Improvements in Electric Signalling Apparatus for Fire Damps.
Year: 1896

page_text: Date of Application, 14th Dec., 1896-Accepted, 22nd May. 1897
COMPLETE SPECIFICATION.
Improvements in Electric Signalling Apparatus for Fire Damps.
1, LEO COHN, of 40 Schmiedebrücke, Breslau, in the Kingdom of Prussia,
German Empire, Mining Engineer, do hereby declare the nature of my invention
and in what manner the same is performed to be particularly described and
ascertained in and by the following statement :-
The present invention consists of an apparatus by means of which the explosion
of fire damp in coal mines and the accidents in consequence thereof may be
prevented by causing an alarm to sound automatically as soon as such gases begin
to collect.
The apparatus consists of a metallic funnel having advantageously a cylindrical
upper part and being closed by a thin counterbalanced aluminium plate which
rests freely on the upper part of the said funnel. If this funnel is placed with its
base on the coal in the mine, the light explosive gases rise under the same and.
raise the aluminium cover by which movement of the said cover a contact is
closed and relay switched in which operates an electric bell, warning that fire damp
is accumulating.
And in order to render the present specification more easily intelligible reference
is had to the accompanying drawing in which Fig. 1 shows the arrangement of
the apparatus.
The funnel A is provided with a cylindrical upper part a which is closed air
tight by means of an aluminium plate B which should be as thin as it is possible
to make, said plate B being mounted on a hinge b and counterbalanced by means
of a counter poise C, so that the slightest interior pressure will raise the plate.
The plate B is provided at the opposite side to the hinge with a small piece of
platinum D adupted to rest on an insulated pin d when the cover is in position on the
top of the funnel.
gases
If the apparatus is placed on the coals in the mine the plate B will be raised if;
are formed under the funnel, said gases being lighter than the air and consequently
moving upwardly. Thus the circuit passing through the platinum piece D, pin d
electrode and a relay + to contact F of the funnel will be interrupted, the armature i
will be released and its spring will actuate the same to make contact at i³, closing
the circuit to the bell H.
In order to control the system a second alarm may be arranged in the inspectors
office.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is performed I declare that what I
claim is:-
1. An electric signalling apparatus for indicating the presence of fire damp in mines
consisting of a funnel adapted to be placed with its mouth on the coals, a thin counter-
balanced plate at the upper end of said funnel to close same and hinged thereto and
means in connection with said plate when it is raised to sound an electric alarm
substantially as described.
2. The combination of a funnel A having a cover b hinged to its upper end and

page_text: adapted to close same, a counterbalance weight to said cover, a hinge to attach it to
the funnel and an electric circuit in connection with a relay and alarm, adapted to be
broken when said cover is raised substantially as described.
Dember 1906
BOULT & WADE,
Agents for the Applicant.