Improvements in Means or Apparatus for Producing a Flash Light, more especially applicable to Photography and Stage Effects.
Year: 1891

page_text: Date of Application, 20th June, 1591
Complete Specification Left, 12th Mar., 1892-Accepted, 16th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Means or Apparatus for Producing a Flash Light,
more especially applicable to Photography and Stage Effects.
We Joux ALEXANDER FORRET 26 Brougham Place, Edinburgh, Chemist and
Druggist, and FREDERICK DUNDAS TODD, 29 Paninure Place, Edinburgh,
Teacher of Shorthand, do hereby declare the nature of this invention to be as
follows
Our invention relates to improvements in means or apparatus for producing a
flash light, more especially applicable to photography, but also intended for other
uses, such for example, as the production of stage effects.
According to our invention, we cause magnesium or other suitable powder in a well
separated or diffused condition to enter the flame of a spirit or other lamp, and so
arrange the lamp as to effect complete combustion of the powder; and also by the
arrangement of the reservoir for the powder, and by the storage of air in a com-
pressed condition, we can control the discharge of the powder into the flame, so
that the flash may exist for a fractional part of a second-commonly called an
instantaneous flash-or it may be prolonged according to pleasure.
For this purpose we employ a reservoir of any suitable material in which to
store the powder. Through the top of the reservoir project two tubes of brass or
other suitable material, the lower end of one of which dips into the powder
contained in the reservoir. The other end of this tube is connected with the air-
chamber by tubing of india-rubber or other suitable material. One end of the
other tube has its orifice underneath the top of the reservoir, and the tube is
continued upwards in a modified shape as hereafter described to form the aperture
through which the powder is discharged into the flame.
We also employ an air-chamber of india-rubber or other suitable material in
which atmospheric air or other gas is stored under pressure by means of india-
rubber hand-bellows or other suitable means.
We also employ a lamp whereby complete combustion of the powder is effected.
The tube through which the powder is discharged from the reservoir is so con-
structed, that it gradually increases in breadth while it gets less in depth, and thus
assumes the shape of a narrow funnel whose sides are almost parallel to each other,
so as to eject a broad streak of powder, and the top of the tube is placed in the
centre of a tank or container for spirit of wine or other suitable flame-producing
material, which is burned by means of a wick.
The apparatus is worked as follows:-
In the powder reservoir is placed a convenient quantity of powder; and the
india-rubber tube leading from the air-chamber to the powder reservoir is closed
by means of a spring clip, pinch-cock or other suitable means. The air-chamber
is filled by means of the bellows hereinbefore referred to a light is applied to the
wick of the lamp, in which spirit has been placed, and the apparatus is ready for
use. On releasing the spring clip a current of air is forced into the powder
reservoir and thence through the discharge tube. In passing through the reservoir
the air violently agitates the powder, and in making its exit carries with it a
portion of the powder, which by the construction of the discharge tube, is projected
into the flame in a uniformly diffused condition. The flash so produced is in the
form of a sheet of white light, and its duration is under complete control of the
operator by means of the spring clip referred to.
If desired a more powerful flash may be obtained by adding one or more exit

page_text: tubes from the reservoir to the lamp, or by modifying the shape of the discharging
orifice, that it may present more surface to the flame.
Dated this 18th day of June 1891
J. A. FORRET.
F. DUNDAS TODD.
COMPLETE SPECIFICATION.
Improvements in Means or Apparatus for Producing a Flash Light,
more especially applicable to Photography and Stage Effects.
We, JOHN ALEXANDER FORRET of 26 Brougham Place, Edinburgh, in the
County of Midlothian, Chemist and Druggist, and FREDERICK DUNDAS TODD of
29 Panmure Place Edinburgh in the County of Midlothian, Teacher of Shorthand
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 improvements in means or apparatus for producing
flash-light more especially applicable to photography, but also intended for other
purposes such for example as the production of stage effects.
According to our invention we cause magnesium powder or other suitable
substance, in a well-separated or diffused condition to enter the flame of a lamp,
burning spirits of wine, coal-gas or other inflammable substance; and we so
arrange the lamp as to effect complete combustion of the powder; and also by
the arrangement of the reservoir for the powder, and by the storing of air in
a compressed condition, we control the discharge of the powder into the flame,
so that a Hash is produced which may exist for a fractional part of a second-
commonly called an instantaneous flash-or it may be prolonged according to
pleasure.
In order that our invention may be clearly understood, we have hereto
appended a sheet of drawings, reference to which is hereinafter made, where
similar parts are shown in different figures, they are indicated by similar
letters.
Fig. 1 is a longitudinal section through the middle of the lamp as arranged
for use with spirits of wine or other liquid inflammable substance.
Fig. 2 is a longitudinal section of the upper part of the lamp at right angles
to that shown in Fig. 1.
L
A is made of wood or metal, is circular in shape and forms a foot or stand
for the lamp. In this stand is a cavity B, open at its upper end. The bottom of
the cavity B is either concave or conical, while the wall may be either cylindrical
or barrel-shaped. The upper end of B is closed by means of a removable cork or
plug C, through which is carried a metal tube D. The lower end of D opens into
the chamber B, and the tube is continued upwards and modified in such a way as
to take the shape of a narrow funnel E, the orifice of which is in the form of a
narrow slit. In the neck of the funnel is a spherical metal valve, f, which rests on
the upper end of the cylindrical part of D. A metal pin, g, inserted through the
lower part of the funnel prevents the valve, f, from becoming jammed in the
narrowing part of the funnel when the lamp is in use.
Surrounding the funnel E is a metal tank H for holding spirits of wine or other
suitable flame-producing material which is burned by a wick, I, as is well under-
stood. When coal-gas is used, the tank, H, is replaced by a metal tube carrying
on its upper surface circular holes or saw-cuts, and connected with a gas supply by
means of india-rubber tubing as is well understood.
Entering into the cavity B either through the side (as shown in the drawing), or
through the plug, C, is a metal tube K, the end of which is directed downwards and
reaches to a quarter of an inch or thereby from the bottom of B. The projecting
end of the tube K is connected by means of a flexible tube with an india-rubber

page_text: ball or bladder in which atmospheric air is stored under pressure by means of
bellows as is well understood. On the flexible tube attached to the tube K, are a
spring-clip and a screw-clip, the purposes of which are hereinafter explained.
The apparatus is worked in the following manner :-
The plug C is removed, a quantity of magnesium powder is placed in the
cavity B, and the plug C re-inserted. The tank H containing the wick is then
filled with spirits of wine or other suitable substance. The Hexible tube which
connects K with the air-chamber is closed by means of the spring-clip herein-
before mentioned. The air-chamber is then filled with compressed air by means of
the bellows already referred to. A light is now applied to the wick I, and the
apparatus is ready for use. On releasing the spring-clip by pressure between the
fingers, a current of air passes from the air-chamber, through the tube K, into the
cavity B, thence through the discharge tube D, and makes its exit by the narrow
slit of the funnel E. The air-current in passing through the cavity B, violently
agitates the magnesium powder, and in making its exit, carries with it a portion of
the powder, which by the construction of the discharge tube is projected into the
flame of the wick I in a uniformly diffused condition, and is there burned or
oxidised, producing a flash in the form of a sheet of white light, the duration
of which is under the control of the operator, being terminated by allowing the
spring-clip to close.
The screw-clip hereinbefore referred to, is used to compress the flexible tube to
a greater or less extent, and thus regulate the delivering capacity of said flexible
tube. When the screw clip is fully open it permits a rapid delivery of air into the
cavity B, and consequently the maximum amount of powder is ejected into the
spirit flame. When the screw clip compresses the flexible tube, the delivery of air
into the cavity B is restricted, the amount of powder ejected is consequently
diminished, and the flash is of less intensity.
The valve,, is thrown upwards by the current of air, and allows a free passage
to the powder; when the current ceases, the valve, f, instantly falls back and
effectually closes the tube, D, thereby preventing the return of any ignited powder
to the cavity B.
We do not bind ourselves to the exact proportions of the different parts of the
apparatus as shown in the drawings, these being merely illustrative.
When necessary two or more lamps may be worked simultaneously from a
common air-supply, by being connected therewith by means of india-rubber tubes
attached to a distributor having as many exit tubes as the number of lamps to be
used.
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) A magnesium flash-lamp constructed, arranged and operating substantially
as hereinbefore described, and as illustrated in the accompanying drawings.
(2) In a magnesium flash-lamp a vertical chamber with a concave or conical
bottom in which to store the magnesium powder, from which chamber the powder
is ejected by a current of air striking upon the aforesaid bottom.
(3) In a magnesium flash-lamp the construction and arrangement of a dis-
charging aperture, containing a valve, and its combination and arrangement with
the chamber for storing the powder as hereinbefore described, and illustrated in the
accompanying drawings.
(4) In a magnesium flash-lamp a method of discharging the lamp by means of a
spring-clip, and of controlling said discharge by means of a screw-clip as herein-
before described.