Where the deserts of the last-mentioned kind are found, did anything like a moderate rainfall happen yearly, they, of course, would not exist. But rain in these localities is very rare, as indeed it is all over the world in such spots. The want of rain, I conceive, _makes_ the desert, and the arid waste responds by keeping off the rain. It is well known vegetation conduces to rainfall, and that a country thickly wooded, when cleared, has less rain after. I have myself seen striking instances of this. On the other hand, vegetation and rain increase simultaneously. It _may_ be, therefore, that, in the course of very many years, a portion of the American deserts will disappear, for where the soil has any vitality in it, and water is procurable, artificial means will bring vegetation, which again, little by little, will increase the rainfall; until at last (it may take centuries) the now said desert tracts will thrive with the rain from heaven alone. While on the subject of rain, I would mention some curious facts. From what we know of the climate in different European localities (or rather let us confine ourselves to Great Britain, where the western parts, especially Ireland, near to and exposed to the effects of the Atlantic, have an increased rainfall), we (by "we" I mean others, like me, ignorant of meteorology) would think the western Pacific coast of America, with that boundless ocean (far wider than the Atlantic, and stretching across to Asia) in front would fare likewise. But it is _not_ so. In fact quite the reverse. On the greater part of that coast, up to about latitude 42° north, the rainfall is exceedingly scanty, so much so that very little vegetation will thrive without artificial watering, and though north of 42° there is much more, it is still less than on our western coasts. The deficiency cannot arise, except very partially, from lack of vegetation, for though the said coast, south of 42°, is very bare, not far back exists a high and well-clad mountain range.[6] What is the cause I know not, perhaps meteorologists do, I only state the fact. But more: though not to the same degree, all the large tract west of the Rocky Mountains has a deficient rainfall, and artificial irrigation is more or less resorted to everywhere. I shall have more to say as to how it is done when, later, I describe the Antelope Valley.