20 SEATS AND SADDLES. 



rests on the fore legs than on the hind ones, owing, 

 as one sees, to the projecting position of the head and 

 neck, which are much heavier than the tail at the 

 other extremity. 



Looking now at the spinal column, the framework of 

 the back, on which the rider's weight is to be placed, 

 we perceive that, whilst the under line of the vertebra? 

 is nearly straight, although not quite horizontal, inclin- 

 ing somewhat downwards towards the forehand, the 

 spinal processes of the first thirteen vertebrae of the 

 back (dorsal vertebrae), reckoning from the point where 

 the neck is attached, incline backwards, whereas those 

 of the fifteenth, sixteenth, seventeenth, and eighteenth 

 dorsal, and the six lumbar vertebrae, incline forwards 

 the fourteenth dorsal vertebra, with its process, stand- 

 ing perfectly upright, and forming, as it were, the 

 keystone of the arch thus presented. It is very obvi- 

 ous that this inclination of the processes towards a 

 central point is intended to and does limit the motion 

 of the back downwards and upwards (i.e., vertically), 

 so that, in fact, this fourteenth dorsal vertebra be- 

 comes the centre of motion of the horse's body the point 

 about which the several movements of the fore and 

 hind legs are performed with various degrees of rapidity, 

 either simultaneously or successively, and which con- 

 stitute the paces of the horse; and this is further 

 shown by the distribution and points of attachment of 

 the muscles of the back and adjacent parts of the fore 

 and hind quarters. Putting, therefore, the progressive 

 movement of the animal out of the question as being 

 equally applicable to all its parts, the internal motion 

 of the several parts of the body increases in proportion 

 to their distance from the fourteenth vertebra; and the 



