There, he stripped his shirt from him.
"Something is happening," he said.

"The mark is smaller." It was as he said.
"I'm escaping," he whispered jubilantly, "Just let me get to Melbourne safely, and then we'll see who'll win! For, Walter, I'm not at all sure that Edith is dead--as we know death--nor that the others are.
There is something outside experience there--some great mystery." And all that day he talked to me of his plans.
"There's a natural explanation, of course," he said.

"My theory is that the moon rock is of some composition sensitive to the action of moon rays; somewhat as the metal selenium is to sun rays.

The little circles over the top are, without doubt, its operating agency.

When the light strikes them they release the mechanism that opens the slab, just as you can open doors with sun or electric light by an ingenious arrangement of selenium-cells.