FIRE-ALARM. FIREARM. ceived upon the common Morse recording in tru ment, and registered on a strip of papei , oi both its receipt, at and transmission ii the eer 1 1 a 1 r^t a t i< >ii may be recorded bj pens on a n volving paper roll. There is mien provided an inner box, to which the firemen only bave I which contains telegraph instruments for use in communicating with headquarters, by mean oi which the officer in charge is enabled to gi information and call for such extra and special supplies as are needed. The outer or fire-als boxes are generally only to be opened with keys intrusted to citizens, the nearest resident, the police, etc., but automatic doors for alarm-bo are also used. These may lie opened without a key by simply twisting the door handle. In cities having a central office in connection with the fire-alarm system, the alarm signals are all received here and then repealed to the local engine or hose house, either by hand or by auto malic machinery under the control of the central operator. The signals are in some systems sent to all the companies, and the fire attended by those that are nearest and assigned to that dis- trict. In other systems the signals an ly sent by the central operator to such companies as should go to the fire. For less important cities an automatic repeater may be used, thus doing away with the necessity of a central office at- tendant. In small towns and villages with only a few alarm-boxes and one wire circuit, the alarm may be operated directly from the call-box. In large cities, however, many circuits are neces- sary, which, in connection with the apparatus at the central office, may he so arranged that two in- dependent signals are sent out to the proper stations for every fire by the use of separate instruments and circuits for each. The first sig- nal in the fire station is sounded on a gong and the box number is printed on a tape. It is sent by a single movement of a lever. The second signal is in accordance with a code, the number of sounds indicating the exact response to be made to the call. A gong sounds the box num- ber, which is also shown on an indicator with large figures. The central stations are equipped with various other devices, such as annunciators to show what companies are sent to a fire, and, therefore, which are still available; automatic circuit-testing machines, reporting breaks in the circuit, if any, at set intervals; switchboards, storage batteries, controlling and testing boards, instruments for measuring the current used to charge the battery, and also that in the wire circuits. The simpler forms of call-boxes are constructed in various ways, and to secure great- er reliability, there are provided lightning ar- resters; cut-outs to prevent interference from high potential lighting or power currents; trap keys which cannot be recovered in ease of alarms sent by private citizens until a fireman releases them by another key: and the keyless boxes and telegraph instruments already mentioned. The wire system may be strung on poles or placed underground. It, must be carefully protected from harm in either case, particularly from ac- cidental connection with any other electric wires. When put underground, wires may be placed in tile, wood, or iron conduits. See SUBWAYS FOB Pipes and Wibes. Auxiliary fire-alarms are extensions of the ordini u, buildir a building, if desired. Small call connected bj propel in ,ith the i which ma; I..' -i I, in opcrat i"Il by breaking ;> lu in tin pulling a chain. A ret urn signs whether or not t lie -i rei i. bo i lu acted. natic jo- ./. /. i /.,, . are in -< rumen! "■- ill i lose :ui elei 1 1 ircuit v, h< n rounding tempi ratun n ache a ci rt mm in operation tl rdinary Ure- alarm telegraph a pp iratu with which it i nected, or giving a local alarm by ringing a or both. Some foi m i nerally used io close t he circuit of whi ■ i . may he used a - ■> re le ired ; or w hat may be a thermos tatic cabh mm y b< walls and ceiling Frei leemed ad isable, or tempora rilj trailed over fli over pili - of g I-. I n such cables one of the wires forming the circuit is coated with expansive metal, wrapped with a yielding in ulator, then further surrounded with a series of spirallj ar ranged fine "ire-, forming I he other half of the circuit. The coating en i he inner wire i panded by heat and brought into contact with the outer wires, so that the circuit i- ch>-er] and a bell rung. Other devices have ei explosion of powder, the cpan-io|i of metallic rods, the breaking of wires, or burning oi Histobical Sketch. Method- of transmitting new- of outbreaks of tire are very old. but the perfection of the electric telegraph was es i to the development of instantaneous and n apparatus, which was largely automatic'. As e;ul :is ] S 4 ."> . Dr. V. F. Channing, of I '■ published an article in the Idvertiser of that city, outlining a fire-alarm telegraph system. In'l851 the city of Boston appropriated $10,000 for testing the plan, and it was put in operation ih.it year. Or. Channing and Moses <;. Farmer developed the system, which was constructed foi Boston by Mr. Farmer, and operated under his direction for several years, lu 1857 these men patented the system. John V Gamewell became interested in the matter in ls."..i. and by ISO 1 acquired the patent right-. Subsequently he did much to improve and introduce the system, but the Civil War. conservatism, and other oh were sufficient to prevent ii- introduction ie than some twenty cities by 1871. New York in- stalled the fire-alarm telegraph system in 1869. In 1875 the number of cities using the system was seventy-live, and since then its increase has been rapid, so thai to-day mosl town- of 10,000 population or over, and nam smaller ones, have the tire-alarm telegraph. Although various sys- tems arc in use, that devised Io Channing and Farmer, and developed and improved by Game- well and his asso is the one most generally employed in America, of the many automatic alarms depending upon either beat or the direct net ion of Same for operation, there may he mentioned om : in 1802, in England, by Joseph Smith, where reliance was placed upon the burning of a string. For teleg- raphy in general, and also a chapter on tire alarm telegraphy, consult Maver, .1 merican raphy (New York. 1899). FIRE-ALARM, At tom :i:v Ai.u:i FIREARM. A device consisting essentially of a straight tube, provided with means of ig-
