ABSTRACT
For half a million years or more man has sought to augment his own bodily power, first with sticks and stones which gave him the mechanical advantage of the lever and the wedge; then, after a vast lapse of time, by means of simple mechanisms operated by man and animal power; and, finally, by an ever-increasing control over the forces of nature. The invention of the wheel and axle is a matter of the highest importance in its bearing on the trend of engineering evolution. Speaking generally, it may be said that the invention of the wheel necessarily preceded the harnessing of external power, the only exception of importance being utilization of the wind for ship propulsion, a step already taken in pre-dynastic Egypt. The matter is of importance in the history of power engineering, as, if this conclusion is correct, it indicates that the windmill was invented at a much earlier time than has hitherto been generally realized.
