and its application to Fire Alarms. 69 
of the armature would be heard on its release, when the Circuit 
was broken, : 
it might be performed by a child. Certain members of the Fire, 
Watch and Police Departments, are also provided with keys to 
yet a suflicient guarantee against its abuse. A periodical report 
should be required from the agents in charge of the Stations. 
Connection may at any time be made between the ground 
conductor of the electrical Discharger and one of the Signal wires, 
for the purpose of special Signalizing to the Central Office, with- 
out the indication of the signals at any intermediate Station. _ 
he Centre of the System in Boston is established in the City 
Building adjoining the City Hall. From its roof which is iso- 
lated, the Wires, elevated on a bracket, radiate in all directions. 
_ The instruments at the Central Office are in part receiving and 
Mm part transmitting, besides the batteries for the whole system, 
and the testing and registering instruments employed in the reg- 
ulation of the Circuits, 
he receiving apparatus consists of an Office Alarm for each 
of the three Signal Circuits, and a single electro-magnetic Regis- 
ter, of the Morse construction, with which they communicate in 
Common, The Alarm is 
represented in fig. 5. It 
tached to the upright lever 
Which carries the ham- 
mer, The bell is of large 
‘ize. For the purpose of 
obtaining a powerful blow 
tom the hammer, suffi- 
Citenit. ‘The Office Alarm 
With local circuit ar- 
