10 INTEODUCTOKY CHAPTER. 



to represent a treatise on equitation or the art of riding, 

 but merely to be a plain and easily intelligible exposi- 

 tion of the mechanical problems connected with the 

 case of a quadruped serving as a bearer to a biped — in 

 other words, of a horse under its rider. 



The plan to be adopted will be, first, as regards 

 " Seats and Saddles," as follows : The horse's skeleton 

 is a framework forminof the basis of the living machine 

 we employ as a bearer ; it is therefore necessary to 

 know something of its construction, less from an ana- 

 tomical than a mechanical point of view. The prin- 

 ciples involved are very simple, and familiar to most 

 people in one way or the other, regarding chiefly equi- 

 librium — that is to say, such a distribution of a weight 

 with reference to its supports as insures stability, or, 

 in other words, prevents its upsetting or falling ; also 

 something about levers. 



The chief weight to be carried by the machine is, of 

 course, the rider, whose seat should therefore be so ad- 

 justed as not to interfere with the free action of the 

 bearer and the preservation of its stability and equilib- 

 rium. But as the seat dej)ends to a great extent on 

 the saddle, it becomes necessary to examine, in the 

 first place, the general principles of construction of 

 this mechanical contrivance, by means of which the 

 twofold object of securing the free action of the horse 

 and the safety of the rider may be best attained. This 

 will be found to depend partly on the absolute amount 

 of surface coming in contact on the one hand with the 

 horse's back, on the other with the rider's seat ; partly 

 on the way in which the weight of the latter is ad- 

 justed on the saddle — that is to say, whether it presses 

 more on one part than on another, and consequently, 



