SIZE OF BIRDS’ WINGS.

Otago Daily Times, Issue 20288, 22 December 1927, Page 7

SIZE OF BIRDS’ WINGS.

A problem -which from the first has called for intense study in aeronautics has been the finding of an answer to “ Why do small birds have to have larger wings than big ones?” and, “ Why do they have to move their larger wings more rapidly?” says Dr Austin H. Clark, of the Smithsonian Institution, at Wasn ington (U.S.A.). “It is a curious fact,” ho says, “ that the larger the animal the smaller in proportion are the wings.” Small birds have relatively larger wings than big ones, according to Dr (Ink, and insects have relatively much >rger wings than birds. In a butterfly of the average size, ho says, etich pound of body weight represents a winged area ot three square yards, eight square feet, and 37 square inches. In the swallow tills is reihif ed io only four square feel .itnl 73 square inches, and in the stork to only l£i square inches, more rapidly than larger ones, says Dr Clark The wing of the humming bird vibrates so rapidly that it is difficult to register it. The wing heats of the sparrow are 730 per minute, of the pigeon 430 and of the crow about 120. Two functions are performed for a bird b v its wines; by them it is lifted from the ground and also is propelled. It has been demonstrated, Dr Clark points out, that if a light object is thrown, it wih not travel so far as a heaviei _ objict thrown a: the same speed. When a large aad heavy bird once gets -tar)eel, •> ,-r.l qivclv --mail fore' l will keep " r oo The lighter and smaller a biro the less

~ "m ,-r j>ll r •,J. d. mg. ol a ■ . heavy bird- servo chiefly to maintain -p.'-il, v.liilc the wings of small ligut biiii- ni'i-t con-tan:lv lift the bird am, cir.T' it forward Laiue bird-, however, while tin v fly with much less effort, have greater difficulty in stopping, says Dr Clark.

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