ntinuity of all the circuits by a ber of the station, to the centre, at each revo- depresses the key marked 3. The bells now & ‘ A lution. The number of the Fire District is strike the district signal of three blows at in- \. given in dots, that of the number of the sta- tervals of two seconds and… … ~The-instruments-receiving the communica- the signal a few times, and the engines in all tions, either of Fire or Police, from the signal parts of the city turn back. boxes, consist, first, of three receiving mag- By a multiplication of signal stations, and a nets mounted on the same stand and…
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