We found the pits at length, a shaft of about 15 feet in depth, and a shallower one of about 6 feet, side by side, and sunk at the side of a dolerite dyke (“Aar”) bisecting the Dwyka shale of the pan, and from which it takes its name. There was nearly a foot of muddy water in the shallow shaft, and a very small pool at the bottom of the other, so we had no anxiety as to water. Indeed, after having drunk our fill from the shallow pit, we got fastidious: it was certainly very muddy and alkaline, and with at least ten mosquito larvæ to the spoonful, not to mention smaller abominations. So van Reenen prepared to go down the deeper shaft, where a little water looked cleaner. An old tree-trunk had been left in it as a ladder, probably by natives, years before, and he swung himself over the edge, trying to reach the top of this pole. As he did so a big owl flew out, brushing past him, and nearly scaring the life out of both of us. It probably saved his life though, for looking down carefully to see if there were others, and our sun-blinded eyes getting accustomed to the gloom, we made out, just gliding lazily away from the water, a huge puff-adder, fully 4 feet long, and bloated as they always are. It was so near the colour of the dark rock that, had it not moved, we should certainly not have seen it, and van Reenen would almost assuredly have been bitten, and to have been bitten would have meant death. The horror of that sluggish, bloated, most deadly of all snakes lurking there by that tiny pool of water, in a spot where water is so precious and certain to be sought by the rare wayfarer, and in a confined space where escape from it would be impossible, appealed to me most vividly, and we resolved that before we left the desert we would make an end of that big puff. Meanwhile we decided that the other water was quite good enough for us. We had been walking about nine hours, and were dog-tired by the time we had climbed to the top of the enormous dune, which can be seen for so far in the Kalahari. It was nearly sunset, the mirage had disappeared, and the big pan, with a smaller one divided from it only by a narrow isthmus of dunes southward, could be seen from end to end, a distance of about eight or nine miles running almost north and south, whilst eastward a vast expanse of desert stretched to the far horizon, broken here and there by the prominent dunes we had learnt to associate with the pans. In all directions the vast “sandscape” was unbroken by a sign of life, and, used to the desert as we were, somehow that highest dune to which we had climbed appeared the loneliest spot in all the Kalahari, and it was quite a relief, after we had lit a fire on the very top, to see an answering flame shine out from the signal dune at the camp some fifteen miles or more away.