A New or Improved Flash Lamp for the Rapid Combustion of Magnesium Powder, to be used for Photographic or other Purposes.
Year: 1889

page_text: Date of Application, 14th Feb., 1889
Complete Specification Left. 28th Oct. 1889--Accented 4th Jan
1890
PROVISIONAL SPECIFICATION.
A New or Improved Flash Lamp for the Rapid Combustion of
Magnesium Powder, to be used for Photographic or other
Purposes.
1.JOHN LEISK of 169 Commercial Street, Lerwick, Shetland, Merchant, do hereby
declare the nature of my invention to be as follows:-
My invention relates to a new or improved form of Flash Lamp for the rapid or
instantaneous combustion of magnesium powder applicable to Photographic or other
purposes whereby the powder is propelled by centrifugal force outwards equally all
round from the surface of a circular horizontal rapidly revolving disc into a suitable
flame or flames completely surrounding said revolving disc, thus securing the total
combustion of the metallic powder under conditions favourable to obtaining the
maximum of incandescence, the result being an instantaneous flash of actinic light
circular or globular in form and many inches in diameter, which from its large area
and diffusive power is imminently suitable for Photographic purposes.
All in contra-
distinction to the methods heretofore used of projecting the Magnesium powder by
means of an air current into a suitable flame either horizontally, obliquely, or
vertically, by which mode, in some instances part of the metallic powder passes
through the Hame unconsumed, and in all the cold air introduced into the flame tends
to disturb the same, lowers the temperature and prevents the maximum incandescence
of the Magnesium powder used.
By one arrangement my invention may be constructed as follows.
A bed plate of metal or other suitable material and which may be five inches square
is prepared and on each corner of the same is erected rigidly a stout pillar one and a
quarter inches high. A second plate of same size as the first is now placed on
the top of these pillars to which it is attached by screws or otherwise.
Pivoted to the centre of the lower or bed plate and rising perpendicularly through
an opening in the centre of the upper plate is an arbor or spindle about three inches
long, on the upper end of which is rigidly fixed at right angles by its centre a
circular metal disc about one and a half inches in diameter, said arbor being fitted so
as to revolve easily and being provided with the necessary collars or shoulders to
prevent it leaving its bearings.
To the lower part of the said arbor is attached a coiled spring for revolving the
same and also a ratchet wheel and suitable detent for stopping the spring when
wound up.
By another method an India rubber band may be substituted for the coiled
spring.
There is also attached to the bed plate a suitable trigger arrangement, brought by
pneumatic or other means under the control of the person using the Lamp, by which
the detent can be instantly removed from the teeth of the ratchet wheel when a flash is
required to be made.
Resting upon the upper plate is a circular Spirit Lamp or Burner, made of metal
in the form of a flat hollow ring two and a half inches in diameter, one and a quarter
inch broad, and one eighth of an inch or more in thickness. The wick of this lamp,
preferably of asbestos, protrudes from the upper open edge of the ring aforesaid, the
other edge being closed and resting upon the plate, while a small capped reservoir at
the side connected to the ring or burner by a short tube supplies the wick with spirit.
This circular lamp or burner is attached to the upper plate in such a manner that it
shall surround equidistantly the circular disc and arbor before mentioned, with the
surface of the wick at a level one half of an inch below the upper surface of the said
circular disc, the part of the top plate thus enclosed being freely perforated so as to
admit a free current of air from below between the circular disc and the Spirit Lamp
wick. An annular cap for extinguishing the Spirit Lamp is also provided.

page_text: By another arrangement a circular Bunsen burner or circle of gas or other flames
may be substituted for the Spirit Lamp in conjunction with the revolving mechanism
before described for igniting magnesium powder and producing a flash.
To use a Flash Lamp as before specified. The Lamp is first filled with Methylated
Spirit. The spring is then wound up by turning the circular disc at the top of the
arbor. The charge of magnesium powder which may be three grains or more is
then spread on the upper surface of the aforesaid disc and the Spirit Lamp lit,
the detent is now withdrawn from the ratchet wheel when the coiled spring thus
suddenly released, causes the arbor and disc instantly to rapidly revolve on its axis
and by the centrifugal force thus generated to scatter the charge of Magnesium
powder into the adjacent flame of the Lamp, thereby producing an instantaneous
Hash of maximum size and brilliancy with a minimum of powder used.
Having thus described my invention, the chief feature of novelty of which consists
in utilizing centrifugal force to project the Magnesium powder into one or more
suitable flames the mechanism here described for carrying out that principle may be
somewhat varied in details or size, the measurements before given being merely
relative must be varied to suit other sizes of Flash Lamps.
When used for taking Photographic portraits a suitable reflector and diffusing
screen should be used in conjunction with the Lamp herein described.
Dated this Eleventh day of February 1889.
JOHN LEISK.
COMPLETE SPECIFICATION.
A New or Improved Flash Lamp for the Rapid Combustion of
Magnesium Powder, to be used for Photographic or other
Purposes.
1, JOHN LEISK of 169 Commercial Street Lerwick Shetland, Merchant, 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:-
My invention relates to a new or improved form of Flash Lamp for the rapid or
instantaneous combustion of Magnesium powder applicable to photographic or other
purposes whereby the powder is propelled by centrifugal force outwards equally all
round from the surface of a circular horizontal rapidly revolving disc into a suitable
flame or flames completely surrounding said revolving disc thus securing the total
combustion of the metallic powder under conditions favourable to obtaining the
maximum of incandescence, the result being an instantaneous flash of actinic light,
circular or globular in form and many inches in diameter which from its large
area and diffusive power is imminently suitable for photographic purposes.
All in contradistinction to the methods heretofore used of projecting the mag-
nesium powder by means of an air current into a suitable flame either horizontally
obliquely or vertically by which mode in some instances part of the metallic powder
passes through the flame unconsumed, and in all the cold air introduced into the
Hame tends to disturb the same, lowers the temperature and prevents the maximum of
incandescence of the magnesium powder used.
By one arrangement my invention may be constructed as follows :
A bed plate of metal or other suitable material, A. A. (Figures 1 and 2 of the
accompanying drawings) and which may be five inches square is prepared and on each
corner of the same is erected rigidly a stout pillar B. B. one and a quarter inch in
height. A second plate of same size as the first C. C. C. is now placed on the top
of these pillars to which it is attached by screws or otherwise.
Pivoted to the centre of the lower or bed plate A. and rising perpendicularly through
an opening in the centre of the upper plate C. is an arbor or spindle D. about
three inches long on the upper end of which is rigidly fixed at right angles by
its centre a circular metal plate or disc E. E. about one and a half inch in diameter,

page_text: said arbor being fitted so as to revolve easily and being provided with the necessary
collars or shoulders to prevent it leaving its bearings.
To the lower part of the said arbor is attached a coiled spring F. for
revolving the same and also a ratchet wheel G. and suitable detent H. for stopping
the spring when wound up.
By another method an India-rubber band may be substituted for the coiled
spring.
There is also attached to the bed plate A. a suitable trigger arrangement at T.
(not shewn in the drawing) brought by pneumatic or other means under the
control of the person using the lamp by which the detent can be instantly
removed from the teeth of the ratchet wheel when a flash is required to be
made.
Resting upon the upper plate C. is a circular spirit lamp or burner I. I. I. I.
made of metal in the form of a flat hollow ring two and a half inches in diameter, one
and a quarter inch broad and one eighth of an inch or more in thickness; the wick of
this lamp J. J. J. J. preferably of asbestos protrudes from the upper open edge of the
ring aforesaid, the other edge being closed rests upon the plate C. while a small capped
reservoir at the side K. K. connected to the ring or burner by a short tube supplies the
wick with spirit; this circular lamp or burner is attached to the upper plate in such
a manner that it shall surround equidistantly the disc E. and arbor beforementioned
with the surface of the wick at a level three eighths of an inch below the upper
surface of the said disc, the part of the top plate C. thus enclosed being freely
perforated so as to admit a free current of air from below between the disc E. and the
spirit lamp wick J.
An annular cap for extinguishing the spirit lamp is also provided.
By another arrangement a circular Bunsen burner or circle of gas or other flames
may be substituted for the spirit lamp, in conjunction with the revolving mechanism
before described, for igniting magnesium powder and producing a flash.
To use a Flash Lamp as before specified, the lamp is first filled with Methylated
spirit, the spring is then wound up by turning the circular disc at the top of the arbor,
the charge of magnesium powder which may be three grains or more is then laid on
the surface of the disc aforesaid and the spirit lamp lit, the detent is now withdrawn
from the ratchet wheel when the coiled spring thus suddenly released causes the arbor
and disc instantly to rapidly on its axis and by the centrifugal force thus generated to
scatter the charge of magnesium powder into and through the adjacent Hame of the
Lamp thereby producing an instantaneous flash of maximum size and brilliancy with
a minimum of powder used; or if a prolonged flash be desired the magnesium powder
may be placed into a small hopper suspended by means of a wire attached to the bed
plate and so placed that the open lower end of the hopper hangs one eighth of an inch
above the surface of the said disc, this by retarding the escape of the powder will
prolong the flash.
When used for taking photographic portraits a suitable reflector should be
placed behind and a large translucent diffusing screen in front of the lamp herein
described.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is,
Applying centrifugal force to magnesium flash lamps and utilizing said force for
projecting magnesium powder into one or more adjacent suitable flame or flames
whereby it is rendered incandescent and a flash produced.
The details and size of the mechanism herein described for generating and
applying said force may be varied and the measurements before given being merely
relative must be varied to suit other sizes of Flash Lamps.
Dated this Therentes Cl
1000
JOHN LEISK.