672 
LECTURES ON HOUSES. 
various movements of which the tail is capable, and with the 
eight, admirably arranged as they are, the tail may be made to 
perform movements in any radial direction of a circle; and, indeed, 
by the alternate action of them, to describe a sort of circular mo- 
tion, such as we every now and then perceive when the horse is 
switching off flies, or making efforts to rid himself of any source of 
annoyance or irritation. 
In the ordinary or natural manner in which a horse carries his 
tail, the action of the muscles may be said to be nicely balanced; 
none are forcibly contracted — none completely relaxed — all are in 
that semi-contracted, semi-relaxed condition, which, by physiolo- 
gists, is characterized as their tone : and this tone is said to be 
good or bad according as, from previous exercise and other cir- 
cumstances, they are in a condition to do much or little work. 
While a horse is going, the coccygeal muscles participating in the 
general action of the body, the tail becomes partially erect ; but, 
while in the stable, every muscle ceasing to act, it droops from its 
own weight, and lies at rest against the quarters : and this is, in 
truth, the only real relaxation or repose these muscles experience; 
for, while the erectors are elevating the tail, the depressors are not 
passively relaxed, but, like hands employed in moderating exten- 
sion, lest the part be over-stretched, are engaged in keeping up a 
proper degree of counter-extension. The operation of knicking 
plainly elucidates the effects of muscular action : the depressor 
muscles of the tail being severed, the erectors, every time the 
horse is set in action, elevate the tail to the uttermost, and main- 
tain it thus preternatural lv erected, there being no controlling 
powers to moderate the elevation. 
Another effect of muscular contraction well exemplified by the 
tail, is, the prodigious force muscles are capable of exerting. All 
practical horsemen full well know that, to raise the tail of a strong- 
docked horse, requires often more than the strength of the strongest 
man’s arm. Horse-dealers and grooms, indeed, and connoisseurs 
in horses, often take the strength of the dock (of the tail) as an 
estimate of the general muscular powers of the animal ; and the 
criterion is one by no means to be despised, it being but reasonable 
to infer that great strength in one part would not be unattended 
with correspondent power in others. 
The limbs of the horse furnish us with beautiful illustrations of 
the force and velocity, extent and variety, of muscular motion. 
In the fore-limb no less than thirty muscles are employed; eighteen 
being occupied in the movements of the shoulder and arm, the 
remaining twelve with those of the leg and foot. When speaking 
of the bones composing these parts, I said that between the shoul- 
ders the fore-quarters of the body were in a manner suspended 
