fore doing so, however, it will be necessary to glance at the advances in weather-research that have led to this undertaking.
The exploration of the vast body of water which surrounds the land-masses of the globe has been, since the sixteenth century, rapidly prosecuted. Its configuration has been determined, its tides have been weighed, its gulf-streams and counter-currents gauged, and even its abyssal depths sounded and surveyed, until we can now hardly speak, save by poetic license, of "the dark, unfathomed caves of ocean." But the exploration of that other and almost boundless ocean of air which envelopes the whole earth and whose winds sweep its surface, swaying the waters of the sea and affecting every form of terrestrial life, has progressed but slowly. The upper atmosphere is pierced by but few of the earth's mountain-peaks upon which meteorological stations can be efficiently maintained, while the spasmodic attempts at aeronautic investigation of the cloud-land, daring as they have been, have realized less knowledge of its currents than that which Columbus in his voyages of discovery acquired of the circulation of the equatorial waters. Investigation has been, therefore, perforce restricted for the most part to the phenomena of storms, cyclones, and anti-cyclones, moving at the bottom of the great sea of air--phenomena involving such insignificant portions of the atmosphere, when compared with the superincumbent mass, that a leading meteorologist has hyperbolically likened them to ordinary "smoke-rings." Even in the lower atmospheric strata, the different national bands of observers have been widely separated--here and there an ocean unsentineled rolling between them--so that their collated reports conveyed no clearly connected account of the transcontinental movements of air; and it is to-day disputed by some that North American storms cross the Atlantic to western Europe. But, worse than all else, the observations taken by the most painstaking and indefatigable observers were, until recently, systematically vitiated, not only by a lack of uniformity in the methods, but by the more fatal lack of uniformity in the hours of observation. What would be thought of a little army confronting immense odds, some of whose regiments had one plan of battle and some another, some asleep when others were engaged, but none acting simultaneously? Yet, such is a fair representation of the world's observational force which was expected to attack the great problems of meteorology, as it was until less than a decade ago.
In 1870 the United States entered the field of weather-research; and, for the first time in the history of meteorology, there was then established a broad system of simultaneous observations and simultaneous reports of the weather. These reports were immediately worked up and graphically embodied in the simultaneous weather-maps, issued thrice daily from the office of the Chief Signal-Officer, U. S. A., General Albert J. Myer, whose original and announced plan was to observe the weather over the whole country "at the same mo-
