"What!" I exclaimed. "You've discovered it?"
"Yes, monsieur. I may tell you it's a very simple problem, so simple that I am anxious to be first in the field. Imagine, if any one else were to publish the truth before me! So I rang up Meudon on the chance of getting you called to the telephone. . . . Oh, do listen to me, monsieur: you must believe me and help me. . . ."
"Of course, of course," I replied, "but I don't quite see . . ."
"Yes, yes," Benjamin Prévotelle implored, appealing to me, clinging to me, so to speak, in a despairing tone of voice. "You can do a great deal. I only want a few particulars. . . ."
I confess that Benjamin Prévotelle's statements left me a little doubtful. However, I answered:
"If a few particulars can be of any use to you . . ."
"Perhaps one alone will do," he said. "It's this. The wall with the screen was entirely rebuilt by your uncle, Noël Dorgeroux, was it not?"
"Yes."
"And this wall, as you have said and as every one had observed, forms a given angle with its lower part."
"Yes."