732 SHOEING. 



THE FOOT AS A SPRING.— Besides the action of the foot as 

 a lever, it also serves as a spring; the mechanical advantages of 

 the one being directly opposed to those of the other. Thus, the 

 better the leverage, the worse the spring ; and vice versd. It is 

 evident from the considerations already discussed, that the lower 

 the heels with relation to the toe and the less upright the pastern, 

 the greater freedom does the leg enjoy from concussion ; although 

 the power which it derives from the back tendons will work at a 

 greater mechanical disadvantage. 



COMPARATIVE LEVERAGE AND SPRING OF THE FORE 

 AND HIND FEET.— Were there no such thing as injury to the 

 limbs from concussion, the hoof would naturally be got as upright 

 as practicable, so as to allow the back tendons to work at the 

 greatest possible mechanical advantage. The bad effects of con- 

 cussion have, however, to be provided for, especially as regards the 

 fore-feet, which are much more liable to suffer from them than are 



Fig. l86.— Slope of 50°, fore hoof. Fig. 187.— Slope of 55°, hind hoof. 



the hind feet. It is impossible to determine with exactness the 

 proper respective slopes of the fore and hind hoofs ; but from an 

 examination of a large number of feet which have never worn iron, 

 I conclude that the former should be about 50° and the latter not 

 less than 56° (Figs. 186 and 187). It is instructive to note that a 

 considerable amount of power of propulsion is lost by the angle of 

 inclination of the hind feet being too small ; which condition is 

 also a predisposing cause of spavin (p. 253). This is a practical 

 point which is very important to owners, and especially to those 

 who keep race-horses. 



MEASURING THE SLOPE OF THE HOOF.— Fig. 188 (p. 733) 

 will explain the action of a clinometer I devised for this purpose. 

 It can be made out of a piece of wood, ivory, metal, cardboard, or 

 other suitable material, and it is provided with a plumb line. 



LOWERING THE HOOF.— If the foot is of the proper slope, 

 but too long, it should be reduced equally at heels, quarters, and 



