SIGNAL SERVICE OF THE UNITED STATES. At the time of the organiza tion of the department of meteorology of the army signal office (see 3IETEonoLooy) there was no general system in operation for " simultaneous meteorology," and the one ever since in use.was devised and carried into effect by gen. Myer (q.v.), chief signal officer. By this system the innovation was introduced of observing and reading off the instru ments, " at the same moment of actual (not local) time." By this arrangement the signal office at Washington can call for and receive reports from all parts of the country, taken at each of the stations, at any hour of the day or night. Thus, the exact condition of the atmosphere over the whole field of inquiry is set down at a given instant, establish ing the existence of conditions on which predictions may be and are fearlessly made. Iu Nov., 1871. a comparison of the tri-daily forecasts, or "probabilities," as they were styled, showed a verification of 69 per cent, which rose to 76.8 per cent by 1872. These results "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." In 1872 and 1873 the expansion of the work of the signal office was very great; extend ing, through the cordial aid of agricultural societies, into a comprehensive weather bureau sustained in the interest of agriculture; and, through its connection with life saving and signal stations, becoming a most certain and effective agent for saving life and property endangered by storms on the sea. " Indication" and "cautionary signals," based upon three series of simultaneous weather-reports telegraphed to IN ashington daily, are issued from the office of the chief signal officer three times each day, and are printed in all newspapers where it may be important to do so, and otherwise made public. The preparation of a graphic weather-map embodying the telegraphic data
furnished to the chief signal officer every eight hours, preserves an accurate picture of existing aerial phenomena, and the conditions on which storm predictions are made. The "Farmers' Bulletins" are reprinted by signal-service observers in 19 cities, and the telegraphic forecasts are circulated among 6,042 sub-centers in agricultural commodities, and thence distributed among the farmers. As the predictions cover twenty-four hours, and often hold good for twice that period, they reach the denser rural populations some times a day and a half and always as much as fourteen hours before the period to which they apply expires. The railroad system has co-operated in this service, and 103 railway companies distribute daily 3,180 reports to as many railway stations, without charge.
Cautionary signals are of two kinds: 1. Those premonishing dangerous winds to blow from any direction; 2. Those premonishing off-shore winds, likely to drive vessels out to sea. The first, distinctively termed the "cautionary signal," consists of a red flag with a black square in the center, for warning in the day-time, and a red light by night. The second, or " cautionary off-shore signal," consists of a white flag with black square in the center shown above a red flag with square black center by day, or a white light shown above a red light by night, indicating that while the storm has not yet passed the station, and dangerous winds may yet be felt there, they will probably be from a northerly or westerly direction. The percentage of verifications for the year ending June 30, 1879; varied between 79.8 and 93.8.