20 THE EXTERIOR OF THE HORSE. 



At the superior part of the members the articular surface is a cavity more 

 or less deep. It may be considered as being formed by a succession of inclined 

 planes whose inclination diminishes from the periphery to the centre. It thus 

 disseminates the weight of the body upon the head, which is adapted to it. The 

 latter acts in the same manner a second time, alternating the actions of the mass 

 by disseminating them upon the ligaments at the same time as upon the bones. 

 On a level with the second articulation of the members we find other inclined 

 surfaces ; these surfaces are multiplied towards the carpus and tarsus ; finally, 

 they are found in the articulations of the hand and foot. 



Thus more and more the weight of the body is disseminated upon the bony 

 columns through the existence of these diverse inclinations, and the volume of the 

 bones decreases in proportion to the efforts which they support. 



Another mode of dispersion, again very remarkable, is that which M. 

 Mignon l calls the inclined plane of the segment, in contradistinction to the pre- 

 ceding, which he names inclined plane of surface. 



" In order to establish the existence of these planes in animal machinery," 

 he says, " it is sufficient to observe that in the members the bony segments super- 

 pose themselves by being diversely inclined and by thus forming a series of angles 

 at their reciprocal points of union. As these angles do not become closed, as the 

 action of the weight is one by its direction, that is to say, vertical, and as the 

 oblique segment, immediately inferior, receives this action, the latter is then trans- 

 mitted in the direction of the osseous segment ; and, since it has followed this in- 

 clined segment, it undergoes the influence of this oblique plane which conducts 

 and supports it ; that is to say, it is decomposed into two parts, one of which is 

 perpendicular to the segment, the other parallel to it and follows its direction. 



"The flexible supports upon which the segments or inclined planes act 

 therefore become one of the elements of these planes. 



" If we now examine the mechanical dispositions of the support, we find that 

 the weight of the body is dispersed and attenuated upon a series of inclined planes, 

 which receive, decompose, and transmit this weight; that the solid segments, 

 more and more numerous, support that portion of the weight transmitted parallel 

 to the plane and decompose it in their turn ; that the flexible parts sustain like a 

 spring the other portion of the weight perpendicular to the different planes ; 

 finally, that the levers and pulleys favor, aid, or increase the action of these 

 springs which move and extend intelligent forces that graduate and measure in 

 some manner the entire influence claimed by the necessity of the moment. 



" Such is the mechanical system, as simple as it is ingenuous, which concen- 

 trates or disseminates action, produces and directs it, increases or diminishes it, 

 resists or combats it." 



These primary ideas being well understood, we may now begin the particular 

 study of the regions. 



1 Mignon, loc. cit., pp. 69 et 71. 



