IMPROVEMENTS IN PHOTOGRAPHY, AND IN THE APPLICATION OF THE SAME TO THE ARTS
Year: 1843

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, ALEXANDER
SIMON WOLCOTT, of City Terrace, City Road, in the County of Middlesex,
Machinist, and JOHN JOHNSON, of Manchester, in the County of Lancaster,
Machinist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Eighteenth day of March, in the sixth year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto us, the said Alexander
Simon Wolcott and John Johnson, Her especial license, full power, sole
privilege and authority, that we, the said Alexander Simon Wolcott and John
Johnson, our exors, adñors, and assigns, or such others as we, the said
Alexander Simon Wolcott and John Johnson, our exors, adññors, or assigns,
should at any time agree with, and no others, from time to time and at all
times during the term of years therein expressed, should and lawfully might
make, use, exercise, and vend, within England, Wales, and the Town of
Berwick-upon-Tweed, our Invention of "IMPROVEMENTS IN PHOTOGRAPHY, AND
IN THE APPLICATION OF THE SAME TO THE ARTS;" in which said Letters Patent is
contained a proviso that we, the said Alexander Simon Wolcott and John
Johnson, or one of us, shall cause a particular description of the nature of our
said Invention, and in what manner the same is to be performed, to be inrolled
in Her said Majesty's High Court of Chancery within six calendar months
next and immediately after the date of the said in part recited Letters Patent,

page_text: as in and by the same, reference being thereunto had, will more fully and at
large appear.
NOW KNOW YE, that in compliance with the said proviso, we, the said
Alexander Simon Wolcott and John Johnson, do hereby declare that the nature
of our said Invention, and the manner in which the same is to be performed,
are fully described and ascertained in and by the following statement thereof,
reference being had to the Drawings hereunto annexed, and to the figures and
letters marked thereon, that is to say:-
Our Invention relates,-
First, to an improvement in the process of making photographic pictures
called daguerreotype, whereby the gradation of light and shade shall generally
be rendered more true to nature, and which shall prevent the picture from
being as much injured from any error in the time of its exposure to the action
of the light in making the impression as it otherwise would be. The
operation is as follows:-When it is supposed that the plate has been suffi-
ciently long exposed to the action of the light to produce the picture if it was
immediately exposed to the action of mercury, instead of arresting the opera-
tion the light is allowed to act a longer time on the plate. The plate is then
removed, and exposed to the vapour of iodine, bromine, chlorine, or a mixture
of any of them, or to any other vapour or vapours that shall have the effect of
lessening the deposit of the mercury when the plate is afterwards exposed to
it; and if the more volatile substances, such as iodine, bromine, or chlorine,
are used, they should be very much diluted with water or otherwise. In using
iodine, for instance, one part of a saturated solution in water, mixed with two
hundred parts more of water, will generally be found sufficiently strong.
Whichever substance is used, it should be put into a vessel with a sliding
cover, extending so far beyond the side of the vessel as to have an opening in
the part beyond of nearly the size of the plate, with a rebate large enough
for the plate to go into, and nearly through the cover. When the plate is
placed in the cover it may be slid over the vessel without allowing the vapour
to escape, thus insuring great regularity in successive operations, otherwise the
vessel may be covered with a porous earthenware or other cover, which would
allow the vapour to pass through it and act on the plate, which should be
brought very near to its upper surface. If the vapour is applied through the
cover it should be much stronger. In the case of iodine being used it may be
put in in the form of crystals. As the proper time of the plate's exposure to
vapour after the impression is made will be varied so much by the extra time
that the light has been allowed to act on the plate, by the strength of the
vapour, by the closeness of the vessel, by temperature, and by other circum-

page_text: stances, no exact time of exposure can be stated. It is recommended first to
get an impression which is known to be overdone, and expose it for a short
time to the vapour, and then to the mercury. If the picture, when formed, is
still found to be overdone, the next impression tried (being as much overdone
as the last), must be exposed longer to the vapour, or the vapour must be
made stronger. By this means a few experiments will give the proper time of
exposure, which will serve as a guide for all future operations. If the
impression is found to be entirely or too much obliterated in the trial, it shews
that the vapour is too strong or the exposure continued too long. The vapour
of iodine is recommended as being the most convenient in practice. The
extra time of exposure of the plate to the action of the light may be from one
quarter longer to several times as long, according to the nature of the object
to be copied. Thus, if it is a living object, it will not do to increase the time
so much on account of the risk of moving; and in cases where the extremes
of light and shade are very great a much longer time should be used, that the
lower lights may not be obliterated by the application of the vapour.
We claim, as the first part of our Invention, the exposing photographic
plates, after the impression is made by the light, to any vapour that shall
prevent the adhesion of as much mercury to the plate in its after exposure to
the vapour of mercury as would have adhered if such previous exposure had
not taken place.
Secondly, our Invention relates to a camera, in which photographic pictures
on polished plates may be copied by the scattered light from the surface of the
plate. That portion of the light which is reflected from the polished surface
at the same angle at which the incident rays fall (according to the laws of
reflection of polished surfaces), being prevented from entering the lenses of the
camera, and in which camera pictures that are distorted in the perspective by
reason of the camera in which it was taken making an improper angle with
the horizon, either accidentally or in order to take in parts of a view which
otherwise would not be seen, may be copied in true perspective.
Figure 1 is the camera, A being the aperture for the entrance of the light
to illuminate the picture to be copied.
Figure 2 is a section of the box through the middle and parallel to the side
B, shewing its internal arrangement. C, C, are two sets of glasses (as also
shewn in Figure 3), placed in the ends of the tubes D, D. E is an aperture
for the passage of the light that may be contracted when required by means of
the revolving diaphragm represented in Figure 4. F, F, is a partition to
which the tubes D, D, are attached, and is made to slide into grooves in the
sides of the box, and at such distance from either end as may be necessary to

page_text: .
produce the various sizes of pictures required. If the glasses are placed at.
equal distances from the picture and the plate on which they are to be copied
the copy will be equal in size to the picture to be copied, and at any other,
distance that will be the largest which is farthest from the glasses. In all.
these changes the focal distance must, be carefully preserved by changing the
position of the plate on which the copy is to be made, as the sum of the focal.
distances becomes greater as the difference between the two focii increases..
G is the picture to be copied. H is the plate on which the copy is to be
made. I, I, are the frames containing the picture and plate. The frame
containing the plate Ḥ must also be made to slide into grooves placed at such
distances that for every change in the position of the glasses a sufficient change
shall also be made in the position of the plate to preserve the focal distance.
Figure 5 is a section of the box Figure 1, through the middle and parallel
to the bottom, representing the arrangement by which distorted pictures may.
be copied in true perspective. In this case the frames I, I, must contain
other frames K, K, moving on a perpendicular axis at L, L, and in which the
plates are placed so as to move with it, and thus allow the face of the plates to
be placed at various angles with the axis of the glasses C, C. To understand.
the action of this arrangement in correcting the perspective, it must be borne
in mind, that, in taking a photographic picture, as the end of the camera
nearest any object is more elevated, the upper part of the object will be more
contracted in the picture than the under part, and that if the same end of the
Thus a row of columns,
camera is depressed the reverse will take place.
instead of being all perpendicular, would in the one case appear falling together,
and in the other to fall outwards. As it often happens, in consequence of some
obstruction, that distance enough from the object cannot be had to bring all
the parts within the field unless the camera is thus elevated or depressed, a
picture in true perspective could never be made unless the evil could be
corrected in the copy, as may be done by the arrangement in Figure 5. The
operation is as follows:-Place the picture and a plate on which the copy is
to be made in the. frames K, and in such manner that the parts which are
perpendicular in the object shall be horizontal in the frame K; then bring the
end of the picture in which the perspective is contracted a little nearer the
glasses by causing it to turn on its axis L. Then, supposing the copy to be of
the size of the original, turn the end of the plate on which the copy is to be
made to the same angle to the glasses as the picture is, and in such direction
that the ends, both of the picture and the plate, for the copy which are nearest
the glasses, shall both be on the same side of the box. Now it will be seen
that by this arrangement the parts of the picture which are nearest to the

page_text: glasses will be copied on to that part of the plate which is farthest from the
glasses, and thereby be copied larger than if the plates were parallel, and that
those parts of the picture which are farthest from the glasses will be copied on
that part of the plate which is nearest to the glasses, and thus be copied
smaller than if they were parallel, thus correcting the perspective in the copy.
The proper angle to place the picture and plate according to the amount of
distortion can soon be determined by a few experiments. As in the picture
and plate those parts which are nearest the glasses in the one are farthest
in the other, the focal distance is very nearly preserved. The sizes of the
plates or pictures, with regard to the focal distance, should be such, that, when
they are adjusted to the proper focal distance, either for pictures and plates
of different sizes or for those of equal size, the angles subtended from the
glasses to the ends of the plate be not more than thirty degrees. For the
convex lenses common plate glass may be used; the concave should be of the
heavy flint, of a specific gravity of about 3.5; and for a focal distance of
about 77 inches, the following proportions will perform very well :-The side
of the concave glass next to the aperture E is plane, and distant 70% of an inch;
the other side of the concave, and also that side of the convex which is next
it, are made to a radius of 17 inch; the other side of the convex
is made to a radius of 21 inches. The thickness of the concave in
the middle is inch, and that of the convex is inch; diameters about
1 inch.
If the pictures that are to be copied have been taken in a camera
that did not contain a reflector, they would be reversed, but the copy would
be correct. If, however, the original has been taken with a reflector, to
prevent the reversion a reflector should be placed as represented by the dotted
lines at O, and the plate horizontal at the top of the box, if it is desired to
have the copy not reversed. A metallic plate has been mentioned as the
surface on which the pictures are to be copied, but any material may be used
that is properly prepared to receive an impression by light. M is intended to
act as a screen to protect the glasses from the direct light which enters the
top of the box near N. The edge of the box at O¹ should be so high that a
ray of light passing into the box close to that part, and falling on to the
polished surface of the picture close to its upper edge, shall, when reflected, be
thrown below the glasses. It having been found that the clearest blacks in a
picture are produced when the polish of the plate has been finished by straight
strokes in that direction which will be horizontal in the picture, it becomes
necessary, in copying pictures formed on plates só polished, to place them in
the box in such a manner that the lines of the polish shall be perpendicular;
and in all cases, in whatever direction the lines of polish in the picture are,

page_text: they must be placed perpendicularly in copying. In cases where the polish
has been made in curved or otherwise than parallel straight lines, that position
should be chosen in which the largest portion of the lines will be perpendicular
or most nearly so, or at all events in which such will be the case in the most
important parts of the picture. If the lines of the polish should be perpen-
dicular in a distorted picture which it is intended to copy, the frames I, I,
which contain the frames K, must be so placed that the axis of the frames K
be horizontal. This will allow the picture to be put in with the polish marks
perpendicular, and at the same time allow the proper part of the picture to
be inclined to the glasses; and that part must be at the top of the frame, for
if the top part of the frame were turned from the glasses it would allow the
light to be directly reflected into the glasses from the polished surface. This
position of the lines will cause the light which falls on the inclined edges of
the lines (the lines of the polish being only so many minute furrows) to be
reflected to that part of the box which is below the glasses, whereas if the
light was allowed to fall at right angles to the lines a large portion of it would
be reflected from the lines into the glasses. Every part of the inside of the
box between the picture and the partition E, F, should be lined with black
cotton velvet, or otherwise blackened so as to prevent any injurious reflection
of light. By these means, if the polished surface of the picture were viewed
from the place occupied by the glasses, no object or light from objects bright
enough to interfere with the operation would be perceived in it, and of course
there would not be much light to act on the plate or other material on which
the picture is to be copied, and thereby injure the copy, which it is only
intended should be made by scattering light from the rough surface produced
by the adhesion of mercury, of which the picture is essentially composed, being
painted on the polished black ground of the plate.
We claim as the second part of our Invention the mode of constructing
cameras containing a chamber for the picture to be copied, and so constructed
that if the picture were viewed from the place occupied by the glasses no
object or light from objects bright enough to prevent a distinct view of all
the parts of the picture could be seen in the polished surface of the picture.
And we also claim the mode of making cameras, whereby a copy in true
perspective may be obtained from a picture not in perspective, as above
explained.
The third part of our Invention relates to the exhibiting photographic
pictures on a screen in a darkened room. The arrangement of apparatus by
which this is effected is shewn in Figures 6 and 7. A is the bottom, to which
the other parts are fastened. B and C are of cast iron. D is a cylinder of

page_text: lime, which is made to revolve slowly on its axis by proper machinery placed
under the bottom A, and on which a jet of mixed hydrogen and oxygen gases
are thrown in the usual manner for producing light. A recess is made in the
casting B, so large that the lime may revolve without any danger of its
touching the iron, and so deep that the sides of the lime D and casting B
next to the casting C shall both be in the same plane. E is a conical opening
in the casting B, with the side next the recess containing the lime a little
flattened in order to get the centre of the opening as near as possible to the
lime. F is a set of achromatic glasses. G is a round polished metallic plate
with a spherical surface (on which the picture to be exhibited is made, of
such radius of curvature that the radius is just equal to the distance of the
centre of the plate from the face of the casting B, and so placed that the
centre of the sphere of which the plate is a section shall be exactly midway
between the opening at E and the centre of the lime D. The picture may
either be made immediately on the spherical plate from the object itself as
usual, or it may be copied from a flat plate on which it was previously taken,
using the camera described in Figures 1, 2, 3, and 5, but substituting two
plano-convex lenses of the same focal distance for the two compound lenses
described, and putting their plane surfaces towards the aperture E. The
nature of a photographic picture on a polished plate being such that those
parts which are to represent the darks are the most highly polished, it
follows that by a strong reflected light (such as that by which those pic.
tures are shewn with this apparatus) those parts will appear brightest;
it therefore becomes necessary to reverse the polish of the parts, so that
the dark parts shall become the least polished and the lightest the most
.so, with the intermediate gradations. This may be done by putting on
to the plate (which in this case forms a convenient dish to hold it) some
sulphuric acid, then heat, it slowly until the desired change takes place, then
wash it clean and dry it, and it is ready for use. The space between the
castings B and C are to be enclosed at the sides by shutters, and on the
top a cover is to be put with a large chimney so as to produce a draft
inwards through the aperture H, just below the lower edge of the plate; this
draft will serve to carry off the dust which arises from the combustion of the
lime, and prevent its being deposited on the picture. The glasses at 1' are to
be placed on the top of a stand, which is to be fastened to the bottom A, so
that the glasses may be adjusted to any distance from the plate, and at such
an angle as will give the best image. If it be found that from a long con-
tinuance of the heat of the lime that the casting B becomes so much heated
as to impart heat enough to the glasses F as to injure the cement by which

page_text: they are fastened together, it may be kept cool by making holes I, I, perpen-
dicularly through the iron, then connecting the lower parts of the holes by a
tube and the upper parts of the holes with two other tubes which should lead
to a vessel of cold water placed over head, which should fill the tube and
passages through the casting B. Under these circumstances, if the casting
becomes a little heated it will cause a current to be formed through the iron,
thus carrying off the heat. It is recommended that the plates G for the
picture be four inches and a half in diameter, and that the radius of the curve
'be four inches, and for these proportions the achromatic glasses should be two
and a half inches in diameter, and of such curvature as are marked on Figure
7 in inches and decimals. The convex to be of common plate, and the con-
cave of flint of specific gravity of about 3.5, as directed in Part Second. The
jet of gas may be conveyed to the lime either through the bottom or sides of
the apparatus. The manner of the action of the apparatus is as follows:-The
lime being illuminated by the heat from the combustion of the gases, the light
which falls on the picture is reflected to a point as much on one side of the
centre of the axis of the plate as the lime is on the other, and as that joint
corresponds to the aperture at E, the light from all parts of the plate passes
through, and also through the glasses F, and as the glasses have a focal
distance just equal to their distance from the plate G the light will form on to
a screen the image of the picture on the plate.
What we claim under this, the third part of our Patent, is, the so arranging
apparatus that photographic pictures may be shewn on screens in dark rooms.
The fourth part of our Invention relates to cameras, arranged so that pho-
tographic pictures on metallic plates may be copied by the direct reflected
light from the polished surface of the plate after the plate has been prepared,
so as to make the dark parts reflect the least light, and the light parts the
most, with intermediate gradations; a method of doing this is described in
Part Third. Figure 8 is a vertical section through the middle of the camera
A, A. C, C, are two sets of glasses mounted and fastened to a partition F, F,
and the same in every respect as those described in Part Second, and shewn in
Figures 2 and 3. D is the picture to be copied, placed at the proper angle to
reflect the light which falls on to it from the lens G into the glasses C. H is
the surface on which it is to be copied placed parallel to the plate D. G is a
lens, either simple or compound, and of such a focal distance that the light
reflected from the picture D, and after passing through the glass C, shall
converge to a focus exactly at the aperture E. The camera box must be
made so as to adinit light in any part except where the light passes from the
Jens G to the plate D. This camera may either be used with the light of the

page_text: sky or any other good even light, either falling directly on the plate without
using the lens G, or else after passing through the glass; but the principal use
of the aperatus is for converging the rays of the sun or any other strong
artificial light, such as the hydro-oxygen (after reflection from the picture to
be copied), through the aperture E on to the prepared surface II. Now it
will be evident that with so strong a light pictures can be formed on surfaces
which are totally unfit for use in the camera in the ordinary way, and that if a
small likeness of a person is taken on a very sensitive metallic plate in the
first instance, it may be copied on to paper (even of that kind which is very
inferior in sensitiveness), and, if desired, of the size of life for the purpose
of painting.
Another method of copying from plates so prepared is with the apparatus
described in Part Third, and shewn in Figures 6 and 7. In this case the image
of the picture on the plate is to be received on to the prepared surface on
which the copy is desired to be made. As the prepared surface would probably
be nearer the lens F, Figure 7, than the screen mentioned in Part Third, the
focal distance would have to be adjusted to suit, or glasses of shorter focal
distance used.
Fourthly, we claim the so arranging apparatus that pictures on polished
plates, which have had their surfaces so acted on as described, may be copied
by the light reflected by their polished surfaces into the glasses of the camera
according to the laws of reflection for polished surfaces.
In witness whereof, I, the said Alexander Simon Wolcott, have hereunto
set my hand and seal, this Thirteenth day of September, in the year of
Our Lord One thousand eight hundred and forty than