We could not do it; it would have been too cowardly.
"The other choice was to wait where we were for night to come; to wait for the rock to open as it had the night before, and to make a sortie through it for Thora before it could close again.
"Our path lay clear before us.

We had to spend that night on Nan-Tauach! "We had, of course, discussed the sleep phenomena very fully.

If our theory that lights, sounds, and Thora's disappearance were linked with secret religious rites of the natives, the logical inference was that the slumber had been produced by them, perhaps by vapours--you know as well as I, what extraordinary knowledge these Pacific peoples have of such things.

Or the sleep might have been simply a coincidence and produced by emanations either gaseous or from plants, natural causes which had happened to coincide in their effects with the other manifestations.

We made some rough and ready but effective respirators.
"As dusk fell we looked over our weapons.