They were passing a half-open door when Chandler suddenly stopped short.  “Look in there,” he said, in a low voice, addressing the father rather than the daughter, “that’s the Finger-Print Room.  We’ve records here of over two hundred thousand men’s and women’s finger-tips!  I expect you know, Mr. Bunting, as how, once we’ve got the print of a man’s five finger-tips, well, he’s done for—­if he ever does anything else, that is.  Once we’ve got that bit of him registered he can’t never escape us—­no, not if he tries ever so.  But though there’s nigh on a quarter of a million records in there, yet it don’t take—­well, not half an hour, for them to tell whether any particular man has ever been convicted before!  Wonderful thought, ain’t it?”

“Wonderful!” said Bunting, drawing a deep breath.  And then a troubled look came over his stolid face.  “Wonderful, but also a very fearful thought for the poor wretches as has got their finger-prints in, Joe.”

Joe laughed.  “Agreed!” he said.  “And the cleverer ones knows that only too well.  Why, not long ago, one man who knew his record was here safe, managed to slash about his fingers something awful, just so as to make a blurred impression—­you takes my meaning?  But there, at the end of six weeks the skin grew all right again, and in exactly the same little creases as before!”

“Poor devil!” said Bunting under his breath, and a cloud even came over Daisy’s bright eager face.

They were now going along a narrower passage, and then again they came to a half-open door, leading into a room far smaller than that of the Finger-Print Identification Room.

“If you’ll glance in there,” said Joe briefly, “you’ll see how we finds out all about any man whose finger-tips has given him away, so to speak.  It’s here we keeps an account of what he’s done, his previous convictions, and so on.  His finger-tips are where I told you, and his record in there—­just connected by a number.”

“Wonderful!” said Bunting, drawing in his breath.  But Daisy was longing to get on—­to get to the Black Museum.  All this that Joe and her father were saying was quite unreal to her, and, for the matter of that not worth taking the trouble to understand.  However, she had not long to wait.

A broad-shouldered, pleasant-looking young fellow, who seemed on very friendly terms with Joe Chandler, came forward suddenly, and, unlocking a common-place-looking door, ushered the little party of three through into the Black Museum.

For a moment there came across Daisy a feeling of keen disappointment and surprise.  This big, light room simply reminded her of what they called the Science Room in the public library of the town where she lived with Old Aunt.  Here, as there, the centre was taken up with plain glass cases fixed at a height from the floor which enabled their contents to be looked at closely.

She walked forward and peered into the case nearest the door.  The exhibits shown there were mostly small, shabby-looking little things, the sort of things one might turn out of an old rubbish cupboard in an untidy house—­old medicine bottles, a soiled neckerchief, what looked like a child’s broken lantern, even a box of pills. . .