An Improved Spring Fastening for the Shutters of Dark Slides of Photographic Cameras.
Year: 1887

page_text: Date of Application, 15th July, 1887
Complete Left, 20th Dec., 1887
Complete Accepted, 20th Jan., 1888
An Improved Spring Fastening for the Shutters of Dark Slides of
Photographic Cameras.
I, THOMAS PARSONS WATSON of 313 High Holborn, London, Manufacturing
Optician, do hereby declare the nature of this invention to be as follows :-
It relates to an improved method of holding in the sliding shutters of dark-slides or
roll-holders, used with Photographic Cameras & consists-1st of a brass spring-No. 1
in sketch-which is drawn to exact size of that used but may be made larger or smaller
if required. The part of the spring "A" marked b. b. in sketch, & consisting of a
forked piece of brass projecting on one side of the spring, is turned over to stand at
right-angles to the remaining portion of the spring, substantially as sketch No. 2.
This spring, as so constructed, I attach to the top of the shutter of the dark-slide, in
such position, that the hand must necessarily grasp it when drawing out the shutter,
and as it is grasped, it sinks back into a recess in the shutter behind it, there being―
for the purpose of allowing it to sink back-a slot at C. sketch No. 3, through which
one of the screws go that hold the spring to the shutter, the other screw that completes
the attachment of the spring to the shutter, being a fixed one. 2nd. A screw, or
headed pin, which I fit permanently in the top of the dark slide, in such place, that
the fork b. b. of the spring, snaps over it, when pushed home in its slide, & is held by it
firmly in position, nor can it be again withdrawn until the spring is pressed, and sinks
into the recess behind it, described above.
Dated this 15th day of July 1887

page_text: An Improved Spring Fastening for the Shutters of Dark Slides of
Photographic Cameras.
I THOMAS PARSONS WATSON, of 313 High Holborn, London, Optician 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 an improved spring latch fastening for retaining the sliding
shutters of photographic dark slides or roll holders, and preventing the said shutters
being inadvertently drawn out when removing the dark slide from the camera, or at
any other time; and the invention has for its object to provide a spring latch fastening of
very simple construction which can be readily applied to the dark slide without involving
cutting away any part of the frame of the slide and so risking danger of leakage of
light at the point where the spring fastening is situated, as in those spring fastenings
generally in use. To this end the invention consists of a spring affixed along the
handle or projecting portion of the shutter of the dark slide and having a nib turned
up along one of its longitudinal edges at about right angles to the plane of the spring,
adapted to engage with or snap under a catch fixed in the end of the frame of the
dark slide, the position of the spring being such that it must necessarily be pressed
back and disengaged from the catch when the handle or projecting part of the shutter
is grasped for the purpose of drawing it out.
Reference is to be had to the accompanying drawing forming part of this
specification, wherein Figure 1 represents an inside face view (on an enlarged scale)
of the upper part of one half of a double dark slide. Figure 2 is a cross-section, and
Figure 3 a top or end view thereof, the spring catch being in engagement with the
head of the fixed stud. Figure 4 is a view similar to figure 3, shewing the catch
as disengaged from the stud by the pressure of the finger upon the spring. The same
letters of reference indicate the same parts in all the figures.
A A' is part of the frame of one part of an ordinary double dark slide, and B is its
usual sliding shutter provided with a handle or projecting piece b to be gripped by the
fingers for the purpose of withdrawing the shutter. The fastening of my invention
consists of a spring c being a flat strip of sheet brass or other suitable metal having a
nib d in one therewith, turned up along a portion of its lower longitudinal edge at
about right angles to the plane of the strip e, as shewn in figure 2, this spring c being
applied along the handle 6 of the shutter over a cavity 6 therein which permits of
flexure of the spring, as shewn in figure 4, under pressure. The spring c is attached
to the handle b by two screws c² c³ of which one passes through an oblong hole in the
spring to permit of the shortening of the distance between the two ends of the spring
when the latter is in the curved form shewn in figure 4. The nib d is cut out in one
piece with the spring c and it is preferably forked so as to embrace about half of the
circumference of the neck of a common round headed screw (or nail) e and take a firm
hold beneath the head thereof. This screw (or nail) e is simply driven into the end

page_text: bar A¹ of the frame in such position that on the shutter B being pushed into the
frame, the nib d will strike the head of the screw and the spring and nib will
thereby be deflected, as shewn in figure 4, and the nib will pass and engage beneath
the head of the screw. Owing to the rounded form of the screw head, the nib d will
easily snap into engagement therewith, without applying pressure to the spring c and
will be securely retained in engagement until the spring is pressed back into the recess
behind it by pressing on stud c' as shewn in figure 4.
It will be seen that owing to the position of the spring along the handle of the
shutter, a spring of sufficient length and flexibility can be obtained whilst the entire
fastening is wholly external of the dark slide, and it is therefore not necessary to cut
away the wood of the cross piece A' on the face adjacent to the shutter and thereby
risk leakage of light.
It will be evident that the nib d need not necessarily be forked, and in that case the
catch e may be a pin or screw with a head or projection bent at right angles to the
stem in position to be engaged by the nib d and bevelled at the extremity to allow of
the nib snapping into engagement with it.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed I declare that what
I claim is ;
1. A spring latch fastening for photographic dark shutters, consisting of a single
spring strip of metal having a nib turned up along one edge at about right angles
thereto, the spring strip being applied along the handle of the shutter and being
adapted to be engaged and disengaged by flexure of the spring in the direction of
its length, in combination with a fixed catch in the end of the frame with which the
nib is adapted to engage, substantially as specified.
2. A spring latch fastening for photographic dark shutters, consisting of a metal
strip c having an outwardly turned forked nib d near the middle thereof secured along
the handle b over a cavity therein, as described, in combination with around headed screw
pin fixed in the end of the frame for engagement with the forked nib, as specified.
3. A spring latch fastening for photographic dark shutters, the spring or movable
portion of which is wholly external, that is to say is applied only to the projecting
portion of the shutter, substantially as herein specified.
4. A spring latch fastening for photographic dark shutters applied to the projecting
portion or handle of the shutter and having a nib adapted to engage with a fixed catch
projecting from the end of the frame.
Datad this 30th day of December 1887
T. P. WATSON.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.