Section 2. 



Locomo tion.* 



The movement of the limbs during locomotion is a question 

 both of theoretical interest and practical importance. This is 

 especially so in the case of the horse, owing to the fact that he is 

 one of the few domesticated animals which has to work, and the fre- 

 quency with which this results in lameness. There are features 

 connected with lameness which can only be explained when the 

 method by which the limbs are employed during progression is 

 understood. Limb movements in the biped are relatively very 

 simple ; in the quadruped there is both simplicity and complexity, 

 the latter owing to the rapidity of movement and the inability to 

 watch four legs at one and the same time. All paces but the simple 

 trot defy accurate visual analysis. It was not until instantaneous 

 photography came to the aid of physiology that the question of the 

 sequence and method of limb combinations during locomotion was 

 finally settled. The name of Muy bridge and his co-workers will for 

 ever remain identified with this inquiry. Without instantaneous 

 photography it would have been impossible to analyse fast paces 

 like the gallop, though it is distinctly remarkable how very close 

 some of the older observers got to the truth. Exactitude, however, 

 was not obtained, nor criticism silenced, until 1878, when the 

 camera, under the direction of Muybridge, set the question of animal 

 locomotion for ever at rest. 



Step and Stride. — When a man walks, the step is the distance 

 between the two feet measured from toe to toe or other con- 

 venient but identical point ; two such steps constitute a stride, 

 which is the distance covered by a foot from the time it leaves 

 the ground until it again reaches it. With quadrupedal locomo- 

 tion the same definition holds good, but the introduction of 

 another pair of legs renders it rather more complex. With 

 the quadruped the step is the distance between any two 

 hind-limbs or any two fore-ltmbs, or any fore and hind limbs 

 employed in moving together. The stride is the distance covered 

 by a fore or hind limb from the time it leaves the ground until 

 it again reaches it. The step and stride can be measured by 

 the impressions left on the ground, though they require great 

 care in order to discriminate carefully between the various feet. 

 In the same horse a step from one hind-foot to its fellow is not 

 always the same length as a step from one fore-foot to its fellow. 

 In the faster paces like the gallop the step taken by the fore- 

 legs is longer than that taken by the hind-legs. In the horse 



* I have to thank Majors F. W. Hunt and Edwards and Captain Wadley, 

 A.V.C., for many observations they have made for me on this subject. 



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