Once upon a time there were no gas (or steam) powered motors. Necessity begets innovation and every discovery simply lays the foundation for the next. Mechanization arose, yet for a long time the only power sources were a person’s two hands or the four legs of a draft animal. An under appreciated amount of hand and draft powered machinery came to be. Among these were horsepower units. A set of gears set in motion by a draft animal walking a circular track pulling a tongue.