that the suspected thumb-print is identical in character with that of
Reuben Hornby--of which, however, I have very little doubt, for the
finger-print experts may fairly be trusted in their own speciality."

"And then?"

"I shall collect fresh facts, in which I look to you for assistance,
and, if we have finished breakfast, I may as well induct you into your
new duties."

He rose and rang the bell, and then, fetching from the office four
small, paper-covered notebooks, laid them before me on the table.

"One of these books," said he, "we will devote to data concerning Reuben
Hornby. You will find out anything you can--anything, mind, no matter
how trivial or apparently irrelevant--in any way connected with him and
enter it in this book." He wrote on the cover "Reuben Hornby" and passed
the book to me. "In this second book you will, in like manner, enter
anything that you can learn about Walter Hornby, and, in the third book,
data concerning John Hornby. As to the fourth book, you will keep that
for stray facts connected with the case but not coming under either of
the other headings. And now let us look at the product of Polton's
industry."

He took from his assistant's hand a photograph ten inches long by eight
broad, done on glazed bromide paper and mounted flatly on stiff card. It
showed a greatly magnified _facsimile_ of one of the thumb-prints, in
which all the minute details, such as the orifices of the sweat glands
and trifling irregularities in the ridges, which, in the original, could
be seen only with the aid of a lens, were plainly visible to the naked