He pointed to a spot near the bottom of the door where, on close
inspection, four good-sized screw-holes were distinguishable. They had
been neatly stopped with putty and covered with knotting, and were so
nearly the colour of the grained and varnished woodwork as to be hardly
visible.

"Evidently," I answered, "there has been a bolt there, though it seems a
queer place to fix one."

"Not at all," replied Thorndyke. "If you look up you will see that there
was another at the top of the door, and, as the lock is in the middle,
they must have been highly effective. But there are one or two other
points that strike one. First, you will notice that the bolts have been
fixed on quite recently, for the paint that they covered is of the same
grimy tint as that on the rest of the door. Next, they have been taken
off, which, seeing that they could hardly have been worth the trouble of
removal, seems to suggest that the person who fixed them considered that
their presence might appear remarkable, while the screw-holes, which
have been so skilfully and carefully stopped, would be less conspicuous.

"Then, they are on the outside of the door--an unusual situation for
bedroom bolts--and were of considerable size. They were long and thick."

"I can see, by the position of the screw-holes, that they were long; but
how do you arrive at their thickness?"

"By the size of the counter-holes in the jamb of the door. These holes
have been very carefully filled with wooden plugs covered with knotting;
but you can make out their diameter, which is that of the bolts, and
which is decidedly out of proportion for an ordinary bedroom door. Let