. British birds. Birds. 116 BRITISH BIRDS. horizon, and the wind due to his own velocity acts at right angles to the plane, offering much support and very little resistance. Great velocity is in all cases essential. When a Rook flaps leisurely along, yet the pace at which the extremities of his wings move is very great. The next point to grasp is that the downward movement of the wings is able not only to lift the bird but to propel him. In rapid flight the wing is first raised high Fig. 1.—Lesser Black-biieked Gulls off Mogador. and then its movement is at once downward and forward, t
. British birds. Birds. 116 BRITISH BIRDS. horizon, and the wind due to his own velocity acts at right angles to the plane, offering much support and very little resistance. Great velocity is in all cases essential. When a Rook flaps leisurely along, yet the pace at which the extremities of his wings move is very great. The next point to grasp is that the downward movement of the wings is able not only to lift the bird but to propel him. In rapid flight the wing is first raised high Fig. 1.—Lesser Black-biieked Gulls off Mogador. and then its movement is at once downward and forward, the front margin being all the while lower than the hinder. The force of the air impinging against the wing acts at right angles to it, and, the wings having the incline I have described, the bird is not only lifted but urged forward. In fact the parallelogram of forces is energetically at work. The force acting at right angles to the wing is resolved into two—one lifting, the other j)ropelling. On this resolution of one force into two all flight Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original London, Witherby & Co
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherl, booksubjectbirds
