MR. GLOAG ON MR. TURNER^ LETTER. 135 
I shall close this letter by merely adverting to one of the many 
points which I hold up to view, and hope those who take any 
interest in the matter will fairly and impartially consider it; and 
he who can answer it satisfactorily deserves the thanks of the 
profession. It is this. On looking at a horse’s foot which has 
been shod for some time, for which the heels of the shoe have 
been made wider than the heels of the foot, and consequently 
project a little on each side, I ask, did any of my friends, even 
in a solitary instance, ever see the slightest brightening on the 
foot surface of the shoe, at the heels, beyond the exact resting- 
place of the foot ! I have never been able to recognise such 
brightening myself, but, on the contrary, have noticed that the 
line of rust corresponds closely with the sides of the foot, up to 
the very heels. I now take this shoe off, and with a certain 
conformation of horse, observe that where the heels rested the 
shoe is as bright as a mirror, nay, even perhaps deeply in¬ 
dented ; but that the line which separated the brightened por¬ 
tions from the external rusted parts is traced with mathematical 
precision. To what does all this lead ? Can we possibly have 
a closer experiment! Surely, some very sharp pair of eyes 
would be clever enough sometimes to detect the expansion. 
Can it, indeed, be so trifling as thus to elude our search ? for, 
if so, the inquiry after it appears a waste of time. But how 
comes the brightening where the shoe rested ? No one, surely, 
will assert that cold iron could become bright without friction; 
and if this produced it where the heels rested, of course it would 
do so on the part external to the foot in its presumed alternate 
expansion and contraction. If my ideas about the slightly 
yielding backward motion of the foot are incorrect, I would like 
to know what kind of position the expansionists would find 
themselves in ; for if we cannot find any brightening of the 
shoe external to where the foot rested, there is only one other 
way to account for this phenomenon, namely, by the contraction 
of the foot, at its lower circumference at the heels, every time 
it comes to the ground. Now, I am not prepared to admit this; 
but I leave the solution in the hands of those opposed to me in 
opinion, and the proper explanation of it will solve the whole 
mystery of the elasticity of the foot. I only ask one question. 
How does the fact of an indentation taking place in the heels of 
the shoe, where the foot rested, accord with the ideas of lateral 
expansion and contraction! 
I am, Sir, 
Your obedient Servant, 
John William Gloag. 
Nottingham, February 9th, 1852. 
