The Flying Falcon and the Flying Eagle

The skeleton of an animal formed for flight must be constructed upon mechanical principles of a very refined character. No one can have examined attentively the bony framework whereby the body of a bird is sustained without being forcibly impressed with the lightness and compactness of its construction. It is by no means our intention to trouble the reader with unnecessary details concerning the anatomy of the creatures upon the history of which he is about to enter. Nevertheless it is indispensable requisite that we should give at least an outline of their internal organization. The extent to which the skeleton is thus filled with air varies in different birds in relation with their powers of flight. In the swifts and the hummingbirds, every bone of the