Improvements relating to the Distribution and Regulation of Electric Current.
Year: 1893

page_text: Date of Application, 19th Sept., 1893
Complete Specification Left, 15th June, 1894-Accepted, 21st July, 1894
PROVISIONAL SPECIFICATION.
Improvements relating to the Distribution and Regulation of
Electric Current.
We, HUBERT HENRY GRENFELL, of 18 Ashburn Place, in the County of
Middlesex, Captain Royal Navy, and OCTAVIUS MARCH, of 70, Sinclair Road,
Kensington, in the County of Middlesex, Electrical Engineer, do hereby declare
the nature of this invention to be as follows :-
Our invention relates to the distribution and regulation of electric current, and
more especially to means for regulating the supply of current to two electric lamps
joined in parallel and lighted from any suitable source.
Our invention is particularly adapted for use with two lamps such as are usually
employed for illuminating the sights of ordnance at night.
In these cases it is very
desirable to have means for adjusting the relative brightness of the lamps.
For this purpose it has hitherto been the custom to place in the circuit of each
lamp a separate resistance so as to reduce the current to the proper amount
required for the lamp, and in order to vary the light given out by either lamp it is
necessary to alter the resistance in circuit with the said lamp; to vary the light of
both lamps therefore the resistance in each circuit must be separately altered, that
is to say, two adjustments must be made. According to our invention we obviate
the inconvenience arising from the necessity of adjusting two resistances, in the
following manner. We provide one resistance part of which is in the circuit of one
lamp, the remaining part being in circuit with the other lamp. The main wire
from the source of electricity is joined to the said resistance at a point intermediate
of its ends by an adjustable contact which can be moved along the resistance so
that the relative proportions of the resistances of the two branches can be varied.
For this purpose the resistance may be conveniently made in the form of a
stretched wire the contact being adapted to be moved along and touch different
points in the wire when desired. Other methods of making the adjustable contact
inay be used. When such adjustable contact is moved the resistance in the circuit
of one lamp is lowered and that in the circuit of the other lamp is raised, the light
given out by one lamp may therefore be varied relatively to the light given out by
the other.
To provide for simultaneously varying the light of both lamps we place a
variable resistance in some part of the main circuit, common to both lamps, and we
preferably arrange a switch in such a manner that when the said switch is turned
in one direction the resistance in circuit is gradually increased until the circuit is
broken, and when the switch is turned in the other direction the resistance is
diminished until it is entirely cut out. The switch is capable of being arrested in
any intermediate position. By this arrangement both lamps may be raised or
lowered simultaneously, the relative brightness of each light, which is determined
by the adjustment of the branched resistance, being maintained throughout.
Dated this 19th day of September 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.

page_text: Improvements relating to the Distribution and Regulation of
Electric Current.
We, HUBERT HENRY GRENFELL, of 18 Ashburn Place, in the County of
Middlesex, Captain Royal Navy, and OCTAVIUS MARCH, of 70 Sinclair Road,
Kensington, in the County of Middlesex, 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:-
Our invention relates to the distribution and regulation of electric current, and
more especially to means for regulating the supply of current to two electric lamps
joined in parallel and lighted from any suitable source.
Our invention is particularly adapted for use with two lamps such as are usually
employed for illuminating the sights of ordnance at night. In these cases it is
very desirable to have means for adjusting the relative brightness of the lamps.
For this purpose it has heretofore been the custom to place in the circuit of each
lamp a separate resistance so as to reduce the current to the proper amount
required for the lamp, and in order to vary the light given out by either lamp it is
necessary to alter the resistance in circuit with the said lamp; to vary the light of
both lamps therefore the resistance in each circuit must be separately altered, that
is to say, two adjustments must be made. According to our invention we obviate
the inconvenience arising from the necessity of adjusting two resistances, in the
following manner. We provide one resistance part of which is in the circuit of one
lamp, the remaining part being in circuit with the other lamp. The main wire
from the source of electricity is joined to the said resistance at a point intermediate
of its ends by an adjustable contact which may be moved along the resistance so
that the relative proportions of the resistances of the two branches, that is to say,
in the circuits of the two lamps, can be varied.
The
To provide for simultaneously varying the light of both lamps we place a
variable resistance in the main wire and we preferably arrange a switch in such a
manner that when the said switch is turned in one direction the resistance in circuit
is gradually increased until the circuit is broken, and when the switch is turned in
the other direction the resistance is diminished until it is entirely cut out.
switch is capable of being arrested in any intermediate position. By this arrange-
ment both lamps may be raised or lowered simultaneously, the relative brightness
of each light, which is determined by the adjustment of the branched resistance,
being maintained throughout.
In order that our invention may be clearly understood we have shewn by way of
example in the accompanying diagram one method of carrying the same into
practice.
A, B are the main leads C, C'are the two lamps one terminal of each lamp being
connected to the lead A. B is a circular resistance box the coils being connected
to suitable contact studs D' with which a central pivoted arm D2 is adapted to make
contact. The second terminal of lamp C is connected to one end of the resistance
box D and the second terminal of lamp C is connected to the other end of said
resistance box. The pivoted contact arm D2 is connected by a wire D³ to the
pivoted contact arm E of another resistance box E' of similar character to that
hereinabove described, one end of said box being insulated as shewn at E² and the
other end being connected to the lead B.
It will be readily understood that the resistance box E' is in the main circuit
while the box D is in general partly in one lamp circuit and partly in the other.
By moving the contact arm E the resistance in the box E' can be varied from
nothing when the arm E is in the dotted position marked 1 to infinity when the

page_text: arm E is in the dotted position marked 2 when the main circuit is broken. Thus
the light of both lamps can be simultaneously varied by manipulating the arm E³.
When the arm D2 is moved some of the resistance in box D is taken out of the
circuit of one of the lamps and inserted in the circuit of the other lamp. The
ratio of the resistances in the circuits of said lamps therefore can be very
considerably varied since the arm D³ can be moved from dotted position 1 when the
resistance is entirely in the circuit of lamp C and no resistance is in the circuit of
lamp C to dotted position 2 when the entire resistance is in circuit of lamp C and
none is in circuit of lamp C. When the switch is half way between the ends of
the box the resistance of the two branches is equal.
The variation of the resistances depends of course on the adjustment of the
several coils composing the resistances and we do not restrict ourselves to using any
particular resistance between the several contact studs of either box.
Instead of using the circular resistance boxes shewn in the diagram other forms
may be used. For example the resistance D may be conveniently made in the
form of a stretched wire the contact D2 being adapted to be moved along and touch
different points in the wire when desired. We may employ other forms of contact
and variable resistance without departing from the spirit of our invention.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
:-
1. The combination with two electric lamps one terminal of each of which is
connected to one supply main, of a resistance joining the other terminals of the
lamps, and an adjustable contact joined to the other supply main and adapted to
connect with the aforesaid resistance at any point intermediate of its ends,
substantially as and for the purpose, specified.
2. The method of regulating the relative brightness of two electric lamps in
parallel by means of one operating piece, substantially as described with reference
to the accompanying drawing for the purpose specified.
Dated this 15th day of June 1894.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicants.