invariable Pendulums

Figure 10.—Henry Kater (1777-1835), English army officer and physicist. His scientific career began during his military service in India, where he assisted in the “great trigonometrical survey.” Returned to England because of bad health, and retired in 1814, he pioneered (1818) in the development of the convertible pendulum as an alternative to the approximation of the “simple” pendulum for the measurement of the “seconds pendulum.” Kater’s convertible pendulum and the invariable pendulum introduced by him in 1819 were the basis of English pendulum work. (Photo courtesy National Portrait Gallery, London.)

Figure 11.—The attempt to approximate the simple (theoretical) pendulum in gravity experiments ended in 1817-18 when Henry Kater invented the compound convertible pendulum, from which the equivalent simple pendulum could be obtained according to the method of Huygens (see text, p. 314). Developed in connection with a project to fix the standard of English measure, Kater’s pendulum was called "compound" because it was a solid bar rather than the fine wire or string with which earlier experimenters had tried to approximate a "weightless" rod. It was called convertible because it is alternately swung from the two knife edges (a and b) at opposite ends. The weights (f and g) are adjusted so that the period of the pendulum is the same from either knife edge. The distance between the two knife edges is then equal to the length of the equivalent simple pendulum.

The systematic survey of the gravity field of the earth was given a great impetus by the contributions of Capt. Henry Kater, F.R.S. In 1817, he designed, constructed, and applied a convertible compound pendulum for the absolute determination of gravity at the house of Henry Browne, F.R.S., in Portland Place, London. Kater’s convertible pendulum (fig. 11) consisted of a brass rod to which were attached a flat circular bob of brass and two adjustable weights, the smaller of which was adjusted by a screw. The convertibility of the pendulum was constituted by the provision of two knife edges turned inwards on opposite sides of the center of gravity. The pendulum was swung on each knife edge, and the adjustable weights were moved until the times of swing were the same about each knife edge. When the times were judged to be the same, the distance between the knife edges was inferred to be the length of the equivalent simple pendulum, in accordance with Huygens’ theorem on conjugate points of a compound pendulum. Kater determined the time of swing by the method of coincidences (fig. 12). He corrected for the buoyancy of the air. The final value of the length of the seconds pendulum at Browne’s house in London, reduced to sea level, was determined to be 39.13929 inches.

The convertible compound pendulum had been conceived prior to its realization by Kater. In 1792, on the occasion of the proposal in Paris to establish the standard of length as the length of the seconds pendulum, Baron de Prony had proposed the employment of a compound pendulum with three axes of oscillation. In 1800, he proposed the convertible compound pendulum with knife edges about which the pendulum could complete swings in equal times. De Prony’s proposals were not accepted and his papers remained unpublished until 1889, at which time they were discovered by Defforges. The French decision was to experiment with the ball pendulum, and the determination of the length of the seconds pendulum was carried out by Borda and Cassini by methods previously described. Bohnenberger in his Astronomie (1811), made the proposal to employ a convertible pendulum for the absolute determination of gravity; thus, he has received credit for priority in publication. Capt. Kater independently conceived of the convertible pendulum and was the first to design, construct, and swing one.

After his observations with the convertible pendulum, Capt. Kater designed an invariable compound pendulum with a single knife edge but otherwise similar in external form to the convertible pendulum (fig. 13). Thirteen of these Kater invariable pendulums have been reported as constructed and swung at stations throughout the world. Kater himself swung an invariable pendulum at a station in London and at various other stations in the British Isles. Capt. Edward Sabine, between 1820 and 1825, made voyages and swung Kater invariable pendulums at stations from the West Indies to Greenland and Spitzbergen. In 1820, Kater swung a Kater invariable pendulum at London and then sent it to Goldingham, who swung it in 1821 at Madras, India. Also in 1820, Kater supplied an invariable pendulum to Hall, who swung it at London and then made observations near the equator and in the Southern Hemisphere, and at London again in 1823. The same pendulum, after its knives were reground, was delivered to Adm. Lütke of Russia, who observed gravity with it on a trip around the world between 1826 and 1829.

Figure 12.—The Kater convertible pendulum in use is placed before a clock, whose pendulum bob is directly behind the extended “tail” of the Kater pendulum. A white spot is painted on the center of the bob of the clock pendulum. The observing telescope, left, has a diaphragm with a vertical slit of such width that its view is just filled by the tail of the Kater pendulum when it is at rest. When the two pendulums are swinging, the white spot on the clock pendulum can be seen on each swing except that in which the two pendulums are in coincidence; thus, the coincidences are determined. (Portion of plate 5, Mémoires publiés par la Société française de Physique, vol. 4.)

Figure 13.—This drawing accompanied John Goldingham’s report on the work done in India with Kater’s invariable pendulum. The value of gravity obtained, directly or indirectly, in terms of the simple pendulum, is called “absolute.” Once absolute values of gravity were established at a number of stations, it became possible to use the much simpler “relative” method for the measurement of gravity at new stations. Because it has only one knife edge, and does not involve the adjustments of the convertible pendulum, this one is called “invariable.” In use, it is first swung at a station where the absolute value of gravity has been established, and this period is then compared with its period at one or more new stations. Kater developed an invariable pendulum in 1819, which was used in England and in Madras, India, in 1821.

Figure 14.—Vacuum chamber for use with the Kater pendulum. Of a number of extraneous effects which tend to disturb the accuracy of pendulum observations the most important is air resistance. Experiments reported by the Greenwich (England) observatory in 1829 led to the development of a vacuum chamber within which the pendulum was swung.

While the British were engaged in swinging the Kater invariable pendulums to determine relative values of the length of the seconds pendulum, or of gravity, the French also sent out expeditions. Capt. de Freycinet made initial observations at Paris with three invariable brass pendulums and one wooden one, and then carried out observations at Rio de Janeiro, Cape of Good Hope, Île de France, Rawak (near New Guinea), Guam, Maui, and various other places. A similar expedition was conducted in 1822-1825 by Captain Duperry.

During the years from 1827 to 1840, various types of pendulum were constructed and swung by Francis Baily, a member of the Royal Astronomical Society, who reported in 1832 on experiments in which no less than 41 different pendulums were swung in vacuo, and their characteristics determined. In 1836, Baily undertook to advise the American Lt. Charles Wilkes, who was to head the United States Exploring Expedition of 1838-1842, on the procurement of pendulums for this voyage. Wilkes ordered from the London instrument maker, Thomas Jones, two unusual pendulums, which Wilkes described as “those considered the best form by Mr. Baily for traveling pendulums,” and which Baily, himself, described as “precisely the same as the two invariable pendulums belonging to this [Royal Astronomical] Society,” except for the location of the knife edges.

Figure 15.—One of Francis Baily’s pendulums (62/2 inches long), shown on the left, is now in the possession of the Science Museum, London, and, right, two views of a similar pendulum (37/8 inches long) made in the late 19th century by Edward Kübel, Washington, D.C., which is no. 316,876 in the collection of the U.S. National Museum. Among a large number of pendulums tried by Baily in London (1827-1840), was one which resembles the reversible pendulum superficially, but which is actually an invariable pendulum having knife edges at both ends. The purpose was apparently economy, since it is equivalent to two separate invariable pendulums. This is the type of pendulum used on the U.S. Exploring Expedition of 1838-1842. It is not known what use was made of the Kübel pendulum.

The unusual feature of these pendulums was in their symmetry of mass as well as of form. They were made of bars, of iron in one case, and of brass in the other, and each had two knife edges at opposite ends equidistant from the center. Thus, although they resembled reversible pendulums, their symmetry of mass prevented their use as such, and they were rather equivalent to four separate invariable pendulums.

Wilkes was taught the use of the pendulum by Baily, and conducted experiments at Baily’s house, where the latter had carried out the work reported on in 1832. The subsequent experiments made on the U.S. Exploring Expedition were under the charge of Wilkes, himself, who made observations on 11 separate occasions, beginning with that in London (1836) and followed by others in New York, Washington, D.C., Rio de Janeiro, Sydney, Honolulu, “Pendulum Peak” (Mauna Loa), Mount Kanoha, Nesqually (Oregon Territory), and, finally, two more times in Washington, D.C. (1841 and 1845).

Wilkes’ results were communicated to Baily, who appears to have found the work defective because of insufficient attention to the maintenance of temperature constancy and to certain alterations made to the pendulums. The results were also to have been included in the publications of the Expedition, but were part of the unpublished 24th volume. Fortunately they still exist, in what appears to be a printer’s proof.

The Kater invariable pendulums were used to investigate the internal constitution of the earth. Airy sought to determine the density of the earth by observing the times of swing of pendulums at the top and bottom of a mine. The first experiments were made in 1826 at the Dolcoath copper mine in Cornwall, and failed when the pendulum fell to the bottom. In 1854, the experiments were again undertaken in the Harton coalpit, near Sunderland. Gravity at the surface was greater than below, because of the attraction of a shell equal to the depth of the pit. From the density of the shell as determined from specimens of rock, Airy found the density of the earth to be 6/2 times greater than that of water. T. C. Mendenhall, in 1880, used a Kater convertible pendulum in an invariable manner to compare values of gravity on Fujiyama and at Tokyo, Japan. He used a “simple” pendulum of the Borda type to determine the absolute value of gravity at Tokyo. From the values of gravity on the mountain and at Tokyo, and an estimate of the volume of the mountain, he estimated the mean density of the earth as 5.77 times greater than that of water.

In 1879, Maj. J. Herschel, R.E., stated:

The years from 1840 to 1865 are a complete blank, if we except Airy’s relative density experiments in 1854. This pause was broken simultaneously in three different ways. Two pendulums of the Kater pattern were sent to India; two after Bessel’s design were set to work in Russia; and at Geneva, Plantamour’s zealous experiments with a pendulum of the same kind mark the commencement of an era of renewed activity on the European continent.

With the statement that Kater invariable pendulums nos. 4 and 6 (1821) were used in India between 1865 and 1873, we now consider the other events mentioned by Herschel.

Repsold-Bessel Reversible Pendulum

As we have noted, Bessel made determinations of gravity with a ball (“simple”) pendulum in the period 1825-1827 and in 1835 at Königsberg and Berlin, respectively. In the memoir on his observations at Königsberg, he set forth the theory of the symmetrical compound pendulum with interchangeable knife edges. Bessel demonstrated theoretically that if the pendulum were symmetrical with respect to its geometrical center, if the times of swing about each axis were the same, the effects of buoyancy and of air set in motion would be eliminated. Laplace had already shown that the knife edge must be regarded as a cylinder and not as a mere line of support. Bessel then showed that if the knife edges were equal cylinders, their effects were eliminated by inverting the pendulum; and if the knife edges were not equal cylinders, the difference in their effects was canceled by interchanging the knives and again determining the times of swing in the so-called erect and inverted positions. Bessel further showed that it is unnecessary to make the times of swing exactly equal for the two knife edges.

The simplified discussion for infinitely small oscillations in a vacuum is as follows: If T1 and T2 are the times of swing about the knife edges, and if h1 and h2 are distances of the knife edges from the center of gravity, and if k is the radius of gyration about an axis through the center of gravity, then from the equation of motion of a rigid body oscillating about a fixed axis under gravity T1 = π(k + h1)/gh1, T2 = π(k + h2)/gh2. Then (h1T1 - h2T2)/(h1 - h2) = (π/g)(h1 + h2) = τ.

τ is then the time of swing of a simple pendulum of length h1 + h2. If the difference T1 - T2 is sufficiently small, τ = (h1T1 - h2T2)/(h1 - h2). Prior to its publication by Bessel in 1828, the formula for the time of swing of a simple pendulum of length h1 + h2 in terms of T1, T2 had been given by C. F. Gauss in a letter to H. C. Schumacher dated November 28, 1824.

The symmetrical compound pendulum with interchangeable knives, for which Bessel gave a posthumously published design and specifications, has been called a reversible pendulum; it may thereby be distinguished from Kater’s unsymmetrical convertible pendulum. In 1861, the Swiss Geodetic Commission was formed, and in one of its first sessions in 1862 it was decided to add determinations of gravity to the operations connected with the measurement—at different points in Switzerland—of the arc of the meridian traversing central Europe. It was decided further to employ a reversible pendulum of Bessel’s design and to have it constructed by the firm of A. Repsold and Sons, Hamburg. It was also decided to make the first observations with the pendulum in Geneva; accordingly, the Repsold-Bessel pendulum (fig. 16) was sent to Prof. E. Plantamour, director of the observatory at Geneva, in the autumn of 1864.

The Swiss reversible pendulum was about 560 mm. in length (distance between the knife edges) and the time of swing was approximately /4-second. At the extremities of the stem of the pendulum were movable cylindrical disks, one of which was solid and heavy, the other hollow and light. It was intended by the mechanicians that equality of times of oscillation about the knife edges would be achieved by adjusting the position of a movable disk. The pendulum was hung by a knife edge on a plate supported by a tripod and having an attachment from which a measuring rod could be suspended so that the distance between the knife edges could be measured by a comparator. Plantamour found it impracticable to adjust a disk until the times of swing about each knife edge were equal. His colleague, Charles Cellérier, then showed that if (T1 - T2)/T1 is sufficiently small so that one can neglect its square, one can determine the length of the seconds pendulum from the times of swing about the knife edges by a theory which uses the distances of the center of gravity from the respective knife edges. Thus, a role for the position of the center of gravity in the theory of the reversible pendulum, which had been set forth earlier by Bessel, was discovered independently by Cellérier for the Swiss observers of pendulums.

In 1866, Plantamour published an extensive memoir “Expériences faites à Genève avec le pendule à réversion.” Another memoir, published in 1872, presented further results of determinations of gravity in Switzerland. Plantamour was the first scientist in western Europe to use a Repsold-Bessel reversible pendulum and to work out methods for its employment.

The Russian Imperial Academy of Sciences acquired two Repsold-Bessel pendulums, and observations with them were begun in 1864 by Prof. Sawitsch, University of St. Petersburg, and others. In 1869, the Russian pendulums were loaned to the India Survey in order to enable members of the Survey to supplement observations with the Kater invariable pendulums nos. 4 and 6 (1821). During the transport of the Russian apparatus to India, the knives became rusted and the apparatus had to be reconditioned. Capt. Heaviside of the India Survey observed with both pendulums at Kew Observatory, near London, in the spring of 1874, after which the Russian pendulums were sent to Pulkowa (Russia) and were used for observations there and in the Caucasus.

The introduction of the Repsold-Bessel reversible pendulum for the determination of gravity was accompanied by the creation of the first international scientific association, one for geodesy. In 1861, Lt. Gen. J. J. Baeyer, director of the Prussian Geodetic Survey, sent a memorandum to the Prussian minister of war in which he proposed that the independent geodetic surveys of the states of central Europe be coordinated by the creation of an international organization. In 1862, invitations were sent to the various German states and to other states of central Europe. The first General Conference of the association, initially called Die Mittel-Europäische Gradmessung, also L’Association Géodésique Internationale, was held from the 15th to the 22d of October 1864 in Berlin. The Conference decided upon questions of organization: a general conference was to be held ordinarily every three years; a permanent commission initially consisting of seven members was to be the scientific organ of the association and to meet annually; a central bureau was to be established for the reception, publication, and distribution of reports from the member states.

Figure 16.—From a Design Left by Bessel, this portable apparatus was developed in 1862 by the firm of Repsold in Hamburg, whose founder had assisted Bessel in the construction of his pendulum apparatus of 1826. The pendulum is convertible, but differs from Kater’s in being geometrically symmetrical and, for this reason, Repsold’s is usually called “reversible.” Just to the right of the pendulum is a standard scale. To the left is a “vertical comparator” designed by Repsold to measure the distance between the knife edges of the pendulum. To make this measurement, two micrometer microscopes which project horizontally through the comparator are alternately focused on the knife edges and on the standard scale.

Under the topic “Astronomical Questions,” the General Conference of 1864 resolved that there should be determinations of the intensity of gravity at the greatest possible number of points of the geodetic network, and recommended the reversible pendulum as the instrument of observation. At the second General Conference, in Berlin in 1867, on the basis of favorable reports by Dr. Hirsch, director of the observatory at Neuchâtel, of Swiss practice with the Repsold-Bessel reversible pendulum, this instrument was specifically recommended for determinations of gravity. The title of the association was changed to Die Europäische Gradmessung; in 1886, it became Die Internationale Erdmessung, under which title it continued until World War I.

On April 1, 1866, the Central Bureau of Die Europäische Gradmessung was opened in Berlin under the presidency of Baeyer, and in 1868 there was founded at Berlin, also under his presidency, the Royal Prussian Geodetic Institute, which obtained regular budgetary status on January 1, 1870. A reversible pendulum for the Institute was ordered from A. Repsold and Sons, and it was delivered in the spring of 1869. The Prussian instrument was symmetrical geometrically, as specified by Bessel, but different in form from the Swiss and Russian pendulums. The distance between the knife edges was 1 meter, and the time of swing approximately 1 second. The Prussian Repsold-Bessel pendulum was swung at Leipzig and other stations in central Europe during the years 1869-1870 by Dr. Albrecht under the direction of Dr. Bruhns, director of the observatory at Leipzig and chief of the astronomical section of the Geodetic Institute. The results of these first observations appeared in a publication of the Royal Prussian Geodetic Institute in 1871.

Results of observations with the Russian Repsold-Bessel pendulums were published by the Imperial Academy of Sciences. In 1872, Prof. Sawitsch reported the work for western Europeans in “Les variations de la pesanteur dans les provinces occidentales de l’Empire russe.” In November 1873, the Austrian Geodetic Commission received a Repsold-Bessel reversible pendulum and on September 24, 1874, Prof. Theodor von Oppolzer reported on observations at Vienna and other stations to the Fourth General Conference of Die Europäische Gradmessung in Dresden. At the fourth session of the Conference, on September 28, 1874, a Special Commission, consisting of Baeyer, as chairman, and Bruhns, Hirsch, Von Oppolzer, Peters, and Albrecht, was appointed to consider (under Topic 3 of the program): “Observations for the determination of the intensity of gravity,” the question, “Which Pendulum-apparatuses are preferable for the determination of many points?”

After the adoption of the Repsold-Bessel reversible pendulum for gravity determinations in Europe, work in the field was begun by the U.S. Coast Survey under the superintendency of Prof. Benjamin Peirce. There is mention in reports of observations with pendulums prior to Peirce’s direction to his son Charles on November 30, 1872, “to take charge of the Pendulum Experiments of the Coast Survey and to direct and inspect all parties engaged in such experiments and as often as circumstances will permit, to take the field with a party….” Systematic and important gravity work by the Survey was begun by Charles Sanders Peirce. Upon receiving notice of his appointment, the latter promptly ordered from the Repsolds a pendulum similar to the Prussian instrument. Since the firm of mechanicians was engaged in making instruments for observations of the transit of Venus in 1874, the pendulum for the Coast Survey could not be constructed immediately. Meanwhile, during the years 1873-1874, Charles Peirce conducted a party which made observations of gravity in the Hoosac Tunnel near North Adams, and at Northampton and Cambridge, Massachusetts. The pendulums used were nonreversible, invariable pendulums with conical bobs. Among them was a silver pendulum, but similar pendulums of brass were used also.

Figure 17.—Repsold-Bessel reversible pendulum apparatus as made in 1875, and used in the gravity work of the U.S. Coast and Geodetic Survey. Continental geodesists continued to favor the general use of convertible pendulums and absolute determinations of gravity, while their English colleagues had turned to invariable pendulums and relative determinations, except for base stations. Perhaps the first important American contribution to gravity work was C. S. Peirce’s demonstration of the error inherent in the Repsold apparatus through flexure of the stand.

Figure 18.—Charles Sanders Peirce (1839-1914), son of Benjamin Peirce, Perkins Professor of Astronomy and Mathematics at Harvard College. C. S. Peirce graduated from Harvard in 1859. From 1873 to 1891, as an assistant at the U.S. Coast and Geodetic Survey, he accomplished the important gravimetric work described in this article. Peirce was also interested in many other fields, but above all in the logic, philosophy, and history of science, in which he wrote extensively. His greatest fame is in philosophy, where he is regarded as the founder of pragmatism.

In 1874, Charles Peirce expressed the desire to be sent to Europe for at least a year, beginning about March 1, 1875, “to learn the use of the new convertible pendulum and to compare it with those of the European measure of a Degree and the Swiss and to compare” his “invariable pendulums in the manner which has been used by swinging them in London and Paris.”

Charles S. Peirce, assistant, U.S. Coast Survey, sailed for Europe on April 3, 1875, on his mission to obtain the Repsold-Bessel reversible pendulum ordered for the Survey and to learn the methods of using it for the determination of gravity. In England, he conferred with Maxwell, Stokes, and Airy concerning the theory and practice of research with pendulums. In May, he continued on to Hamburg and obtained delivery from the Repsolds of the pendulum for the Coast Survey (fig. 17). Peirce then went to Berlin and conferred with Gen. Baeyer, who expressed doubts of the stability of the Repsold stand for the pendulum. Peirce next went to Geneva, where, under arrangements with Prof. Plantamour, he swung the newly acquired pendulum at the observatory.

In view of Baeyer’s expressed doubts of the rigidity of the Repsold stand, Peirce performed experiments to measure the flexure of the stand caused by the oscillations of the pendulum. His method was to set up a micrometer in front of the pendulum stand and, with a microscope, to measure the displacement caused by a weight passing over a pulley, the friction of which had been determined. Peirce calculated the correction to be applied to the length of the seconds pendulum—on account of the swaying of the stand during the swings of the pendulum—to amount to over 0.2 mm. Although Peirce’s measurements of flexure in Geneva were not as precise as his later measurements, he believed that failure to correct for flexure of the stand in determinations previously made with Repsold pendulums was responsible for appreciable errors in reported values of the length of the seconds pendulum.

The Permanent Commission of Die Europäische Gradmessung met in Paris, September 20-29, 1875. In conjunction with this meeting, there was held on September 21 a meeting of the Special Commission on the Pendulum. The basis of the discussion by the Special Commission was provided by reports which had been submitted in response to a circular sent out by the Central Bureau to the members on February 26, 1874.

Gen. Baeyer stated that the distance of 1 meter between the knife edges of the Prussian Repsold-Bessel pendulum made it unwieldy and unsuited for transport. He declared that the instability of the stand also was a source of error. Accordingly, Gen. Baeyer expressed the opinion that absolute determinations of gravity should be made at a control station by a reversible pendulum hung on a permanent, and therefore stable stand, and he said that relative values of gravity with respect to the control station should be obtained in the field by means of a Bouguer invariable pendulum. Dr. Bruhns and Dr. Peters agreed with Gen. Baeyer; however, the Swiss investigators, Prof. Plantamour and Dr. Hirsch reported in defense of the reversible pendulum as a field instrument, as did Prof. von Oppolzer of Vienna. The circumstance that an invariable pendulum is subject to changes in length was offered as an argument in favor of the reversible pendulum as a field instrument.

Peirce was present during these discussions by the members of the Special Commission, and he reported that his experiments at Geneva demonstrated that the oscillations of the pendulum called forth a flexure of the support which hitherto had been neglected. The observers who used the Swiss and Austrian Repsold pendulums contended, in opposition to Peirce, that the Repsold stand was stable.

The outcome of these discussions was that the Special Commission reported to the Permanent Commission that the Repsold-Bessel reversible pendulum, except for some small changes, satisfied all requirements for the determination of gravity. The Special Commission proposed that the Repsold pendulums of the several states be swung at the Prussian Eichungsamt in Berlin where, as Peirce pointed out, Bessel had made his determination of the intensity of gravity with a ball pendulum in 1835. Peirce was encouraged to swing the Coast Survey reversible pendulum at the stations in France, England, and Germany where Borda and Cassini, Kater, and Bessel, respectively, had made historic determinations. The Permanent Commission, in whose sessions Peirce also participated, by resolutions adopted the report of the Special Commission on the Pendulum.

During the months of January and February 1876, Peirce conducted observations in the Grande Salle du Meridien at the observatory in Paris where Borda, Biot, and Capt. Edward Sabine had swung pendulums early in the 19th century. He conducted observations in Berlin from April to June 1876 and, by experiment, determined the correction for flexure to be applied to the value of gravity previously obtained with the Prussian instrument. Subsequent observations were made at Kew. After his return to the United States on August 26, 1876, Peirce conducted experiments at the Stevens Institute in Hoboken, New Jersey, where he made careful measurements of the flexure of the stand by statical and dynamical methods. In Geneva, he had secured the construction of a vacuum chamber in which the pendulum could be swung on a support which he called the Geneva support. At the Stevens Institute, Peirce swung the Repsold-Bessel pendulum on the Geneva support and determined the effect of different pressures and temperatures on the period of oscillation of the pendulum. These experiments continued into 1878.

Meanwhile, the Permanent Commission met October 5-10, 1876, in Brussels and continued the discussion of the pendulum. Gen. Baeyer reported on Peirce’s experiments in Berlin to determine the flexure of the stand. The difference of 0.18 mm. in the lengths of the seconds pendulum as determined by Bessel and as determined by the Repsold instrument agreed with Peirce’s estimate of error caused by neglect of flexure of the Repsold stand. Dr. Hirsch, speaking for the Swiss survey, and Prof. von Oppolzer, speaking for the Austrian survey, contended, however, that their stands possessed sufficient stability and that the results found by Peirce applied only to the stands and bases investigated by him. The Permanent Commission proposed further study of the pendulum.

The Fifth General Conference of Die Europäische Gradmessung was held from September 27 to October 2, 1877, in Stuttgart. Peirce had instructions from Supt. Patterson of the U.S. Coast Survey to attend this conference, and on arrival presented a letter of introduction from Patterson requesting that he, Peirce, be permitted to participate in the sessions. Upon invitation from Prof. Plantamour, as approved by Gen. Ibañez, president of the Permanent Commission, Peirce had sent on July 13, 1877, from New York, the manuscript of a memoir titled “De l’Influence de la flexibilité du trépied sur l’oscillation du pendule à réversion.” This memoir and others by Cellérier and Plantamour confirming Peirce’s work were published as appendices to the proceedings of the conference. As appendices to Peirce’s contribution were published also two notes by Prof. von Oppolzer. At the second session on September 29, 1877, when Plantamour reported that the work of Hirsch and himself had confirmed experimentally the independent theoretical work of Cellérier and the theoretical and experimental work of Peirce on flexure, Peirce described his Hoboken experiments.

During the discussions at Stuttgart on the flexure of the Repsold stand, Hervé Faye, president of the Bureau of Longitudes, Paris, suggested that the swaying of the stand during oscillations of the pendulum could be overcome by the suspension from one support of two similar pendulums which oscillated with equal amplitudes and in opposite phases. This proposal was criticized by Dr. Hirsch, who declared that exact observation of passages of a “double pendulum” would be difficult and that two pendulums swinging so close together would interfere with each other. The proposal of the double pendulum came up again at the meeting of the Permanent Commission at Geneva in 1879. On February 17, 1879, Peirce had completed a paper “On a Method of Swinging Pendulums for the Determination of Gravity, Proposed by M. Faye.” In this paper, Peirce presented the results of an analytical mechanical investigation of Faye’s proposal. Peirce set up the differential equations, found the solutions, interpreted them physically, and arrived at the conclusion “that the suggestion of M. Faye … is as sound as it is brilliant and offers some peculiar advantages over the existing method of swinging pendulums.”

In a report to Supt. Patterson, dated July 1879, Peirce stated: “I think it is important before making a new pendulum apparatus to experiment with Faye’s proposed method.” He wrote further: “The method proves to be perfectly sound in theory, and as it would greatly facilitate the work it is probably destined eventually to prevail. We must unfortunately leave to other surveys the merit of practically testing and introducing the new method, as our appropriations are insufficient for us to maintain the leading position in this matter, which we otherwise might take.” Copies of the published version of Peirce’s remarks were sent to Europe. At a meeting of the Academy of Sciences in Paris on September 1, 1879, Faye presented a report on Peirce’s findings. The Permanent Commission met September 16-20, 1879, in Geneva. At the third session on September 19, by action of Gen. Baeyer, copies of Peirce’s paper on Faye’s proposed method of swinging pendulums were distributed. Dr. Hirsch again commented adversely on the proposal, but moved that the question be investigated and reported on at the coming General Conference. The Permanent Commission accepted the proposal of Dr. Hirsch, and Prof. Plantamour was named to report on the matter at the General Conference. At Plantamour’s request, Charles Cellérier was appointed to join him, since the problem essentially was a theoretical one.

The Sixth General Conference of Die Europäische Gradmessung met September 13-16, 1880, in Munich. Topic III, part 7 of the program was entitled “On Determinations of Gravity through pendulum observations. Which construction of a pendulum apparatus corresponds completely to all requirements of science? Special report on the pendulum.”

Figure 19.—Three pendulums used in early work at the U.S. Coast and Geodetic Survey. Shown on the left is the Peirce invariable; center, the Peirce reversible; and, right, the Repsold reversible. Peirce designed the cylindrical pendulum in 1881-1882 to study the effect of air resistance according to the theory of G. G. Stokes on the motion of a pendulum in a viscous field. Three examples of the Peirce pendulums are in the U.S. National Museum.

The conference received a memoir by Cellérier on the theory of the double pendulum and a report by Plantamour and Cellérier. Cellérier’s mathematical analysis began with the equations of Peirce and used the latter’s notation as far as possible. His general discussion included the results of Peirce, but he stated that the difficulties to be overcome did not justify the employment of the “double pendulum.” He presented an alternative method of correcting for flexure based upon a theory by which the flexure caused by the oscillation of a given reversible pendulum could be determined from the behavior of an auxiliary pendulum of the same length but of different weight. This method of correcting for flexure was recommended to the General Conference by Plantamour and Cellérier in their joint report. At the fourth session of the conference on September 16, 1880, the problem of the pendulum was discussed and, in consequence, a commission consisting of Faye, Helmholtz, Plantamour (replaced in 1882 by Hirsch), and Von Oppolzer was appointed to study apparatus suitable for relative determinations of gravity.

The Permanent Commission met September 11-15, 1882, at The Hague, and at its last session appointed Prof. von Oppolzer to report to the Seventh General Conference on different forms of apparatus for the determination of gravity. The Seventh Conference met October 15-24, 1883, in Rome, and, at its eighth session, on October 22, received a comprehensive, critical review from Prof. von Oppolzer entitled “Über die Bestimmung der Schwere mit Hilfe verschiedener Apparate.” Von Oppolzer especially expounded the advantages of the Bessel reversible pendulum, which compensated for air effects by symmetry of form if the times of swing for both positions were maintained between the same amplitudes, and compensated for irregular knife edges by making them interchangeable. Prof. von Oppolzer reviewed the problem of flexure of the Repsold stand and stated that a solution in the right direction was the proposal—made by Faye and theoretically pursued by Peirce—to swing two pendulums from the same stand with equal amplitudes and in opposite phases, but that the proposal was not practicable. He concluded that for absolute determinations of gravity, the Bessel reversible pendulum was highly appropriate if one swung two exemplars of different weight from the same stand for the elimination of flexure. Prof. von Oppolzer’s important report recognized that absolute determinations were less accurate than relative ones, and should be conducted only at special places.

The discussions initiated by Peirce’s demonstration of the flexure of the Repsold stand resulted, finally, in the abandonment of the plan to make absolute determinations of gravity at all stations with the reversible pendulum.

Peirce and Defforges Invariable, Reversible Pendulums

The Repsold-Bessel reversible pendulum was designed and initially used to make absolute determinations of gravity not only at initial stations such as Kew, the observatory in Paris, and the Smithsonian Institution in Washington, D.C., but also at stations in the field. An invariable pendulum with a single knife edge, however, is adequate for relative determinations. As we have seen, such invariable pendulums had been used by Bouguer and Kater, and after the experiences with the Repsold apparatus had been recommended again by Baeyer for relative determinations. But an invariable pendulum is subject to uncontrollable changes of length. Peirce proposed to detect such changes in an invariable pendulum in the field by combining the invariable and reversible principles. He explained his proposal to Faye in a letter dated July 23, 1880, and he presented it on September 16, 1880, at the fourth session of the sixth General Conference of Die Europäische Gradmessung, in Munich.

As recorded in the Proceedings of the Conference, Peirce wrote:

But I obviate it in making my pendulum both invariable and reversible. Every alteration of the pendulum will be revealed immediately by the change in the difference of the two periods of oscillation in the two positions. Once discovered, it will be taken account of by means of new measures of the distance between the two supports.

Peirce added that it seemed to him that if the reversible pendulum perhaps is not the best instrument to determine absolute gravity, it is, on condition that it be truly invariable, the best to determine relative gravity. Peirce further stated that he would wish that the pendulum be formed of a tube of drawn brass with heavy plugs of brass equally drawn. The cylinder would be terminated by two hemispheres; the knives would be attached to tongues fixed near the ends of the cylinder.

During the years 1881 and 1882, four invariable, reversible pendulums were made after the design of Peirce at the office of the U.S. Coast and Geodetic Survey in Washington, D.C. The report of the superintendent for the year 1880-1881 states:

A new pattern of the reversible pendulum has been invented, having its surface as nearly as convenient in the form of an elongated ellipsoid. Three of these instruments have been constructed, two having a distance of one meter between the knife edges and the third a distance of one yard. It is proposed to swing one of the meter pendulums at a temperature near 32° F. at the same time that the yard is swung at 60° F., in order to determine anew the relation between the yard and the meter.

The report for 1881-1882 mentions four of these Peirce pendulums.

A description of the Peirce invariable, reversible pendulums was given by Assistant E. D. Preston in “Determinations of Gravity and the Magnetic Elements in Connection with the United States Scientific Expedition to the West Coast of Africa, 1889-90.” The invariable, reversible pendulum, Peirce no. 4, now preserved in the Smithsonian Institution’s Museum of History and Technology (fig. 34), may be taken as typical of the meter pendulums: In the same memoir, Preston gives the diameter of the tube as 63.7 mm., thickness of tube 1.5 mm., weight 10.680 kilograms, and distance between the knives 1.000 meter.

The combination of invariability and reversibility in the Peirce pendulums was an innovation for relative determinations. Indeed, the combination was criticized by Maj. J. Herschel, R.E., of the Indian Survey, at a conference on gravity held in Washington in May 1882 on the occasion of his visit to the United States for the purpose of connecting English and American stations by relative determinations with three Kater invariable pendulums. These three pendulums have been designated as nos. 4, 6 (1821), and 11.

Figure 20.—Support for the Peirce pendulum, 1889. Much of the work of C. S. Peirce was concerned with the determination of the error introduced into observations made with the portable apparatus by the vibration of the stand with the pendulum. He showed that the popular Bessel-Repsold apparatus was subject to such an error. His own pendulums were swung from a simple but rugged wooden frame to which a hardened steel bearing was fixed.

Another novel characteristic of the Peirce pendulums was the mainly cylindrical form. Prof. George Gabriel Stokes, in a paper “On the Effect of the Internal Friction of Fluids on the Motion of Pendulums” that was read to the Cambridge Philosophical Society on December 9, 1850, had solved the hydrodynamical equations to obtain the resistance to the motions of a sphere and a cylinder in a viscous fluid. Peirce had studied the effect of viscous resistance on the motion of his Repsold-Bessel pendulum, which was symmetrical in form but not cylindrical. The mainly cylindrical form of his pendulums (fig. 19) permitted Peirce to predict from Stokes’ theory the effect of viscosity and to compare the results with experiment. His report of November 20, 1889, in which he presented the comparison of experimental results with the theory of Stokes, was not published.

Peirce used his pendulums in 1883 to establish a station at the Smithsonian Institution that was to serve as the base station for the Coast and Geodetic Survey for some years. Pendulum Peirce no. 1 was swung at Washington in 1881 and was then taken by the party of Lieutenant Greely, U.S.A., on an expedition to Lady Franklin Bay where it was swung in 1882 at Fort Conger, Grinnell Land, Canada. Peirce nos. 2 and 3 were swung by Peirce in 1882 at Washington, D.C.; Hoboken, New Jersey; Montreal, Canada; and Albany, New York. Assistant Preston took Peirce no. 3 on a U.S. eclipse expedition to the Caroline Islands in 1883. Peirce in 1885 swung pendulums nos. 2 and 3 at Ann Arbor, Michigan; Madison, Wisconsin; and Ithaca, New York. Assistant Preston in 1887 swung Peirce nos. 3 and 4 at stations in the Hawaiian Islands, and in 1890 he swung Peirce nos. 3 and 4 at stations on the west coast of Africa.

The new pattern of pendulum designed by Peirce was also adopted in France, after some years of experience with a Repsold-Bessel pendulum. Peirce in 1875 had swung his Repsold-Bessel pendulum at the observatory in Paris, where Borda and Cassini, and Biot, had made historic observations and where Sabine also had determined gravity by comparison with Kater’s value at London. During the spring of 1880, Peirce made studies of the supports for the pendulums of these earlier determinations and calculated corrections to those results for hydrodynamic effects, viscosity, and flexure. On June 14, 1880, Peirce addressed the Academy of Sciences, Paris, on the value of gravity at Paris, and compared his results with the corrected results of Borda and Biot and with the transferred value of Kater.

In the same year the French Geographic Service of the Army acquired a Repsold-Bessel reversible pendulum of the smaller type, and Defforges conducted experiments with it. He introduced the method of measuring flexure from the movement of interference fringes during motion of the pendulum. He found an appreciable difference between dynamical and statical coefficients of flexure and concluded that the “correction formula of Peirce and Cellérier is suited perfectly to practice and represents exactly the variation of period caused by swaying of the support, on the condition that one uses the statical coefficient.” Defforges developed a theory for the employment of two similar pendulums of the same weight, but of different length, and hung by the same knives. This theory eliminated the flexure of the support and the curvature of the knives from the reduction of observations.

Pendulums of 1-meter and of /2-meter distance between the knife edges were constructed from Defforges’ design by Brunner Brothers in Paris (fig. 21). These Defforges pendulums were cylindrical in form with hemispherical ends like the Peirce pendulums, and were hung on knives that projected from the sides of the pendulum, as in some unfinished Gautier pendulums designed by Peirce in 1883 in Paris.

Figure 21.—Reversible pendulum apparatus of Defforges, as constructed by Brunner, Paris, about 1887. The clock and telescope used to observe coincidences are not shown. The telescope shown is part of an interferometer used to measure flexure of the support. One mirror of the interferometer is attached to the pendulum support; the other to the separate masonry pillar at the left.

Figure 22.—Because of the greater simplicity of its use, the invariable pendulum superseded the convertible pendulum towards the end of the 19th century, except at various national base stations (Kew, Paris, Potsdam, Washington, D.C., etc.). Shown here are, right to left, a pendulum of the type used by Peirce at the Hoosac Tunnel in 1873-74, the Mendenhall /2-second pendulum of 1890, and the pendulum designed by Peirce in 1881-1882.

Figure 23.—The overall size of portable pendulum apparatus was greatly reduced with the introduction of this /2-second apparatus in 1887, by the Austrian military officer, Robert von Sterneck. Used with a vacuum chamber not shown here, the apparatus is only about 2 feet high. Coincidences are observed by the reflection of a periodic electric spark in two mirrors, one on the support and the other on the pendulum itself.

Figure 24.—Thomas C. Mendenhall (1841-1924). Although largely self-educated, he became the first professor of physics and mechanics at the Ohio Agricultural and Mechanical College (later Ohio State University), and was subsequently connected with several other universities. In 1878, while teaching at the Tokyo Imperial University in Japan, he made gravity measurements between Tokyo and Fujiyama from which he calculated the mean density of the earth. While superintendent of the U.S. Coast and Geodetic Survey, 1889-94, he developed the pendulum apparatus which bears his name.

Von Sterneck and Mendenhall Pendulums

While scientists who had used the Repsold-Bessel pendulum apparatus discussed its defects and limitations for gravity surveys, Maj. Robert von Sterneck of Austria-Hungary began to develop an excellent apparatus for the rapid determination of relative values of gravity. Maj. von Sterneck’s apparatus contained a nonreversible pendulum /4-meter in length, and /2-second time of swing. The pendulum was hung by a single knife edge, which rested on a plate that was supported by a tripod. The pendulum was swung in a chamber from which air was exhausted and which could be maintained at any desired temperature. Times of swing were determined by the observation of coincidences of the pendulum with chronometer signals. In the final form a small mirror was attached to the knife edge perpendicular to the plane of vibration of the pendulum and a second fixed mirror was placed close to it so that the two mirrors were parallel when the pendulum was at rest. The chronometer signals worked a relay that gave a horizontal spark which was reflected into the telescope from the mirrors. When the pendulum was at rest, the image of the spark in both mirrors appeared on the horizontal cross wire in the telescope, and during oscillation of the pendulum the two images appeared in that position upon coincidence. In view of the reduced size of the pendulum, the chamber in which it was swung was readily portable, and with an improved method of observing coincidences, relative determinations of gravity could be made with rapidity and accuracy.

By 1887 Maj. von Sterneck had perfected his apparatus, and it was widely adopted in Europe for relative determinations of gravity. He used his apparatus in extensive gravity surveys and also applied it in the silver mines in Saxony and Bohemia, by the previously described methods of Airy, for investigations into the internal constitution of the earth.

On July 1, 1889, Thomas Corwin Mendenhall became superintendent of the U.S. Coast and Geodetic Survey. Earlier, he had been professor of physics at the University of Tokyo and had directed observations of pendulums for the determination of gravity on Fujiyama and at Tokyo. Supt. Mendenhall, with the cooperation of members of his staff in Washington, designed a new pendulum apparatus of the von Sterneck type, and in October 1890 he ordered construction of the first model.

Like the Von Sterneck apparatus, the Mendenhall pendulum apparatus employed a nonreversible, invariable pendulum /4-meter in length and of slightly more than /2-second in time of swing. Initially, the knife edge was placed in the head of the pendulum and hung on a fixed plane support, but after some experimentation Mendenhall attached the plane surface to the pendulum and hung it on a fixed knife edge. An apparatus was provided with a set of three pendulums, so that if discrepancies appeared in the results, the pendulum at fault could be detected. There was also a dummy pendulum which carried a thermometer. A pendulum was swung in a receiver in which the pressure and temperature of the air were controlled. The time of swing was measured by coincidences with the beat of a chronometer. The coincidences were determined by an optical method with the aid of a flash apparatus.

Figure 25.—Mendenhall’s /4-meter (/2-second) apparatus. Shown on the left is the flash apparatus and, on the right, the vacuum chamber within which the pendulum is swung. The flash apparatus consists of a kerosene lantern and a telescope, mounted on a box containing an electromagnetically operated shutter. The operation of the shutter is controlled by a chronograph (not shown), so that it emits a slit of light at regular intervals. The telescope is focused on two mirrors within the apparatus, one fixed, the other attached to the top of the pendulum. It is used to observe the reflection of the flashes from these mirrors. When the two reflections are aligned, a “coincidence” is marked on the chronograph tape. The second telescope attached to the bottom of the vacuum chamber is for observing the amplitude of the pendulum swing.

The flash apparatus was contained in a light metal box which supported an observing telescope and which was mounted on a stand. Within the box was an electromagnet whose coils were connected with a chronometer circuit and whose armature carried a long arm that moved two shutters, in both of which were horizontal slits of the same size. The shutters were behind the front face of the box, which also had a horizontal slit. A flash of light from an oil lamp or an electric spark was emitted from the box when the circuit was broken, but not when it was closed. When the circuit was broken a spring caused the arm to rise, and the shutters were actuated so that the three slits came into line and a flash of light was emitted. A small circular mirror was set in each side of the pendulum head, so that from either face of the pendulum the image of the illuminated slit could be reflected into the field of the observing telescope. A similar mirror was placed parallel to these two mirrors and rigidly attached to the support. The chronometer signals broke the circuit, causing the three slits momentarily to be in line, and when the images of the slit in the two mirrors coincided, a coincidence was observed. A coincidence occurred whenever the pendulum gained or lost one oscillation on the beat of the chronometer. The relative intensity of gravity was determined by observations with the first Mendenhall apparatus at Washington, D.C., at stations on the Pacific Coast and in Alaska, and at the Stevens Institute, Hoboken, New Jersey, between March and October 1891.

Figure 26.—Vacuum receiver within which the Mendenhall pendulum is swung. The pressure is reduced to about 50 mm. to reduce the disturbing effect of air resistance. When the apparatus is sealed, the pendulum is lifted on the knife edge by the lever q and is started to swing by the lever r. The arc of swing is only about 1°. The stationary mirror is shown at g. The pendulum shown in outline in the center, is only about 9.7 inches long.

Under Supt. Mendenhall’s direction a smaller, /4-second, pendulum apparatus was also constructed and tested, but did not offer advantages over the /2-second apparatus, which therefore continued in use.

In accordance with Peirce’s theory of the flexure of the stand under oscillations of the pendulum, determinations of the displacement of the receiver of the Mendenhall apparatus were part of a relative determination of gravity by members of the Coast and Geodetic Survey. Initially, a statical method was used, but during 1908-1909 members of the Survey adapted the Michelson interferometer for the determinations of flexure during oscillations from the shift of fringes. The first Mendenhall pendulums were made of bronze, but about 1920 invar was chosen because of its small coefficient of expansion. About 1930, Lt. E. J. Brown of the Coast and Geodetic Survey made significant improvements in the Mendenhall apparatus, and the new form came to be known as the Brown Pendulum Apparatus.

Figure 27.—The Michelson interferometer. The horizontal component of the force acting on the knife edge through the swinging pendulum causes the support to move in unison with the pendulum, and thereby affects the period of the oscillation. This movement is the so-called flexure of the pendulum support, and must be taken into account in the most accurate observations.

In 1907, the Michelson interferometer was adapted to this purpose by the U.S. Coast and Geodetic Survey. As shown here, the interferometer, resting on a wooden beam, is introduced into the path of a light beam reflected from a mirror on the vacuum chamber. Movement of that mirror causes a corresponding movement in the interference fringes in the interferometer, which can be measured.

The original Von Sterneck apparatus and that of Mendenhall provided for the oscillation of one pendulum at a time. After the adoption of the Von Sterneck pendulum in Europe, there were developed stands on which two or four pendulums hung at the same time. This procedure provided a convenient way to observe more than one invariable pendulum at a station for the purpose of detecting changes in length. Prof. M. Haid of Karlsruhe in 1896 described a four-pendulum apparatus, and Dr. Schumann of Potsdam subsequently described a two-pendulum apparatus.

Figure 28.—Apparatus which was developed in 1929 by the Gulf Research and Development Company, Harmarville, Pennsylvania. It was designed to achieve an accuracy within one ten-millionth of the true value of gravity, and represents the extreme development of pendulum apparatus for relative gravity measurement. The pendulum was designed so that the period would be a minimum. The case (the top is missing in this photograph) is dehumidified and its temperature and electrostatic condition are controlled. Specially designed pendulum-lifting and -starting mechanisms are used. The problem of flexure of the case is overcome by the Faye-Peirce method (see text) in which two dynamically matched pendulums are swung simultaneously, 180° apart in phase.

The multiple-pendulum apparatus then provided a method of determining the flexure of the stand from the action of one pendulum upon a second pendulum hung on the same stand. This method of determining the correction for flexure was a development from a “Wippverfahren” invented at the Geodetic Institute in Potsdam. A dynamometer was used to impart periodic impulses to the stand, and the effect was observed upon a pendulum initially at rest. Refinements of this method led to the development of a method used by Lorenzoni in 1885-1886 to determine the flexure of the stand by action of an auxiliary pendulum upon the principal pendulum. Dr. Schumann, in 1899, gave a mathematical theory of such determinations, and in his paper cited the mathematical methods of Peirce and Cellérier for the theory of Faye’s proposal at Stuttgart in 1877 to swing two similar pendulums on the same support with equal amplitudes and in opposite phases.

Figure 29.—The Gulf pendulum is about 10.7 inches long, and has a period of .89 second. It is made of fused quartz which is resistant to the influence of temperature change and to the earth’s magnetism. Quartz pendulums are subject to the influence of electrostatic charge, and provision is made to counteract this through the presence of a radium salt in the case. The bearings are made of Pyrex glass.

In 1902, Dr. P. Furtwängler presented the mathematical theory of coupled pendulums in a paper in which he referred to Faye’s proposal of 1877 and reported that the difficulties predicted upon its application had been found not to occur. Finally, during the gravity survey of Holland in the years 1913-1921, in view of instability of supports caused by the mobility of the soil, F. A. Vening Meinesz adopted Faye’s proposed method of swinging two pendulums on the same support. The observations were made with the ordinary Stückrath apparatus, in which four Von Sterneck pendulums swung two by two in planes perpendicular to each other. This successful application of the method—which had been proposed by Faye and had been demonstrated theoretically to be sound by Peirce, who also published a design for its application—was rapidly followed for pendulum apparatus for relative determinations by Potsdam, Cambridge (England), Gulf Oil and Development Company, and the Dominion Observatory at Ottawa. Heiskanen and Vening Meinesz state:

The best way to eliminate the effect of flexure is to use two synchronized pendulums of the same length swinging on the same apparatus in the same plane and with the same amplitudes but in opposite phases; it is clear then the flexure is zero.

In view of the fact that the symmetrical reversible pendulum is named for Bessel, who created the theory and a design for its application by Repsold, it appears appropriate to call the method of eliminating flexure by swinging two pendulums on the same support the Faye-Peirce method. Its successful application was made possible by Maj. von Sterneck’s invention of the short, /4-meter pendulum.

Figure 30.—The accumulated data of gravity observations over the earth’s surface have indicated that irregularities such as mountains do not have the effect which would be expected in modifying gravity, but are somehow compensated for. The most satisfactory solution to this still unanswered question has been the theory of isostasy, according to which variations in the density of the material in the earth’s crust produce a kind of hydrostatic equilibrium between its higher and lower parts, as they “float” on the earth’s fluid core. The metals of different density floating in mercury in this diagram illustrate isostasy according to the theory of Pratt and Hayford.

Absolute Value of Gravity at Potsdam

The development of the reversible pendulum in the 19th century culminated in the absolute determination of the intensity of gravity at Potsdam by Kühnen and Furtwängler of the Royal Prussian Geodetic Institute, which then became the world base for gravity surveys.

We have previously seen that in 1869 the Geodetic Institute—founded by Lt. Gen. Baeyer—had acquired a Repsold-Bessel reversible pendulum which was swung by Dr. Albrecht under the direction of Dr. Bruhns. Dissatisfaction with this instrument was expressed by Baeyer in 1875 to Charles S. Peirce, who then, by experiment and mathematical analysis of the flexure of the stand under oscillations of the pendulum, determined that previously reported results with the Repsold apparatus required correction. Dr. F. R. Helmert, who in 1887 succeeded Baeyer as director of the Institute, secured construction of a building for the Institute in Potsdam, and under his direction the scientific study of the intensity of gravity was pursued with vigor. In 1894, it was discovered in Potsdam that a pendulum constructed of very flexible material yielded results which differed markedly from those obtained with pendulums of greater stiffness. Dr. Kühnen of the Institute discovered that the departure from expectations was the result of the flexure of the pendulum staff itself during oscillations.

Peirce, in 1883, had discovered that the recesses cut in his pendulums for the insertion of tongues that carried the knives had resulted in the flexure of the pendulum staff. By experiment, he also found an even greater flexure for the Repsold pendulum. In order to eliminate this source of error, Peirce designed a pendulum with knives that extended from each side of the cylindrical staff, and he received authorization from the superintendent of the Coast and Geodetic Survey to arrange for the construction of such pendulums by Gautier in Paris. Peirce, who had made his plans in consultation with Gautier, was called home before the pendulums were completed, and these new instruments remained undelivered.

In a memoir titled “Effect of the flexure of a pendulum upon its period of oscillation,” Peirce determined analytically the effect on the period of a pendulum with a single elastic connection between two rigid parts of the staff. Thus, Peirce discovered experimentally the flexure of the staff and derived for a simplified case the effect on the period. It is not known if he ever found the integrated effect of the continuum of elastic connections in the pendulum. Lorenzoni, in 1896, offered a solution to the problem, and Almansi, in 1899, gave an extended analysis. After the independent discovery of the problem at the Geodetic Institute, Dr. Helmert took up the problem and criticized the theories of Peirce and Lorenzoni. He then presented his own theory of flexure in a comprehensive memoir. In view of the previous neglect of the flexure of the pendulum staff in the reduction of observations, Helmert directed that the Geodetic Institute make a new absolute determination of the intensity of gravity at Potsdam. For this purpose, Kühnen and Furtwängler used the following reversible pendulums which had been constructed by the firm of A. Repsold and Sons in Hamburg:

1. The seconds pendulum of the Geodetic Institute procured in 1869.

2. A seconds pendulum from the Astronomical Observatory, Padua.

3. A heavy, seconds pendulum from the Imperial and Royal Military-Geographical Institute, Vienna.

4. A light, seconds pendulum from the Imperial and Royal Military-Geographical Institute.

5. A /2-second, reversible pendulum of the Geodetic Institute procured in 1892.

Work was begun in 1898, and in 1906 Kühnen and Furtwängler published their monumental memoir, “Bestimmung der Absoluten Grösze der Schwerkraft zu Potsdam mit Reversionspendeln.”

The acceleration of gravity in the pendulum room of the Geodetic Institute was determined to be 981.274 ± 0.003 cm/sec. In view of the exceptionally careful and thorough determination at the Institute, Potsdam was accepted as the world base for the absolute value of the intensity of gravity. The absolute value of gravity at some other station on the Potsdam system was determined from the times of swing of an invariable pendulum at the station and at Potsdam by the relation T1/T2 = g2/g1. Thus, in 1900, Assistant G. R. Putnam of the Coast and Geodetic Survey swung Mendenhall pendulums at the Washington base and at Potsdam, and by transfer from Potsdam determined the intensity of gravity at the Washington base to be 980.112 cm/sec. In 1933, Lt. E. J. Brown made comparative measurements with improved apparatus and raised the value at the Washington base to 980.118 cm/sec.

In view of discrepancies between the results of various relative determinations, the Coast and Geodetic Survey in 1928 requested the National Bureau of Standards to make an absolute determination for Washington. Heyl and Cook used reversible pendulums made of fused silica having a period of approximately 1 second. Their result, published in 1936, was interpreted to indicate that the value at Potsdam was too high by 20 parts in 1 million. This estimate was lowered slightly by Sir Harold Jeffreys of Cambridge, England, who recomputed the results of Heyl and Cook by different methods.

Figure 31.—Map showing the distribution of gravity stations throughout the United States as of December 1908.

Figure 32.—Map showing the distribution of gravity stations throughout the United States in 1923.

In 1939, J. S. Clark published the results of a determination of gravity with pendulums of a non-ferrous Y-alloy at the National Physical Laboratory at Teddington, England, and, after recomputation of results by Jeffreys, the value was found to be 12.8 parts in 1 million less than the value obtained by transfer from Potsdam. Dr. Hugh L. Dryden of the National Bureau of Standards, and Dr. A. Berroth of the Geodetic Institute at Potsdam, have recomputed the Potsdam data by different methods of adjustment and concluded that the Potsdam value was too high by about 12 parts in a million. Determination of gravity at Leningrad by Russian scientists likewise has indicated that the 1906 Potsdam value is too high. In the light of present information, it appears justifiable to reduce the Potsdam value of 981.274 by .013 cm/sec for purposes of comparison. If the Brown transfer from Potsdam in 1933 was taken as accurate, the value for the Washington base would be 980.105 cm/sec. In this connection, it is of interest to note that the value given by Charles S. Peirce for the comparable Smithsonian base in Washington, as determined by him from comparative methods in the 1880’s and reported in the Annual Report of the Superintendent of the Coast and Geodetic Survey for the year 1890-1891, was 980.1017 cm/sec. This value would appear to indicate that Peirce’s pendulums, observations, and methods of reduction of data were not inferior to those of the scientists of the Royal Prussian Geodetic Institute at Potsdam.

Doubts concerning the accuracy of the Potsdam value of gravity have stimulated many new determinations of the intensity of gravity since the end of World War II. In a paper published in June 1957, A. H. Cook, Metrology Division, National Physical Laboratory, Teddington, England, stated:

At present about a dozen new absolute determinations are in progress or are being planned. Heyl and Cook’s reversible pendulum apparatus is in use in Buenos Aires and further reversible pendulum experiments have been made in the All Union Scientific Research Institute of Metrology, Leningrad (V N I I M) and are planned at Potsdam. A method using a very long pendulum was tried out in Russia about 1910 and again more recently and there are plans for similar work in Finland. The first experiment with a freely falling body was that carried out by Volet who photographed a graduated scale falling in an enclosure at low air pressure. Similar experiments have been completed in Leningrad and are in progress at the Physikalisch-Technische Bundesanstalt (Brunswick) and at the National Research Council (Ottawa), and analogous experiments are being prepared at the National Physical Laboratory and at the National Bureau of Standards. Finally, Professor Medi, Director of the Istituto Nazionale di Geofisica (Rome), is attempting to measure the focal length of the paraboloidal surface of a liquid in a rotating dish.

Application of Gravity Surveys

We have noted previously that in the ancient and early modern periods, the earth was presupposed to be spherical in form. Determination of the figure of the earth consisted in the measurement of the radius by the astronomical-geodetic method invented by Eratosthenes. Since the earth was assumed to be spherical, gravity was inferred to be constant over the surface of the earth. This conclusion appeared to be confirmed by the determination of the length of the seconds pendulum at various stations in Europe by Picard and others. The observations of Richer in South America, the theoretical discussions of Newton and Huygens, and the measurements of degrees of latitude in Peru and Sweden demonstrated that the earth is an oblate spheroid.

Figure 33.—Gravity characteristics of the globe. Deductions as to the distribution of matter in the earth can be made from gravity measurements. This globe shows worldwide variations in gravity as they now appear from observations at sea (in submarines) as well as on land. It is based on data from the Institute of Geodesy at Ohio State University.

The theory of gravitation and the theory of central forces led to the result that the intensity of gravity is variable over the surface of the earth. Accordingly, determinations of the intensity of gravity became of value to the geodesist as a means of determining the figure of the earth. Newton, on the basis of the meager data available to him, calculated the ellipticity of the earth to be /230 (the ellipticity is defined by (a-b)/a, where a is the equatorial radius and b the polar radius). Observations of the intensity of gravity were made on the historic missions to Peru and Sweden. Bouguer and La Condamine found that at the equator at sea level the seconds pendulum was 1.26 Paris-lines shorter than at Paris. Maupertuis found that in northern Sweden a certain pendulum clock gained 59.1 seconds per day on its rate in Paris. Then Clairaut, from the assumption that the earth is a spheroid of equilibrium, derived a theorem from which the ellipticity of the earth can be derived from values of the intensity of gravity.

Figure 34.—An exhibit of gravity apparatus at the Smithsonian Institution. Suspended on the wall, from left to right, are the invariable pendulums of Mendenhall (/2-second), Peirce (1873-1874), and Peirce (1881-1882); the double pendulum of Edward Kübel (see fig. 15, p. 319), and the reversible pendulum of Peirce. On the display counter, from left to right, are the vacuum chamber, telescope and flash apparatus for the Mendenhall /4-second apparatus. Shown below these are the four pendulums used with the Mendenhall apparatus, the one on the right having a thermometer attached. At bottom, right, is the Gulf apparatus (cover removed) mentioned in the text, shown with one quartz pendulum.

Early in the 19th century a systematic series of observations began to be conducted in order to determine the intensity of gravity at stations all over the world. Kater invariable pendulums, of which 13 examples have been mentioned in the literature, were used in surveys of gravity by Kater, Sabine, Goldingham, and other British pendulum swingers. As has been noted previously, a Kater invariable pendulum was used by Adm. Lütke of Russia on a trip around the world. The French also sent out expeditions to determine values of gravity. After several decades of relative inactivity, Capts. Basevi and Heaviside of the Indian Survey carried out an important series of observations from 1865 to 1873 with Kater invariable pendulums and the Russian Repsold-Bessel pendulums. In 1881-1882 Maj. J. Herschel swung Kater invariable pendulums nos. 4, 6 (1821), and 11 at stations in England and then brought them to the United States in order to make observations which would connect American and English base stations.

The extensive sets of observations of gravity provided the basis of calculations of the ellipticity of the earth. Col. A. R. Clarke in his Geodesy (London, 1880) calculated the ellipticity from the results of gravity surveys to be 1/(292.2 ± 1.5). Of interest is the calculation by Charles S. Peirce, who used only determinations made with Kater invariable pendulums and corrected for elevation, atmospheric effect, and expansion of the pendulum through temperature. He calculated the ellipticity of the earth to be 1/(291.5 ± 0.9).

The 19th century witnessed the culmination of the ellipsoidal era of geodesy, but the rapid accumulation of data made possible a better approximation to the figure of the earth by the geoid. The geoid is defined as the average level of the sea, which is thought of as extended through the continents. The basis of geodetic calculations, however, is an ellipsoid of reference for which a gravity formula expresses the value of normal gravity at a point on the ellipsoid as a function of gravity at sea level at the equator, and of latitude. The general assembly of the International Union of Geodesy and Geophysics, which was founded after World War I to continue the work of Die Internationale Erdmessung, adopted in 1924 an international reference ellipsoid, of which the ellipticity, or flattening, is Hayford’s value /297. In 1930, the general assembly adopted a correlated International Gravity Formula of the form γ = γE(1 + β(sin φ) + ε(sin 2φ)) where γ is normal gravity at latitude φ, γE is the value of gravity at sea level at the equator, β is a parameter which is computed on the basis of Clairaut’s theorem from the flattening value of the meridian, and ε is a constant which is derived theoretically. The plumb line is perpendicular to the geoid, and the components of angle between the perpendiculars to geoid and reference ellipsoid are deflections of the vertical. The geoid is above the ellipsoid of reference under mountains and it is below the ellipsoid on the oceans, where the geoid coincides with mean sea level. In physical geodesy, gravimetric data are used for the determination of the geoid and components of deflections of the vertical. For this purpose, one must reduce observed values of gravity to sea level by various reductions, such as free-air, Bouguer, isostatic reductions. If g0 is observed gravity reduced to sea level and γ is normal gravity obtained from the International Gravity Formula, then Δg = g0 - γ is the gravity anomaly.

In 1849, Stokes derived a theorem whereby the distance N of the geoid from the ellipsoid of reference can be obtained from an integration of gravity anomalies over the surface of the earth. Vening Meinesz further derived formulae for the calculation of components of the deflection of the vertical.

Geometrical geodesy, which was based on astronomical-geodetic methods, could give information only concerning the external form of the figure of the earth. The gravimetric methods of physical geodesy, in conjunction with methods such as those of seismology, enable scientists to test hypotheses concerning the internal structure of the earth. Heiskanen and Vening Meinesz summarize the present-day achievements of the gravimetric method of physical geodesy by stating that it alone can give:

1. The flattening of the reference ellipsoid.

2. The undulations N of the geoid.

3. The components of the deflection of the vertical ζ and η at any point, oceans and islands included.

4. The conversion of existing geodetic systems to the same world geodetic system.

5. The reduction of triangulation base lines from the geoid to the reference ellipsoid.

6. The correction of errors in triangulation in mountainous regions due to the effect of the deflections of the vertical.

7. Geophysical applications of gravity measurements, e.g., the isostatic study of the earth’s interior and the exploration of oil fields and ore deposits.

With astronomical observations or with existing triangulations, the gravimetric method can accomplish further results. Heiskanen and Vening Meinesz state:

It is the firm conviction of the authors that the gravimetric method is by far the best of the existing methods for solving the main problems of geodesy, i.e., to determine the shape of the geoid on the continents as well as at sea and to convert the existing geodetic systems to the world geodetic system. It can also give invaluable help in the computation of the reference ellipsoid.

Summary

Since the creation of classical mechanics in the 17th century, the pendulum has been a basic instrument for the determination of the intensity of gravity, which is expressed as the acceleration of a freely falling body. Basis of theory is the simple pendulum, whose time of swing under gravity is proportional to the square root of the length divided by the acceleration due to gravity. Since the length of a simple pendulum divided by the square of its time of swing is equal to the length of a pendulum that beats seconds, the intensity of gravity also has been expressed in terms of the length of the seconds pendulum. The reversible compound pendulum has served for the absolute determination of gravity by means of a theory developed by Huygens. Invariable compound pendulums with single axes also have been used to determine relative values of gravity by comparative times of swing.

The history of gravity pendulums begins with the ball or “simple” pendulum of Galileo as an approximation to the ideal simple pendulum. Determinations of the length of the seconds pendulum by French scientists culminated in a historic determination at Paris by Borda and Cassini, from the corrected observations with a long ball pendulum. In the 19th century, Bessel found the length of the seconds pendulum at Königsberg and Berlin by observations with a ball pendulum and by original theoretical considerations. During the century, however, the compound pendulum came to be preferred for absolute and relative determinations.

Capt. Henry Kater, at London, constructed the first convertible compound for an absolute determination of gravity, and then he designed an invariable compound pendulum, examples of which were used for relative determinations at various stations in Europe and elsewhere. Bessel demonstrated theoretically the advantages of a reversible compound pendulum which is symmetrical in form and is hung by interchangeable knives. The firm of A. Repsold and Sons in Hamburg constructed pendulums from the specifications of Bessel for European gravity surveys.

Charles S. Peirce in 1875 received delivery in Hamburg of a Repsold-Bessel pendulum for the U.S. Coast Survey and observed with it in Geneva, Paris, Berlin, and London. Upon an initial stimulation from Baeyer, founder of Die Europäische Gradmessung, Peirce demonstrated by experiment and theory that results previously obtained with the Repsold apparatus required correction, because of the flexure of the stand under oscillations of the pendulum. At the Stuttgart conference of the geodetic association in 1877, Hervé Faye proposed to solve the problem of flexure by swinging two similar pendulums from the same support with equal amplitudes and in opposite phases. Peirce, in 1879, demonstrated theoretically the soundness of the method and presented a design for its application, but the “double pendulum” was rejected at that time. Peirce also designed and had constructed four examples of a new type of invariable, reversible pendulum of cylindrical form which made possible the experimental study of Stokes’ theory of the resistance to motion of a pendulum in a viscous fluid. Commandant Defforges, of France, also designed and used cylindrical reversible pendulums, but of different length so that the effect of flexure was eliminated in the reduction of observations. Maj. Robert von Sterneck, of Austria-Hungary, initiated a new era in gravity research by the invention of an apparatus with a short pendulum for relative determinations of gravity. Stands were then constructed in Europe on which two or four pendulums were hung at the same time. Finally, early in the present century, Vening Meinesz found that the Faye-Peirce method of swinging pendulums hung on a Stückrath four-pendulum stand solved the problem of instability due to the mobility of the soil in Holland.

The 20th century has witnessed increasing activity in the determination of absolute and relative values of gravity. Gravimeters have been perfected and have been widely used for rapid relative determinations, but the compound pendulums remain as indispensable instruments. Mendenhall’s replacement of knives by planes attached to nonreversible pendulums has been used also for reversible ones. The Geodetic Institute at Potsdam is presently applying the Faye-Peirce method to the reversible pendulum. Pendulums have been constructed of new materials, such as invar, fused silica, and fused quartz. Minimum pendulums for precise relative determinations have been constructed and used. Reversible pendulums have been made with “I” cross sections for better stiffness. With all these modifications, however, the foundations of the present designs of compound pendulum apparatus were created in the 19th century.

Formatting of equations has been altered from the original to display them ‘in line,’ and brackets have been added to clarify expressions where necessary.

Footnotes have been moved to the end of the paper. Illustrations and the Glossary of Gravity Terminology section have been moved to avoid breaks in paragraphs. Minor punctuation errors have been corrected without note. Typographical errors and inconsistencies have been corrected as follows:

P. ‘difference T1 - T2 is sufficiently’—had ‘sufficlently.’

P. ‘faites à Genève avec le pendule à réversion’—had ‘reversion.’

P. ‘Schwere mit Hilfe verschiedener Apparate’—had ‘verschiedene.’

P. ‘between the yard and the meter.’—closing quote mark deleted.

P. ‘Mendenhall apparatus were part of’—‘was’ changed to ‘were.’

P. ‘of the Geodetic Institute at Potsdam’—had ‘Postdam.’

P. ‘The gravimetric methods of physical’—had ‘mtehods.’

Footnote ‘Société française de Physique’—had ‘Française.’

Footnote ‘Cogitata physico-mathematica’—had ‘physica.’

Footnote ‘mathématiques et de physique par MM. de l’Académie Royale’—had ‘mathematiques,’ ‘Royal.’

Footnote ‘par ordre du Roy au Pérou, pour observer’—had ‘Perou, pour observir.’

Footnote ‘Opticam et Astronomiam’—had ‘Astronomian.’

Footnote ‘connaître la longueur du pendule qui’—had ‘connaitre la longuer.’

Footnote ‘Abhandlungen der Königlichen Akademie’—had ‘Königliche.’

Footnote ‘pour déterminer la longueur du pendule’—had ‘longeur.’

Footnote ‘Survey of India (Calcutta, 1879)’— had ‘Surey.’

Footnotes and ‘Société de Physique et d’histoire’—had ‘d’historire.’

Footnote ‘Über die Grösse und Figur der Erde’—had ‘Grosse.’

Footnote ‘Bestimmung der Länge’—had ‘Lange’; ‘Astronomisch-Geodätische Arbeiten’—had ‘Astronomische’; ‘Veröffentlichungen des Königlichen’—had ‘Königliche.’

Footnote ‘(1768), vol. 58, pp. 329-335.’—had ‘329-235.’

Footnote ‘Comptes-rendus de l’Académie’—had ‘L’Académie.’

Footnote ‘Sur l’Intensité absolue’—had ‘l’Intensite.’

Footnote ‘Sitzungsberichte der Königlicher’—had ‘Königliche.’

Footnote ‘Veröffentlichungen des Königlichen’ had ‘Veröffentlichungen Königliche.’

Capitalisation of ‘Von’/‘von’ has been regulaized to ‘von’ for all personal names, except at the beginning of a sentence, and when referring to the Von Sterneck pendulum.

Index

Quick link to each letter:

A

Adams, W. B.,
Agricola, Georgius, ,
Airy, G. B., , ,
Albrecht, Karl Theodore, ,
Aldini, Giovanni,
Al-Mamun, seventh calif of Bagdad,
Almansi, Emilio,
Ames Manufacturing Company, ,
Ampère, André Marie, ,
Anckerswärd, Col. Michael,
Angle, Edward H.,
Arago, Dominique François Jean,
Aristarchus of Samos,
Aristotle, ,
Astor, John Jacob,

B

Baeyer, Adolf,
Baeyer, J. J., , , –, ,
Baily, Francis,
Baldwin, Matthias William,
Baltimore, Lord. See Calvert.
Barlow, Peter W., ,
Bartlett, Charles A.,
Basevi, James Palladio,
Battison, E. A.,
Beach, Alfred Ely, , –, ,
Bechil, Achild,
Bemis, Will, –,
Bennet, Abraham,
Bennett, Frank M., , ,
Benz, Carl, ,
Bergh, Christian,
Berroth, A.,
Berthelot, Marcellin,
Bertolla, Alessandro,
Bertolla, Bartolomeo Antonio, , , –, , , , –, ,
Berzelius, Jöns Jakob, ,
Bessel, Friedrich Wilhelm, , , , , , , ,
Besson, Jacques,
Bettany, G. T.,
Beyer, Dr. Henry Gustav, ,
Biddle, James,
Biot, Jean Baptiste, , ,
Black, G. V.,
Black and Bell, plant at Stratford,
Blake, John B., ,
Bohnenberger, Johann Gottlieb Friedrich,
Bollman, W., and Company, ,
Bollman, Wendel, , –, , –, –
Borda, J. C., , , , , ,
Borghesi, Father Francesco, –, ,
Boscovitch, Père R. J., ,
Boston Locomotive Works,
Bouguer, Pierre, , – , ,
Boussingault, Jean Baptiste,
Boyd, John C.,
Boyle, Robert, ,
Brackenridge, S. M.,
Brahe, Tycho, ,
Brand, H., ,
Brewington, M. V.,
Brown, Adam and Noah, , ,
Brown, Alexander Crosby,
Brown, E. J., ,
Brown, Noah, , ,
Browne, Charles,
Browne, Henry, ,
Browns’ yard, ,
Bruhns, C., , ,
Brunel, I. K., ,
Brunel, Marc Isambard (the elder), , , , , , , , ,
Brunner Brothers (Paris),
Buchner, Hans, ,
Burleigh, Charles, ,
Burleigh Rock Drill Company,
Burr, S. D. V.,
Butzjäger, Johann Georg, ,

C

Calvert, George, Lord Baltimore,
Calvin, Melvin,
Canning, Stratford,
Carlisle, Anthony,
Carrel, Alexis,
Casciarolo, Vicenzo,
Cassini, Giovanni-Domenico, ,
Cassini, Jacques,
Cassini de Thury, J. D., , , , , ,
Cavallo, Tiberio,
Cavendish, Henry,
Cellérier, Charles, , , , , ,
Chapman, Fredrik Henrik af, ,
Charles II of England, ,
Charles VI, Emperor of Austria,
Chevreul, Michel,
Clairaut, Alexis Claude, , , ,
Clark, J. S.,
Clark, John,
Clarke, A. R.,
Cles, Baron of, ,
Coast and Harbor Defense Company,
Coast Defense Society, ,
Cochrane, Sir Thomas, ,
Colbert, Jean Baptiste,
Colburn, Zerah,
Colden, C. D.,
Coleman, Laurence V.,
Colgan, P.,
Colton, Arthur, and Company,
Cook, A. H.,
Cook, Guy S., ,
Copernicus,
Copperthwaite, William Charles,
Cori, Carl F.,
Cori, Gerti T.,
Crookes, William,
Cummings, James, , –, –

D

Dagger, Benjamin M.,
Danforth Cooke & Co.,
Danish Greenland Company,
Danish Royal Archives, ,
Davy, Sir Humphry,
Dearborn, Henry, ,
Deats, William,
Decatur, Stephen,
Defforges, C., , ,
De Freycinet, Louis Claude de Saulses,
De Hevesy, George, ,
De la Hire, Gabriel Philippe,
De la Vega, Garcilaso,
De Prony, M. G.,
Deptford Yard (England),
De Saussure, Théodore,
Di Noris, Cristoforo Sizzo,
Dixon, William S.,
Doane, Thomas, , , ,
Dodrill, Forest D.,
Donner, Joseph,
Douglas, W. & B., Company,
Drake, Edwin L.,
Drinker, Henry S., ,
Drury, Gardner P.,
Dryden, Hugh L.,
Du Buat, L. G.,
Duperry, Capt. Louis Isidore,
Duryea, Charles, 3-, , , –, ,
Duryea, J. Frank, 3-7, 9-, –, ,
Duryea Motor Corporation,
Duryea Motor Wagon Company, ,
Duryea Power Company,

E

Eastwick, Andrew M.,
Eckford, Henry,
Einthoven, Willem,
Emerson, John Haven,
Emmet, ——,
Eratosthenes, , ,
Erman, Paul, , , ,
Eudoxus of Cnidus,
Euler-Chelpin, Hans von, ,
Evans, Samuel, ,
Evelyn, John,

F

Faraday, Michael,
Faye, Hervé, –, –, ,
Ferchl, Fritz,
Fernel, Jean,
Fernelius, Jean,
Feulgen, Robert,
Fink, Albert, ,
Fischelis, Robert P.,
Fischer, Emil,
Fleming, Sir Alexander, ,
Flint, James Milton, –
Fox, Josiah,
Francis I, Emperor of the Holy Roman Empire, , , ,
Fulton, Robert, , , , , , , , , ,
Furtwängler, P., –

G

Gahn, Johann Gottlieb,
Galilei, Galileo, , ,
Galvani, Luigi,
Garfield, James A.,
Garrison, Fielding H.,
Gauss, C. F.,
Gautier, P.,
Gay-Lussac, Joseph Louis, ,
Gilbert, L. W., –,
Gobley, Nicolas Théodore,
Godin, Louis,
Goldingham, John, ,
Goode, G. Brown,
Graham, Thomas, , ,
Gravatt, C. U.,
Greathead, James Henry, , , , , , , –
Greely, A. W.,
Griffenhagen, George B., ,
Grubenmann, Hans,
Grubenmann, Johann Ulrich,
Gulf Oil and Development Company,
Gurley, Ralph R. (USN), ,
Gustav III of Sweden, ,
Gwynn, Stuart,

H

Hahn, Father Philipp Matthäus,
Haid, M.,
Hall, Basil,
Hammond, William Alexander,
Hankwitz, Gottfried,
Harden, Arthur, ,
Harrington, Frank,

Harrison, Joseph, Jr.,
Hartford Machine Screw Company,
Hartmann, Immanuel Peter,
Haskin, DeWitt C., , , –
Haupt, Herman, , , ,
Hawley, C. E., ,
Hawthorn, Leslie, and Company (Scotland),
Heaviside, W. J., ,
Heiskanen, W. A., , ,
Hellot, Jean,
Helmert, F. R., ,
Helmholtz, Hermann von,
Henderson, Alfred R.,
Henkel, Silon,
Henry II, King of France,
Herschel, John, , ,
Heyl, Paul R., ,
Hindle, Charles F.,
Hinkley, Holmes, , ,
Hirsch, Adolph, , –
Hittorf, Wilhelm,
Hobson, Joseph,
Hoefer, Ferdinand,
Holmberg, Wilhelm,
Holt, L. Emmett,
Hoppe-Seyler, Felix,
Howard, George W., & Company,
Hull, A. S., ,
Humboldt, Alexander von,
Huygens, Christiaan, , , , , , ,

I

Ibañez, Carlos,
Incas,

J

Jefferson, Thomas,
Jeffreys, Sir Harold,
Jones, Jacob,
Jones, Thomas,
Jones, William,

K

Kater, Henry, , –, , , , ,
Kells, Charles E.,
Klein, Father ——,
Kletwich, Johann Christopher,
Knight, ——,
Koett, Albert B.,
Koppe, Émile,
Kornberg, Arthur,
Kossel, Albrecht,
Kraft, Johann Daniel,
Kramer, Dr. ——,
Kühnen, F., –
Kunckel, Johann,

L

La Condamine, Charles Marie de, , , ,
Lange, W.,
Laplace, Marquis Pierre Simon de, , ,
Latrobe, Benjamin H., , , , –, ,
Laurie, J.,
Lavoisier, Antoine Laurent, ,
Law, Henry,
LaWall, Charles H.,
Laws, John Bennet,
Lederle Laboratories,
Leibnitz, Gottfried Wilhelm von,
Lennox, Charles, third Duke of Richmond,
Leonhardi, Johann Gottfried,
Levine, Phoebus Aaron Theodor,
Lewis, Jacob,
Lewis, Morgan,
Lewton, Frederick L.,
Liebig, Justus, , ,
Liebreich, Oscar,
Lilly, Eli, and Company,
Lindbergh, Charles A.,
Lipmann, Fritz,
Lippi, Fra Lippo,
London, E. S.,
Long, Crawford W.,
Long, Stephen H.,
Longomontanus, Christian Severin,
Lorenzoni, Giuseppe, ,
Lütke, Count Feodor Petrovich, ,

M

Macquer, Peter Joseph,
Marestier, Jean Baptiste, , , ,
Marggraf, Andreas Sigismund,
Maria Theresa, Empress of Austria, , , , , ,
Mariners’ Museum,
Markham, Erwin F., , , , , –,
Marmion, R. A.,
Marsh, James,
Marshall, Charles, ,
Maudslay, Henry, ,
Maupertius, P. L. Moreau de, ,
Maxwell, James Clerk,
May, Arthur J.,
Mayer, Jo,
McMurtrie, Daniel,
Medi, Enrico,
Meigs, M. C.,
Meineke, ——,
Mendenhall, Thomas Corwin, , , , ,
Merrick, C. E.,
Mersenne, P. Marin,
Meton,
Meyerhof, Otto, ,
Miescher, Johann Friedrich,
Miller, Patrick, ,
Mitchill, Samuel L., ,
Monauni, Giovanni Battista, ,
Monroe, James,
Montgéry, M., , –,
Morgan, "Mr.",
Morris, Tasker and Company,
Morris, Thomas, ,
Morton, Arthur O.,
Morton, William,
Mount Clair shops, , ,
Mowbray, George W., ,
Muspratt, James,

N

Nagel, Oscar P.,
Nason, Joseph,
National Maritime Museum (England), , ,
Nelson, Robert J.,
Nesbitt, Mr. and Mrs. D. H.,
Newton, Sir Isaac, –, , , ,
Nicholson, William,
Nietzsche, Friedrich, , ,
Nobel, Alfred B.,
North, Simeon, arms factory,
Norwood, Richard,

O

Ochoa, Severo,
Oersted, Hans Christian, –, –
Ohm, Georg Simon, ,
Oken, Lorenz,
Olson, Carl G.,
Oppolzer, Theodor von, , –
Owen, H. S.,

P

Page, Irving,
Parke, Davis & Company,
Parmelee, L. J.,
Patapsco Bridge and Iron Works, ,
Patrick, Mr. and Mrs. ——,
Patterson, Carlile Pollock, ,
Peirce, Charles Sanders, , –, , –, , –
Pelouze, Théophile Juste,
Pepys, Samuel,
Perry, Oliver,
Peters, C. A. F., ,
Petty, Sir William, , , ,
Pfaff, Christian Heinrich,
Philolaus,
Phoenix Iron Works,
Physick, Philip Syng,
Picard, Abbé Jean, , –,
Plantamour, E., –, –
Poggendorf, Johann Christian, –, –,
Poissant, A. A.,
Pope Manufacturing Company, ,
Porter, David,
Posidonius,
Pratt, Thomas W.,
Preston, E. D., ,
Ptolemy,
Purcell, William,
Putnam, G. R.,
Putnam Machine Works,
Pythagoras, ,

Q

Quare, Daniel,

R

Raschig, Christoph Eusebius,
Rasmussen, Kjeld,
Reed, D. A.,
Reeves, Samuel J., ,
Repsold, A., and Sons (Hamburg), , , , ,
Richer, Jean, ,
Richmond, Duke of. See Lennox.
Riciolus,
Rigsarkivet (Denmark),
Ritter, Johann Wilhelm,
Roebling, John A., ,
Roentgen, Wilhelm Konrad, ,
Rouelle, Guillaume François,
Royal Society of London,
Russell, John W., & Sons Company, , , ,
Russell, William J., , , ,
Rutgers, Henry, ,

S

Sabine, Capt. Edward, , , ,
San Cajetano, Brother David à,
San Daniele, Father Aurelianus à,
Savage Factory,
Savart, Felix,
Sawitsch, A., ,
Scheele, Karl W.,
Schieffelin and Company,
Schmiedeberg, Oswald,
Schrader, Gerhard,
Schrötter, Anton,
Schumacher, H. C.,
Schumann, R., ,
Schweigger, Johann Salomo Christoph, –, –,
Seebeck, T., ,
Shanley, Walter,
Shanley Bros.,
Shea, T.,
Smith, —— (Captain, USN),
Smith, Alba F., , , ,
Smith, Sir Sidney (RN),
Smith Carriage Company,
Snell, Willebrord,
Snow, ——,
Soemmering, S. T.,
Sommeiller, Germain,
Sonnedecker, Glenn,
Speter, M., ,
Squibb, E. R., and Sons, ,
Statens Sjöhistoriska Museum (Sweden),
Stephenson, Robert,
Stephenson, Robert, & Hawthorns, Ltd.,
Sterneck, Robert von, , ,

, ,
Stevens, J., Arms and Tool Company,
Stevens-Duryea Company,
Stewart, Charles,
Stiles, George,
Stokes, George Gabriel, , , , ,
Stoklasa, Julius,
Storrow, Charles S.,
Stoudinger, Charles,
Strecker, Adolf Friedrich,
Stuart, Charles B., ,
Stuart, J. E. B.,
Sully, Henry,
Swaine, Jack,
Symington, William,

T

Tanner, Paul H.,
Taunton Locomotive Works,
Taylor, Frank A.,
Tegmeyer, John H.,
Thames Iron-works Company (England),
Thenard, Louis Jacques,
Thomas, George S.,
Thudichum, Ludwig,
Todd, Lord Alexander,
Tompion, Thomas,
Toner, Joseph Meredith,
Tovazzi, Giangrisostomo, ,
Town, Ithiel,
Tromsdorff, Johann Bartholomacus,
Tweed, William Marcy (Boss),
Tyler, Daniel, ,
Tyler, David B.,

U

Ulloa, Antonio de,
Union Works,
Uppercu, Inglis M.,

V

Vander Woerd, Charles, ,
Van Marum, Martin,
Vening Meinesz, F. A., , , –
Volet, Charles,
Volta, Alessandro, , ,
Vulcan Foundry,

W

Wallace Brothers,
Ward, Frederick A.,
Warrington, Samuel,
Warwick, George,
Watts, Frederick,
Weale, John,
Wernwag, Lewis,
Westhaeffer, Paul,
Wetmore, Dr. Alexander,
Wetschgi, Emanuel,
Wetschgi, Manuel, ,
Whipple, Squire, , , , ,
Whistler, George W.,
White, C. H.,
Whitebread, Charles, , , , , ,
Whitney arms factory,
Wilkes, Charles, ,
Wilkinson, David,
Williamson, Dowe,
Williamson, Joseph,
Willm, Edmond,
Willstätter, Richard,
Wilmarth, Seth, , , , ,
Wilson, Frank E.,
Wilstack, Paul,
Winans, Ross,
Winters, Joseph,
Winters, Father S. X., S. J.,
Winz, Johann Christian, ,
Wisshofer, Peter, ,
Wolcott, Oliver, ,
Wollaston, W. H.,
Wright, Benjamin,
Wurtz, Adolphe, ,

Y

Youle, John, foundry,

Z

Zamboni, Giuseppe,

‘Emmet, ——, 144’—was ‘Emmett, ——, 144’.

Compiler's Notes