1 66 Gait of the American Trotter and Pacer 



the flexion of the hock joint cannot be as easily and as completely 

 accomplished as that of the knee joint. The very fact that it is the 

 reverse of the forward flexion, with its angle toward the direction 

 of motion, tends to show that the effort of flexing cannot be so long 

 and so fully sustained as in the knee. The respective compensations 

 in the legs and their attachments are worth noting. The comparative 

 rigidity of shoulder is compensated or corrected by the ready flexibility 

 of fore leg, and on the other hand the comparative stiffness of hind 

 leg is compensated or corrected by the greater looseness or mobility 

 of the hip bone or femur. These differences in flexion have as a 

 consequence corresponding differences in elevation of the hind and 

 fore feet. Action proper, however, is determined by the elevation 

 of the knee and hock joints because these are not only prominent 

 points in locomotion, but they are also more easily and readily located 

 by the eye. 



To exemplify such a comparative elevation we need only appeal 

 to the facts or deductions from the famous pictures of Muybridge. 

 In Fig. 134 such comparative elevations are illustrated for each of 

 the four horses previously considered. The curves here are only 

 conventional arcs of a circle and are meant merely to indicate the scope 

 of action and not its precise movements, the latter having been in- 

 vestigated and shown before. It so happens that the points of ele- 

 vation of these joints and feet were measurable by forty-eighth parts 

 of an inch and such was the standard taken to get the proportions. 

 But in order to make everything more visible Fig. 134 was made on 

 double that scale, or twenty-fourth -parts of an inch, and as in the 

 former standard so also in this : five parts made up one foot as given 

 on the photographs. The accuracy of the illustration depends on 

 that of the pictures as reproduced ; but they are, upon closer examina- 

 tion and after making allowance for blurs, very good attitudes from 

 which to deduce these results. The horse Occident having the 

 highest knee action, which rose to 15, gives us the extreme from 

 which we derive the various proportions. We should bear in mind 

 that the hock joint stands higher than knee joint, and in these pictures 

 the latter is about 80 per cent, of the height of hock joint, this 



