EXPANSION OF THE HORSE’S FOOT. 
265 
The descent of the navicular-bone was, however, completely regu¬ 
lated, for its articulating surface seemed to form only a portion of 
the segment of a circle, of which it was the highest point; and 
when it was forced downwards by the descent of the coronet-bone, 
it could only be to that point where the two segments formed by 
the articulation of the coffin and navicular-bones made the articu¬ 
latory surface of the coffin joint, and beyond this it could not de¬ 
scend. This seemed to be, at the utmost, about a quarter of an 
inch under the strongest pressure, although, in the experiment with 
the living cart-horse, the frog opposite to the navicular bone only 
descended to the thickness of the back of the blade of a penknife. 
The coffin-bone seemed perfectly fixed, as also the sole and the base 
of the frog. 
Ylth Experiment. 
A common well-seated shoe, very long at the heels, was applied 
and fitted accurately to the fore foot of a carriage-horse. 
The angular space between the projecting heel of the shoe and 
the foot to the bulbs of the heels was filled up very carefully with 
prepared wax, whilst the horse’s foot was held up, and an oiled 
knife was then passed between the heel of the shoe and the wax, 
leaving a thin space. The idea was, if the descent of the foot 
were downwards and backwards, this space, on pressure being ap¬ 
plied, would immediately close. The horse was now made to throw 
all his weight on this foot. 
Result .—The crack in the wax did not close, the wax not hav¬ 
ing descended even the thickness of the blade of a knife. 
13 th Experiment, 
On the dead fore foot of a cart-horse, moderately concave, and 
cut off at the small coronet-bone, and shod exactly as in the last 
experiment. A piece of wood was fitted to the coronet-bone, hav¬ 
ing a flat upper surface. The angular space at the heels was filled 
up, as in the last experiment, with prepared wax, and the oiled 
knife passed through the under surface of the wax close to the 
shoe, as before, leaving a thin slit. The foot thus prepared was put 
into a powerful vice, and pressure applied, the piece of wood and 
the shoe being the opposing surfaces. 
Result .—The crack did not close. Whilst the pressure was 
being applied I could feel a sensible expansion at all the upper 
parts of the foot around the coronet, but principally at the upper 
and back parts, towards the heels, which swelled out, and became 
firm and rigid, and the lateral cartilages evidently expanded. 
