It was diamond hard and smooth.

The nearest cones were but a scant nine feet from its rim.
Suddenly we saw the tablet; stood beside it.

The shape of a great T, glimmering with a faint and limpid violet phosphorescence, it might have been, in shape and size, the palely shining shadow of the Keeper.

It was a foot above the floor, and had apparently no connection with the cones.
It was made of thousands of close-packed tiny octagonal rods the tops of some of which were cupped, of others pointed; none was more than half an inch in width.

There was about it a suggestion of wedded crystal and metal--as about its burden was the suggestion of mated energy and matter.
The rods were movable; they formed a keyboard unimaginably complex; a keyboard whose infinite combinations were like a Fourth Dimensional chess game.