“Air’s all I can think of.”

“All I can,” Teverson admitted. “And, with that in mind, I believe I’ll have a look around our directors’ room myself, if you’ll hold, up our meeting for a few minutes.”

“Damn foolishness,” acceded Sencort graciously.

“Pipes were what I was particularly warned against,” I said to Teverson.

“Come along,” he invited me; so I went with him to the fifth floor, passed Weston and Reed on guard outside to see that nobody carted in time bombs since they’d last reported the room clear, and we stepped into the regular, long-tabled, black-walnut panelled mausoleum sort of room which directors picked for their deliberations a generation or so ago.

There it was, with two windows to the street and both closed; it was winter, you see, and Sencort wasn’t the only near octogenarian to rally round that walnut. It had electric lights and nothing else but a steam radiator, carpet and chairs and five old etchings on the walls. Everything was clear; nothing was wrong in the drawers or under the tables or chairs or even under the carpet. Reed had carefully tested the radiators and steam pipes. They were absolutely in order.

But I kept poking about the room and, behind an etching, I found the capped head of an old gas pipe which evidently brought illuminating gas to the room in the days before electric lighting.

It was capped, I say, and looked quite all right, but I happened to put my fingers behind the cap. Then I called Teverson; and he felt, and called Reed.

“What do you think of that?” he asked.