380 
EXPERIMENTS ON THE 
have before mentioned that this occurred in every case I tried, 
and it deserves very particular notice. 
Observations .—I consider this experiment decidedly unfair to¬ 
wards producing this action, inasmuch as any thing nailed or fixed 
to the hoof in any way must, more or less, partake of its motion. 
I have felt reluctant to give this experiment, as I know it will 
prove very unsatisfactory, although the motion of the hoof will be 
seen by this means on some horses ; but it is an experiment quite 
unfitted for the purpose. I have tried it on many horses, and in 
most of them I have failed to shew it: in others it was evident. 
I did not succeed in shewing this action by such means on light 
horses. In any experiment, the great difficulty of shewing whether 
this motion of the hoof exists, consists in planning something that 
shall act quite independently of the hoof, (for, as I said before, any 
thing fastened to the hoof must partake of its motion,) and that 
shall be able to measure the angle of obliquity in all situations in 
which the foot may be placed. I trust that a better plan will 
strike some of the readers of this paper. I believe this motion in 
light horses is very slight; but I am convinced it must go on, 
more or less, in a state of nature, in all description of horses. In 
what other way can we satisfactorily account for the increased 
width of the heels often produced under certain kinds of shoeing, 
as with tips, one-sided nailing, bar-shoes, or the old panton shoe of 
Solleysel! How else can we accuunt for the ease obtained by 
the use of these shoes, as also with shoes having some elastic ma¬ 
terial between them and the hoof at the heels and quarters only 1 
That the foot of the horse does at times become wider at the 
quarters under certain treatment and modes of shoeing, will not, I 
think, be denied; and if such be the case, it can only be produced, 
1 consider, by the gradual growth of parts from their being left at 
liberty, and by their being called upon to perform certain functions 
compatible with their organism, and which they could not pre- 
viouslv perform to the same extent. Increased growth of parts 
will not go on without increased action, for Nature gives nothing 
superfluous. It is easy to perceive that any sudden attempt to 
expand the foot at the quarters must be productive of the greatest 
pain and inconvenience to the animal, by placing many delicate 
membranes on the stretch; and as the horny sole is an arch, and 
is intimately united to the concavity of the coffin-bone, it is pretty 
clear that the former cannot descend and force out the walls ex¬ 
cept it be pressed down by the coffin-bone; but as this happens to 
be a bone, and will not bend, I cannot see how the sole is to receive 
the pressure to force out the walls. It may appear strange that 
it is so difficult satisfactorily to demonstrate the downward and 
backward action of the foot; but 1 cannot plan a suitable experi- 
