for a lamp, supply it with oil. A profound remark, Markham—one of those seemingly simple quips that contain a great truth. A lamp without oil, y' know, is useless. The police always have plenty of lamps—every variety, in fact—but no oil, as it were. That's why they never find anyone unless it's broad daylight."
Markham's mind was now busy in another direction, and he rose and began to pace the floor.
"Until now I hadn't thought of Captain Leacock as the actual agent of the crime."
"Why hadn't you thought of him? Was it because one of your sleuths told you he was at home like a good boy that night?"
"I suppose so." Markham continued pacing thoughtfully. Then suddenly he swung about. "That wasn't it, either. It was the amount of damning circumstantial evidence against the St. Clair woman. . . . And, Vance, despite your demonstration here to-day, you haven't explained away any of the evidence against her.—Where was she between twelve and one? Why did she go with Benson to dinner? How did her hand-bag get here? And what about those burned cigarettes of hers in the grate?—they're the obstacle, those cigarette butts; and I can't admit that your demonstration wholly convinces me—despite the fact that it is convincing—as long as I've got the evidence of those cigarettes to contend with, for that evidence is also convincing."
"My word!" sighed Vance. "You're in a pos'tively ghastly predic'ment. However, maybe I can cast illumination on those disquietin' cigarette butts."
