154 NINTH ANNUAL REPORT OF 



easy. In the publication of these experiments, the induction of the 

 electric telegraph as thenceforth possible was distinctly made by him ; 

 and at a period not much, later, wei^^hts were released and bells rung 

 by him at a distance by electric influence transmitted through long 

 conductors. 



In Boston, where the fire-alarm telegraph has been in successful ope- 

 ration for nearly three years, a star of wires is seen radiating from the 

 top of the city building. These are the signal circuits connecting into 

 one system forty-six signal boxes scattered over the city, and the alarm 

 circuits connecting twenty-four belfries on church, school and engine 

 houses. A few large bells would be preferable to this multiplicity of 

 smaller ones, but this whole number are struck by the touch of a single 

 man's finger in the central station. For the sake of economy in battery 

 power, the district keyboard is so arranged as to throw the battery on 

 the four alarm circuits separately, but in rapid succession at each blow. 

 Practically, the bells strike together or as much so as is desirable. At 

 night, sometimes out of the prolbundest stillness, the district number 

 will suddenly strike upon the ear in a chime of perhaps eight or ten 

 bells, their sound coming in one after the other in proportion to their 

 distance from the ear, but always in an invariable succession at each 

 blow. Then the alarm ceases and the whole city is as suddenly silent. 

 The operator at the central station is sometimes able to throw the 

 bells on, and tap back to the signal boxes before the originator of the 

 alarm has ceased to turn his crank in the immediate neighborhood of 

 the fire. As soon as the bells strike, groups of persons will be seen 

 clustering round each signal box to listen to the tapping of the station 

 number, and it is soon known to the whole fire department exactly 

 where the alarm originated. 



The battery employed on the Boston signal circuits is Farmer's 

 protected Grove's battery, which keeps in action several weeks or 

 even months without being replenished. Instead of a galvanic battery 

 on the alarm circuits, a large magneto-electric machine has been re- 

 cently substituted, which is driven by a water meter, and which fur- 

 nishes the electric current by which the bells are rung. 



The heaviest hammer in the system at Boston weighs one hundred 

 pounds, and it is wielded by the Cochituate water at an expense of 

 only one gallon for each blow, and tripped by telegraph from a chstance 

 of two miles. By virtue of the electric current and the pent up water, 

 this bell, and others associated with it, might be rung in measured 

 strokes from the beginning to the end of the year by the pressure of a 

 single man's finger in a distant room. 



All of the stations in Boston are provided with " lightning catchers" 

 or ground conductors for atmospheric or induced electricity. Hence 

 an incidental protection from lightning commensurate with the extent 

 of the network of wires above is obtained tor the city. When these 

 ground conductors have been temporarily removed from the alarm-bell 

 stations, a flash of lightning has been occasionally followed by a single 

 blow from one or more of the bells. But where the lightning catchers 

 have been in place, they have proved sufficient, except in rare instances, 

 to divert atmospheric or induced currents from the electro-magnets 

 to the ground. No practical or serious inconvenience has resulted 



