change in parallel cycles, and affect every feature in terrestrial meteorology."
But, apart from every aid furnished by cosmic meteorology to that of our individual planet, the extension of the international simultaneous weather-reports will, we believe, ultimately afford the data requisite for approximately forecasting some main features of the seasons. A single example (the great heat of last October on the eastern side of the United States) will illustrate the possibility of attaining in some degree this long-desired object, which, like an ignis fatuus, has eluded the pursuit of men for so many ages. The summer of 1879 presented in North America no strongly marked high pressure; but after the 24th of July the barometric conditions were generally "low," and in the "Monthly Weather Review" for August, the Signal-Service stated: "The barometric pressure, as compared with the means of the
Chart of Equal Barometric Pressures during August, in and around North America. (Arrows show prevailing winds for August.)
seven preceding years, shows that the mean of the entire country has been abnormally low." We may compare the atmosphere then resting upon the interior to a vast and fixed dry cyclone, the elongated central area of which covered the Upper Lake region, and the country stretching northward, probably to the sixtieth parallel of latitude—the whole extent of the depression not less than 1,500,000 square miles.
