疯狂山脉（IX）(2)

It was now 8 P.M., and we had not enough battery replacements to let our torches burn on forever. We had done so much of our studying and copying below the glacial level that our battery supply had had at least five hours of nearly continuous use; and despite the special dry cell formula would obviously be good for only about four more—though by keeping one torch unused, except for especially interesting or difficult places, we might manage to eke out a safe margin beyond that. It would not do to be without a light in these Cyclopean catacombs, hence in order to make the abyss trip we must give up all further mural deciphering. Of course we intended to revisit the place for days and perhaps weeks of intensive study and photography—curiosity having long ago got the better of horror—but just now we must hasten. Our supply of trail-blazing paper was far from unlimited, and we were reluctant to sacrifice spare notebooks or sketching paper to augment it; but we did let one large notebook go. If worst came to worst, we could resort to rock-chipping—and of course it would be possible, even in case of really lost direction, to work up to full daylight by one channel or another if granted sufficient time for plentiful trial and error. So at last we set off eagerly in the indicated direction of the nearest tunnel.