IMPROVEMENTS IN PHOTOGRAPHY."
Year: 1875

page_text: LETTERS PATENT to Edward Thomas Hughes, of the Firm of Hughes
and Son, Patent Agents, 123, Chancery Lane, London, for the
Invention of "IMPROVEMENTS IN PHOTOGRAPHY."-A communication
PROVISIONAL SPECIFICATION left by the said Edward Thomas
Hughes at the Office of the Commissioners of Patents, with his
Petition, on the 31st August 1875.
I, EDWARD THOMAS HUGHES, of the Firm of Hughes and Son,
Patent Agents, 123, Chancery Lane, London, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN PHOTOGRAPHY," a
communication to me from abroad by Adolf Hommel, of Hanau,
Prussia, to be as follows:-
I cover a glass plate, cleaned on both sides, with a skin or film of
sensitive collodion rendered sensitive for the light of the sun or daylight
by steeping it in a bath of nitrate of silver, and I take a copy of the

page_text: person or of the object to be photographed in the camera in the
ordinary way, and thus two latent images are produced, one in the recto
or front, and the other in the verso or back, and I develop, fix, and
cover both these images with a preserving varnish.
I call this double negative, produced at the same time upon both sides 5
of a glass plate, a photo-plasto-graphical negative, and the copies which I
can take from it photo-plastographs.
By producing a photo-graphical negative on one side of a glass plate
as at present there is a great loss of light reflected from the person or
the object traversing the sensitive skin of collodion, and even if the 1
negative image furnishes good and receivable copies they have to be
reinforced or strengthened by chemical reagents, an operation which
produces well-known differences requiring artificial aid or retouching.
The essential advantages of the Invention are as follows:-
First. I receive upon the sensitive skin of collodion in the verso or 1
back of the glass plate the light which is traversing the skin of the
recto or front, thereby rendering it efficaceous, and thus I obtain from
the person or from the object a maximum effect of the light upon the
glass plate, and I do not alter or destroy by an ulterior working the
harmony between light and shadow.
Secondly. The supplementary negative upon the verso or back of the
plate receives by the refraction of the rays of light traversing the
plate a small enlargement, which has the advantage that in copies of
the negative the sharp outlines or contours on the recto or front of the
plate will be diminished and rendered softer, and thereby obtain without
retouching very soft copies of perfect images which cannot be produced
in any other way than as herein-before described.
2
The copies taken from a photo-plasto-graphical negative will be made
by employing a dispersed light, the light rays falling nearly vertically
upon the plate, and the production of photo-plastographs by superposing a
two or more negatives prepared in the herein-before described manner
are the results of the Invention.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Thomas Hughes in the Great Scal Patent
Office on the 29th February 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
THOMAS HUGHES, of the Firm of Hughes and Son, Patent Agents,
123, Chancery Lane, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirty-first day of August, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said Edward Thomas Hughes, Her special licence
that I, the said Edward Thomas Hughes, my executors, administrators,
and assigns, or such others as I, the said Edward Thomas Hughes, my
executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter, during
the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for
"IMPROVEMENTS IN PHOTOGRAPHY,' a communication to me from abroad
by Adolf Hommel, of Hanau, Prussia, upon the condition (amongst
others) that I, the said Edward Thomas Hughes, my executors or
administrators, by an instrument in writing under my, or their, or one
of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Scal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
وو
NOW KNOW YE, that I, the said Edward Thomas Hughes, do hereby
declare the nature of the said Invention, and in what manner the same

page_text: by steeping it in a bath of nitrate of silver, and I take a copy of the
person or of the object to be photographed in the camera in the ordinary
way, and thus two latent images are produced, one in the recto or front,
and the other in the verso or back, and I develop, fix, and cover both
theso images with a preserving varnish.
I call this double negative, produced at the same time upon both
sides of a glass plate, a photo-plasto-graphical negative, and the copies
which I can take from it photo-plastographs.
By producing a photo-graphical negative on one side of a glass plato
as at present there is a great loss of light reflected from the person or
the object traversing the sensitive skin of collodion, and even if the
negative image furnishes good and receivable copies they have to be
reinforced or strengthened by chemical reagents, an operation which
produces well-known differences requiring artificial aid or retouching.
The essential advantages of the Invention are as follows:-
First. I receive upon the sensitive skin of collodion in the verso or
back of the glass plate the light which is traversing the skin of the
recto or front, thereby rendering it efficaceous, and thus I obtain from
the person or from the object a maximum effect of the light upon the
glass plate, and I do not alter or destroy by an ulterior working the
harmony between light and shadow.
Secondly. The supplementary negative upon the verso or back of the
plate receives by the refraction of the rays of light traversing the plate
a small enlargement which has the advantage that in copics of the
negative the sharp outlines or contours on the recto or front of the plate
will be diminished and rendered softer, and thereby obtain without
retouching very soft copies of perfect images which cannot be produced
in any other way than in that herein-before described.
The copies taken from a photo-plasto-graphical negative will be made
by employing a dispersed light, the light rays falling nearly vertically
upon the plate and the production of photo-plastographs by superposing
two or more negatives prepared in the herein-before described manner
are the results of this Invention.
Having thus described the nature and particulars of the said Invention

page_text: as communicated to me, I claim, the improvements in photography
substantially as herein described.
In witness whereof, I, the said Edward Thomas Hughes, have herc-
unto set my hand and seal, this Twenty-eighth day of February,
One thousand eight hundred and-seventy-six.