A foot above and on each side of the corner of the grey rock's lintel was a slight convexity, visible only from the angle at which my gaze struck it.
"We carried with us a small scaling-ladder and up this I went.

The bosses were apparently nothing more than chiseled curvatures in the stone.

I laid my hand on the one I was examining, and drew it back sharply.

In my palm, at the base of my thumb, I had felt the same shock that I had in touching the slab below.

I put my hand back.