"It's a child having a game!" I cried, after a moment or two, feeling a little irritated by the trivial occupation that had been thrust upon me.

"Never mind, go on!"

And I counted away.... And I put down rows of figures.... And the sun continued to play in front of me, with mathematical precision.

"Well?" said Lupin, after a longer pause than usual.

"Why, it seems finished.... There has been nothing for some minutes...."

We waited and, as no more light flashed through space, I said, jestingly:

"My idea is that we have been wasting our time. A few figures on paper: a poor result!"

Lupin, without stirring from his sofa, rejoined:

"Oblige me, old chap, by putting in the place of each of those numbers the corresponding letter of the alphabet. Count A as 1, B as 2 and so on. Do you follow me?"

"But it's idiotic!"