In the fall, the annual cycle of the seasons turns once more—and one of the great phenomena of this season is the migration of the birds.
Stand on the shore of one of our northern lakes some quiet evening. You will hear hundreds of tiny chirps above you as vast flights of small birds—sparrows, warblers, and the like—move toward the south.
For many, many years, men have wondered why the birds migrate as they do, and more to the point, how they do it. They are still wondering.