EFFECT OF INSTABILITY OF EQUILIBRIUM ON SPEED. 71 



not sufficient to raise the centre of gravity to the required height 

 at fast paces ; extra work is required for the upward projection 

 of the fore-hand, from the muscles which straighten the fore leg. 

 Hence, the faster the pace, the greater will be the muscular expendi- 

 ture of the fore limbs, as compared to the speed. Consequently, when 

 a horse gallops fast, the muscles of his fore-hand tire much more 

 quickly than those of his hind limbs. Agreeably to this fact, we 

 find that when pedestrians and skaters respectively compete in short 

 distance races, they bend their bodies much more for\vard, than when 

 going a long journey. Also, when a horse begins to tire in a long 

 distance race, like the Cesarewitch, his ordinary " level " style of 

 " going " generally becomes changed more or less into an up-and- 

 down motion, which is caused by the muscles of his fore-hand being 

 too fatigued to work in unison with those of his hind quarters. A 

 reasonable deduction from the foregoing remarks, is that a saddle- 

 horse, to be a stayer, should be light in front, especially as the 

 presence of his rider causes a disproportionate amount of weight to 

 be placed on his fore legs. 



It is evident that the chief advantage which is gained from the 

 " crouching jockey's seat," as regards speed, is due to the fact that 

 the forward position of the rider increases the instability of the 

 equilibrium of the horse. As this seat puts extra work on the 

 muscles of the fore-hand, it is not suitable for a long distance 

 journey, or for jumping. 



The fact of a horse "pulling," naturally brings the weight forward, 

 by means of the reins, and thus increases the instability of equilibrium. 



In the case of a saddle-horse travelling at a fast pace, the resist- 

 ance of the rider's body to the wind decreases, to some extent, the 

 instability of his animal's equilibrium. Hence, in this respect, speed 

 is favoured by the crouching position, and is diminished by an erect 

 one. As a somewhat parallel case, we find that a well-marked accelera- 

 tion of speed on American trotting tracks has been obtained by dis- 

 carding high sulkies for low ones (Fig. 60), and increasing the short- 

 ness of the " hitch." In modern sulkies, the weight is brought 

 forward and the resistance to the air is reduced as much as possible. 

 In heavy draught, the stability of the horse's equilibrium is greatly 

 increased, as a rule, by the resistance which the collar offers to 

 forward movement, and consequently the muscles of his hind limbs 

 usually become much more quickly tired, than those of his fore legs. 



As it is imperative that the body of an animal intended for speed 

 should be as light as possible, provided he has sufficient bone and muscle 

 to meet his requirements ; the preponderance of weight on the fore 

 hand should be obtained by conformation, and not by any approach to 

 " heaviness " in that part. 



