it is not necessary that we should know for the moment. M. Fauville erased the postmarks and the addresses and inserted the letters in a machine constructed for the purpose, of which he regulated the works so that the first letter should be delivered a fortnight after his death and the others at intervals of ten days.
"At this moment it is certain that his plan was concerted down to the smallest detail. Knowing that Sauverand was in love with his wife, watching Sauverand's movements, he must obviously have noticed that his detested rival used to pass under the windows of the house every Wednesday and that Marie Fauville would go to her window.
"This is a fact of the first importance, one which was exceedingly valuable to me; and it will impress you as being equal to a material proof. Every Wednesday evening, I repeat, Sauverand used to wander round the house. Now note this: first, the crime prepared by M. Fauville was committed on a Wednesday evening; secondly, it was at her husband's express request that Mme. Fauville went out that evening to go to the opera and to Mme. d'Ersinger's."
Don Luis stopped for a few seconds and then continued:
"Consequently, on the morning of that Wednesday, everything was ready, the fatal clock was wound up, the incriminating machinery was working to perfection, and the proofs to come would confirm the immediate proofs which M. Fauville held in reserve. Better still, Monsieur le Préfet, you had received from him a letter in which he told you of the plot hatched against him, and he implored your assistance for the morning of the next day—that is to say, after his death!
