66 



THE ANIMAL AS A MACHINE. 



of the wheel and representing a 36-lb. pull. The load 

 having been moved farther to the rear, the lift at the 

 belly-band is still 10 lbs. at P — the load is moved back- 

 ward to shift the centre of gravity. The resultant of 

 the two components PA and PB is PC, and PC now 

 equals about 35.9 lbs., whereas the resultant AD in 

 Fig. 6 is only 33 lbs., or 2.9 lbs. less than on the level. 

 It will now be found that 36 lbs. pull through PA will 

 increase the horse's weight 4.5 lbs., represented by 

 PO, which is determined by drawing AO from A 

 parallel with the horizon, cutting the line of gravity 



Fig. 2.— Haulage of Vehicles. 



But, as the disposition of the load is such that 10 lbs. 

 are taken from the horse, it is obvious that, if only 4.5 

 lbs. are put back by the stated pull of 36 lbs., the horse 

 has still 5.5 lbs. less than his natural weight in Fig. 2, 

 while in Fig. i he has 4 lbs. more than his natural 

 weight. 



