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The coast of northern Chile is quite the driest of which there is any record in the world. For a 21-year period Iquique has an average rainfall of 1.5 mm. (0.6 inch), and Arica (for a 19- year period) has still less, 0.6 mm. But an average in the desert is as nearly useless a computation as even the desert affords. There is no such thing as a normal desert rainfall. Years of absolute drought pass, and the foreigner who comes out on a three-year or five-year contract may stay his time and depart without having known a drop of rain to fall; and he may even assert that it never falls and speak as one who knows because he ‘has lived there.”’ The British Consul at Iquique told me that he had advised some of his friends who were coming out from England not to bring umbrellas, for in the fourteen years that he had then known the coast no rain had fallen. Yet on the night on which they disembarked from the steamer it was raining hard. In 1906 there was a three days’ rain, a succession of light showers with intervals of heavy mist, which pene- trated the houses and collected and ran off walls and ceilings and soaked the carpets and beds. It is only the rare downpour that gives Iquique anything at all to average through the vears. It is as nearly like a rainless land as any that we know on the earth today.

Yet it must be impressed that rains actually do occur at intervals in the Desert of Atacama and that some of them are of extraordinary character. The reason for their occurrence is not quite clear. In the Cordillera of the Andes and the western foothills periodic summer rains fall as far down as 8000 or 10,000 feet, lower still in some places, higher up in others. At long intervals the usual rains may be supplemented by an extraordinarily heavy snowfall or an equally heavy rainfall. The sudden precipitation of rain in unusual quantities is a