Improvements in Electric Lighting Systems for Stage Effects.
Year: 1899

page_text: Date of Application, 11th July, 1899-Accepted, 2nd Sept., 1899
COMPLETE SPECIFICATION.
Improvements in Electric Lighting Systems for Stage Effects.
I, ARTHUR WILLIAM BERRESFORD, of Westfield, in the County of Union and
State of New Jersey, United States of America, Manufacturer, 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:-
: -
In obtaining the lighting effects used in connection with threatrical scenes, to
produce the illusions called for by the piece, it is necessary to mix the various
colours of light, and to obtain gradual changes for varying the quantity of light
of cach colour by variation in the amount emitted by cach source of light. This
is accomplished by introducing a gradually increasing or decreasing resistance
into the lamp circuit, and thus controlling the current supplied.
In the construction of apparatus for producing the above effects, which
apparatus is generally known as "theatre dimmers," it has been the
practice to assemble or bank the resistance plates into a rigid whole
by passing tie-rods through the plates, and into supporting frames
therefor, and separating the several plates by short lengths of pipe
surrounding the rods between the plates. In this structure it was necessary to
dismantle more or less of the apparatus, before removing any one of the resistance
plates, if, for any cause, the removal of such plates became desirable.;
In operation, it becomes necessary to move several of the independent contact
levers at the same time, to produce a certain effect. This is ordinarily accom-
plished by providing a master lever shaft, which is mounted in brackets carried
by the resistance plates, which shaft communicates motion to the several contact
levers by rigid connections with segments mounted to rotate freely on the axes
of the contact levers, which segments are arranged to interlock with the said
contact levers.
One object of my invention is to obviate the necessity of dismantling the
structure in order to remove any one of the resistance plates, the said plates, in
my improved structure, being independently mounted in the supporting frame
work.
Another object of my invention is to mount the master lever shaft in the frame
independently of the resistance plates, in such a manner as to permit the said
shaft to be adjusted laterally and vertically, without interfering with the said
plates, to compensate for any distortion in the framework, due to derangement in
shipment, unevenness of setting, &c.
This structure enables anyone of the plates to be removed without removing the
shaft, and without disturbing any of the remaining plates, and further obviates
the difficulties which occur in attempting to align the holes in the several plates,
so as to mount the shaft therein, as has heretofore been customary.
A further object is to provide flexible connections between the master lever
shaft and the several contact lever segments or wheels, so as to ensure the easy

page_text: operation of the said levers by the master lever, without any tendency to bind or
cramp.
A still further object is to provide means for reversing the flexible connection
between the master lever shaft and any of the several contact levers, so that
when the master lever is swung in one direction, certain of the contact levers will
be caused to swing in the reverse direction, when interlocked with their segments
or wheels, to produce certain desired effects.
A practical embodiment of my invention is represented in the accompanying
drawings, in which
Fig. 1 represents my improved apparatus in end elevation,
Fig. 2 is a side view of the same;
Fig. 3 is a transverse vertical section in the plane of the line 3-3 of Fig. 2.
Fig. 4 is an enlarged detail sectional view of one form of insulating adjustable
coupling for securing together the free ends of the flexible connections; and
Fig. 5 represents a detail view showing the manner of crossing the flexible
connections, to reverse the movement of the contact lever segment or wheel.
The resistance plates are denoted by A, and the supporting frame therefor
comprises upright frames B and cross bars B1, B2, B3, which cross bars serve to
connect the upright frames. Two of these upright frames B are shown in the
accompanying drawings as end frames, but it is to be understood that there may
be one or more intermediate upright frames to strengthen the structure where a
large number of resistance plates are carried by the frame, if found desirable.
The several crossbars B1, 132, 133, may be bolted firmly to the upright frames B,
so as to produce a rigid structure. In the accompanying drawings, I have repre-
sented the upper cross-bar B₁ as a flat bar; the rear lower cross-bar B2 as a T bar;
and the front cross bar B3 as an L bar.
I have represented a bank of four resistance plates A in the accompanying draw-
ings, but there may be a greater or lesser number, according to different require-
ments.
Each of these plates A is removably secured to the several cross-bars, inde-
pendently of the other plates, in the following manner:-The plate A rests upon
the lower cross-bars B2, B, and is secured to the front lower cross bar B by
bolts b, which pass through the said cross bar and through lugs
a extended
laterally from the front of the lower edge of said plate. The plate is secured
to the rear lower cross bar B2 by means of bolts b', which pass through the said
cross bar and through lugs a¹ extended laterally from the bottom of the rear edge
of the said plate. The plate is also bolted to the upper cross-bar B₁ by means
of bolts 62, which pass through the said cross-bar and through lugs a projecting
laterally from the top of the rear edge of the said plate.
The contact lever is denoted by C, and it is mounted on a stub axle a³ pro-
jecting from about the middle of the plate A. The contact lever controlling
segment or wheel is denoted by D, and it is mounted to rock freely upon the
stub axle ³, and is fitted to be interlocked with the said contact lever. The
means which I have shown for interlocking the lever and segment or wheel con-
sists of a dog c, arranged to enter a notch d in the periphery of the segment or
wheel D. This dog e is connected to an operating handle c¹, located on the handle
of the contact lever. The dog may be held in its raised position for, releasing the
lever from the segment or wheel D by means of a ring, which embraces the
handle and the handle of the contact lever. The contact lever C may be
provided with the usual contact plates c³, c, arranged to travel over the upper and
lower series of contact points a¹, a³.
In order to move several of the independent contact levers C at the same time,
I provide a master lever shaft E, which shaft is provided with a plurality of wheels
or segments e, mounted fast thereon, corresponding to the contact lever segments
or wheels D.
The shaft E is provided with a master lever e¹, which extends upwardly, in
the present instance, to a point above the frame between one of the end upright

page_text: frames B and the adjacent resistance plate. However, the master lever might
project from the said shaft at any place along the bank of resistance plates, as
found desirable.
The segments or wheels e impart a rocking movement to the wheels or seg-
ments D, through flexible connections F. Each of these flexible connections I
preferably consists of a wire rope divided into two sections having their adjacent
ends clamped within insulating couplings G, so that there will be no electrical
connection between the upper segment or wheel and the lower segment or wheel.
This insulating coupling G is arranged to take up any slack in the rope F, as it
is essential that the said flexible connection or rope shall be very taut, so as to
ensure the proper operation of the contact lever controlled thereby.
In the present instance, the ends of the rope are held in position within the
coupling by means of set screws g, gl. When it is desired to move the contact
lever in the same direction as the movement of the master lever, the rope leads
from one side of the periphery of the lower segment or wheel to the same side of
the upper segment or wheel. When it is desired to cause the contact lever to move
in the opposite direction to the movement of the master lever, the ends of the
upper section of the rope are crossed, so that the rope leads from the periphery
of one side of the lower segment or wheel to the periphery at the other side of
the upper segment or wheel. This flexible connection is preferably wire rope or
other suitable material which will not stretch.
The master lever shaft E is mounted to rock in the upright frames B in such a
manner that it may be adjusted both laterally and vertically, to accommodate
itself to any unevenness in the setting of the frame. In the present instance, this
adjustment is secured by providing each end of the shaft with a bearing sleeve e²,
which sleeve is engaged on each side by adjusting screws e³, projecting from a
vertically adjustable bracket et, carried by one of the upright frames B. In the
present instance, these brackets et are made vertically adjustable, by providing
them with vertically elongated slots e, through which bolts e pass into engage-
ment with the said upright frame.
In the structure as above described, the master lever shaft is mounted in the
frame entirely independent of the several resistance plates, so that any of the said
resistance plates may be removed without disturbing the said shaft."
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
1 claim is:
1. A theatre dimmer comprising a suitable supporting frame, a plurality of
resistance plates, a contact lever and contact points carried by each plate inde-
pendently of adjacent plates, and means for securing each plate to the supporting
frame in removable adjustment, substantially as set forth.
2. A theatre dimmer comprising a supporting frame consisting of upright
frames and cross-bars connecting the said frames, a plurality of resistance plates,
a contact lever and contact points carried by each plate independently of adjacent
plates, and means for securing each plate to the said cross-bars in removable
adjustment, substantially as set forth.
3. A theatre dimmer comprising a supporting frame, resistance plates carried
thereby, contact levers for the resistance plates and a master lever shaft con-
nected with the said contact levers, the said shaft being mounted in the supporting
frame independently of the said resistance plates, substantially as set forth.
4. A theatre dimmer comprising a supporting frame, a plurality of resistance
plates carried thereby, contact levers for the plates, a master lever shaft connected
with the said contact levers, and mounted in the frame independently of the
resistance plates, and means for adjusting the shaft laterally and vertically for
the purpose set forth.
5. A theatre dimmer comprising a supporting frame resistance plates carried
thereby, contact levers, segments or wheels arranged to interlock with said levers,

page_text: a master lever shaft mounted in the frame, segments or wheels carried thereby,
and flexible connections between the contact lever segments or wheels and the
master lever shaft segments or wheels, substantially as set forth.
6. A theatre dimmer comprising a supporting frame, resistance plates carried
thereby contact levers, contact lever segments or wheels arranged to interlock
with the contact levers, a master lever shaft mounted in the frame, segments or
wheels carried by the said shaft, flexible connections between the contact lever
segments or wheels and the master lever shaft segments or wheels, and means
for reversing the said flexible connections, whereby one or more of the contact
lever segments or wheels may be caused to rock in the reverse direction to the
movement of the master-lever shaft segments or wheels, substantially as set forth.
7. A theatre dimmer comprising a supporting frame, resistance plates carried
thereby, contact levers therefor, contact lever segments or wheels arranged to
interlock with the said levers, a master lever shaft mounted in the frame, segments
or wheels carried thereby, flexible connections between the shaft segments or
wheels and the contact lever segments or wheels, comprising upper and lower
sections, and means for insulating the upper and lower sections of the flexible
connections and adjusting their tension, substantially as set forth.
Dated this 11th day of July 1899.
NEWTON & SON
Agents for the Applicant.