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burning soil, the temperature runs rapidly down to freezing, because there is no vapor overhead to check the calorific drain.
Even in deserts—the home of the simoom and sirocco—where "the soil is fire, and the wind is flame," refrigeration at night is painful to bear, and hoar frost is not unfrequently produced. Eastern travellers in the desert often complain of the broiling heat of the day, and of its chill temperature at night. Beautiful allusions are also found in Scripture to the same law, where it is related that one of the greatest hardships which Jacob experienced while tending the flocks of Laban was that through the "drought by day, and the frosts by night, sleep departed from his eyes."
The Dry Line.
Much has been said respecting European emigration following in America isothermal lines. Isohygrometic lines, however, are far more important. The elements of fertility are heat and moisture, and one is fully as essential as the other.
From these facts, then, the 98th meridian becomes one of great importance to him who is studying the climate of the United States. Lay its map before you, and you will find that it cuts off into the desert a portion of Minnesota, nine-tenths of Nebraska, a large part of Kansas, half of the Indian Territory, and more than half of Texas. The climatic line is not absolutely confined, however, to this degree: it varies with the prevailing wind, whose hot breath brings drought, and sometimes desolation with it.
In Minnesota, for instance, we have this account of a destructive drought, in the Agricultural Report of 1863:—"The drought of last year must not be overlooked, however. From October, 1862, to August 4, 1863, we had but about twelve inches of snow and three inches of rain, the result of which (being confined to the northern part of our State chiefly) cut off our grain crops on many farms. Fortunately, the work being pushed on the Pacific Railroad, the labour required furnished aid to many, and a very mild winter following, much suffering was prevented. With a judicious expenditure by our own State of money, and perhaps a small appropriation in aid of the enterprise by Congress, the irrigation of a large portion of this section of the State may be effected, to prevent droughts hereafter, as well as bring a good return to the State Treasury, and an increase of crops to the farmers who will take advantage of the enterprise."
Thus it will be seen that in a State settled up very largely, and still drawing into it thousands of the Scandinavians of Europe, they are already looking to artificial means to remedy the defects of their climate. Scarcity of timber and water are the great difficulties which are everywhere met with in the great trans-Mississippi plains. In Nebraska the scarcity of timber forces the new settlers to make "dug-outs" in the side of the hills, until they can construct mud or "adobe houses."
In the State of Texas, the "dry line," in entering it on the north, recedes to the west; and the western limit of the cotton-fields of the United States is a line passing north and south through San Antonio. It curves, however, round to the south-east, and touches the Gulf of Mexico about the mouth of the Nueces, on the ninety-seventh parallel of longitude.
Looking from this point towards the Pacific, over this arid waste, along the El Paso route, for fourteen hundred miles, except a strip on the Rio Grande, and a spot on the Rio Gila, which are rendered productive by irrigation, that wide expanse is entirely unfitted for the uses of practical agriculture. Along this dreary, rainless, treeless tract, every species of growth is spinous. The grass has thorns; and original explorers thought even the frogs had horns. The cactus, which is sometimes forty feet high, and two feet in diameter, supplies the place of trees. The "Llano estacado," or "staked plain," of Western Texas, is so devoid of trees, to guide the traveller, that even the wild Comanche is compelled to set up stakes to navigate this ocean-like plain: hence, its name.
