“One moment, Jervis,” said he.  “What do you make of this?”

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 me show you a light.”

He flashed his lamp into the dark corner, and I was able to see distinctly the portentously large holes into which the bolts had fitted, and also to note the remarkable neatness with which they had been plugged.

“There was a second door, I remember,” said I.  “Let us see if that was guarded in a similar manner.”

We strode through the empty room, awakening dismal echoes as we trod the bare boards, and flung open the other door.  At top and bottom, similar groups of screw-holes showed that this also had been made secure, and that these bolts had been of the same very substantial character as the others.

Thorndyke turned away from the door with a slight frown.

“If we had any doubts,” said he, “as to what has been going on in this house, these traces of massive fastenings would be almost enough to settle them.”

“They might have been there before Weiss came,” I suggested.  “He only came about seven months ago and there is no date on the screw-holes.”

“That is quite true.  But when, with their recent fixture, you couple the facts that they have been removed, that very careful measures have been taken to obliterate the traces of their presence, and that they would have been indispensable for the commission of the crime that we are almost certain was being committed here, it looks like an excess of caution to seek other explanations.”