186 
ON THE CONFORMATION OF HOUSES. 
hoof, according to the peculiar make of the animal, and the man- 
ner in which the weight is thrown upon the foot; and it seems to 
be produced by the sole, influenced by the weight, abutting against 
that particular portion of the crust, and causing a gradual shelving 
out and increased growth of the hoof at this part, and this always 
opposite to where the greatest degree of weight is sustained ; and 
the shelving generally commences about the middle portion of the 
wall, and gradually extends to the lowermost edges. In well 
formed feet in a state of nature there is always a degree of this 
shape on the outer quarter, which, however, according to the ge- 
neral custom of shoeing from its projecting beyond the edge of 
the circular shoe, is taken away by the knife or rasp, instead of 
being preserved and the shoe properly adapted to it ; and conse- 
quently the nails, instead of being driven through firm insensible 
horn, are too frequently inserted near enough to the sensible parts 
to cause pain to the animal, and if not absolute lameness, yet a short 
contracted step, too common with newly-shod horses. The upper 
portion of the hoof may be considered to approach nearly to the 
cylindrical shape. The disposition of horn that forms the shelving 
is dependent on the original conformation of the animal in regard 
to weight, as also on the structure of the extremities, and the 
consequent action and position, which thereby influences the 
degree of weight and the distribution of it on particular parts of 
the hoof ; thus more weight is thrown on the hoof of a heavy than 
a light animal, and on the fore than the hind hoofs; for the fore 
hoofs support the head, neck, and anterior extremities, whilst the 
hind hoofs support but the posterior extremities and compara- 
tively little of the body ; except in the paces of progression, when 
the posterior extremities more particularly form the levers to pro- 
pel the body forwards. According as the action is high or low, 
so is the weight in progression thrown more or less frequently on 
the hoofs, causing a difference in the weight received, and influ- 
encing the shape of different parts of the foot; also, as the joints 
are more or less angular, that is, the pastern bones placed obtuse 
or acute, so is the distribution of weight to particular parts of the 
foot, and thus at different ages up to puberty, in the same animal, 
we have a variety in the shape of the hoof. To the lesser degree 
of weight sustained may we attribute the difference in shape of 
the hind and fore feet ; and to the peculiar upright position of the 
limbs, and general light make of the anterior part of the body, 
may also be attributed the fact of the shape of the feet of the ass 
and zebra, and of the mule ( except under peculiar circumstances 
hereafter to be described), differing from those of horses : being 
circular, but not shelving. I consider that the proper declination 
of the hoof in a healthy foot ought to be 33° from the perpendi- 
