rman agreed. "Pray proceed."

"There was another remarkable peculiarity about these footprints,"
Thorndyke continued, "and that was their distance apart--the length of
the stride, in fact. I measured the steps carefully from heel to heel,
and found them only nineteen and a half inches. But a man of Hearn's
height would have an ordinary stride of about thirty-six inches--more if
he was walking fast. Walking with a stride of nineteen and a half inches
he would look as if his legs were tied together.

"I next proceeded to the Bay, and took two moulds from the footprints
of the man with the nailed shoes, a right and a left. Here is a cast
from the mould, and it shows very clearly that the man was walking
backwards."

"How does it show that?" asked the magistrate.

"There are several distinctive points. For instance, the absence of the
usual 'kick off' at the toe, the slight drag behind the heel, showing
the direction in which the foot was lifted, and the undisturbed
impression of the sole."

"You have spoken of moulds and casts. What is the difference between
them?"

"A mould is a direct, and therefore reversed, impression. A cast is the
impression of a mould, and therefore a facsimile of the object. If I
pour liquid plaster on a coin, when it sets I have a mould, a sunk
impression, of the coin. If I pour melted wax into the mould I obtain a
cast, a facsimile of the coin. A footprint is a mould of the foot. A
mould of the footprint is a cast of the foot, and a cast from the mould
reproduces the footprint."

"Thank you," said the magistrate. "Then your moulds from these two
footprints are really facsimiles of the murderer's shoes, and can be
compared with these shoes which have been put in evidence?"

"Yes, and when we compare them they demonstrate a very important fact."

"What is that?"

"It is that the prisoner's shoes were not the shoes that made those
footprints." A buzz of astonishment ran through the court, but Thorndyke
continued stolidly: "The prisoner's shoes were not in my possession, so
I went on to Barker's pond, on the clay margin of which I had seen
footprints actually made by the prisoner. I took moulds of those
footprints, and compared them with these from the sand. There are
several important differences, which you will see if you compare them.
To facilitate the comparison I have made transparent photographs of both
sets of moulds to the same scale. Now, if we put the photograph of the
mould of