have had far more. So large a number of people could not be supported to-day without a radical change in the system of irrigation. Fortunately, the river changed its course as soon as the desertion of the village allowed the rude dam of boulders at the head of the old channel to fall into decay. Accordingly, the irrigation works have not been subjected to much destruction by floods, and I found them still almost intact. The difficulty of keeping the river in its old bed may have been the immediate cause of the abandonment of the village, but it had nothing to do with the sufficiency of the water supply of the past as compared with that of the present. The supply depends upon the character and width of the river-bed, which are essentially the same in both cases, the old channel being the wider, if anything. It also depends on the nature of the irrigation system, which, again, was precisely the same in the past as it is to-day. Then, as now, the innumerable minor channels into which the river divides were simply dammed with banks of gravel dug up close at hand. Thus all the water was gathered in a single larger channel on one side of the flood-plain, — a mile wide,— and was led off into canals, mere ditches dug in gravel or sandy clay, as the case might be. If the river should again be turned into the old canals, the available supply of water at the ruins would apparently be essentially the same as that at the village to-day.
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