grams and Reports for the Benefit of Commerce and Agriculture."

This was the first attempt of the United States Government to inaugurate a national weather service. The peculiar geographical extension of the country, stretching over fifty-seven degrees of longitude and twenty-two of latitude, afforded exceptional advantages for investigating and predicting the storms which cross its broad area; for experience and observation had shown that they generally move from west to east, and not frequently along the meridians. But the vast extent of the storm-field, coupled with the fact that the "law of storms was then but roughly outlined, made the execution of this task a very difficult and tedious work, calling for great caution and the most accurate observations. Redfield had demonstrated from ship-reports that on the sea cyclonic disturbances in the northern hemisphere rotate from right to left-in a direction contrary to the hands of a watch. Ferrel and others had demonstrated that, mathematically or mechanically, this law should in theory hold good for both land and sea. The Dutch investigator Buys-Ballot, from actual weather-observations, had shown that the law held good for Holland. But its demonstration on the wider continental field of America, as well as the discovery of many details affecting its practical application to weather-prediction, awaited further, more extensive, and more exact research. It was not until November 1, 1870, that the Chief Signal Officer was able to issue weather-bulletins. On that day, from twenty-four stations, the first systematized simultaneous reports of the weather ever taken in the United States were read from their instruments by the Signal Service observers, and telegraphed to the Central Signal Office at Washington. The same day the bulletins made up from these reports were prepared and telegraphed by the Chief Signal Officer to more than twenty cities. The first storin-warning was bulletined along the lakes a week later, for the benefit of the large commercial and marine interests exposed to the furious gales which sweep, especially in autumn, over their waters. These tentative attempts to introduce the novel system of practical weathertelegraphy were vigorously followed up, and the success realized so early in the operations of the service was as gratifying to the public as to the office itself. This success was due in large measure to the system of observation and reports being in the strictest sense simultaneous. Weather-Maps. To arrive at any result, it was found necessary almost from the first to chart weather-maps from the reports thus received by telegraph. The Signal Service weathermap is a map of the United States on which all the Signal Service stations are entered in their appropriate geographical places, and having annexed to each station the figures expressing the readings of the barometer and thermometer, the velocity of the wind, the amount of rainfall within the previous twenty-four or

eight hours, etc.; and also symbols indicating the direction of the wind, and the form and amount of cloud, at the given time of observation. The observations taken at each station are all put down on the map, and the relations between them are thus made sensible to the eye of the Signal Officer, by the figures and symbols, and also by lines drawn to group the geographical areas over which like conditions prevail. The weather-map is, therefore, to the meteorologist what the telescope is to the astronomer-an indispensable means of obtaining a survey, and prosecuting a careful and connected study of the phenomens he seeks to understand. The accompanying " War Department Weather-Map," prepared by the Signal Service, illustrates the method of charting the map graphically. This specimen map is about three eighths the size of those from which the Signal Office works. It represents the atmospheric conditions as they were simultaneously observed at 7 A. M. mean Washing ton time, December 23, 1879: the area marked "Low" defining a storm or cyclonic area in Texas with low pressure, and that marked "HIGH" defining the limits of an anticyclonic area, in which the barometer is high. Around the latter the winds are seen to draw in the direction of the hands of a clock; but around the former, in a contrary direction.

Simultaneous Weather Observations.-In organizing this service, the first problem that presented itself was to devise a system of observations which would when mapped accurately represent the aerial phenomena in their actual relations to each other, and thus enable the investigator to discover the laws of storms and their rates of movement over the earth's surface. "The history of science," says one of its foremost representatives, "proves that unconnected, unsystematic, inaccurate observations are worth nothing." Certainly, in the domain of meteorology, no solid foundation for the science of the weather could have been laid in 1870 upon any of the then existing observational systems. The European weather-stations at that date, and long after, were engaged in making non-simultaneous reports; no two of them, unless they happened to be on the same meridian, read off their instruments at the same time; and consequently their records, valuable as they were for purposes of local meteorology, were inadequate and untrustworthy for purposes of rigidly scientific comparison, or for giving accurate numerical data of changes in the ever-restless and fickle atmospheric ocean. In this state of the research, which had made meteorology a proverb for inexactness, General Myer proposed a new, independent, and original system of investigation- the system of SIMULTANEOUS METEOROLOGY - on the results of which the weather-predictions and stormwarnings of the Signal Service have been based from the beginning of its work until now.

This novel, yet perfectly simple, scheme aimed at the rescue of weather-research from

the chaos in which for ages it had lain. Its cardinal principle of observation is to gain a daily or tri-daily view of the atmospheric conditions and movements over the country as they actually are, and as they would be seen could they, so to speak, be photographed. In all previous systems this was far from attainable, for lack of simultaneous reports. As formerly observers had read off their barometers and other instruments at the given hours of local time, and not at the same moment of actual time, the reports from stations at widely separated meridians necessarily yielded unnatural and distorted representations of the phenomena to be studied. The Chief Signal Officer's plan reversed this vicious arrangement, and inaugurated one by which all the weather-observers over the entire field of inquiry, from the Atlantic to the Pacific coast, were to observe and read off their instruments "at the same moment of actual (not local) time." Under the new method, introduced by General Myer in 1870, all the members of the Signal Corps registered and reported the weather of the United States, as it were, by given strokes of a single clock -the same moments of physical time-corresponding to certain fixed moments of Washington mean time.

Simple as this innovation appears, it is vital to all successful research in an aerial sea whose currents and waves rush with great rapidity, and perform some of their evolutions while the sun in his daily march is passing from one meridian to another. The old methods, without exception, though called "synchronous," were not truly so,* since each one of the observers reported at the local time of his own special station. When, therefore, the stations were extended over thousands of miles in an east and west direction (as was necessarily the case in the United States, owing to its geographical shape), their data were misleading. Columbus on his first voyage to America discovered that within the tropics the waters of the ocean move from east to west; but in the extra-tropical belt they move from west to east. As with the waters of the sea, so with the winds: from the equator nearly to the polar circles the great perennial air-currents (in which cyclones lie imbedded and in which they move forward as eddies in a stream) move on the surface of the earth along the parallels of latitude, and but seldom along the

By "synchronous" weather-reports meteorologists only mean reports taken nominally at the same hour. Thus, if a London observer reported the weather at 7 A. M. Greenwich time, and a Berlin observer reported it at 7 A. M. Berlin time, the two reports would be called "synchronous"; but, in reality, they would not be synchronous, for the difference between 7 A. M. at one and the other point is about 54 minutes. But 54 minutes makes a great difference in the flight of a storm and the shiftings of atmospheric masses, which can not therefore be represented on weather-maps based upon "synchronous" reports. A weather-map prepared from such "synchronous" reports reflects the aerial elements untruly, as a telescopic lens having many irregular faces, and not a single focus, would reflect the surface of the moon. "Simultaneous reports, on the contrary, when entered on a weather-map, form a true mirror of the atmospheric masses and movements as they are in nature.

meridians of longitude. For this physical reason, it was found to be of the utmost importance to observe these great movements at many points over long portions of the parallels of latitude simultaneously. In no other way can the bearings of the various stormwinds and their connected phenomena be detected, or the rates of their transition determined. All the predictions and deductions of the Signal Office, therefore, have from its beginning until now been based on reports taken simultaneously.

Early Developments.-As the early developments of the Signal Service were necessarily pioneer work, it being the first attempt to institute a system of "simultaneous" weathertelegraphy, and finding many of the laws of storms now defined then scarcely formulated or entirely unknown, its advance in 1871 was cautious and slow. But, when once it had established the fact that at any hour of the day or night it could almost instantly call for reports from all parts of the country, and receive them from all its stations, taken at the same moment of time and revealing the actual status of the atmosphere over its whole field of inquiry, the sense of security in its scientific processes, and the confidence that the results were built upon "the solid ground of nature," gave it a powerful forward impulse. The new method of simultaneous reports, it was felt, was a sure road to the desired goal. In a short time additional stations were established within the United States, making sixty-six in

cent.; and during the year ending June 30, 1872, 354 cautionary signals were issued, with an estimated percentage of correctness amounting to 70. These results also afforded the best elucidation and the most complete demonstration of the law of storms and the movements of cyclones that had ever been obtained in any country.

By act of Congress approved June 10, 1872, the Signal Service was charged with the duty of providing such stations, signals, and reports as might be found necessary for extending its research in the interests of agriculture. The agricultural societies over the land earnestly entered into and cooperated with the Service in this new development of its inquiries and reports. Eighty-nine such societies, thirtyeight boards of trade or chambers of commerce, numerous scientific institutions, colleges, and leading professional men put themselves in communication with the Chief Signal Officer, with a view to facilitate this branch of his work. The scientific societies at home and abroad began to take the liveliest interest in the general labors of the Office, and to express the highest approval of the results attained. And, beyond the limits of the United States, numerous marine observations, which General Myer had previously desired, with the purpose of studying the atmosphere as a unit both on the ocean and the land, were forwarded regularly to his office.

The expansion of the work in 1873, under the stimulus of a world-wide favorable notice, was even more rapid than in the previous year. On March 3d Congress authorized the establishment of Signal Service stations at the lighthouses and life-saving stations on the lakes and seacoast, and made provision for connecting the same with telegraph-lines or cables "to be constructed, maintained, and worked under the direction of the Chief Signal Officer of the Army, or the Secretary of War, and the Secretary of the Treasury." Early in this year the Office also began the regular publication of a "Monthly Weather Review," summarizing all its data and showing the results of its investigations, as well as presenting these in graphic weather-charts adapted to the comprehension of the unscientific part of the communities it was destined to reach. The library of the Signal Office was increased to some 2,500 volumes bearing on the special scientific duties imposed upon it. The tests of meteorological instruments previously instituted enabled it to greatly improve and simplify its entire instrumental apparatus at all stations. The percentage of verification of its predictions for the year ending June 30, 1873, was for each geographical division as follows:

New England.. Middle States..

It was in September of this year also that, at the proposal of the Chief Signal Officer in the International Congress of Meteorologists convened at Vienna, the system of world-wide coöperative weather-research, since then so extensively developed, was inaugurated, and began to contribute its observational data to the Signal Office records. Thus, in his report for 1873, the Chief Signal Officer was able to say of its labors, "Their utility is no longer questioned, and effort at home and abroad turns only toward their development." The Service was now no longer an experiment, but an assured success.

The operations of this division of the Signal Service, popularly known as the "Weather Bureau," have been, every year since its creation, somewhat enlarged by Congress, until they have become numerous and varied. The first to be specially mentioned is the daily work of weather-prediction, including storm-warnings. These are issued from the office of the Chief Signal Officer three times every day, under the title of "Indications" and "Cautionary Signals," and are based upon three series of simultaneous weather-reports telegraphed to Washington from all parts of the United States and Canada. The observations are taken simultaneously at all stations at 7 A. M., 3 P. M., and 11 P. M., and at once put upon the wires. The number of stations from which tri-daily telegraphic reports are received at the central office is 133. Telegraphic reports have been also regularly received from one West India station, and during the hurricane season from five. The total number from which such reports are received daily is 159; but, including those sent by mail, it is much larger; while the total of reporting stations within the United States territory, including the special river and sunset stations, on the 30th of June,

81.50

81.17

1879, was 229. The vertical range of the observations extends from sea-level to the summits of Mount Washington (6,286 feet) and Pike's Peak (14,151 feet).