Drake and Ventnor drew close to them, questioningly, anxious.

But I stepped forward, out of the dim gleaming.
Before me were two cubes; one I judged in that uncertain light to be six feet high, the other half its bulk.

From them a shaft of pale-blue phosphorescence pierced the murk.

They stood, the smaller pressed against the side of the larger, for all the world like a pair of immense nursery blocks, placed like steps by some giant child.
As my eyes swept over them, I saw that the shining shaft was an unbroken span of cubes; not multi-arched like the Lilliputian bridge of the dragon chamber, but flat and running out over an abyss that gaped at my very feet.

All of a hundred feet they stretched; a slender, lustrous girder crossing unguessed depths of gloom.