. Animal flight; a record of observation . gs are flexed the greater is the decrease of camberand the greater is the speed. I shall have to describethese changes in greater detail when I bring forwardevidence in a later chapter as to the direction fromwhich the energy of soarability is operative. On the other hand, I discovered that if flexing iscarried out at the metacarpal joint no effect on camberis produced. This metacarpal flexing retires the wing-tip, as seen in the descending bird, but leaves the wingsat their maximum camber. There can, I think, be no doubt that the peculiarappearance o
. Animal flight; a record of observation . gs are flexed the greater is the decrease of camberand the greater is the speed. I shall have to describethese changes in greater detail when I bring forwardevidence in a later chapter as to the direction fromwhich the energy of soarability is operative. On the other hand, I discovered that if flexing iscarried out at the metacarpal joint no effect on camberis produced. This metacarpal flexing retires the wing-tip, as seen in the descending bird, but leaves the wingsat their maximum camber. There can, I think, be no doubt that the peculiarappearance of the descending bird is due to the flexingbeing metacarpal and not carpal. I propose the term metacarpal descent for the mode of descent nowunder 1 Supposing a bird is gliding horizontally with wings extended. Supposing a fore andaft section is taken through the wing, such a section is a section at right angles to, or trans-verse to, the long axis of the wing. The sections shown in figs. 27, 28, and 29 are of ANIMAL FLIGHT. 129 In fig. 27 I show two sections of the wing of theadjutant bird. A represents the section with the wingfully extended, and B the section taken with thesecondaries relaxed by flexing at the carpal joint. .... For taking these sections the wing was held upsidedown. The feathers wereFig. 27. X^A consequently merely ex-tended by their own weight. Sections of wing of an adjutant at elbow-joint : At A withwing extended, at B with wing flexed. For taking these sectionsthe wing was held upside down. The quill feathers assumed theposition given to them by their own weight only. But in actual flight the feathers must be pressedby a force much greater than their own weight. Iattempted to imitate this force by attaching a weightof 10 grammes to each sec-ondary while the wing was . ^-:z--- B held upside down as weight was chosen Fig. 28. Sections of wing of an adjutant taken at junction of middleand inner thirds of the wing.
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