AN IMPROVED FIRE-PROOF SCREEN OR SHUTTER FOR SEPARATING THE STAGE FROM THE AUDITORIUM OF THEATRESTRES TOGETHER WITH MEANS AND APPARATUS FOR WORKING THE SAME.
Year: 1883

page_text: LETTERS PATENT to Alexander Clark of Lancaster Gate in the County of
Middlesex Gentleman for an Invention of AN IMPROVED FIRE-PROOF SCREEN
OR SHUTTER FOR SEPARATING THE STAGE FROM THE AUDITORIUM OF THEATRES,
PROVISIONAL SPECIFICATION .left by the said Alexander Clark at the
Office of the Commissioners of Patents on the 24th May 1883.
ALEXANDER CLARK of Lancaster Gate in the County of Middlesex Gentleman,
"AN IMPROVED FIRE PROOF SCREEN OR SHUTTER FOR SEPARATING THE STAGE
FROM THE AUDITORIUM OF THEATRES TOGETHER WITH MEANS AND APPARATUS
FOR WORKING THE SAME.
"
My Invention consists in an improved proscenium curtain, screen, or shutter for
separating the stage from the auditorium of a theatre in case of fire and in the
means and apparatus for working the same whereby its immediate availability in
case of need is ensured.
The curtain, screen, or shutter is a rigid structure made of iron or steel plates
rivetted to suitable channel and angle iron framing, the curtain, screen, or shutter
being constructed double a sufficient air space being left between the two skins to
prevent the rapid transmission of heat. Or the intervening space may be filled
with water or lined or packed with fire resisting or non conducting material. The
curtain would be arranged to slide or work up and down in wrought iron channels
of the proper depth (allowing for a proper lap of the curtain) affixed to the
proscenium walls. The top portion of the curtain is constructed of channel iron
and forms a transverse girder whose ends project at the sides of the curtain and
are attached to the heads of hydraulic rams by which the curtain is to be raised
and lowered. The cylinders of the hydraulic rams are fixed at each side of the
proscenium opening and are equal to the whole vertical motion of the curtain, the
ram being of course of corresponding length. The cylinders are charged with
water under adequate pressure from a suitable source and under the control of

page_text: valves operated from any convenient point. The escape of this water from the
cylinders permits and regulates the descent of the curtain. With this arrangement
the curtain would be partially counterbalanced by suitable weights to enable it to
be raised or lowered without too great an expenditure of power.
According to another arrangement instead of the curtain being counterpoised
by separate balance weights, the hydraulic cylinders and rams are so constructed
and fixed in such position, and the curtain is so connected thereto that the rams
themselves act also as counterbalances for the weight of the curtain.
Another arrangement consists in constructing the curtain of two sections, an
upper and a lower one arranged to work in opposite directions, the one rising as
the other descends and meeting in the centre of the vertical height of the proscenium.
The two sections would be so connected by mechanical or hydraulic gear that the
one section would more or less counterbalance the other, the working of the two
sections being in any case controlled by hydraulic power.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Clark in the Great Seal Patent Office on the
24th November 1883.
ALEXANDER CLARK of Lancaster Gate in the County of Middlesex Gentleman
"AN IMPROVED FIRE PROOF SCREEN.OR. SHUTTER FOR SEPARATING THE STAGE
FROM THE AUDITORIUM OF THEATRES TOGETHER WITH MEANS AND APPARATUS,
FOR WORKING THE SAME."
My Invention consists in an improved proscenium curtain screen or shutter
for separating the stage from the auditorium of a theatre in case of fire and in the
means and apparatus for working the same whereby its immediate availability in
case of need is ensured.
10
11
The curtain, screen or shutter is a rigid structure made of iron or steel plates
rivetted to the opposite sides of suitable channel and angle iron framing thus
forming a double skin with a sufficient air space between the two skins to prevent
the rapid transmission of heat. Or the intervening space may be filled with water
or lined or packed with fire resisting or non conducting material. The curtain
would be arranged to slide or work up and down in wrought iron channels of the
proper depth affixed to the proscenium walls. Near the top of the curtain is a
transverse girder constructed of channel iron whose ends project at the sides of
the curtain and rest on the heads of hydraulic rams by which the curtain is to be
raised and lowered. The cylinders of the hydraulic rams are fixed at each side of
the proscenium opening and are equal to the whole vertical motion of the curtain,
the ram being of course of corresponding length. The cylinders are charged with
water under adequate pressure from a suitable source and under the control of
valves operated from any convenient point. The escape of this water from the
cylinders permits and regulates the descent of the curtain. With this arrangement
the curtain would be partially counterbalanced by suitable weights to enable it to
be raised or lowered without too great an expenditure of power.
According to another arrangement instead of the curtain being counterpoised by
separate balance weights, the hydraulic cylinders and rams are so constructed and
fixed in such position, and the curtain is so connected thereto that the rams them-
selves act also as counterbalances for the weight of the curtain.
DESCRIPTION OF DRAWINGS
Figure 1 is a rear elevation of the curtain showing the hydraulic gear and figure 2
is a vertical section of same. Figure 3 is a horizontal section of one side of the
curtain (on line 1-1 figure 1) drawn to a larger scale and figure 4 is a vertical
section of the upper part of the curtain showing the girder.
A is the curtain screen or shutter and B are the guides in which it works. C is
the transverse girder and D are guides in which its ends work. E are the hydraulic
rams and F their cylinders, G are counterweights attached to chains passing over
sheaves H and connected to the girder C.
The framing of the curtain A is composed of channel irons a around the edges
and of upright ribs of iron b united by through rivets. The girder C is preferably
of box section and may be made of two channel irons united by through bolts
after the plates have been rivetted to their respective halves of the girder. A
sufficient space is left between the channel irous to permit the free circulation of
air and the top and bottom channel irons a are drilled at intervals for the same
11

page_text: The plates composing the two skins are rivetted to the framing a b and to the
respective halves of the girder C. The plates butt joint and are rivetted to inside
covering plates at the horizontal joints.
The curtain is rather wider and higher than the opening in the proscenium
wall K to the back of which the guides B are fixed. The cylinders F_rest on a
suitable foundation and are fixed to the back of the proscenium wall K, and are.
constructed in the ordinary way.
+
The heads of the rams take under the projecting ends of the girder C which
work in the guides D formed on the stanchions which carry the sheaves H and
which are also fixed against the proscenium wall. The counter balance weights G
work in boxes fixed against the wall K. The curtain preponderates sufficiently:
over these weights to descend slowly of itself when the water is released from the
ram cylinders. The cylinders F are supplied with water under pressure from
the same main and the supply and release of the water is controlled by a valve L
operated by a lever M at one side of the proscenium.
When separate counterbalance weights are not used the cylinders would be
inverted and would be fixed to a suitable support and the chains would pass
over sheaves mounted on top of the cylinders and under sheaves attached to the'
lower ends of the rams in the usual way.
Having described the nature of the said 'Invention and the manner of performing
the same I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is:
1. A fire resisting proscenium screen or shutter constructed of a double skin'
composed of iron or steel plates secured to a suitable frame work with an intervening
space between the two skins substantially as shown and described.
2. The combination of a proscenium screen or shutter constructed as herein
specified and of hydraulic gear arranged for operation substantially as shown and
described.
In witness whereof I the said Alexander Clark, have hereunto set my hand and
seal this Twenty fourth day of November A.D. 1883.