The Bookshelf for boys and girls: Nature and Outdoor Life (1912)
University Society, New York · New York. : University Society · leaf 40
isfact very properly leads us to believe the typicalshape of these primaries must be the best for thepurpose of flight. Flight-feathers are found to be stiffest andstrongest at their quill ends and most yielding attheir tips. They always overlap in the same way,the outermost feather of the extended… … A TYPICAL BIRD IN FLIGHT. To show the tight overlapping of the flight-feathers, to resist the air, in the downward stroke of the wings. By these arrangements the wing has a valve-likeand an oar-like action upon the air, according,more or less, to the will and purpose of the birdwhether to sail,…
Children's literature · Children's encyclopedias and dictionaries · Literature · Encyclopedias and dictionaries
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