Improvements in Apparatus for Developing Photographic Plates in Daylight.
Year: 1895

page_text: Date of Application, 28th Jan., 1895-Accepted, 2nd Mar., 1895
COMPLETE SPECIFICATION.
Improvements in Apparatus for Developing Photographic Plates
in Daylight.
A communication to me from FRIEDRICH OSWALD GRAF, of Zwickau, Saxony,
in the Empire of Germany, Photographer.
I, EDMUND EDWARDS, of the Firm of Edwards and Co., Patent Agents and
Engineers, of 65 and 66, Chancery Lane, in the County of Middlesex, 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, and accompanying drawings, that is to say :-
It is necessary that photographic dry plates, after having been exposed, should'
be made insensible to light. For this purpose they are developed in a bath in
which they are kept immersed for a sufficient time. During this operation, they
must be very carefully protected from direct, and especially white light, as
otherwise, in case the smallest ray of light should reach them what is known as
fogging would take place. The treatment in the development lasts for a time,
which varies with the time of exposure and the character of the plate, of from four
to fifteen minutes, and is conducted in a tray which is rocked during the process,
either by hand, or by well-known rocking devices.
The photographer dares not leave the dark room while this operation is in
progress, lest light should enter. Moreover, a beginner or amateur, whilst the
plate is developing in the bath, should frequently watch its progress, which can
only be done in the dark room, by viewing the picture in the tray, which is made
of a material (celluloid) having a certain degree of transparency, by means of a
light surrounded with a red glass shade, the liquid then running to the side of the
tray. The work of the photographer in the dark room, often for hours, is very
tiring and injurious to the eyes and to the health.
To avoid these objections is the object of the present invention.
The accompanying drawings are in illustration of the invention, Figure 1 being
a general view, Figure 2 a plan, and Figure 3 a transverse section.
The improved apparatus consists essentially of a light-tight case or box, in
which the tray is placed: As shewn in the drawings, the case or box consists of a
lower part a,
which is specially intended to receive the bath or tray, and the upper
cover b, both parts being provided with red or ruby glass plates s, and s¹, which
can be closed by the shutters k and k¹. When the dry plate to be developed has
been placed in the case, by closing the shutters k, k the plate is completely
protected from light, and the photographer can safely leave the dark room; and
he can at any time without troubling himself to exclude the light, return to the
room, and place the case containing the plate upon the rocking apparatus, and then
open both the shutters k and k¹, and watch the development of the picture by
daylight.
To observe small pictures, a smaller shutter m may be fitted in the principal
one k.
By the use of the improved box or case, the photographer is only exposed to the
unpleasant and unhealthy atmosphere of the dark room for a short time, and his
eyes are saved from the ill effects of longer darkness, whilst from the more easy
observation a better development and more uniformity in the plate are obtained.
The box or case described may be made of any suitable material, such
as hard

page_text: rubber, cardboard, wood, sheet metal, or celluloid, and it may be so arranged that
the cover, instead of being separate, may be hinged to the lower part, or it may be
made in the form of an ordinary sliding lid.
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 :-
For the development of photographic plates, the case or holder of which the
lower part a and the upper part & are provided with plates 's and s' of red or ruby
glass, having moveable shutters k and k', so that by the use of a sufficiently
transparent developing tray, the plates can be observed, without injury from the
daylight, substantially as described and illustrated.
Dated this 28th day of January 1895.
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.