Improvements in Gravity Electrical Contact Makers.
Year: 1896

page_text: Date of Application, 22nd Jan., 1996
Complete Specification Left. 22nd Oct.. 1896-Accepted. 2nd Jan., 1897
Date of application, Galval
Complete Specification Left. 22nd Oct.. 1896-Accepted, 2nd Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in Gravity Electrical Contact Makers.
I, RICHARD PEARSON of 2, Great St. Helens, Loudon, E.C. Engineer, do
bereby declare the nature of this invention to be as follows:-
My invention relates to electric circuit closers in which mercury is used,
particularly those applied in connection with railway signals for informing the
signalman by the closing of a bell circuit that the signal has been fully moved to
the position intended and that it has not remained in an intermediate and uncertain
position in consequence of the slacking of the wire connections with the handing
lever in the signal cabin from which it is operated.
Such mercurial circuit closers are liable to become inefficient in consequence of the
mercury oxidizing and gradually destroying the platinum contacts which enter the
tube in which the mercury is contained and this I obviate by insulating and
protecting the contacts from the mercury vapours by means of wood creosote or
other hydrocarbon specially prepared so as to eliminate the lighter hydrocarbons
and thus increase its density, there being two sets of contacts respectively adapted
to close different circuits and situated at different parts of the tube which is so
formed that when moved by the signal the mercury will be displaced in the tube
and will close the circuit between one pair of contacts at a time, the creosote always
covering the mercury and heing interposed between the mercury and the contacts
so as to protect the latter (which it also serves to lubricate) except during the
actual closure of the circuit.
The creosote is prepared by maintaining it at a uniform temperature of about
300 degrees Fahrenheit to volatilize and eliminate the lighter hydrocarbons, the
fatty matters being skimmed off the surface from time to time, and this treatment
continued until the creosote acquires a boiling point of about 400 degrees
Fahrenheit and a specific gravity of about 107 under normal atmospheric
conditions.
กล
I, RICHARD PEARSON of 2, Great St. Helens, London, E.C. Engineer, 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 electric circuit closers in which mercury is used as the
circuit-closing medium particularly those applied in connection with railway

page_text: semaphore signals for informing the signalman (by the closing of a bell or other
return signal circuit) that the signal has been fully moved to the position intended
and that it has not remained in an intermediate and uncertain position in con-
sequence of the slacking of the wire connections with the handing lever from which
it is operated.
Such mercurial circuit closers are liable to become inefficient in consequence of
the platinum contacts which enter the mercury-containing tube becoming corroded
or destroyed in course of time and this I obviate by insulating and protecting the
contacts from the mercury vapours by means of specially prepared wood creosote
or other hydrocarbon from which the lighter hydrocarbons have been eliminated.
For the purpose of verifying the operation of railway signalling, there would
usually be two sets of contacts respectively adapted to close different circuits and
so situated relatively to each other and to the miercury when in its normal position -
that when by the movement of the signal arm from one extreme position to the
other the mercury is displaced it will close the circuit between one or other pair
of contacts, the creosote always covering the mercury and always being interposed
between the mercury and the contacts except during the actual closure of the
circuit, whereby the contacts are protected from the action of the mercury and
lubricated by becoming coated with the creosote before the mercury makes contact
with them.
The creosote is prepared by maintaining it at a uniform temperature of about
300° Fahrenbeit in order to volatilize and eliminate the lighter hydrocarbons, the
fatty matters being skimmed off of the surface from time to time and this treatment
being continued until the ereosote acquires a density such that its boiling point is
raised to about 400° Fahrenheit and its specific gravity to about 1-07 under normal
atmospheric conditions.
In the accompanying drawing forming part of this specification I have
illustrated two modifications of the invention, Figure 1 shewing two positions of a
single tube containing both pair of contacts and Figure 2 similar positions of two
tubes acting as one in which the two pairs of contacts are separately contained.
In each example A is the tube or tubes, B the mercury, C the creosote or other
hydrocarbon prepared as above described, de, f e', pairs of contacts formed of
platinum wires sealed into the tube or tubes and connected as shewn to the
members D F and to the common return or earth wire E of two electric circuits
connected with any suitable return signalling devices G in proximity to the hand
lever by which the signal is worked. The form of the underside of the tube or
tubes is so curved in a vertical plane that the mercury normally reats in each
position of the signal in proximity to the pair of contacts corresponding to that
position without however touching them, the closing of the circuit by the mercury
being momentary and due to the fact of the mercury flowing beyond that normal
position and over the contacts when by the movement of the signal arm the
inclination of the tube is so altered that the mercury is caused to flow along it.
Such tubes need not be exhausted of air since the creosote protects the mercury
from oxidation as well as the contacts from the action of mercurial vapours.
The lubricating effect of the creosote on the contacts enables the two contacts of
a pair to be placed close together by diminishing the adhesion of the mercury and
avoiding liability of accidental permanent closure of the circuit by a detached
globule of mercury caught between the contacts..
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is :-
A gravity electrical contact maker in which mercury is used as the circuit closer
consisting in the combination with the mercurial mass of a covering layer of heavy
hydrocarbon, and one or more pairs of contact terminals entering the containing
tube or vessel, the tube or vessel being so shaped and placed in such a position that
the hydrocarbon is normally interposed between the mercury and the contact

page_text: terminals the tube or vessel being movable so as to cause the mercury to
momentarily flow on to the pair or one of the pairs of contact terminals sub-
stantially as and for the purpose specified.
Dated this 21st day of October 1896.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.