Page:Popular Science Monthly Volume 2.djvu/164

152 the increase of each sun-spot cycle of the same eleven-year duration. The last observed occurrences of such heat-wave, which is very short-lived, and of a totally different shape from the sun-spot curve, were in 1834.8, 1846.4, 1857.8, and 1868.8; whence, allowing for the greater uncertainty of the earlier observation, we may expect the next occurrence of the phenomenon in or about 1880.0. The next largest feature is the extreme cold close on either side of the great heat-wave: this phenomenon is not quite so certain as the heat-wave, partly on account of the excessive depth and duration, of the particular cold-wave which followed the hot season of 1834.8. That exceedingly cold period, lasting as it did through the several successive years 1836, 1837, and 1838, was, however, apparently a rare consequence of an eleven-year minimum, occurring simultaneously with the minimum of a much longer cycle of some forty or more years, and which has not returned within itself since our observations began. Depending, therefore, chiefly on our later observed eleven-year periods, or from 1846.4 to 1857.8, and from the latter up to 1868.8, we may perhaps be justified in concluding that the minimum temperature of the present cold-wave was reached in 1871.1; and the next similar cold-wave will occur in 1878.8." Between the dates of these two cold-waves there are located, according to all the cycles observed, even including that earlier one otherwise exceptional, three moderate and nearly equidistant heat-waves, with their two intervening and very moderate cold-waves, but their characters are quite unimportant. With regard to all the waves, it may be just to state that there has been in observation more uniformity, and will be therefore in prediction more certainty, for their dates than for their intensities.

We have thus very briefly surveyed the position of meteorology, and little remains to be said beyond that the results are highly in favor of the hopes of physicists to render meteorology an exact science.—Quarterly Journal of Science.



N an age like ours, when philosophical criticism, applied to all ideas, has dissipated most of the fictitious charms lent to existence by the imagination of mankind—when the advance of science leads us more and more to look on the world as it is—when, no longer able to find consolation in creeds and myths, we grow more closely and constantly 