Improvements in Apparatus for Examining and Displaying Transparent Photographs.
Year: 1895

page_text: Date of Application, 6th Dec., 1895
Complete Specification Left, 5th Sept., 1896-Accepted, 28th Nov., 1896
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Examining and Displaying
Transparent Photographs.
I, JOSHUA HYDE IRWIN of No. 2 Mowbray Terrace, Sunderland, Engineer,
do hereby declare the nature of this invention to be as follows:-
There is a certain amount of difficulty experienced in ordinary circumstances
in judging of a photograph on a glass plate when it is merely held up against the
light, that is to say in judging of its degree of density and as to the perfection of its
detail; but for lantern slides for instance it is of much importance that very accurate
definition should be obtained. To obviate this difficulty it is common (and in fact
for the display of such photographs in shop windows it is common) to place the
glass plate on which the photograph exists between sky and a plate of looking
glass, which looking glass set at a convenient angle for reflection. By this
means a more accurate definition of the picture is obtained.
1 do not claim any part of this idea as my invention. It is in use, and it is
moderately effectual in meeting the difficulty I have referred to. But I find that
the definition so obtained is much less perfect than it is made by my invention.
I construct a frame with a piece of good looking glass in its base. At one end
of this frame I hinge a shelf which can be lifted up on its hinges and supported in
the desired position (that is to say at the proper angle) by a crutch falling into
one of several notches cut on the base. In this shelf I cut an opening of nearly
the size of the plate to be examined, but so much smaller as to prevent the plate
from falling through, and there is a supporting piece at the lower end of this
opening to prevent the plate from slipping down by reason of the slope of the
shelf. When the picture is thus arranged, by turning the top side of the shelf to
the source of light an image is reflected from the looking glass much more
perfectly defined than if the photograph were merely looked at direct. The
definition is however usually greatly short of that perfection which is obtained by
my invention.
By my invention I apply between the source of light and the photograph, and
so as nearly to touch the photograph, a diffusing arrangement whereby the rays of
light are broken up, and spread as it were uniformly over the whole picture, and by
this means an exceedingly improved definition is secured.
I use for the purpose of diffusion finely frested or ground glass; and I prefer
to fix it in a small frame hinged to what I have called the shelf, so that when the
picture is in position this glass and its frame may be turned over upon it so as
nearly to touch it. The diffuser may however be formed of certain kinds of
tracing paper or tracing cloth. And I may use colorless or colored diffusers which
latter in certain circumstances enhance the effect.
Dated this Fifth day of December 1895.
J. JAMESON,
Akenside Hill, Newcastle-on-Tyne, Agent for Applicant.

page_text: Improvements in Apparatus for Examining and Displaying
Transparent Photographs.
I, JOSHUA HYDE IRWIN, of No. 2 Mowbray Terrace, Sunderland Engineer,
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:-
There is a certain amount of difficulty experienced in ordinary circumstances in
judging of a photograph on a glass plate when it is merely held up against the
light, that is to say in judging of its degree of density, and as to the perfection of
its detail; but for lantern slides for instance it is of much importance that very
accurate definition should be obtained. To obviate this difficulty it is common
(and in fact for the display of such photographs in shop windows it is common) to
place the glass plate on which the photograph exists between sky, and a plate
of looking glass, which looking glass is set at a convenient angle for reflection.
By this means a more accurate definition of the picture is obtained.
I do not claim any part of this idea as my invention. It is in use and it is
moderately effectual in meeting the difficulty I have referred to. But I find that
the definition so obtained is much less perfect than it is made by my invention.
I construct a frame with a piece of good looking glass in its base. At one end
of this frame I hinge a shelf which can be lifted up on its hinges, and supported in
the desired position (that is to say at the proper angle) by a crutch falling into
one of several notches cut on the base. In this shelf I cut an opening of nearly
the size of the plate to be examined, but so much smaller as to prevent the plate
from falling through, and there is a supporting piece at the lower end of this
opening to prevent the plate from slipping down by reason of the slope of the
shelf. When the picture is thus arranged, by turning the top side of the shelf to
the source of light an image is reflected from the looking glass much more perfectly
defined than if the photograph were merely looked at direct. The definition is
however usually greatly short of that perfection which is obtained by my invention.
By my invention I apply between the source of light, and the photograph, and
so as nearly to touch the photograph, a diffusing arrangement whereby the rays of
light are broken up, and spread as it were uniformly over the whole picture, and
by this means an exceedingly improved definition is secured.
I use for the purpose of diffusion finely frosted or ground glass; and I prefer to
fix it in a small frame hinged to what I have called the shelf, so that when the
picture is in position this glass, and its frame may be turned over upon it so. as
nearly to touch it. The diffuser may however be formed of certain kinds of
tracing paper or tracing cloth. And I may use colorless or colored diffusers which
latter in certain circumstances enhance the effect.
It will be seen that the form in which my invention may be applied may vary within
very wide limits, and as I do not claim any particular form of apparatus, and for the
sake of clearness I illustrate the application of my invention in skeleton outline.
A. B. is a base plate, and C. D. a piece of looking glass upon it. E. F. is the photo-
graph on glass plate to be illuminated and defined, and G. H. the diffusing plate of
frosted or ground glass or tracing paper or other suitable material which can be shut
down so as to be in contact with the photograph or nearly so.
This skeleton form is
part of a box with sides to prevent strong light falling on the looking glass
excepting through the photograph. Rays of light falling on G. H. from any
direction are broken up and deflected in all directions by the diffusing action of
the plate and spread as it were evenly upon the picture and altho' the source of

page_text: light may be even at an acute angle to the picture it is so deflected by the plate
as practically to pass to the looking glass at a right angle and be thence reflected.
Manifestly the apparatus may be also so constructed as to bring the eye of the
observer into the position occupied by the plate of looking glass, but I consider
the glass more convenient.
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 :-
The use of a diffusing plate substantially as described for the purpose of
obtaining more perfect illumination and definition of photographic pictures on
glass.
Daven buis fourth day of Sep
J. JAMESON,
Newcastle-on-Tyne, Agent for Applicant.
J. JAMESON,
Newcastle-on-Tyne, Agent for Applicant.