For example, I found the words 'Hofgaard', 'Luneville', and 'Avocado' pretty often, and especially the word 'Pavia'.
Now I was certain that Scudder never did anything without a reason, and I was pretty sure that there was a cypher in all this.

That is a subject which has always interested me, and I did a bit at it myself once as intelligence officer at Delagoa Bay during the Boer War.

I have a head for things like chess and puzzles, and I used to reckon myself pretty good at finding out cyphers.

This one looked like the numerical kind where sets of figures correspond to the letters of the alphabet, but any fairly shrewd man can find the clue to that sort after an hour or two's work, and I didn't think Scudder would have been content with anything so easy.

So I fastened on the printed words, for you can make a pretty good numerical cypher if you have a key word which gives you the sequence of the letters.
I tried for hours, but none of the words answered.