Sherlock Holmes had pushed away his untasted breakfast and lit the unsavoury pipe which was the companion of his deepest meditations.

"I wonder!" said he, leaning back and staring at the ceiling.

"Perhaps there are points which have escaped your Machiavellian intellect. Let us consider the problem in the light of pure reason.

This man's reference is to a book. That is our point of departure." "A somewhat vague one." "Let us see then if we can narrow it down. As I focus my mind upon it, it seems rather less impenetrable. What indications have we as to this book?" "None." "Well, well, it is surely not quite so bad as that. The cipher message begins with a large 534, does it not?

We may take it as a working hypothesis that 534 is the particular page to which the cipher refers.

So our book has already become a large book, which is surely something gained.

What other indications have we as to the nature of this large book? The next sign is C2. What do you make of that, Watson?" "Chapter the second, no doubt." "Hardly that, Watson. You will, I am sure, agree with me that if the page be given, the number of the chapter is immaterial.

Also that if page 534 finds us only in the second chapter, the length of the first one must have been really intolerable." "Column!" I cried.

"Brilliant, Watson. You are scintillating this morning. If it is not column, then I am very much deceived.

So now, you see, we begin to visualize a large book, printed in double columns, which are each of a considerable length, since one of the words is numbered in the document as the two hundred and ninety-third.