There are two mechanical arrangements, heavier than air, which have been proposed for obtaining flight, namely, wings and aeroplanes. The latter is the one chiefly in favour with the public as there have been more or less successful experiments brought to its notice. There are, however, many advantages for a machine made with wings in imitation of a bird or flying fox as in Nature.

Wings with their large spread and slow motion give more effective action on the air than the small blades of a screw propeller. It is known from experiment that a large surface working slowly is more efficient than a small one working rapidly in a rarefied medium such as air, for the same power expended.