Lesson III

How Birds Fly

Leading thought—A bird flies by pressing down upon the air with its wings, which are made especially for this purpose. The bird’s tail acts as a rudder during flight.

Method—The hen, it is hoped will by this time be tame enough so that the teacher may spread open her wings for the children to see. In addition, have a detached wing of a fowl such as are used in farm houses instead of a whisk-broom.

Observations—1. Do you think a bird’s wings correspond to our arms? If so why?

2. Why do birds flap their wings when they start to fly?

3. Can you press against the air with a fan?

4. Why do you jump so high with a vaulting pole? Do you think the bird uses the air as you use the pole?

5. How are the feathers arranged on the wing so that the bird can use it to press down on the air?

6. If you carry an umbrella on a windy morning, which catches more wind, the under or the top side? Why is this? Does the curved surface of the wing act in the same way?

7. Take a wing feather. Are the barbs as long on one side of the quill as on the other? Do they lie at the same angle from the quill on both sides? If not why?

8. Which side of the quill lies on the outer side and which on the inner side of the wing?

9. Is the quill of the feather curved?

10. Which side is uppermost in the wing, the convex or the concave side? Take a quill in one hand and press the tip against the other. Which way does it bend easiest, toward the convex or the concave side? What had this to do with the flight of the bird?

11. If the bird flies by pressing the wings against the air on the down stroke, why does it not push itself downward with its wings on the up stroke?

12. What is the shape and arrangement of the feathers so as to avoid pushing the bird back to earth when it lifts its wings?

13. Why do you have a rudder to a boat?

14. Do you think a bird could sail through the air without something to steer with? What is the bird’s rudder?

15. Have you ever seen a young bird whose tail is not yet grown, try to fly? If so, how did it act?

16. Does the hen when she flies keep the tail closed or open like a fan?

17. Compare a tail feather with a wing feather and describe the difference.