But he never did that.

Afraid of mosquitoes, very likely.
Neither was he ever tempted by the silence to address any casual remarks to the companion glow of the volcano.

He was not mad.

Queer chap--yes, that may have been said, and in fact was said; but there is a tremendous difference between the two, you will allow.
On the nights of full moon the silence around Samburan--the "Round Island" of the charts--was dazzling; and in the flood of cold light Heyst could see his immediate surroundings, which had the aspect of an abandoned settlement invaded by the jungle: vague roofs above low vegetation, broken shadows of bamboo fences in the sheen of long grass, something like an overgrown bit of road slanting among ragged thickets towards the shore only a couple of hundred yards away, with a black jetty and a mound of some sort, quite inky on its unlighted side.

But the most conspicuous object was a gigantic blackboard raised on two posts and presenting to Heyst, when the moon got over that side, the white letters "T.