 | Perry Fairfax Nursey - 1827 - 472 pàgines
...necessary that they should all shut close together, forming each wing into a complete surface or weo, when they are, by the muscular power of the bird,...specific gravity indeed. The webs of the quill feathers arc broader on one side of the shafts than the other, which causes them to open as the wings move up,... | |
 | 1835 - 430 pàgines
...upper air pass through the wings, to facilitate their ascent, when they are struck upwards ; it was also necessary that they should all shut close together,...astonishing strength with elasticity, and very little specifick gravity indeed. The webs of the quill feathers are broader on one side of the shafts than... | |
 | 1835 - 430 pàgines
...upper air pass through the wings, to facilitate their ascent, when they are struck upwards ; it was also necessary that they should all shut close together,...astonishing strength with elasticity, and very little specifick gravity indeed. The webs of the quill feathers are broader on one side of the shafts than... | |
 | Aeronautical Society of Great Britain - 1877 - 556 pàgines
...upper air pass through the wings, to facilitate their ascent when they are struck upwards ; it was also necessary that they should all shut close together,...the quill feathers are broader on one side of the shaft than the other, which causes them to open as the wings move up and to shut as they come down,... | |
 | 1894 - 642 pàgines
...upper air pass through the wings, to facilitate their ascent when they are struck upwards ; it was also necessary that they should all shut close together,...the quill feathers are broader on one side of the shaft than the other, which causes them to open as the wings move up and to shut as they come down,... | |
 | 1908 - 766 pàgines
...through the wings to facilitate their ascent when they are struck upwards, and to shut close together when they are, by the muscular power of the bird,...to give a more secure hold upon the air below, and thus sustain the bird. The main point emphasized in his treatise is that of the great importance of... | |
 | Francis Herbert Wenham - 1910 - 168 pàgines
...AERONAUTICAL SOCIETY OF GREAT BRITAIN, By KING, SELL & OLDING, LTD , 27, Chancery Lane, WC 1 9 1 O the bird, forced down in order to give a more secure...the quill feathers are broader on one side of the shaft than the other, which causes them to open as the wings move up and to shut as. they come down,... | |
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... elasticity ; it was expedient too that the quill feathers should separate and open to let the upper air pass through the wings, to facilitate their ascent when they are struck upwards ; it was also necessary that they should all shut close together,... 