Page:Popular Science Monthly Volume 16.djvu/309

Rh of actual (not local) time," as was stated on every weather-map. This conception aimed at the rescue of meteorological researches from that disorder and disconnectedness which had always characterized the observational work. The prime object was to gain a daily conspectus of the atmosphere over the country as it actually was, and as it would be seen if a photographic view of it, so to speak, could be taken. The simultaneous method, when announced, seemed so natural and simple that one might have wondered that any other was ever attempted. Observations called "synchronous" had been, indeed, before this time, energetically made in several countries; but the term "synchronous" was used to signify that every observer read off his instruments at given hours of his own local time, and not at the same moment of physical time. Etymologically, there might be little or no difference between "synchronous" and "simultaneous," but, for all the purposes of atmospheric investigations over a vast territory like that of the United States, the practical difference was by no means insignificant. When observers, who on the old "synchronous" method reported the weather-status each at the same hour of local time, were separated by hundreds of miles, their reports failed to represent the actual fluctuations of the atmosphere and the true bearings of its cyclonic and anti-cyclonic movements; so that, when the meteorologist came to compare and chart the combined data, they yielded necessarily a distorted or untrue picture of the ever-restless aerial ocean. On the other hand, in the "simultaneous" method, since all the observers over the wide field of the research read their instruments at one and the same moment (7.35 Washington mean time), their reports, when charted, gave a true and life-like representation of the physical phenomena as they actually coexisted and conspired. As on the screen of the artist's camera the sun instantly paints the true image of the human face before its expression can be changed, so does the process of simultaneous observation seize and secure all the elements necessary to delineate the current physical features and conditions of the atmosphere, as existing at d, fixed moment, and before they can have time to undergo change. Simple as this expedient is, it is evidently the key to all effective research in a vast gaseous ocean whose currents and waves are ceaselessly rolling and rapidly altering their geographical bearings, even while the sun is quickly passing from one meridian to another. Were all the weather observers of the world to read off their instruments as it were by a given tick of one clock, their collective data would furnish materials for the most exact delineations of the complex atmospheric machinery which it is possible to obtain. Instead of piling up a mass of weather bulletins unsuited for purposes of a rigidly scientific inter-comparison, as was so long done, they would contribute