Improvements in Electric Fire Alarm Apparatus.
Year: 1893

page_text: Date of Application, 17th Apr., 1893-Accepted, 20th May, 1893
COMPLETE SPECIFICATION.
Improvements in Electric Fire Alarm Apparatus.
I, ERNST KLOss, of Stettin, in the Kingdom of Prussia, German Empire,
Engineer of the Stettin Electric Supply Company, Limited 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 :-
My invention relates to an improved apparatus for closing an electric circuit when
the surrounding atmosphere has reached a given or predetermined temperature, the
object being that the said closed circuit may then be used to agitate a bell or other
sonorous signal as an alarm in case of fire.
The apparatus constituting my invention consists of a metallic box, hermetically
sealed at a low temperature, to which is connected, but electrically insulated there-
from, a metallic bridge, carrying a milled headed contact point adjustable to make
contact with the cover of said box at any given or predetermined temperature, such
contact being caused by the rising of the lid of the box, by reason of the expansion
of the air enclosed therein, as the box becomes heated by the surrounding
atmosphere.
In order that my invention may be better and fully understood reference may be
made to the accompanying drawings in which;
Fig. 1 is a vertical section of the apparatus upon the line A. B. of Fig. 2.
Fig. 2 being a plan view of same.
In carrying my invention into effect, I construct of any suitable metal, by
pressing, moulding or otherwise, a preferably circular box, the bottom of which A,
would be corrugated, fluted or otherwise rendered undulatory, in order that a
greater surface may be presented externally and internally, than would be the case
if this was flat, the upturned sides of which B, may be formed integrally with A, or
soldered or otherwise connected thereto, and upon this is placed and fixed by
solder or otherwise, a metallic cover C (having a preferably platinum contact
plate C¹) in which a small pin-hole is provided. The apparatus may then be partly
immersed in very cold water, or the temperature otherwise reduced, when the whole
may be hermetically sealed by closing up the said pin-hole.
Upon the said box is mounted a metallic bridge piece D, connected thereto by
pins or screws a, but insulated therefrom by vulcanite or other blocks E, and F, or
their equivalents, and collars G. Upon the centre of D is mounted a milled headed
contact point H, the upper surface of which is divided into sectors b, which may be
numbered or otherwise marked so as to indicate, in conjunction with an index J,
mounted upon D, the distance the point of H is from contact point C¹ of the
cover C, or the temperature at which contact would be made between C and H.
A suitable terminal screw K is electrically connected to B, and a like terminal
screw L to the bridge piece D, from which may lead wires connected to a suitable
electric generator and bell or other sonorous signal, capable of being agitated
electrically. The action of the apparatus is as follows:-
The contact screw H having been suitably adjusted and the apparatus placed in
the position desired, upon the surrounding atmosphere reaching a higher temperature
than that at which it would be under ordinary conditions, or that for which H was
adjusted, such for instance as the commencement of a conflagration, the box A and B
becoming heated, the air therein contained would expand, and cause the cover C to
bulge and make contact by C¹ with the point of H, and so close the electric circuit
and sound the alarm, which would continue so long as such contact remained
unbroken. Suitable provision may be made for fixing the screw H in any position
desired relatively to the index J.

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 I declare that what I
claim is :-
:-
First. The construction and use of the automatic apparatus herein described and
the combination of parts constituting the same, connected and operating substan-
tially as herein set forth and for the purposes stated.
Second. In an automatic electric fire alarm, the combination of a heremetically
sealed box, consisting of a corrugated bottom A, sides B, and cover C with contact
plate C, surmounted by a bridge piece D, connected to B, by screws or pins a, but
insulated therefrom by blocks E and F or their equivalents and collars G, with
terminal screws K and L electrically connected to B and C respectively, and
connected to a suitable electric generator and bell or other sonorous signal. The
set screw H marked with sectors or divisions b, numbered or otherwise as desired,
to operate in connection with an index J, for regulating the degree of temperature
at which the plate C would rise and make electrical contact with the point of H,
the whole connected, combined and operating substantially as and for the purposes
herein described and shewn by the appended drawings.
Dated this 15th day of April 1802
GEO. THOS. HYDE,
4, Moorfields, Fore Street, London, E.C., Agent for the Applicant.