neous Observations" is a generalization in itself, and offers the meteorologist every day a bird's-eye view of the aërial world as it actually was at that fixed moment of physical time when all the observations embodied in it were made. Nothing can be simpler or more intelligible to even unscientific eyes than a chart which, by means of suggestive symbols, displays the different elements of the weather over a hemisphere, each in its own color. Just as Mercator's projection represents the entire ocean to the mariner—as if there were no horizon or sphericity—and all objects in their true meridional bearings to each other, so the "International Weather-Chart" depicts the aerial ocean in its beautiful integrity and all its parts in their true physical relations to each other, as certified by strictly simultaneous reports. Of course, the two charts are entirely independent and different; but we refer to the invention of the old Flemish geographer merely to illustrate and enforce the immense value of every really synoptic chart as a weapon of research and as a medium of scientific discovery.
The cartographic method, by which truly synoptic views of the atmosphere are obtained, is indeed the natural accompaniment and handmaid of the method of "simultaneous weather-reports," both of which are peculiar to the national weather-service inaugurated at Washington in 1870, and, through the adoption of General Myer's proposition at Vienna, in 1873, extended to the new international weather-service. Without "simultaneous" weather observations, it is obvious, no truly "synoptic" weather-chart is possible; and, as has been said, the first "simultaneous" observations were those instituted by the United States in 1870, The unique and novel feature of the international weather-charts, and the feature which will most commend them to meteorologists, is that they furnish a faithful pictorial history of the atmosphere and its revolutions, enabling the inquirer to trace its currents and counter-currents, to witness the behavior of its cyclonic storms and other barometric waves as they traverse continents and deploy upon the ocean, and to form clarified conceptions of its massive yet orderly machinery. The well-known English journal of science, "Nature," "earnestly hopes that the navies and the mercantile vessels of all nations will soon join in carrying out this magnificent scheme of observations, originated by the Americans in 1873, and since then further developed and carried on by them with the highest ability and success." Its French namesake, "La Nature," said recently, when speaking of this service, "One ought not to be surprised to learn that the United States, encouraged by their first successes, are to attempt a new extension of a system of observations which has already, in so few years, produced considerable results." It would not be an easy task to predict the future results to be obtained by such a system of investigation; but we may confidently conclude that no system of weather inquiry ever before undertaken promised a richer harvest of meteorological lore than that which rigidly follows up its simultaneous obser-
