A Improvements in Apparatus for Preserving and Changing Sensitive Plates Used in Producing Photographic Pictures.
Year: 1887

page_text: Date of Application, 25th Apr., 1887.
Complete Left, 26th May, 1887.
Complete Accepted, 28th June, 1887
[Communicated from abroad by Messieurs KOPPE and MOH, of Goerlitz, in the
Empire of Germany, Manufacturers.].
A
Improvements in Apparatus for Preserving and Changing Sensitive
Plates Used in Producing Photographic Pictures.
I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of Middlesex
do hereby declare the nature of this invention to be as follows:--
This invention relates to the apparatus used for obtaining photographic pictures
upon what are known as dry sensitized glass or other plates, and more especially to
apparatus by means of which such plates can be changed when required, a fresh
sensitive plate being substituted for one which has been exposed in a camera and a
picture obtained upon it.
It has for its object a novel method of constructing and using such apparatus so that
it is light, cheap, and easily used, whilst it occupies little space, separate dark slides
for each plate being dispensed with.
For this purpose a bag is used, of flexible material impervious to light, and so made
and arranged that the sensitive plate or plates contained in it can be transferred to or
removed from the camera when required, the back of the latter being specially
constructed to receive the open end of the bag.
The flexible bag, of a size adapted to the sensitive plates which it is to contain,
made of silk or other suitable fabric coated inside with a lining of india rubber,
gutta-percha, or other smooth substance of the like kind, of sufficient density to
completely exclude all light.
The smooth inner surface coming in contact with the surface of the sensitive dry
plate, does not at all injure the latter. The bag is made of sufficient depth to allow
its open upper end (when the plate or plates are in it) to be folded over against its
side. This open upper end or mouth is surrounded by a metal frame to which the
edge of the fabric is attached.

page_text: The sensitive plates being dropped into the bag in a dark place, the upper end is
folded down as described and is held down by an elastic band passed round near the
upper end of the plates, the extreme open end and metal frame hanging loose below
the band. In this way all light is entirely excluded, and the plates may be preserved
for any length of time without losing their quality.
When the plates are to be used, the bag is connected to the back of the camera or
to the dark slide which fits upon the back of the camera in which the pictures are to
be taken. The lower edge of this slide is open and is provided with a groove or guide
into which the metal frame at the mouth of the bag is inserted, and is then held firmly
in its position by means of a sliding or other clamp or catch, the fabric of the bag
which fits round the metal frame serving to make a perfectly tight and elastic fitting
between the parts. When the bag has been thus arranged, the elastic band already
described may be removed and the sensitive plate or plates raised up into the dark
slide above.
Where two sensitive plates are used they may be supported by a sheet metal plato
between them, the ends of this plate being bent over in opposite directions, one to the
right and one to the left, so as to hold both sensitive plates firmly in position.
The dark slide may be provided with a novel device for adjusting the position of the
dry plate. This consists of a revolving disc recessed into the back of the slide and
having a semicircular groove upon its front face, the depth of this groove gradually
diminishing so that its bottom forms an inclined plane against which the end of a pin
works which is carried by a flat flexible spring covered with velvet. By turning the
disc round with the fingers, the pin and with it the spring is forced outward against
the back of the sensitized plate which is thus pressed forward to the desired position.
After exposure, the sensitized plate is returned to the bag, the open end of which is
again folded down and held by the elastic band, and it can then be safely removed
from the dark slide.
When sensitive plates of large size are to be used, it is preferable to make the bag
contain one such plate only.
The improved changing bag may be adapted to any existing dark slide, upon which
it is only necessary to provide a groove to receive the metal frame at the mouth of
the bag in the way described.
In order to be able to use sensitive plates of different sizes in the same dark slide
separate frames of corresponding sizes are provided, either of which can be fitted into
the dark slide itself.
Each of these frames is open below and is provided with a groove or guide to receive
the metal frame at the mouth of the flexible bag in the way described.
By this invention, considerable saving in weight, space, and cost, is effected.

page_text: I, EDMUND EDWARDS, of the firm of Edwards and Co., Patent Agents and
Engineers, of 35, Southampton Buildings, Chancery Lane, in the County of Middlesex,
do hereby declare the nature of this invention and in what manner the same is to
bo performed, to be particularly described and ascertained in and by the following
statement and accompanying drawing, that is to say :-
Our invention relates more especially to an improved bag or case for preserving the
dry sensitive plates employed in obtaining photographic pictures, as also to sundry
appliances connected therewith; the improved bag is constructed in such a manner
as to perfectly shut out the light, thereby keeping the sensitive plates in absolute
darkness as required; the improved bag allows the sensitive plates to be introduced
into the changing apparatus without the use of a dark room, the said changing
apparatus being constructed according to one part of the invention to fit the plate bag
itself.
Photographers and amateurs, when travelling or moving about to take photographs
are obliged to carry with them a considerable number of prepared sensitive plates in
order to avoid the necessity of changing such plates in the changing apparatus.
Such change is usually performed in a dark room, but as such dark room, cannot,
or only with difficulty, be had access to in any place on the road, sensitive plates
carried in stock, must be completely mounted each in a frame and the necessary
supply of such sensitive plates, accordingly occupies even when carefully packed
considerable space, and weight, which encumbers the traveller and increases his
expenses out of proportion.
The object of the present invention therefore is to provide improved means and
apparatus for preserving and conveying the sensitive dry plates.
By the bag or case hereinafter described the necessity of preserving and trans-
porting each of the said plates in a separate frame as heretofore is avoided.
The improved bag or case is shown in the accompanying drawings in figures 1
and 2. The bag or pocket shaped case is made of a suitable fabric coated inside with
a lining of india rubber, gutta percha, or a similar smooth substance of sufficient
density to completely exclude the light. The smooth inside coating of the fabric,
coming into contact with the dry plate, does not at all injure or impair the qualities of
the latter.

page_text: The bag or pocket is flat and of sufficient depth to allow its open upper end to be
folded above the plates when in their place, as shewn in figure 1. The upper open
end of the bag is surrounded by a metal frame a to which the edge of the fabric is
fastened.
The sensitive plates are placed in this bag immediately after being dried and as soon
as they are in, the empty upper end of the bag is folded down and an elastic band b
strung over it to keep the bag closely shut. Not the slightest ray of light is suffered
to enter into this bag and the dry sensitive plates may thus be preserved for years
without losing their quality..
When the plates are to be used the bag or case is brought into connection with the
change case A, constructed to receive the frame a of the bag which slides within an
aperture, groove, or grooves B, provided in the lower part of the said case A, as shewn
in figures 3, 4, and 5. The frame a is held secured within said grooves B by means of
a forked clamp C, figure 6. The fabric of the bag, bent round the metal frame a,
serves to effect a perfectly tight and elastic fitting of the parts.
When the bag has thus been secured to the change case A, the elastic band 6 is
removed and the sensitive plate or plates within the said bag may then be raised or
fed up into the case A.
Where double plates aro to be employed, they may be secured upon a sheet metal
plate D, figure 4, each glass plate upon one side of the metal plate D which keeps
them separate. The side edges of the said sheet metal plate D are cut into flaps,
which, being bent alternately to the right and left side, embrace the edges of the glass
plates and keep the latter firmly together.
The slide frames E within the change case A are provided according to this
invention, with a peculiar device for adjusting the position of the dry plate previous to
its exposure. This device consists of a turn plate with a semi-circular groove G, as
shown in figures 3 and 11. The depth of the said groove gradually increases and in
the groove a pin H fits and works the free end of which bears against a spring I
covered with velvet. On turning the said plate F by the pressure of a finger, the
pin H will gradually force down the spring I and the latter, bearing against tho
prepared sensitive glass plate, causes the latter to advance until it rests against
the metal band R.
When the glass plate is to be changed, the metal plate F is turned in the opposite
direction, the pin H consequently releases its pressure upon the spring I and the
latter allows the glass plate to recede; when the slide frame E' is introduced, the
change case drawn out, turned over and readjusted as before described.
After the exposure, the glass plate is again passed into the bag below the case A,
the said bag is then closed by the elastic band b, the forked clamp C withdrawn and
the bag frame a removed from the grooves B.
When using glass plates of the larger sizes it will be preferable to employ a simple
change case, the arrangement and manipulation of which are essentially the same as
those already described with reference to a double case.
The improved bag case offers the great advantage that it may be used in connection
with all existing change cases, the frames of which need only be provided with the
grooves B for receiving the metal frame a of the bag.
And finally the invention relates to an improved means which allows the use of one
and the same change-case for glass-plates of different size. For this purpose a special
frame M, figures 9, 10 and 11, is provided fitting exactly into the change case of the
larger size, but with a width of opening that serves for the small size. The lower end
of this frame M is also provided with the grooves B, as already described to receive
the bag. The free space between the small sized glass plate and the frame of the
large change case are filled up by the sides of the fraine M.
It will be evident from the foregoing description that as the frame cases hitherto
necessary for preserving and conveying dry sensitive glass plates are replaced by
the bag cases described, a considerable saving in weight space, and expenditure is
effected.

page_text: 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. For the purpose of conveying and preserving the sensitive glass plates of
photographic apparatus the construction and use of bag cases made of a suitable
fabric coated inside with india-rubber or similar material the open end of which bag is
secured to a metal frame fitting into a corresponding aperture of the change case
(either single or double), where the said metal frame is secured by a clamp C, an
elastic band serving to keep the said bag tightly closed and the contents in absolute
darkness, substantially as described.
2. The combination with a frame M of the width to hold small sized glass plates
(for instance of the size of "cartes de visite") of a change case corresponding with
the larger sized glass plates (for instance of cabinet size) for the purpose of using one
and the same change case for photographs of different size, substantially as described.
3. The construction of the slide frames of photographic apparatus with a turn
plate F, semicircular groove G, gradually increasing in depth, a pin H working
within the said groove and bearing against a spring I which advances the glass plate
towards the band K or removes it from the same, for the purpose of adjusting the said
glass plate in the proper position for exposure, substantially as described.
4. The arrangement of two sensitive glass plates upon a sheet metal plate, one upon
each side, the sides of the said metal plate being bent over alternately to hold the said
glass plates, substantially as described.
EDWARDS & Co.,
Agents for the Patentee.