It is our proximity to the Atlantic that makes it impossible to predict the weather beyond two days at the utmost. In Norway and the Baltic, and places toward the east of Europe, the weather may be predicted for a longer time owing to the more easterly situation of these places. In America also, where storms advance chiefly from w. to e., gales and unsettled weather are predicted to places on the sea-board in the east some days before.
The collecting of this information by the telegraph is a work which, owing to the expense, governments only can accomplish; and from its public importance, it is an incumbent duty which they should discharge for the benefit of the sea-faring and agri cultural population. A good deal may. however, be done by one for himself, by observing his barometer, the winds, and the face of the sky—especially the cirrus cloud —the most elevated and delicate of the clouds. But ere these simple observations can. be turned to account, and made the basis of au intelligent prediction, some knowledge of the general features of storms (q.v.) is indispensable. These specially—(t) Storms have a circular area; and (2) advance in an easterly direction, bearing a low barometric pressure with them. (3) Winds blow from a high to a low barometer, the observer, standing with his back to the wind, having always the low barometer to his left in the northern hemisphere, and (4) with a force proportioned to the difference of the pressure, or to the steepness of the barometric gradient. (5) Storms are first noticed in the upper regions of the atmosphere, or in the region of the cirrus cloud. (6) In front Of the storm the air is warm and humid; in the rear of it, cold, or cool and dry. With such observa tions, requiring only a barometer intelligently interpreted, particularly if hills form part of the landscape, the character of the weather may be foreseen for one day, or even on occasions longer. ' To the agriculturist and horticulturist, not high winds but hails, heavy rains, frosts and fine weather are what are required to be known. Such forecasts have been issued for some time by gen. Myer in the United Stotes, were also begun in France by Lever rier shortly before his lamented death, and are gradually being introduced over the con tinent of Europe, with great advantage to those national interests. But though no pre
diction of the weather for weeks or months beforehand can be made with any preten sions to trustworthiness, yet guesses or surmises may be formed not without some value. All observation goes to prove that predictions based on solar or other astronomical causes are without foundation, and that averages based on terrestrial observations are the only guides in the matter. Of this class are the interruptions which occur in the regular march of temperature in the course of the year. Thus, cold weather generally prevails. fromthe 11th to the 14th of April—that is, the period of the "borrowing days" (O.S.), and in the second week of May; and these, with some ,other cold and warm periods,* are almost co-extensive with the northern hemisphere of the globe. Hence, then, at these times, when the weather becomes cold or warm, it may be predicted that such , weather will last for several days. Again, if, after a long-continued prevalence of s.w. winds, the n.e. wind should set in, it is highly probable that easterly winds will prevail for some time; so that, if the season be winter, a continuance of frost, and perhaps. snow, may be looked for; but if midsummer, the weather will become dry, warm, and bracing, But suppose easterly winds have been unusually predominant in autumn, and icauth•westerly winds begin to prevail in the end of November or the beginning of December, it is most probable that the weather will continue exceptionally mild, with frequent heavy storms of wind mid rain till about Christmas.
A good beginning has been made in India by Mr. Blauford in predicting the character of the monsoon season, it having been shown by him that abnormal distributions of atmospheric pressure which happen to prevail about its commencement, tend to perpetu ate themselves during the season. Since the distribution of the rains depends on the distribution of atmospheric pressure, forecasts of the coming monsoon have been issued, which thus proceed from a scientific basis, and the event has shown them to have been remarkably successful. It may be predicted that as systematic observation advances, the power to predict the character of the coming season will be extended to higher lati tudes. See .11 ETEOROLOGY.