CENTRE OF GRAVITY. 9 



We have also sought to appreciate the extent of the posterior and anterior dis- 

 placements of the line of gravitation in other different conditions, for example, with 

 the mounted horse, according as the rider sits erect, leans forward or backward, 

 or as he carries his head high or low. The displacements of this line are then 

 determined, whether in front of or behind its average position, which oscillate be- 

 tween two and six centimetres, sometimes more, according to the case. Differ- 

 ences of weight, quite considerable, are equally produced in weighing both of the 

 lateral bipeds when the head, the neck, the trunk, or the rider is inclined ~to 

 one side, facts which show the importance of the lateral displacements of the 

 centre of gravity during locomotion, especially the work of dressing. But it is 

 in horses high or low in front that the variations of the weight of the fore or 

 hind extremity assume importance. These have no longer the momentary or 

 accidental character of the preceding, and from this fact always involve, accord- 

 ing to the case, a permanent surcharge of one of the two bipeds, anterior or 

 posterior, and consequently their premature ruin. Their gravity augments in 

 horses low over the withers when from the nature of their employment they 

 are obliged to carry burdens, as in the service of the saddle, the shafts, or the 

 pack-saddle. 



In order to prove this, we weighed successively several subjects, by placing 

 them first upon the plank of a weighing-machine perfectly horizontal ; then we 

 raised gradually sometimes the anterior quarters, sometimes the posterior, so as 

 to obtain, at will, horses having the fore or hind quarters low. The height was 

 carefully noticed at the beginning of each trial, and then it was known exactly 

 how much the croup or the withers were raised or lowered. The results were 

 then in all points comparable, since in all cases the observations were made 

 upon the same subject. They were found to be in conformity with the theory, 

 and may be considered as a corroboration of the preceding experiments. We 

 have chronicled them in the following tables : 



l.-ELEVATION OF THE HEIGHT AT THE WITHERS. 



