72 



MECHANISM OF DRAUGHT. 



The force applied to the collar by the animal is obtained in two different 

 ways, first, by the weight of the animal, and second, by the force of propulsion 

 to which I have just alluded. 



The weight of the animal acts on the collar by reason of the centre of 

 gravity being placed in front of the base of support {see p. 57), the anterior 

 limit of which is marked by the position of the toe of the fore foot which is 

 on the ground. It is evident that the further a perpendicular dropped from 

 the centre of gravity falls in front of the base of support, the more effectively 



Fig. 33. — Mechanism of Draught. (From Colin's Physiologic Comparee) 



will the weight of the body act in propulsion. This forward translation of 

 the centre of gravity with reference to the position of the base of support, is 

 influenced, first, by the degree of slope which the fore leg makes with the 

 ground immediately before it quits it, and before the other fore leg is brought 

 down ; and, second, by the lowering of the head and neck. I need hardly 

 say that horses with toe-pieces to their fore shoes can bring the centre of 

 gravity farther beyond the base of support, by the slope of the fore leg which 

 rests on the ground, than they could do with flat shoes ; supposing, of course, 



