Improvements in or relating to Resistances for Electric Current Circuits.
Year: 1891

page_text: Date of Application, 15th May, 1891
Complete Specification Left, 15th Feb., 1892-Accepted, 19th Mar., 1892
PROVISIONAL SPECIFICATION.
Improvements in or relating to Resistances for Electric Current
Circuits.
I, HARRY SOUTH, of 10 and 12 Garrick Street, Covent Garden, in the County
of London, Electrical Engineer, do hereby declare the nature of this invention to
be as follows:-
My invention relates to resistances which are introduced into electric current
circuits for modifying the strength of the current in the circuit. It is especially
serviceable in theatres for varying the amount of light given by electric lamps,
but it may be used for other useful purposes..
My invention is applied by introducing a resisting portion of the circuit into a
suitably closed receptacle containing a certain amount of mercury. The receptacle
is fixed, pivoted or otherwise made moveable; and the resisting portion of the
circuit (hereinafter called the resistance), is preferably so formed or arranged with
reference to the mercury that, a small portion thereof is always in contact with the
mercury in whatever position the receptacle may be. By relatively moving the
receptacle or resistance from that position in which the resistance is only slightly
in contact with the mercury to that in which there is the maximum of contact, the
resistance is varied from its maximum to its minimum, and lamps in the circuit
vary from darkness to full light.
From the above description, it will appear that the current strength in the
circuit and consequently the light giving power of the lamps can be varied very
gradually, and without sudden jumps, by immersing the resistance more or less
deeply in the mercury. The apparatus employed may take many forms, according
to circumstances. In one type, the circuit connections may be on different sides
of the receptacle, with the resistance running through the same from one side to
the other; while in the other type, the circuit connections may be on the same
side of the receptacle, the resistance starting from one terminal and returning to
the other, like the filament in an ordinary glow lamp. I may use more than one,
resistance within a receptacle.
The receptacle may be of any convenient material, adapted to receive the circuit'
connections or terminals, the resistance connecting the said terminals; or the
receptacle may form one pole of the circuit connections. The receptacle may be.
exhausted of air and hermetically sealed, and it must also be strong enough to
withstand the weight of mercury employed, and any shock caused by a sudden
movement of the saine. In some cases it is further adapted-either by itself, or
in combination with a frame or case-to be swung upon pivots, or otherwise made
moveable. By moving the receptacle, or the resistance, the immersion of the
resistance is varied, thus varying the length of the said resistance through which
the current has to pass.
A.
The resistance may be made of platinum or other suitable wire, carbon rods or
filaments, or other suitable material, for the purpose. A bracket or support is
made to carry the receptacle direct or in combination with a frame or casing.
suitable handle may be adapted to the apparatus for adjusting its position, and I
may use a scale and pointer to indicate the amount of resistance introduced into
the circuit. Two or more receptacles, or resistance therein, may be combined,
and adapted to be joined up in series or in parallel, and the resistances inay be
made to standard units of measurement.
Dated this 15th day of Max 1891
FAIRFAX & WETTER,
433, Strand,, London, Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Resistances for Electric Current
Circuits.
I, HARRY SOUTH; of 10 and 12 Garrick Street, Covent Garden, in the
County of London, Electrical 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 resistances which are introduced into electric current
circuits for modifying the strength of the current in such circuits. The invention
is especially serviceable in theatres for varying the amount of light given by
electric lamps but it may be used for other useful purposes.
My invention is applied by introducing a resisting portion of the circuit into a
suitable closed receptacle containing a certain amount of mercury or other fluid
conductor. The receptacle may be fixed or moveable, and the resisting portion of
the circuit (hereinafter called the resistance) is preferably so formed or arranged
that a small portion thereof is always in contact with the mercury in whatever
position the receptacle may be. By the relative movement of the receptacle or
the resistance from the position of minimum contact with the mercury to the
maximum contact, the resistance is varied from its maximum to its minimum, and
lamps in the circuit correspondingly vary from darkness to full light.
In the further description of the invention reference is made to the accompanying
drawings in which the figures shown are diagrammatic..
Fig. 1 indicates a vertical section through a non-conducting receptacle a placed
in a horizontal position,
Fig. 2 is the same but with the receptacle a placed in a vertical position, and
Fig. 3 is a plan of the same.
In these figures a is a closed receptacle of glass porcelain or other suitable
material, having sealed into it a stout carbon filament or resistance and con-
taining mercury c The receptacle a is hung upon trunnions or pivots d placed in
suitable bearings (not shown), and adapted to be readily moved therein.
In Fig. 1 the resistance is shown as entirely covered by the mercury c, and
consequently the resistance is short-circuited and the lamps in the circuit will give
their maximum amount of light:
In Fig. 2-on the contrary-only the end of the carbon resistance is immersed
in the mercury c, so that the minimum amount of current passes to the lamp with a
corresponding result. By gradually varying the position of the pivoted receptacle à
between the horizontal position in Fig. 1, and the vertical in Fig. 2 the light
giving power is likewise gradually varied without "jumping." A suitable handle
may be adapted to the apparatus for adjusting its position, and a scale and pointer
may be used, to indicate tlie amount of resistance introduced into the circuit, but
as these are not essential they are not shown in the drawings.
In Fig. 4 a similar receptacle a is shown in plan as containing a zig-zag
resistance b, of platinum wire, carbon rods, or other suitable material.
Fig. 5 indicates a cross section through Fig. 4, in which the resistance bis
entirely covered by the mercury e, and
Fig. 7 is a similar section but with the réceptacle
the resistance is entirely out of the mercury.
a reversed in position so that
Fig. 6 is also a similar section, in a midway position between Figs. 5 and 7,
(moving as indicated by the arrow), and consequently with about one half the
resistance immersed in the mercury c; the light being correspondingly affected.
The receptacle may be exhausted of air and hermetically scaled, and it will be
understood that flexible circuit connections are made to the resistance terminals to
allow of free movement of the receptacle a. The receptacle itself, need not, how-
ever, be pivoted; as it may be combined with a moveable frame or case to which

page_text: motion is given. The resistance may be an ordinary filament, or of iron, platinum,
or other suitable material.
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 ;-
Ut
1. An adjustable resistance for electric current circuits comprising a receptacle
containing a resistance and mercury c arranged and operating so that any move-
ment of the receptacle a will vary the relative position of the resistance with the
mercury c substantially as and for the purpose herein described.
2. The combination of a closed receptacle a, adapted to move upon trunnions d
and containing mercury c and a resistance, so placed within the said receptacle
that the relative position of the mercury will vary the immersion therein of the
resistance when the receptacle a is moved, substantially as and for the purpose
herein shown and described.
Dated this 15th day of February 1892.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.