86 FARM MECHANICS 



tumbling rod by means of keys or set-screws. The 

 mowing-machine drive wheel travels around in a cir- 

 cle behind the mule turning the shaft which works the 

 walking-beam and operates the pump. It would be 

 difficult to design another horse or mule power so 

 cheap and simple and effective. The mule grows wise 

 after a while, so it is necessary to use a blindfold, or he 

 will soldier on the job. With a little encouragement 

 from a whip occasionally a mule will walk around and 

 around for hours pulling the mowing-machine wheel 

 after him. 



HORSEPOWER 



One horsepower is a force sufficient to lift 33,000 

 pounds one foot high in one minute. 



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 cir- 

 cle 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 limita- 

 tions which the separator outgrew. 



