72 MECHANISM OF EQUINE LOCOMOTION. 



Fatigue from the various Paces. — In comparing the fatigue 

 undergone during certain paces, we must be guided by the consideration 

 of the respective distances through which the centre of gravity of the 

 body has to be moved. Let us first of all consider its vertical, and 

 afterwards its horizontal, displacement out of the straight line of the 

 direction in which it has to travel. In the walk and at all other paces in 

 which there is no period of suspension (p. lOo), it is carried nearly parallel 

 to the ground, with only a slight fall when each fore leg is taken up. 

 At paces in which there is a period of suspension, the centre of gravity 

 will have to be raised just as much as it will fall during that time. This 

 fact is best marked in jumping ; for in making even a long leap, the 

 centre of gravity will have to be raised a considerable height. Thus, 

 when Howard, of Bradford, the famous jumper and sprinter, leaped 

 over a full-sized billiard-table lengthwise, he was computed to have 

 cleared a height of five feet four inches. Hence, animals like the antelope 

 and cheetah, which adopt, when going at full speed, a leaping style of 

 gallop (p. 142), can keep it up only for a short time. This fact is par- 

 ticularly well marked in the case of the kangaroo. For the same reason, 

 a horse can go a distance with more ease to himself at a slow trot (which 

 has no period of suspension), than at the flying trot (p. 102) or gallop 

 (p. 120), in both of which there is a period of suspension. Not only 

 does the consideration of the comparative rise and fall of the centre of 

 gravity give us an idea of the relative fatigue undergone during the 

 various paces ; but it also furnishes us with a guide to judge the 

 comparative ease with which different horses move at the same pace. 

 Consequently, we may conclude that the more " level " a horse goes, 

 whether at the fast trot, gallop, or other pace, the less will he fatigue 

 himself : a fact which proves how thoroughly reasonable is the admir- 

 ation every good judge has for a " level " style of movement — that is, 

 one in which there is the least possible rise and fall of the fore-hand 

 at each stride. I have purposely used the word " fore-hand " here. 

 When noting whether the action of a horse is level or not, we are usually 

 guided by the presence or absence of up-and-down motion of the fore- 

 hand ; for the special' prominence of the head and neck will more or 

 less rivet the attention of our eyes. Besides, the centre of gravity of 

 a horse's body is nearer his fore legs than his hind ones. 



As soon as fast antelopes, like the Indian Black Buck and South 

 African Springbok, get tired in their bounding gallop, they " settle 

 down " to one resembhng that of the horse (Figs. 172 to igi). When 

 the cheetah — which, as far as I have seen, galloj^s like the cat 

 (Figs. 212 to 217), in a succession of leaps — becomes tired of that 

 pace, he drops into a walk or trot. 



On pages 68 and 69, allusion has been made to the effects of lateral 

 displacement of the centre of gravity in causing fatigue. 



