Improvement in Photographic Dark Slides by an Appliance showing Automatically when Plates therein have been Exposed.
Year: 1894

page_text: Date of Application, 9th Nov., 1894
Complete Specification Left, 30th July, 1895-Accepted, 9th Nov., 1895
Improvement in Photographic Dark Slides by an Appliance showing
Automatically when Plates therein have been Exposed.
I, EDWIN ARCHDALE WHITBY of 26 Philpot Lane in the City of London,
Accountant, do hereby declare the nature of this invention to be as follows:-
It relates to photographic apparatus, and consists of improvements in holders
for the sensitized plates. The framing of the holder which is known technically
as the "dark slide" is fitted with a moveable tablet on which is marked words or
signs to indicate whether the shutter of the slide has been drawn accidentally or
for exposure of the plate in the camera: Thus when the sensitized plates are
placed in the slide and the same closed, the moveable tablet displays the word
"unexposed" or the like. The said tablet is however so arranged that upon
insertion of the slide in the camera and the withdrawal of the shutter, or of the
shutter being accidentally drawn the tablet automatically changes and the word
"exposed" or the like is displayed. The accidental double exposure of any plate
is thus obviated.
21 1
CAY
L
1004
Improvement in Photographic Dark Slides by an Appliance showing
Automatically when Plates therein have been Exposed.
I, EDWIN ARCHDALE WHITBY of 26 Philpot Lane in the City of London,
Accountant 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 photographic apparatus and consists in an improvement
in the holders for sensitized plates-the object being to prevent the plates being
exposed a second time. In order that my invention may be clearly rendered,
reference may be had to the accompanying drawings in which I Sheet Fig. 1
(A) shows that portion of the holder affected before the exposure of the plate
and Fig. 2 (B) during the exposure of the plate with the shutter (E) drawn
and Fig. 3 (C) after the exposure-shutter (E) being returned to position. In
constructing the holder which is technically known as a dark slide according to
my invention the framing (D) is fitted with a moveable tablet (G) on which is
printed the words or signs to indicate whether the shutter (E) of the slide has
been drawn either accidentally, or for exposure of plates in the camera. Thus
when the sensitized plates are placed in the slide and the same is closed the
moveable tablet G displays the word "unexposed" or the like A Fig. 1. The said
tablet G. however is so arranged that upon insertion of the slide in the camera
and the withdrawal of the shutter E or of the shutter E being accidentally
drawn, the tablet G shall automatically change and the word exposed or the like
he displayed. Error is thus obviated by the accidental double exposure of any
plate.

page_text: Actuation of the plate G is better explained by the drawing numbered II and
the following description.
Figs. 1. 2. & 3:-
A is an ivory plate on which is engraved the words unexposed and exposed and
which has two slots for D or F to catch into.
B. shows the outline of the metal frame work which covers the plate and in
which the plate A travels, the dotted lines round the word unexposed represent
the opening through which the same is visible.
C shows a portion of the moving shutter of a dark slide.
D is a projection on the moving shutter which forms the catch.
E is a spiral spring which as soon as the plate is released causes the same to
travel across the opening and thus changes the indication.
G is a pin secured in the ivory plate which forms a stop to hold same in right
position in relation to the opening.
Fig. 4. 5. & 6:—
Parts A B C E. remain precisely the same as in 1, 2, 3, but D is replaced by a
small spring F which is fixed on to the metal frame B, and is turned in at the end
so that when it is pressed home it catches in the slots of the ivory plate A.
Operation is as follows:-
After filling the dark slide with plates close the shutters & in doing so with
the finger and by means of the projecting stop push the tablet across the opening
so that the word unexposed appears. The tablet is now held in this position by
the closed shutter as in Illustrations I and 4. As soon as the shutter is drawn the
ivory plate occupies the position as illustrated in Figs. No. 2 & 5. Close the
shutter again and the positions are obtained as illustrated by Fig. 3 and 6.
Further my invention relates to the automatic changing tablet G. whether it is
supplied for inserting in present dark slides or sold as part and parcel of new dark
slides.
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 the novelty
I claim is
An automatic indicator A B & C. I sheet fitted into the frame of photographic
dark slides.