He began to explain the machine with the manner and tone of a lecturer at a scientific institution.  In spite of themselves, the officers burst out laughing.  I looked round at Screw as the doctor got deeper into his explanations.  The traitor was rolling his wicked eyes horribly at me.  They presented so shocking a sight, that I looked away again.  What was I to do next?  The minutes were getting on, and I had not heard a word yet, through the peephole, on the subject of the reserve of Bow Street runners outside.  Would it not be best to risk everything, and get away at once by the back of the house?

Just as I had resolved on venturing the worst, and making my escape forthwith, I heard the officers interrupt the doctor’s lecture.

“Your lunch is a long time coming,” said one of them.

“Moses is lazy,” answered the doctor; “and the Madeira is in a remote part of the cellar.  Shall I ring again?”

“Hang your ringing again!” growled the runner, impatiently.  “I don’t understand why our reserve men are not here yet.  Suppose you go and give them a whistle, Sam.”

“I don’t half like leaving you,” returned Sam.  “This learned gentleman here is rather a shifty sort of chap; and it strikes me that two of us isn’t a bit too much to watch him.”

“What’s that?” exclaimed Sam’s comrade, suspiciously.

A crash of broken crockery in the lower part of the house had followed that last word of the cautious officer’s speech.  Naturally, I could draw no special inference from the sound; but, for all that, it filled me with a breathless interest and suspicion, which held me irresistibly at the peephole—­though the moment before I had made up my mind to fly from the house.

“Moses is awkward as well as lazy,” said the doctor.  “He has dropped the tray!  Oh, dear, dear me! he has certainly dropped the tray.”

“Let’s take our learned friend downstairs between us,” suggested Sam.  “I shan’t be easy till we’ve got him out of the house.”

“And I shan’t be easy if we don’t handcuff him before we leave the room,” returned the other.

“Rude conduct, gentlemen—­after all that has passed, remarkably rude conduct,” said the doctor.  “May I, at least, get my hat while my hands are at liberty?  It hangs on that peg opposite to us.”  He moved toward it a few steps into the middle of the room while he spoke.

“Stop!” said Sam; “I’ll get your hat for you.  We’ll see if there’s anything inside it or not, before you put it on.”

The doctor stood stockstill, like a soldier at the word, Halt.

“And I’ll get the handcuffs,” said the other runner, searching his coat-pockets.

The doctor bowed to him assentingly and forgivingly.

“Only oblige me with my hat, and I shall be quite ready for you,” he said—­paused for one moment, then repeated the words, “Quite ready,” in a louder tone—­and instantly disappeared through the floor!