Improvements in the Method and Apparatus for Producing Magnesium-flash-light.
Year: 1892

page_text: Date of Application, 31st Mar., 1892-Accepted, 7th May, 1892
COMPLETE SPECIFICATION.
Improvements in the Method and Apparatus for Producing
Magnesium-flash-light.
I; NEWNHAM BROWNE, of 73 Cheapside, in the City of London, Fellow of the
Chartered Institute of Patent Agents, do hereby declare the nature of this inven-
tion, which has been communicated to me by Emil Wünsche, of Dresden in the
Kingdom of Saxony and Empire of Germany, Manufacturer of Photographic
Apparatus, and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
In photographing living subjects by magnesium light it is invariably found that
the subject or subjects are adversely influenced as regards the photographing by the
flame usually employed for igniting the magnesium powder. The disturbance of
the subject by this flame is frequently the cause that makes the resulting picture
defective.
To obviate this disturbing influence of the magnesium light by dispensing with
a flame for igniting it, is the object sought by this new method for igniting the
magnesium powder.
According to this invention the well known paper cased percussion caps, or other
percussion caps, or detonators, of a like character which ignite with a report
when struck, say by a hammer are employed to ignite the magnesium powder.
This method only sometimes succeeds in igniting the magnesium powder (experi-
ments tend to show that this takes place only in about four cases out of a hundred)
but these can only be deemed accidental exceptions, nor is a materially better
result obtained even when the magnesium powder is strewed near to or even upon
the fulminant material.
The reason why ignition of the magnesium powder by these percussion caps so
often fails, the inventor thinks to be this, that when the fulminant is exploded by a.
blow, its ignition is too rapid to be capable of communicating itself to the magnesium
powder.
The inventor's endeavour therefore has been so to retard combustion of the
fulminant that its ignition may with reasonable certainty be communicated to the
magnesium powder.
This he obtains by substituting for the blow of a hammer the prick of a needle
which perforates the fulminant material. In this manner a small portion only of
the said material is immediately ignited instead of the entire mass, and the com-
bustion therefrom spreads to the remainder, thus taking place more slowly, and is
with certainty communicated to the magnesium powder strewed upon the cap so
that the magnesium becomes luminous.
The device for carrying this method into practice is shown in the accompanying
drawings and is as follows:
A flanged plate a serves to receive the cap and some magnesium powder to be
strewed partly beside the cap partly upon it. Perpendicularly to the plate a is
provided a needle 6 capable of movement in a longitudinal_direction.
A lever d
at its upper end, controlled by spring e, serves to exert that pressure upon the
needle which is needful for causing it to pierce the cap.
The upper end of a two armed lever e extends into the line of motion of lever d
retaining the latter in its raised position so as to prevent the pressure thereof upon
the needle and consequently the piercing of the cap by the needle point.
A handle carries the plate a and by the side of the handle is placed the lower
end of the levere held in position by a spring g so as to stop the descent of the
lever d.
Under the point of the needle b when the same is raised the percussion cap is

page_text: placed, then magnesium powder is strewed by its side and over it, and the needle
cautiously lowered again whilst the lever d is held out of contact with the needle
by the end of lever e. When the lower end of lever e is pressed against handle f
the lever d is liberated and forced down upon the needle by the spring c.
needle then pricks the cap igniting it and thereby the magnesium powder.
The
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed as communicated to me
by my foreign correspondent I declare that what I claim is
For producing magnesium flash light
1. A process consisting of the use of percussion caps or detonators as the means
of ignition, the ignition of such caps being so caused by the prick of a needle that
the combustion of the fulminant is comparatively slow and is therefore com-
municated with certainty to the magnesium powder strewed by and upon
the cap.
2. The device for carrying this method into practice, characterized by a
plate a for receiving the magnesium powder and cap and the needle capable of
longitudinal motion and having its point turned towards the cap, the needle being
forced upon the cap (so as to ignite it) by a lever d acted upon by a spring e when
released from the lever e retaining the same.
3. The method of and apparatus for producing the flash-light by means of
magnesium powder substantially as hereinbefore described and set forth.
Dated the Thirty-first day March 1892.
NEWNHAM BROWNE.