The establishment of meteorological societies during. the last twenty years must also be commemorated as contributing in a high degree to the solid advancement of the science which, more than any other, must depend on extensive and carefully conducted observation. In this respect, the United States stand pre-eminent, the observers there numbering nearly 800. Great Britain is also well represented in the English and Scot tish societies, which together number above 200 observers. In France, Germany, Rus .sia, etc., the science is also being widely cultivated. Owing to the disastrous flooding of the Rhone, an inquiry has been carried on for several years, having for its object the deter mination of those' causes which affect the rainfall in the basins of Rhone and Bafine. Observers in Germany and Great Britain have been secured to co-operate with the French observers, and under the management of a commission it may be expected' that important conclusions respectim, the rainfall and the progress of storms will be arrived at, and means devised to avert'the calamity of these great floods by timely warn ing being given of their approach.
A special object of meteorological societies is to ascertain the degrees of heat, cold, and moisture in various localities, and the usual periods of their occurrence, together with their effects on the health of the people and upon the different agricultural produc tions; and by. searching into the laws by which the growth of such products is re,011 lated the agriculturists may be enabled to judge with some degree of certainty whether any given article can be profitably cultivated.
But perhaps none of the arts have benefited to so large an extent by the labors of meteorologists, as navigation. The knowledge thus acquired of the prevailing ,winds ,over the different parts of the earth during the different seasons of the year—and the regions of storms and calins—and the lziws of storms, have both saved innumerable lives, and by pointing out the most expeditious routes to be followed, shortened voyages. to a remarkable degree. In connection with this, the name of Captain Maury (q. v.) deserves special commendation for the signal service he has rendered to navigation.
Another fruit of the multiplication of meteorological stations is the prediction of storms and " forecasts" of the'weather, which have been carried on in the United States, and commenced with ability and success by Admiral Fitzroy. in England. These " forecasts " are based on telegrams which are received every morniu„n. from above forty selected stations in Great Britain and Ireland, and on the continent, from Haparanda as. far south as Lisbon. These telegrams give the exact state of the barometer, thermom eter, hygrometer, and rain-gauge, with the direction and force of the wind, and appear ance of the sky, at each of these forty stations at eight in the morning. In the event of" there being any storm or other atmospheric disturbance at one or more of these places, a full and accurate description of it is thus conveyed to London; and it is thence the duty of the officials there to consider the direction in which the storm is moving, so as to enable them to give warning of its approach by special signals. But in addition to
warnings of storms, Fitzroy also issued daily " forecasts" of the weather likely to occur in the different districts of Great Britain for the following two days, and which were in: like manner founded on the state of the atinosphere at distant points, keeping in view the atmospheric currents known generally to prevail at that particular time of -the year. As the cost of this system was about £2000 annually, a severe test was applied, at the instance of the Treasury, from July 1861 to June 1862, for the purpose of ascertaining whether the expenditure was justified by the success attending it. During the first six months, 413 signals were hoisted, and in 214 cases a storm occurred where a warning was given. It must not be inferred that in the remainino- 199 cases there was no storm anywhere; all that -was meant was, that no storm occurreql at the places where t.he signal .v was given; but a storm may have occurred, and probably did occur, in some other part of the country. Now that the system has been longer in use, the signals are given from a, better knowledge of the movements of the atmosphere, so that if the test were again applied, the number of failures would be found to be much feNter. Since the barom etric depression is in almost all cases spread over a wider area than the storm -which ,accompanies it, and since the storm occasionally passes into the upper regions of the atmosphere, so as to be less felt on the earth's surface at that place, it is obvious that a .considerable time must yet elapse before a sufficiently intimate knowledge of the move ments of the air be acquired in. order to indicate with certainty the-particular places where the storm will break out, and where it will not. The problem to be practically worked out is this: Given the telegrams from the stations showing the exact meteoro logical conditions prevailing over the included area, with indications of a storm approaching in a certain direction, to determine, not the probable arca over which the tempest will svveep, but the precise localities which will altogether escape, the places. where the storm will rage, and the places where it vvill not touch the earth, but pass. innocuously into the upper regions of the atmosphere; its continuance, its violence, and the particular directions front which the wind will blow at the places visited by the storm while it lasts. Considerable progress has already been made towards the solution of this difficult problem; and if a complete solution be impossible, such an approxima tion to a solution will doubtless be arrived at as will render it foolhardy to disregard the warnings given.