Improvements in Photographic Dark Slides.
Year: 1891

page_text: Date of Application, 4th Apr., 1891-Accepted, 9th May, 1891
COMPLETE SPECIFICATION.
Improvements in Photographic Dark Slides.
We THOMAS SCOTT of Victoria Crescent Eccles in the County of Lancaster,
Builder, and JAMES DAVENPORT of Peel Causeway near Bowdon in the County
of Chester, 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 :-
Our said invention relates to an improved construction of dark slides for use in
photographic cameras.
In dark slides made in accordance with our said invention we provide one or more
movable catches for holding the plate in its proper position when the slide is
charged ready for use.
Our said invention is applicable to single as well as to double dark slides.
Referring to the accompanying drawings
Fig. 1 is a plan of a single dark slide made in accordance with our said
invention.
Fig. 2 is a section through x y of Fig. 1.
In the said figures a is a frame provided with grooves in which slides a
shutter c. This shutter may be drawn entirely out and is not shown in Fig. 1 in
order to render the description clearer.
In a single slide as shown in Figs. 1 and 2 the slide forms a shallow tray
provided with a back d on which the plate rests with its sensitive surface upper-
most. At e is a projecting part under which one edge of the plate is slid when
being inserted in the slide. is a catch which is drawn back when the plate is
lowered into the slide and is pushed forward when the plate has been inserted.
The plate his then held between the projecting part e and the catch fand is
prevented from falling out when the shutter c is withdrawn.
Preferably the catch consists of a sliding piece operated from the outside and
provided with a slot through which projects a pin to regulate the traverse of the
catch. Or in lieu of a catch of the kind shown we may use a spring catch so
arranged that when in its normal position it projects inwards and over the plate
and requires to be withdrawn when it is necessary to insert or remove a plate.
In order to keep the sensitive surface of the plate "in register" springs g g are
provided underneath the plate.
Double dark slides, that is to say slides carrying two plates may be formed by
uniting two such single dark slides back to back. Or the back of the tray d may
be removed and fixed projections are then provided for preventing the bottom plate
from falling through the frame a. Two sets of grooves and two shutters è are
then provided as is well understood.
In such a double dark slide as last described one plate is inserted face downwards.
A screen opaque to actinic rays is laid thereon and a second plate is inserted face
upwards and the whole is held in position by the projecting part e and the
catch f
In small dark slides one catch is sufficient but two or more may be used in
larger slides and they may be arranged at the sides as well as the ends of the dark
slides.
Instead of a fixed projecting part e two or more movable catches may be used for
retaining the plates in the dark slide.
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 photographic dark slide having a fixed projecting part and a removable

page_text: catch for holding the plate in position substantially as hereinbefore described and
shown.
2. In a photographic dark slide the combination of a fixed projecting part with
movable catches operated from the outside substantially as hereinbefore described
and set forth.
3. In a
photographic dark slide the use of movable catches operated from the
outside substantially as and for the purpose hereinbefore described and shown.
Dated this Third day of April 1891.
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for the Applicants.