A NEW AND IMPROVED THIEF DETECTER AND FIRE-ALARM APPARATUS
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Antoine Arnaud at the Office of the
Commissioners of Patents on the 26th May 1876.
ANTOINE ARNAUD, of Blackfriars Road, in the County of Surrey. "A NEW
AND IMPROVED THIEF DETECTER AND FIRE-ALARM APPARATUS."
This Invention consists in a new and improved thief detecter and fire-alarm
constructed on an improved principle whereby greater accuracy and effectiveness is
obtained than with the apparatuses now in use for that purpose.
The following is the manner I propose to construct a thief detecter according to
my said Invention.
I employ an electric bell apparatus similar to those generally in use, with the excep-
tion that I use in conjunction therewith an additional electro-magnet, the magnet and
armature of which are connected with the battery of the bell apparatus, and with
the electro-magnet and armature of the said bell apparatus by means of binding
screws, so that at any given time the current of electricity shall pass either through
the additional electro-magnet, and thence back to the battery or through the electro-
maguet of the bell apparatus.
All round the rooms or building, or parts of the said rooms or building, safes, and
other places which it is desired to secure, I fix a wire or rod which is cut and kept
at a small distance asunder at the doors, windows, or safes aforesaid. On the said
doors, windows, or safes I fix small metallic plates, the object of which is to connect
the two parts of the wire or rod aforesaid (where they are cut) when the doors,
windows, or safes are closed.
The arrangement of the electro-magnet of the bell apparatus and additional
electro-magnet are such that when the doors or windows are closed the current of
electricity shall pass through the whole length of the wires round the rooms or
building, and thence by the additional electro-magnet to the battery, but on the
event of one of the said doors or windows being opened, the current being cut by
the reason that one of the plates aforesaid is withdrawn the current will pass through
the bell apparatus and give the alarm at once. The least attempt at opening &
door or window or cutting one of the wires will break the current and ring the
bell.
The fire-alarm is constructed on the same principle, that is to say, a break in the
current causing the bell to ring.
For this purpose I make use of pieces of metallic wire made of a very fusible
alloy, the composition of which varies according to the temperature it is desired
that a room or building should not exceed.

page_text: ATNⱭAN 8 Improved invej Detector ANA ILI ITC-AWATm Apparaa8.
The wire which goes round the rooms or buildings is cut at any desired places, and
a piece of the alloyed wire inserted so as to allow the current of electricity to pass.
Should the temperature of any part of the building or room exceed the melting
point of the alloyed wire, this will immediately melt, break the current, and give thie
alarm.
It will thus be seen that a thief detecter and fire-aların constructed according to
my said Invention differs from those generally in use, for this roason, that instead
of establishing a current when a door or window is opened and thus giving aların,
I give that alarm when the current is cut, either by opening a door or window, or
by melting an alloyed wire when the temperature exceeds that which it is desired
a room should not surpass.