Page:The American Cyclopædia (1879) Volume XV.djvu/42

 SIGNAL SERVICE life-saving stations, which are connected by telegraph, ami. in addition to displaying storm signals and making the regular meteorological reports, are required to mako special reports upon tempests ut sea, the sea swell, currents, . They also summon assis- tance to di "tress, either from neigh- boring -tat ions or from the nearest port. Stations for river reports, to give notice of danger-.M" floods r conditions of the rivers affecting navigation, are established upon the courses of the great interior rivers. The offi- cers and men of the signal service are instructed for the different branches of the service at the .1 of instruction at Fort Whipple, i ;it the central office in Washington.
 * v tauu'ht the use of meteorological in-

struments, the modes of observing, and the f.>rms and duties required at stations of obser- vation, and for the display of storm signals. The fon-e is also drilled with arms and in the duties 'of soldiers. The field telegraph trains of the signal service are organized for use with armies, and are managed by soldiers who are drilled to march with, manoeuvre, work, and protect them. The trains carry
 * field telegraph lines, which can be very

qiiii-kh run out at the rate of two or three miles an hour. They can be put in use for any distance, and as rapidly taken down, repacked, and marched off with the detach- ment to be used elsewhere. For the duties of the observation of storms, and for the dis- play of storm signals, all stations communicate directly with the signal office in Washington over telegraphic circuits arranged with the different telegraph companies, or connecting with the office at fixed hours each day and night. Each station is supplied with the fol- instruments: barometer, thermometer, maximum thermometer, minimum thermome- ter. Robinson's anemometer with electrical at- tachment and self-registering apparatus, hy- grometer, wind vane, rain gauge, and, on stations located on rivers, lakes, or soacoast, thermometers designed for taking the temper- >f water at different depths. The read- ings of these instruments, made three times a day at fixed hours, are reported to the cen- Tu-o in cipher. The stations at which cautionary signals are displayed are equipped with Hags and apparatus for exhibiting the nary day or night signal. These stations are established (with the exception of those in the principal cities) solely with reference to LMCC of their position for meteoric i. Three graphic charts are pre- pared at the central office on the receipt of each report, as follows: 1. A chart of baro- metric pressure-, temperatures, and winds, to- gether with t'..- wind velocities at the differ- ent stations and tin- precipitation occurring; it exhibits the barometric pressures and the temperature* in their relation to districts and
 * by a system of isobaric and iso-

thermal lines, and the wind directions by ar- rows at the different stations. 2. A chart of the cloud conditions prevailing over the Uni- ted States, on which the different varieties and amount of clouds visible at the different sta- tions appear by symbols; on this chart is also indicated the weather as reported at each sta- tion, the direction and movement of upper and lower clouds, and each morning the minimum temperature of the preceding night, in relation to districts of territory. 3. A chart showing the relative humidities over territorial districts, with the temperature at the several stations ; this enables studies to be made for territorial sections, the difficulties attending the study of observations of this character being obviated to a very considerable degree by the intercor- rections of the stations among themselves, and by the great extent of the regions over which the readings are simultaneously made. In the study of the charts for the reports, the well known rules and generalizations established by the experience of meteorologists are used. The published office report, based upon each gen- eral report of observations, consists of a synop- sis of the meteoric conditions existing over the territory of the United States at the time of the report, and a statement of the changes likely to occur within the next 24 hours. For the purposes of convenient study and of con- densed description, the territory of the Uni- ted States is arbitrarily divided into districts. The reports from the stations, extending over territory reaching from the Atlantic to the Pacific, and from the capes of Florida into British America, are not unfrequently concen- trated at the central office in the space of 45 minutes. In military lines connecting frontier posts and lines connecting life-saving stations upon the seacoast, the telegraphic duties are performed by the men of the signal service. The reports are those of readings of the dif- ferent meteorological instruments made as nearly simultaneously as possible. The re- ports, made simultaneously from all the sta- tions and received at the central office thrice daily, at intervals of about eight hours, are at once entered graphically upon synoptic charts (the weather maps), and from the study of these charts a deduction is had as to probable weather changes within the ensuing 24 hours. This deduction is furnished to the press and is telegraphed to 21 centres of distribution, to be there published and distributed in bulletin form for the use of farmers. The bulletins are displayed at post offices in numerous vil- lages in the agricultural districts. In the case of serious storms noticed as approaching the lakes, or threatening any part of the seacoast, cautionary signals are ordered from the cen- tral office to be displayed at the different lake and sea ports and upon the coasts, as a warn- ing to mariners. The fortunate position of the territory of the United States and its great extent enable a service of this kind to be con- ducted with especial advantage. The move- ments of the storms over the continent can be