ty of thin tracing-paper into a small compass by tight
rolling."

"And this--this was the way they were brought back!" the engineer
exclaimed. "I see that clearly. But how did they get away? That's as
mysterious as ever."

"Not a bit of it! See here. Mirsky gets hold of Ritter, and they agree to
get your drawings and photograph them. Ritter is to let his confederate
have the drawings, and Mirsky is to bring them back as soon as possible,
so that they sha'n't be missed for a moment. Ritter habitually carries
this Malacca cane, and the cunning of Mirsky at once suggests that this
tube should be made in outward fac-simile. This morning Mirsky keeps the
actual stick, and Ritter comes to the office with the tube. He seizes the
first opportunity--probably when you were in this private room, and
Worsfold was talking to you from the corridor--to get at the tracings,
roll them up tightly, and put them in the tube, putting the tube back into
the umbrella-stand. At half-past twelve, or whenever it was, Mirsky turns
up for the first time with the actual stick and exchanges them, just as he
afterward did when he brought the drawings back."

"Yes, but Mirsky came half an hour after they were--Oh, yes, I see. What a
fool I was! I was forgetting. Of course, when I first missed the tracings,
they were in this walking-stick, safe enough, and I was tearing my hair
out within arm's reach of them!"

"Precisely. And Mirsky took them away before your very eyes. I expect
Ritter was in a rare funk when he found that the drawings were missed. He
calculated, no doubt, on your not wanting them for the hour or two they
would be out of the office."

"How lucky that it struck me to jot a pencil-note on one of them! I might
easily have made my note somewhere else, and then I should never have
known that they had been away."

"Yes, they didn't give you any too much time to miss them. Well, I think
the rest pretty clear. I brought the tracings in here, screwed up the sham
stick and put it back. You identified the tracings and found none missing,
and then my course was pretty clear, though it looked difficult. I knew
you would be very naturally indignant with Ritter, so, as I wanted to
manage him myself, I told you nothing of what he had actually done, for
fear that, in your agitated state, you might burst out with something that
would spoil my game. To Ritter I pretended to know nothing of the return
of the drawings or _how_ they had been stolen--