consisted in making a very precise triangulation all over the hill of Gizeh; including points around all the three pyramids, and on the temples and walls belonging to them. A fine theodolite was used, by which single seconds of angle could be read; and the observations were repeated so many times, that if I finished the work at a single station in one day I was well satisfied. The result of all this mass of checked observations, after duly reducing and computing, was that there was scarcely a point about which one quarter inch of uncertainty remained, and most of the points were fixed to within one-tenth of an inch. These points were, however, only arbitrary marks put on suitable spots of the rock; and it needed a good deal of less elaborate work to connect these with the traces of the ancient constructions near them. The second season I obtained permission from Prof. Maspero to search for the ancient casing and points of construction of the pyramids. Many points were found easily enough; but some required long and dangerous work. To reach the casing, which still remains at the middle of each side of the great pyramid, was a hard matter; it was heaped over with broken chips a dozen to twenty feet deep, and they lay so loosely that they soon fell into any hole that we dug. It was needful therefore to begin with a very wide space, and gradually taper the hole, walling the sides roughly with loose blocks. Thus we succeeded in finding the casing on each of the three sides, where it was as yet unknown; the north casing having been cleared by a huge excavation of Col. Vyse over forty years before. These holes were very ticklish places, make them as we would; the Arabs dared not work them, and I had to get negroes to face the business. As it was, we could not venture to knock a bit of the stone, for fear of the vibration loosening the sides; and I was all but buried once, when--just as I had come out of the bottom of the hole--many tons of stones went pouring down the pit from the loose stuff above. At the third pyramid the difficulty was varied; there the pyramid was encumbered with loose blocks lying on a bed of sand. So soon then as we dug into the sand, the blocks came sliding down into our hole. But here the matter was settled by adding more stones, and so wedging all the blocks around into a ring; thus they balanced around the hole, and kept each other out. The casing of the third pyramid has never been finished. [Illustration: 4. GRANITE CASING THIRD PYRAMID.]