40 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
with extra short fore-arm and long front cannon will finally be knee 
sprung almost to a certainty—“ buck-kneed ” and stumbling as he 
walks, a perfect picture of decrepitude. (See illustration.) For the 
stylish coach or carriage horse, the proud high stepper, with the short 
fore-arm and relatively longer cannon, will be greatly in demand; but 
for speed and stamina in long heat races, tie your fortunes to the horse 
that reaches out in front and moves the body forward on an even line 
at no great distance from the ground. 
Rear leverage in the horse means something more than muscle force 
which gives propelling power. No horse can carry speed at any gait 
with insufficient muscle, but the natural impulse of the horse to strike 
a gallop when he wants to travel faster may be so constrained by cer¬ 
tain leverage in rear development as to make the artifical gait a second 
nature, breaking only when the brain is worried or the speed is car¬ 
ried past the limit which the horse can reach. 
The motion of the hind legs, from the fetlocks up, is modified by 
four distinct true levers, each one more or less complex in action — 
one especially remarkable; the muscles from the haunch or hip bone 
and the Illiac fossa extend in two directions — downward to the stifle, 
and down and backward to the leg bone (Tibia) and the hock. The 
upper thigh bone (Femur) works at upper end against the lower por¬ 
tion of the Illium in connection with the other pelvic bones, and the 
muscles running downward from the hip, together with the bones of 
upper thigh and leg, form a double compound lever — really two in 
purpose—moving separate or jointly in obedience to the brain’s direct 
or reflex action. The muscles of the lower thigh which flex the can¬ 
non on the leg present a simple lever of the third class (power be- 
