EXPANSION OF THE HORSE’S FOOT. 
261 
in this case, I feel convinced there must be sufficient motion, by 
means of the elastic periosteal covering of the coffin-bone, to take 
off the jar from the foot, although this action may be very limited; 
yet if this periosteal covering possesses the slightest elasticity, 
which property our talented author, Mr. Percivall, has ascribed to 
it, and I believe with great justice, there must be a slight spring 
in every direction. 
1th Experiment 
Another foot, of the same character as in the preceding case, was 
fitted with the piece of wood to the articulatory surface of the small 
pastern, and a common seated shoe, laid even to the heels, nailed 
on. The foot thus prepared was put into the vice, the shoe and 
the piece of wood being the opposing surfaces. Pressure was 
applied, and the soles and frog and every other part most carefully 
watched. 
Result .—The frog, about one inch behind the toe, was the first 
point that yielded, and this it seemed to do continuously with the 
pressure employed, until it sank about a quarter of an inch; but 
further pressure did not seem to increase the descent. 1 should 
consider that there must have been at times a pressure of more 
than two tons. The sole did not seem in this case to alter in any 
way, nor could I detect any difference whatever at the base of the 
frog, although T most carefully noticed it, and I laid a flat piece of 
iron across the heels of the shoe for the purpose of watching if 
there was any descent, but could not see any. This experiment 
may be compared with Nos. 2 and 3. As far as my experience 
goes, the sole will bear a certain amount of pressure, or rather 
support, at particular parts, as at the toe, with advantage if left 
strong; and I do not think that there is any descent of the sole in 
a healthy moderately concave foot, except what appertains to it in 
connexion with the slight yielding backwards and downwards of 
the whole foot in a state of nature, or under particular states of 
shoeing. None of these observations apply to horses with very 
flat or pumiced feet. 
The sole appears to be formed in flakes lying one upon another, 
with a powdery substance between them; they are something like 
the springs of a carriage. When the sole is thin, the least pressure 
is felt; but when the sole is thick, the pressure becomes deadened 
and lost over the numerous plates. 
8th Experiment , 
On the dead fore foot of a cart-horse, cut off at the small pastern 
joint. 
VOL. XXII. 
M m 
