THE FOOT AND SHOEING. 223 



The frog. — The whole surface of the frog being naturally in contact The frog, 

 with the ground, helps to sustain the animal's weight ; but its main 

 functions are to give a firm non-slipping foot-hold, and save the leg from 

 the effects of the tremendous shock, jar, and concussion which half a ton 

 weight of horse travelling at anything up to twenty miles an hour must 

 produce, every time the hoof comes to the ground. Its consistency, that 

 of indiarubber, is perfectly adapted to obviate slipping and also to minimise 

 concussion, and in this last duty it is but one part of the beautiful 

 natural machinery provided for the purpose and which deserves special 

 consideration. 



The effects of concussion are minimised as follows : — When the leg The effects 

 is extended for a step forward, at whatever pace, the toe is slightly ^^^R"" 

 turned up and the heel comes to the ground first. The weight of the ^i^Tm^sed 

 body then passes over the foot, and as it does so, the pastern is bent i^y 

 downwards and backwards, the cannon, knee and arm are kept straight, shoulder, 

 and the angles made by the shoulder bones vary as the weight passes, pastern, 

 The elastic angles made by the pastern and shoulder at each end of the 

 limb greatly lessen the shock, as compared with that which would be 

 sustained by a rigid, upright column, and they are greatly assisted by the 

 structure of the back of the foot. Here, as previously stated, there is 

 no bony foundation, but two springy cartilages, a thick cushion of cushion of 

 elastic material between them, and an indiarubber-like frog beneath ; heels, frog, 

 and this is the part which first makes contact with the ground at 

 each stride. The frog is squashed downwards and forwards giving a firm 

 hold, and both it and the cushion above bulge out a little as the weight is and 

 imposed, and aided by the cartilages regain their shape when it is cartilages, 

 removed. The whole mechanism acts like a non-skidding, pneumatic 

 tyre to the body, excepting that it does not wear out from constant 

 use. In actual shoeing it is not always practicable to get the frog 

 absolutely on the ground when the shoe is new ; depending of course 

 on the thickness of the web ; but the sooner this can be brought about 

 the better. 



The movements of the hoofs when the foot comes to the ground, and jJ^gntT of^~ 

 the weight of the body passes over it, are very slight ; and for the ^.j^g hoofs, 

 practical purpose of shoeing, may be disregarded. There is a slight 

 bulging round the coronet, where the horn is thin and soft, and a little 

 widening of the heels. This latter may be readily appreciated by looking at 

 a well-worn shoe, when a bright spot will be observed from the constant 

 rubbing to and fro at this place. It is not, however, a movement which 

 has to be allowed for in shoeing, as it does not extend as far forward as 

 the heel nails. 



