I replied that I was much puzzled by his question.

Then he begged me to try, in my turn, to take my reason in hand "by the right end." "Very well," I said.

"It seems to me that the point of departure of my reason would be this--there can be no doubt that the murderer you pursued was in the gallery." I paused.
"After making so good a start, you ought not to stop so soon," he exclaimed.

"Come, make another effort." "I'll try.

Since he disappeared from the gallery without passing through any door or window, he must have escaped by some other opening." Rouletabille looked at me pityingly, smiled carelessly, and remarked that I was reasoning like a postman, or--like Frederic Larsan.
Rouletabille had alternate fits of admiration and disdain for the great Fred.