A Combined Spring-catch and Lock for Photographic Dark Slides.
Year: 1893

page_text: Date of Application, 7th Nov., 1893
Complete Specification Left, 2nd Apr., 1894-Accepted, 5th May, 1894
PROVISIONAL SPECIFICATION.
A Combined Spring-catch and Lock for Photographic Dark Slides.
ALFRED JOSEPH DEWEY High Street Sidcup Kent Photographic Apparatus
Maker and Dealer etc. do hereby declare the nature of this invention to be as
follows:-
My invention consists of an improved spring and catch for the shutter of a
photographic dark-slide that is constructed in such a way that the spring acts as
a fastening or catch before the plate is exposed and automatically as a lock after
exposure thus preventing exposing the same plate more than once but in the
event of not exposing the plate the spring can be reset while the slide is in the
camera.
The following is how I purpose to construct the spring and catch and carry out
my invention:
The spring consists of a piece of sheet hard brass steel or other suitable
material preferably hard brass into which holes are made for fixing to the dark
slide and one end has a slot cut in it or is left projecting for the catch hereafter
described.
The spring is fastened to the dark slide preferably on the top.
The catch is made with a taper or bevelled top and a shoulder each side this
is fixed to the dark slide in such a place so that the slot or projecting end of the
spring before mentioned will catch under the shoulder of the catch.
To use this invention set the spring by keeping it pressed close to the shutter
when it is pressed home it now acts as a fastening which when the spring is released
by pulling the shutter out automatically places itself in a position to spring the
other side of the catch and so forms a lock as it cannot now be released in the
usual way.
When it is desired to open the shutter of the dark slide it can be unlocked
by inserting the thumb or suitable key under the spring until it will pass the
catch.
What I claim is an improvement in the spring catch or fastening for photographic
dark slides constructed so that it will automatically lock the shutter and prevent
exposing the same plate more than once.
Dated the Sixth day of November 1893.
COMPLETE SPECIFICATION.
A Combined Spring-catch and Lock for Photographic Dark Slides.
Alfred Joseph Dewey High Street Sidcup Kent Photographic Apparatus
Maker etc. 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 consists of an improved spring and catch for the shutter of a
photographic dark slide that is constructed in such a way that the spring acts
as a fastening or catch before the plate is exposed and automatically as a lock.
after exposure thus preventing exposing the same plate more than once but in the
event of not exposing the plate the spring can be reset. while the slide is in the
camera.

page_text: The following is how I purpose to construct the spring and catch and carry out
my invention :
The spring A consists of a piece of sheet hard brass steel or other suitable
material (preferably bard brass) into which holes C C are made for fixing to the
dark slide also a slot at D for putting a screw into to regulate the distance of
the spring A from the dark slide, and one end has a slot cut into it or is left
projecting at E for the catch B hereafter described.
The spring A is fastened to the dark slide preferably on the top as in Fig. 1.
The catch B is made with a taper or bevilled top and a shoulder each side this is
fixed to the dark slide in such a place so that the slot or projecting end of the
spring A before mentioned will catch under the shoulder of catch B as shown
in Fig. 1.
To use this invention set the spring A. by keeping it pressed close to the shutter
when it is pressed home, it now acts as a fastening as the spring A is caught
under the inside of catch B as shown in Fig. 1. When the spring A is released
by pulling the shutter out it automatically places itself in position as shown in
Fig. 2 to spring the other side of catch B and after closing the shutter forms a
lock as it cannot now be released in the usual way. Fig. 3 shows the position of
the spring A after locking. When it is desired to open the shutter of the dark
slide it can be unlocked by inserting the thumb or suitable key under the spring A
until it will pass the catch B.
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
An improvement in the spring catch or fastening for photographic dark slides
constructed so that it will automatically lock the shutter and prevent exposing the
same plate more than once.
Dated this the 2nd day of Anvil 1801