430 THE HORSE. 



is directed behind the centre of the foot, and the yielding point? 

 of the framework are the pastern, coronary and navicular joints ; 

 as the upper part of the coronary bone works backward and down- 

 ward, it, with the action of the tendon, slightly spreads the heels 

 laterally, and the whole crust partakes of the movement, diminish- 

 ing in effect towards the toe ; were the foot completely inelastic, the 

 motion might be detected at the quarters, but the whole of a healthy 

 foot is of a yielding nature ; the fatty heels, in particular, may be 

 compressed like cork, while the frog resembles a piece of india- 

 rubber, and there is a spring in every fibre of the crust. These 

 conditions so far distribute motion, that there is practically none 

 in the ground surface of the crust forward of the centre. 



From the fact of this style of shoe allowing free expansion, its 

 advocates proclaim it a preventive of contracted heels (which, un- 

 fortunately, is so prevalent among shod horses) ; but if, as we sup- 

 pose, there be no spreading of the front part of the crust by pressure, 

 a shoe nailed only at, and forward of the quarters, will not interfere 

 with any natural movement of the heels. 



This disease (contracted heels), which has been described on 

 page 409, appears to be an absorption or waste of a portion of 

 the frog and fatty heels, accompanied by an undue secretion of 

 crust at the posterior part of the foot, encroaching upon the pro- 

 vince of the softer tissue of the heels. 



Many reasons have been assigned for this disturbance of the 

 natural nutrition of the different parts, all or none of which may 

 be correct, for no theory has yet been so clearly demonstrated and 

 proven, as to leave the causes and nature of the disease beyond a 

 doubt, but we have never known any tendency to contraction, in 

 horses that have been shod in such manner as to allow the frog a 

 fair amount of exercise, indicated by its position. 



An india-rubber shoe intended to be used as a cushion between 

 the iron and the foot, has been designed, patented and tried, within 

 the last two or three years, but we believe has failed to give gene- 

 ral satisfaction* The rubber mashes out in a short time by con- 

 cussion, and leaves a loose shoe. Good sole leather is much more 

 durable. 



Until recently, the whole process of making the shoe was per- 

 formed by hand, but now in the United States, the greater bulk is 

 made by machinery, and at one immense establishment. 



The manufactory of Messrs. Burden & Sons, at Troy, New York 

 state, with its six forging machines, turns out six shoes per second, 

 and in four years made twenty-five thousand tons ; or calculating 

 one and a half pounds to the shoe, thirty-seven million shoes. 

 These shoes are of the very best iron, warranted to bend double 

 cold, and to wear as long as any made by hand j the iron used in 



