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Page:Popular Science Monthly Volume 32.djvu/400

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THE POPULAR SCIENCE MONTHLY.

a somewhat regular gradation, two to five degrees, during one, two, or three years. And in the approach to maxima a rise nearly as precipitate. This has its parallel in the rainfall—the precipitation experiencing a sudden increase in the high extremes of from eight to thirteen inches, and during low extremes of from four to eight inches, within one or two years.

In these records of the past century, imperfect as they are, will be found suggestions of more subtile and fundamental laws. The reader may notice a succession of three large sun-spot waves or periods followed by three lesser ones. They call to mind that succession of waves in the sea, called by sailors "the three sisters," and of the three day weather period with which we are familiar. The conjecture may be warranted that we have here an indication of a major vibration of a six-period duration. It may be that all these cycles are but members of a grander whole, whose circles reach beyond our present ken, and to a perfect conception of which we may never attain, except perchance in that good time coming, when man's knowledge shall equal his aspirations. These considerations, and many more of which we are in ignorance, must enter into a calculation of the true horoscope of the future.

Nevertheless, we know that Nature governs by unvarying law. Assuming that her periodicities will bring about the same average results in the future as in the past half-century, I might undertake to be in some sort her interpreter of the coming events which cast their shadows before, along the pathway of a few unborn years; provided the same latitude be accorded me which was claimed by the old almanac makers, to qualify the record with "about. . . these. . . days."

In each of our half-century cycles we have seen that there are five maxima and five minima of sun-spots, whose periodic times average for the first cycle a little more than eleven and a half years, and for the last cycle a little less. We may reasonably conclude that the next half-century will witness no material change, but that the like phenomena will continue, with a mean period of about eleven years; also, that the temperature and the rainfall will continue to exhibit their dependent phenomena as before. On this basis let us construct our diagram for the coming years.

Premising that the sun-spot curve, which for five years had been on the rising scale, attained its maximum in 1882, we may infer that the temperature is now on its descending grade, and should reach its minimum by 1889 or 1890. The yearly mean, which for ten years past has maintained an unusually high degree, with small range, will fall rapidly five degrees or more. "Look out for. . . cold. . . weather. . . about. . . these. . . years." The wary will also provide for cold winters about the years 1901, 1912, and 1923, and for epochs of high temperature about 1894, 1905, and 1917.

The rainfall, which, in accordance with its law of opposition and