Improvements in Electric Alarm Thermometers.
Year: 1889

page_text: Date of Application, 7th Jan., 1889
Specification Accepted, 16th Feb., 1889
COMPLETE SPECIFICATION.
Improvements in Electric Alarm Thermometers.
I, PERCY FRERE LUCK, of Jakobsgatan 18, Stockholm Sweden, Merchant, do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement:-
This invention relates to a thermometer, which, combined with an electric bell, has
for its object to give an alarm at the outbreak of a fire or in general, to indicate when
the temperature of the surrounding air has risen to a certain degree.
The accompanying drawing represents the improved thermometer and fire alarm.
The thermometer itself consists of a bent glass tube, the leg.A or the ascending
pipe of which is straight and open at the top, so that a wire which is adjustable
according to a scale a may be moved easily up and down in the same, the other leg B
on the contrary is closed and may be straight, helical or of any other shape. The said
leg B is filled with alcohol spirit, glycerine or any other liquid of great expansive
capacity. The bend C between the sides is turned downward and provided with
two ball shaped receptacles e and f which at the bend contains mercury. The
balls e and being only reservoirs for the mercury may be dispensed with, if
the bend be made so large that it can contain the quantity of mercury requisite in
order that its lower part may be full of mercury at high temperatures as well as at
low temperatures. In the lower part of the tube a wire of platina o is melted in,
touching the mercury and united with the one pole wire of an electric circuit l-k.
The movable wire g is adjusted to any suitable position and is maintained there and
in contact with the other conductor k in the electric circuit by means of an attachment
screw i. When the thermometer is to be used for signalling when the temperature
has risen to a certain degree, the end of the wire is placed above the level of the
mercury in the ascending pipe A at the corresponding line on the scale and fixed by
means of the attachment screw. The electric circuit is thus interrupted, but as soon
as the mercury, owing to the rising of the temperature has risen so high as to touch
the wire, the circuit is closed and in this way the bells inserted in the said circuit will
be caused to ring.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
First. An alarm thermometer consisting of a U-shaped glass tube open at the one
enp, the closed side of which is separated from the open one by means of mercury and
contains a liquid other than mercury which has a great expansive power and in the
open side is inserted an adjustable wire connected with one wire of an electric bell
circuit, the other wire being united with a wire of platina melted into the glass tube
the said wire of platina being in constant contact with the mercury.
Second. In an alarm thermometer, consisting of a U-shaped tube, the one side of
which is open and separated from the closed side by means of mercury, an arrange-
ment for effecting a rapid motion of the mercury levels at a change of temperature,
consisting in filling the closed side above the mercury with any other liquid of a great
expansive power.
HASELTINE LAKE & Co.,
45, Southampton Buildings, London,
Agents for the, Applicant.