Was it possible that this could be an imaginary cavity into which he was looking?
He drew back; he was about to put out one foot to feel if it were really solid ground upon which this light was pouring, but he refrained.

He got a long stick, and with it touched the centre of the light.

What he felt was hard and solid; the end of the stick seemed to melt, and this startled him.

He pulled back the stick--he could go on no further by himself.

He must have somebody in here with him; he must have the testimony of some other eyes; he needed the company of a man with a cool and steady brain.
He ran to the door and called Bryce.