“Well?”

“Tell me why Martinez did it.”

Coquenil’s face darkened.  “Ah, that’s the question.  We’ll know that when we talk to the woman.”

The old man leaned forward eagerly:  “Why do you think the woman helped him?”

“Somebody helped him or the chips would still be there, somebody held back those hangings while he worked the auger, and somebody carried the auger away.”

Tignol pondered this, a moment, then, his face brightening:  “Hah!  I see!  The sofa hangings were held back when the shot came, then they fell into place and covered the holes?”

“That’s it,” replied the detective absently.

“And the man in Number Seven, the murderer, lifted that picture from its nail before shooting and then put it back on the nail after shooting?”

“Yes, yes,” agreed M. Paul.  Already he was far away on a new line of thought, while the other was still grappling with his first surprise.

“Then this murderer must have known that the billiard player was going to bore these holes,” went on Papa Tignol half to himself.  “He must have been waiting in Number Seven, he must have stood there with his pistol ready while the holes were coming through, he must have let Martinez finish one hole and then bore the other, he must have kept Number Seven dark so they couldn’t see him——­”

“A good point, that,” approved Coquenil, paying attention.  “He certainly kept Number Seven dark.”

“And he probably looked into Number Six through the first hole while Martinez was boring the second.  I suppose you can tell which of the two holes was bored first?” chuckled Tignol.

M. Paul started, paused in a flash of thought, and then, with sudden eagerness:  “I see, that’s it!”

“What’s it?” gasped the other.

“He bored this hole first,” said Coquenil rapidly, “it’s the right-hand one when you’re in this room, the left-hand one when you’re in Number Seven.  As you say, the murderer looked through the first hole while he waited for the second to be bored; so, naturally, he fired through the hole where his eye was. That was his first great mistake.”

Tignol screwed up his face in perplexity.  “What difference does it make which hole the man fired through so long as he shot straight and got away?”

“What difference?  Just this difference, that, by firing through the left-hand hole, he has given us precious evidence, against him.”

“How?”

“Come back into the other room and I’ll show you.”  And, when they had returned to Number Seven, he continued:  “Take the pistol.  Pretend you are the murderer.  You’ve been waiting your moment, holding your breath on one side of the wall while the auger grinds through from the other.  The first hole is finished.  You see the point of the auger as it comes through the second, now the wood breaks and a length of turning