ANIMAL MOTORS 289 



to be noticed in roads in the amount of grip which a horse 

 may get upon the surface while pulling a heavy load. 

 Under ordinary circumstances the improved stone road 

 will not provide the horse with as good a grip as a com- 

 mon earth road. 



407. Height and length. A low, rather long-bodied 

 horse has much the advantage over a tall, short horse 

 for heavy draft work. He has his weight in a position 



FIG. IQ7 OBTAINING THE WORK OF A HORSE WITH A RECORDING 

 DYNAMOMETER 



where he can use it to better advantage. It is an ad- 

 vantage to have the horse's weight well to the front, since 

 there is a tendency, as mentioned before, to balance his 

 weight over his rear foot as a fulcrum. Horses heavy 

 in the foreshoulder have an advantage in pulling over 

 those that are light, as weight in the foreshoulder adds 

 greatly to the ability of the horse to pull. To prove that 

 this is true, it is only necessary to refer to the fact that 

 horses when pulling extend their heads well to the front. 

 408. Direction of trace. A heavy load may be lifted by 

 a common windlass if the pull be vertical, but if the pull 

 be transferred over a pulley and carried off in a horizontal 

 direction the machine must be fastened or it will move. 

 It must be staked and weighted to prevent slipping. This 



