FARM ANIMALS. 129 



the whole body would be at rest in any position, whatever. 

 The vertical line through the center of gravity is called 

 the line of gravitation. In draft horses the center of 

 gravity is low, and tends to a forward position ; in horses 

 having speed the center of gravity is high, and tends to 

 a rear position. 



The point at which the line of gravitation meets the 

 ground may be determined if we know (1) the weight of 

 the horse, (2) weight on fore feet, and (3) length of base 

 of support (distance between fore and hind feet when 

 standing). 



423. A horse weighs 978 pounds, of which 565 pounds 

 are on the front feet, and 413 pounds on the hind feet. 

 When the distance between the points of contact with the 

 ground of the front and hind feet is 43 inches, how far in 

 front of point of contact of hind feet does the line of 

 gravitation fall? 



Process : 



Let F weight on front feet. 

 H = weight on hind feet. 

 D = distance between points of contact (front and hind 



feet). 



X = distance of line of gravitation forward of hind feet. 

 Y = distance of line of gravitation back of fore feet. 



F X D 



X = - and Y = D X 

 F + H 

 565 X 413 

 X = = 25 



565 4- 413 

 Y = 43 25 = 18 



Note. This formula is an expression of the following prin- 

 ciple in physics. The line of action of the resultant of two 

 parallel forces divides the distance between them in the inverse 

 ratio of that of the two forces. This formula contains four 

 quantities. It may be used to find any one of them when the 

 remaining three are known. 



424. A horse sustains 570 pounds on his fore feet and 



