550 CONFORMATION OF HORSES* FEET. 
with its growth and magnitude, in its relative position to 
that of the sensible foot, which is always in the same situation. 
There is not the slighest disposition in the periphery of 
either to eccentric action, as pressure causes the upper sur¬ 
face of the declined cylinder to shelve from within outwards , 
and the lower surface to be pressed upwards and inwards. 
As the coffin bone diverges by growth, one or both the heels 
of the bone are, in consequence of the pressure, in heavy 
horses, absorbed, so that its periphery does not, as with 
coffin bones of lighter horses, whose feet have been preserved, 
or in hind coffin bones, rest throughout on a plane, as noticed 
by the late Mr. W. Goodwin, and which occurs only in 
heavy horses. 
I shall now make extracts from my own notes of the late 
Professor Coleman*s lectures, to prove that his theory was 
concentric expansion. This differs essentially from eccentric 
expansion revived by Mr. B. Clark, which is not the action of 
a horse's foot. The late Professor said— 
“ The hoof, in growing , becomes wider than the shoe, and it 
is a common expression to say, the shoe has been c eating* 
into the hoof. The disposition of the hoof is to grow out and 
become wider , the nails would confine it to the same diameter , 
but the disposition of the hoof to grow is greater than the 
power of resistance of nails, and this is the reason they are 
bent in proportion to the weight of the horse. The hoof 
expands in some degree notwithstanding the resistance of 
nails.** Here the part where the hoof expands is distinctly stated, 
and is quite at variance with the eccentric theory of widen¬ 
ing from heel to toe, like a hinge shoe. Again, he said,— 
“Mr. B. Clark supposes contraction to be caused by nails 
being placed too near the heels; but in cart horses nails are 
often, from weakness of the crust at other parts, obliged to 
be placed near the heels, yet there is no contraction, for 
the pressure of weight overcomes the resistance of nails.” 
Now, we all know the part in which nails are driven is not 
the heels, but quarters and toe, and the expansion that thus 
overcomes the resistance of nails is concentric , being opposite, 
and not the widening of the heels from heel to toe, or 
eccentric action. .Again, “It is the want of pressure to the 
frog that is the chief cause of contraction. The foot may be 
contracted from heel to heel, or from quarter to quarter, or 
from below upwards. When the sole is convex upwards, 
dry, hard, thick, and concave below, this happens to horses 
of light weight and low action, and these horses are so much 
disposed to contraction, that the best precautions will not 
sometimes prevent it; and there are other horses that the 
