order in which they are written, first the number of the page of
some book, then the line on which the word is to be found--say, the
tenth line from the top, or maybe from the bottom--and then the
position of the word--second from the left or perhaps from the
right."

"It's utterly impossible to solve that unless you have the book," he
remarked; "therefore, why speculate, Miss Erith?"

"I'm going to try to find the book."

"How?"

"By breaking into the shop of Herman Lauffer."

"House-breaking? Robbery?"

"Yes."

Vaux smiled incredulously:

"Granted that you get into Lauffer's shop without being arrested,
what then?"

"I shall have this cipher with me. There are not likely to be many
books in the shop of a gilder and maker of picture frames. I shall,
by referring to this letter, search what books I find there for a
single coherent sentence. When I discover such a sentence I shall
know that I have the right book."