540 THE EXTERIOR OF THE HORSE. 



of the step, and permits each foot to leave the ground only after a well- 

 balanced position of the one which has preceded in the action, the body 

 being supported after each elevation by the other three members. 1 



In descending an inclined plane the centre of gravity, on the con- 

 trary, draws nearer to the fore-limbs and hinders their free displace- 

 ment forward, while the posterior, less burdened, have a tendency to 

 take longer steps. It happens, then, that the latter mark their imprints 

 well in front of the former. If the load be heavy, however, the 

 animal endeavors to fix himself to hold the burden, and the base 

 remains constantly tripedal, to give more stability to the equilibrium. 

 The steps, in this case, are short and the posterior imprints by no 

 means cover the anterior. 



Length. The absolute length of the step cannot be indicated 

 with precision, on account of the individual differences and also the 

 numerous variations of this gait, according as it is slow, ordinary, or 

 accelerated. Nevertheless, it oscillates within mean limits which it is 

 proper to recognize. 



According to Vincent and Goiffon, the length of the step should be 

 equal to the height of the body measured from the withers to the 

 ground. The cavalry regulation of 1829 places it at 1.66 m. Vallon, 

 Messrs. Raabe and Barroil, and M. Lenoble du Teil estimate it at 1.80 

 m. for a horse 1.60 m. high, or one and a half times the length of the 

 base of support. Finally, M. Duhousset considers it equal to the 

 length of the body measured from the point of the arm to that of the 

 buttock. 



This difference of opinion is due to the fact that these authors 

 have studied neither the same variety of the walk nor subjects of the 

 same height, the same race, the same temperament, and the same con- 

 formation. Besides, the steps in the same animal are not absolutely 

 equal. They vary, according to Professor Colin, 2 within the limits of 

 11 to 13 centimetres for the short walk, 17 for the ordinary walk, and 

 20 for the long walk ; the horses upon which our learned colleague has 

 experimented had a mean height of 1.55 m. and a base of support of 

 1.20 m. 



Speed. The absolute speed of this gait is almost as difficult of 

 appreciation, for analogous reasons. At the same time it is possible to 

 adjust it to an almost uniform standard. 



The cavalry regulation of 1829 relegates it to 100 metres per 



1 G. Colin, Physiologic compare des animaux, 3e.6d., t. i. p. 471. 



2 G. Colin, loc. cit., 3e d., t. i. p. 472. 



