ACTION OF THE MUSCLES. 67 



his hind-quarters of weight and puts it on his fore-hand. When, on the 

 contrary, he prepares to rear, he raises his head and neck and more or 

 less hollows his loins, so as to lighten his fore-hand and put more weight 

 on his hind-quarters. If we examine Figs, 147 and 148 of the canter, 

 Figs. 172 to 175 of the gallop, and Figs. 224 to 228 of the leap, we shall 

 see that the muscles which enable a horse to rear, greatly aid the forward 

 reach of the fore legs in these movements. Also, the heavier the fore- 

 hand, the greater difficulty will they have to raise it. In the leap, they 

 assist the leading fore leg in raising the fore-hand. If the horse carries 

 a rider, these muscles will have an increased amount of work to do on 

 account of extra weight being put in front, and will tire at a proportion- 

 ately rapid rate. On examining the illustrations of horses in Chapter XII. 

 at the various paces, we shall see that the faster the movement, the more 

 will these muscles be taxed, on account of the greater distance of the 

 centre of gravity from the hind feet, during the period one or both of 

 the hind limbs support and propel forward the weight of the body. 

 Hence we find that to gallop fast or to jump " big," a horse must have 

 good " rearing muscles " which consist principally of those that straighten 

 the hock, draw back the thigh, and extend the vertebrae of the loins. 

 These muscles also help to " lighten " the fore-hand in the flying trot 

 and fast " pacing," in both of which there is a period of suspension, 

 which will vary in length according to the weight that is on the fore- 

 hand. From these considerations, we may lay down the law that the 

 faster the speed required, the stronger should the " rearing muscles " 

 be. The pair of them (one on each side) that is most readily noticed, 

 is the loin muscles, which in the ox constitute the upper cut of a sirloin,; 

 and which, in the horse, we may see just behind the cantle of the saddle. 

 It is evident that the heavier the shoulder, the sooner will these 

 muscles become tired ; the shorter will be the stride ; and the slower 

 will be the speed. Consequently, horses for fast work ought to have 

 light shoulders. Carrying out the same train of reasoning, we may 

 see that the longer a horse's body, the greater will be the mechanical 

 disadvantage at which these muscles will work ; hence, a short body is 

 a desirable point in the race-horse and jumper. 



The combined working of oblique shoulders, well -sloped pasterns and 

 strong rearing muscles, by preventing the fore-hand going down at each 

 stride, aids in obtaining the much admired " level " action in the race- 

 horse. An animal which has a long body, heavy shoulders, upright 

 pasterns and weak loins (showing deficiency in the points just advocated), 

 will, if he be put to a gallop, go in an up-and-down style ; because his 

 rearing muscles will be over-taxed by the weight of the fore-hand at 

 the end of the long lever made by his body, and because his fetlock 

 joints will have deficient " play." 



Although the loin muscles appear to be almost quiescent during 



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