He beckoned us.
"Flash your pocket-light down there," he said to me, pointing into the thick darkness below us.

The little electric circle quivered down as though afraid, and came to rest upon a surface that resembled nothing so much as clear, black ice.

I ran the light across--here and there.
The floor of the corridor was of a substance so smooth, so polished, that no man could have walked upon it; it sloped downward at a slowly increasing angle.
"We'd have to have non-skid chains and brakes on our feet to tackle that," mused Larry.

Abstractedly be ran his hands over the edge on which he was leaning.

Suddenly they hesitated and then gripped tightly.
"That's a queer one!" he exclaimed.