THE HORSE— A MACHINE 5 



nate pair of legs supports the weight while the other pair is 

 executing a stride. The primary motive for the stride is fur- 

 nished by the hindquarters, the propulsive action of which dis- 

 places the centre of gravity forward, to such an extent as to 

 necessitate locomotion in order to maintain or regain the equi- 

 librium. There are five distinct phases of the stride : 



1. A preliminary, during which the leg is imdergoing flexion, 

 but the foot has not left the ground, at which point tlie real stride 

 begins. 



2. The breaking over, in which the foot is raised heel first, 

 finally leaving the ground by being rocked up and over at the 

 toe. 



FiQ. 3. — Each and every phase of the stride ia demonstrated by some one of tlie ten fore 

 and ten hind legs shown. 



3. Flight, during which the foot is describing a more or less 

 regular arc of a perpendicular circle. 



4. Contact, at which point the foot is again brought to the 

 ground.- 



5. [Recovery, as the weight gradually falls on tlic foot and 

 the original position of the leg is momentarily established, pre- 

 paratory to, a repetition of the stride (Fig. 3). 



Mechanical Analogy. — In order to carry out the idea of a 

 mechanical analogy, the digestive system of the horse may be 

 regarded as the boiler whence the energy is supplied ; the mus- 

 cular system as comprising the motors ; the power exerted by the 

 muscle motors at the expense of the energy derived from the 

 digestive boilers, operating the bone columns, by the alternate 



