THE ANIMAL AS A MOTOR. 



65 



the load being behind the axle, the forward weight 

 of the animal is reduced by the lift of the shafts at A, 

 and the result is the same as if the traces had been 

 put up at the point D, and the load, with a 33-lb. pull 

 through such a trace, would be exactly balanced. 



Let UV represent the horizon passing through the 

 point D. If DA represents 33 lbs., then FA will 



(J 



Besultant of Coviponents A B and A C as A or N D added 

 to Horse's Weight, ND equals h taken from the Load 

 and Carried by the Horse. 



Fig. I . — Haulage of Vehicles. 



represent 4 lbs., so that 4 lbs. must be added to the 

 horse's natural weight by the pull AD. Or, if the pull 

 through the trace AB is 36 lbs., then, drawing BE 

 parallel with the horizon UV, EA (14 lbs.) will repre- 

 sent the depression due to a 36-lb. pull through AB. 

 But when the hft due to the shafts, 10 lbs., is deducted 

 from the depression of 14 lbs., there remains as before 

 an increased weight of 4 lbs. on the horse. 



When the horse is pulling with the same force upon 

 a level, as in Fig. 2, we find very different results. 

 Let PA be the direction from the hames to the centre 



