AN EFFECTIVE FRICTION-BBEAK. 77 



as effective in performing this as the Westinghouse on a raih'oad 

 train. 



Short bulky muscles can exert a more potent contractile force than 

 those which are longer, but the thinner and elongated fibres can ac- 

 complish more extensive movements. This is the difference between 

 the part bred quarter-horse and the thoroughbred. The former goes 

 into his stride at once, the quick action of the bunched up muscles 

 in arm and gaskin quickening the action, while the longer leap is 

 deliberate, and the animal is scarcely well settled in his stride when 

 the other is exhausted. 



There has been a great deal of controversy over the question of 

 the greater frequency of break-downs in the long distance runner in 

 comparison with the short horse. Both are shod similarly, and the 

 immunity of the latter would appear to be a strong argument against 

 the claim that the elevation of the heel is detrimental. This does 

 not follow. 



The quarter-horse has little work in proportion, and his races are 

 not so violent a strain. He runs on a hard track, and this is addi- 

 tional proof that it is the effort to rise which injures the tendons. 

 The deeper the sinking of the feet the more violent will be the 

 muscular contractions, and the greater strain on the cords which 

 convey the power. 



Veterinary writei-s agree that one of the surest symptoms of navic- 

 ular diseases is the " pointing " of the afflicted foot. If one only is 

 diseased, it will be constantly thrust forward ; if both, there will be 

 a change every few minutes from the intolerable pain when the foot is 

 under the body. This does not arise so much from the weight as from 

 the position. The further forward the foot is placed, the more resem- 

 blance there is to the low heel, and the similar posture afibrds relief. 

 Cases of navicular disease are extremely rare, excepting where the 

 heels are high, and those we have seen are almost invariably marked 

 by severe contraction. A natural foot, one entirely free from disease, 

 and which has never been shod, presents at the heel a very difierent 

 appearance. The base line is formed by two curvatures of the inner 

 and outer quarters, and these are joined by a reverse curve repre- 

 senting the posterior part of the frog. If the animal be permitted 



