The term "horsepower" in popular use years ago meant a collection of gear-wheels and long levers with eight or ten horses solemnly marching around in a circle with a man perched on a platform in the center in the capacity of umpire. This was the old threshing-machine horsepower. It was the first real success in pooling many different farm power units to concentrate the combined effort upon one important operation. Not many horses are capable of raising 33,000 pounds one foot in one minute every minute for an hour or a day. Some horses are natural-born slackers with sufficient acumen to beat the umpire at his own game. Some horses walk faster than others, also horses vary in size and capacity for work. But during a busy time each horse was counted as one horsepower, and they were only eight or ten in number. And it so developed that the threshing horsepower had limitations which the separator outgrew. The old threshing horsepower has been superseded by steam engines and gasoline and kerosene power, but horses are more important than ever. [Illustration: Figure 109.--Horse Power, showing the manner of attaching the braced lever to the bull wheel.] Farm horses are larger and more powerful; they are better kept, better trained, and hitched to better machinery, because it pays. One man drives three 1,600-pound draft horses as fast as he used to drive two 1,000-pound general-purpose horses. The three drafters make play of a heavy load, while the two light horses worry themselves poor and accomplish little. Modern farm machinery is heavier, it cuts wider and digs deeper and does more thorough work. Modern farm requirements go scientifically into the proper cultivation and preparation of soil to increase fertility. Old methods used up fertility until the land refused to produce profitably. Although the old familiar horsepower has been greatly outclassed, it has not been discarded. There are many small horsepowers in use for elevating grain, baling hay, cutting straw for feed and bedding, grinding feed and other light work where engine power is not available. WATER-POWER