A Device for the Better Regulation of Electric Currents.
Year: 1895

page_text: Date of Application, 21st Mar., 1895
Complete Specification Left, 23rd Dec., 1895-Accepted, 21st Mar., 1896
PROVISIONAL SPECIFICATION.
A Device for the Better Regulation of Electric Currents.
WE, JOHN HALL of Church Gresley in the County of Derby JOHN HENERY
ROBOTTOM Coppice Side, Swadlincote in the County of Derby, and FREDERIC
CHARLES GEARY of Church Gresley aforesaid Electrical Engineers, do hereby
declare the nature of this invention to be as follows:-
The invention consists
A device for the better regulation of electric currents.
of, a method for the better regulation of electric currents, by means of suitable
resistances. The resistances consisting of a mixture of various metals or earths in
The
suitable proportions, mixed together in a granular or pulverized form.
powders or granules are placed together in a suitable recepticle, which may be
either a box or tube. The regulation is effected by means of sliding rods or
screws. The current is made to traverse the resistance mixture in such a manner
that the greater the distance the rods or screws are separated the greater the
resistance to the passage of the electric current and vice versa.
1007
JOHN HALL.
J. H. ROBOTTOM,
oppice Side, Swadlincote, Electrical Engineer.
F. C. GEARY,
Church Gresley, Electrical Engineer.
March 1650.
JOHN HALL.
J. H. ROBOTTOM,
Coppice Side, Swadlincote, Electrical Engineer.
F. C. GEARY,
Church Gresley, Electrical Engineer.
A Device for the Better Regulation of Electric Currents.
We, JOHN HALL of Church Gresley in the County of Derby, JOHN HENERY
ROBOTTOM of Coppice Side, Swadlincote in the County of Derby and FREDERIC
CHARLES GEARY of Church Gresley aforesaid, Electrical Engineers, 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 consists of a device for the better regulation of electric currents
by means of suitable resistances. The resistances consist of a mixture of various
metals or earths in suitable proportions mixed together in a granular or pulverized
form, one or more of the ingredients of the mixture being more or less good
conductors of electricity, and one or more others of the ingredients being non-
conductors or bad conductors. The powders or granules are intimately mixed and
are placed in a suitable receptacle, such for example as a box or tube, in which
they should be well rammed, and they may be agglomerated. The regulation is
effected by means of adjustable rods, screws or otherwise so as to cause the electric
current to traverse a greater or less distance through the mixture, the greater the
D

page_text: distance traversed the greater being the resistance to the passage of the electric
current, and vice versa.
The invention can be carried into effect in various ways. Two ways are
illustrated by way of example in the accompanying drawings.
According to the way represented in Figure 1, which is a longitudinal section of
the device, we employ a box or receptacle a of non-conducting material, which we
fill with the resistance mixture b as shown. At one end of the box a is one of the
terminal screws c and at the other end is a screw d which is adjustable in the box
so that its distance from the screw c can be regulated as desired. The screw d is
in metallic connection by means of the piece e with the other terminal screw f. It
will readily be understood that the nearer the adjustable screw d is to the terminal
screw c, the less will be the resistance and vice versa. Instead of the screw d a
sliding rod may be employed.
According to the modification of our device shown in Figures 2 and 3, Figure 2
being a vertical section on the line -x of Figure 3, and Figure 3 a plan, we
employ a number of tubes or receptacles for the resistance mixture and bring more
or fewer of these tubes into the circuit as required by means of a regulating handle
or switch. a'a² a³ aª a³ aª a² a³ aº are the tubes of non-conducting material containing
the resistance mixture. 91 to 9° are contact pieces the lower ends of which pass into
the resistance mixture in the tubes a¹ to a respectively; these contact pieces pass
through the cover of the box i containing the tubes a¹ to aº. The cover is made
of slate or other suitable non-conducting material and is supported by an insulating
shelf which supports the upper ends of the tubes. The resistance mixture in the
tubes a', a³, a and a respectively is connected at the lower ends of these tubes by
means of screws and wires as shown with the mixture in the tubes a³, a', a and a while
the contact pieces 92, 94, 98 and 98 at the upper ends are respectively connected as shown
with the contact pieces 93, 9, 97 and 9°. The mixture in the last receptacle a³ is
connected at the lower end with one of the terminals by means of a wire f while the
other terminal wire c is connected with a handle or switch which can be turned
on the pivot m so as to bring it in contact with any one of the contacts g¹ to g³.
According to the position of this handle it brings more or fewer of the resistance
tubes into the electric circuit, and therefore proportionately increases or diminishes
the resistance to the passage of the current.
The ingredients of the mixture should as already stated be partly of a conductive
character and partly of a non-conductive character the two kinds being intimately
admixed in a pulverized or granular form and then rammed together or agglomerated.
As conductive ingredients black-lead, graphite or gas carbon are suitable; as non-
conductive or bad conductive ingredients emery, corundum, gypsum, glass or other
silicates or aluminous carths are examples of what may be used. In practice we
prefer to employ a mixture of black lead and emery. The proportions of these
ingredients will depend to some extent upon the diameter and length of the
receptacles containing the mixture, but for a 50 volt circuit and 15 amperes we
consider that 7 parts by weight of black lead to 1 part of emery will generally be
found good.
Our device may be usefully applied to various purposes where a regulation of
electric currents is required, for example to the regulation of electric lights or the
governing of the speed of electro-motors, or to standardizing, testing and measuring
instruments.
Having now particularly described and 'ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :-
1. A device for the better regulation of electric currents in which a resistance
mixture of conducting and non-conducting or bad conducting granular or pulverized
materials is contained in a receptacle, and means are provided for bringing more or
less of the resistance mixture into the electric circuit as required, substantially as
herein before described.

page_text: 2. The respective modifications of the device substantially as hereinbefore
described and represented in Figure 1 and in Figures 2 and 3 for the purpose set.
forth.
Dated this 20th day of December 1895.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Chartered Patent Agents..