

TIIK HOKSI-: ix MOTION. 107 



run, to check the force of the descent, which, from the loss of hori- 

 zontal momentum, has little more than the momentum of gravity to 

 deal with. This is the moment of extreme clanger to the pastern joint 

 and flexor tendons; but before these parts are put to the extreme test 

 the other fore leg comes to the relief of its fellow, and immediately 

 after the posterior extremities, one after the other, are planted under 

 the centre of gravity, and by their great lifting force relieve the ante- 

 rior extremities, and all the limbs are free to act their various parts in 

 the run, which is not fairly resumed in this series, the velocity at 

 no time being sufficient to enable the animal to clear the ground. 

 The action after the leap may be still further traced in Plate XXXIII. 

 where the run is not yet fully resumed, the speed being only equal to 

 the disposition of the limbs as in the canter, the order being the same 

 as in the run. The last illustration of the leap that we offer is very 

 curious. The horse was very reluctant to perform the leap required of 

 him, and came to a standstill immediately in front of the hurdle, and 

 only after great urging did he attempt to surmount it. The action of 

 the locomotive organs is shown to be the same in this as in the other 

 series representing the leap, only with less courage manifested ; and 

 there is little danger in its execution. As the horse lost his horizontal 

 momentum before leaping, so he had none when he reached the ground 

 on his descent. It should be observed that in all these series the 

 intervals between the successive pictures are those of space and not of 

 lime, as the horse makes his own pictures in a manner that will be 

 fully explained in the Appendix. The intervals in all the series of 

 twenty-four pictures represent distances of one foot in a horizontal 

 direction. Fig. 2, Plate XXXV., shows the position of the skeleton 

 as the animal meets the contact with the earth. By means of these 

 skeleton views the reader is enabled to build up the entire loco- 

 motive apparatus with the aid of the anatomical plates, and satisfy him- 

 self as to the forces that are employed in producing the movements. 



On reference to Plates XXIII. and XXIV., it will be perceived how 

 great is the correspondence in the action of the deer in bounding and 

 the horse in leaping. In both the action on leaving the ground is 

 the same. When the hind feet are upon the ground, well under the 



