Page:Popular Science Monthly Volume 36.djvu/384

370 have artesian water. The whole valley is hot as a furnace, and the steaming canals probably make it seem hotter than it would, and may breed malaria as well as frogs and mosquitoes.

The Secretary of the Interior is reported to have sent an agent to Europe to study the subject of irrigation. We have a corps of engineers and a senatorial committee studying it in America. On the whole, it looks as if we ought to find out something about it. I have made a special study of it, and find it quite interesting. There is, perhaps, no more striking application of science to agriculture. You must know how to compute the mass of water that will flow through a ditch of a given size with a given fall. You must also know how much water will irrigate your particular piece of land. This will depend on its character as well as its size, and also on its annual rainfall.

It is astonishing how much the commonest Californians know about rainfall records. Rain-gauges are kept everywhere. The morning after a shower the farmers, instead of merely informing one another that it has rained, fall to talking of the quantity—and there is a good deal of sense in that. "My gauge showed fifty-seven hundredths of an inch," says Farmer Jones. "That makes 11·24 inches we have had this season," says Farmer Brown; "last season up to this time we had 13·42." And then they discourse of the precipitation yet needed to produce a crop without irrigation, or with partial irrigation, and the amount of irrigating water that will be required. The morning paper will give the rainfall in hundredths of an inch for a number of points throughout the coast country.

The size and strength of dams, head-gates, levees, etc., are matters requiring mathematical calculation of a delicate kind. Johnstown tells with terrible earnestness how important it is that these calculations should be to the last degree accurate. A careful survey of the route of each important ditch is also necessary. In fact, a number of sciences are involved in irrigating, but "practice makes perfect." Little by little the Western farmers are learning to depend more on cultivation and less on irrigation. They find it better in many ways; they now irrigate a greater area with the same amount of water. This hastens the day when the much-talked-of storage will pay.

What ought the Government to do in the premises? Tax the East to dam the West? I should say not, unless the expense were recouped. Perhaps it might construct the works and increase its prices on the land benefited. It gives lands to railroads in alternate sections, and then gets even by doubling the price of its own lands. What sort of a plan would it be for Uncle Sam to follow the example of the land-operators above mentioned—irrigate his land and sell it off at auction? He might sell it on sealed bids.