Page:Popular Science Monthly Volume 60.djvu/167

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RAINFALL AND COMMERCE AND POLITICS.

fluences on man's political and business relations are not more frequently considered.

One of the fundamental needs of man, in fact a prime necessity, is a sufficient food supply. When food is abundant and hunger is satisfied there is a surplus of energy to expend on other human affairs, and this, I presume, most people will admit is the primary condition of prosperity.

The food-supply at present is obtained almost entirely from the soil, and its growth is intimately dependent on weather conditions. The relation of the food-supply to the weather has been investigated to some extent, and it is found that the factors which most powerfully influence the food-product are temperature and moisture, which latter is derived from rainfall. The annual change in temperature is comparatively regular and certain, so that the factor which, by its changes, most powerfully influences the food-product, is the rainfall.

J. T. Wills investigated the relation of the rainfall to the wheat-product per acre in south Australia for the six winter months (the growing season there), and found that for the seven best years there was a yield of 12.4 bushels of wheat with 18.5 inches of rain; for the next best years there were 10.0 bushels of wheat with 15.4 inches of rain; and for the six worst years there were 6.6 bushels of wheat with 13.5 inches of rain. The product of wheat in the first case was nearly twice as great as in the last. If such a relation holds for the United States, it is easy to understand what great effect a general drought may have on the food product. If the amount of wheat raised in the United State were reduced one half or even one third by a year of deficient rainfall, it is easy to imagine an enormous strain on the business of the country, and with a succession of such years the effect might mean disaster. Such a deficiency in the wheat supply, with wheat at 80 cents a bushel, would mean for a single year a direct loss in wealth of more than $100,000,000; it would mean that nearly all the wheat which is usually shipped abroad would be needed at home; it would mean that thousands of railroad cars and ships which ordinarily transport this grain would lie idle; that hundreds of men who usually handle this grain in transport would be out of employment; that farmers in large numbers would be unable to meet their obligations; and consequently, that banks and business of all kinds would suffer.

But the deficiency in rainfall would not affect the wheat alone; every product of the soil would likewise suffer. Rawson has worked out a simple formula in the case of Barbadoes by means of which the amount of sugar to be exported the next year can be calculated with great accuracy from the rainfall of the current year. This calculation is accurate within six per cent, in most cases. Similar calculations for Jamaica have been made by Maxwell Hall. He shows that 56 inches of