CERTAIN IMPROVEMENTS IN THE PROCESS OR MEANS OF AND APPARATUS FOR OBTAINING IMAGES OR REPRESEN- TATIONS OF NATURE OR ART
Year: 1841

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANTOINE
JEAN FRANCOIS CLAUDET, of High Holborn, in the County of Middlesex,
Glass Merchant, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Royal Letters under the Great Seal of Great Britain, bearing date at
Westminster, the Eighteenth day of December, in the fifth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Antoine Jean Francois Claudet, Her especial licence, full power, sole
privilege and authority, that I, the said Antoine Jean Francois Claudet,
my executors, administrators, and assigns, or such others as I, the said
Antoine Jean Francois Claudet, my executors, administrators, 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 mentioned, should and lawfully
might make, use, exercise, and vend, within England, Wales, and the Town
of Berwick-upon-Tweed, my Invention of "CERTAIN IMPROVEMENTS IN THE
PROCESS OR MEANS OF AND APPARATUS FOR OBTAINING IMAGES OR REPRESEN-
TATIONS OF NATURE OR ART;" in which said Letters Patent is contained a
proviso obliging me, the said Antoine Jean Francois Claudet, by an instru-
ment in writing under my hand and seal, particularly to describe and
ascertain the nature of my said Invention, and in what manner the same

page_text: is to be performed, and to cause the same to be inrolled in Her Majesty's
High Court of Chancery within six calendar months next and immediately
after the date of the said in part recited Letters Patent, 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, I, the said
Antoine Jean Francois Claudet, do hereby declare that the nature of my
said Invention, and the manner in which the same is to be performed, arc
particularly described and ascertained in and by the following description
thereof (that is to say) :-
The improvements to which the above in part recited Letters Patent refer
apply to the process of obtaining images from objects on the principle called
the daguerreotype; and as they apply to various parts of the operation, I shall
first briefly state the different heads of my improvements before entering into
their full description. They may be divided into five parts, and consist,--
Firstly, of a camera obscura constructed in such a manner that I can change
the lenses and adapt it to any particular optical arrangement to render it
applicable to object glasses of various foci, in order to obtain a greater
range of means from one portable apparatus, and by which one and the same
camera obscura will enable the operator to work either upon large or small
plates, and obtain the representation of near or distant objects.
By the second part of my improvements the operations which heretofore
require two distinct processes may now be conducted simultaneously in one.
This is effected by applying within the camera obscura the vapours of mercury
at the same moment that the light is producing its effect upon the plate, so
that the two operations of the light and of the mercury, which were consecutive
and separate before, are now performed at one time. By this arrangement the
process is simplified, the apparatus is less bulky, since I entirely suppress the
separate mercury box, and obtain two important advantages, which are, that
when the mercury acts simultaneously with the light, the effect is more intense
and more perfect, and that being able, by the construction of the apparatus, to
watch the process, as I shall hereafter explain, I can judge when the image
has attained its full effect, and therefore there is no danger of having pictures
either too dark or too faint.
The third feature of my improvements consists in applying, to portraits takon
by the daguerreotype process, painted backgrounds, or scenes representing
objects which, by the various distances of their parts, could not otherwise be
correctly introduced in a daguerreotype portrait on account of the different foçi
of the several objects combined,

page_text: The fourth feature of my Invention consists in the employment of a certain
artificial light in taking portraits at night or in the day in apartments or other
situations where the natural light is not sufficiently strong. This artificial
light is produced, first, by the combustion of coal promoted by a jet of oxygen
gas; second, by the flame of combustible gases and carburetted liquids burning
together with oxygen; third, by a solid refractory body suspended in a jet of
inflammable gas, which is burnt together with oxygen or in a jet of oxygen
gas charged with the vapour of sulphuric ether; the adaptation of these modes
of illumination I claim only so far as they are produced in the manner I shall
hereafter describe, and when applied to the photographic or daguerreotype
operation.
The fifth and last of my improvements consists in performing all the opera-
tions upon the plates which were formerly carried on in the dark now in a
room lighted through media of various colors, such as red, orange, green, and
yellow, but red I prefer, which, having very little eflect upon the plates
covered with the sensitive coating, allows the operator to see how to perform the
work without being obliged as before to remain in a dark room.
I now proceed to explain the particulars or details of the several heads above
mentioned,
First, the improved construction of the camera obscura consists in affording
the means of applying thereto several optical arrangements, either consisting
of single or compound object glasses of any convenient aperture or size,
and any focal distances, either alone or combined with reflectors or prisms, by
which means the daguerreotype apparatus is rendered more portable, less
complicated, and less expensive for those operators who wish to take pictures
or representations of different sizes, and which could not be done conveniently
if they were obliged to comprehend in their daguerreotype apparatus as many
cameras as would otherwise be required for cach different optical arrangement.
This improvement has been contrived with the view of rendering the daguerre-
otype apparatus as complete and compact as possible, like telescopos and
microscopes, which are usually supplied with many different changeable
powers. This improvement is effected by giving to the front of cach camera
obscura contained in a daguerreotype apparatus a sufficiently large aperture to
admit the largest object glass intended to be used. Each optical arrangement
is fixed upon a board of given size, so that by means of slides in the open front
of the camera it is casy to substitute one for another in the same camera
obscura. The distance at which the sensitive plate is to be placed for the
focus of each optical arrangement is to be regulated by a rack and pinion or
other suitable means for sliding the frame (in which the plate is fixed) to and

page_text: fro in the axis of the lens. The frame holding the plate should also have the
means of sliding vertically, which may be done by a sliding tube like a tele-
scope, furnished with a thumb screw to fix it at the proper height. One of the
greatest difficulties in the daguerreotype process, as heretofore carried on, is
the impossibility of ascertaining the precise moment at which the light has
produced on the prepared plate the effect required to enable the vapours of
mercury to bring out the image. The intensity of light which varies according
to the time of the day, and the state of the atmosphere, and the impossibility
of preparing plates having exactly the same chemical sensitiveness, has com-
pelled the daguerreotypist hitherto to operate at random, with regard to the time
required for the exposition of the plate to the action of the light in the camera
obscura, so that the image, when ultimately brought out by mercury, is almost
always either too dark or too faint. As there are no means of ascertaining
when the light has sufficiently operated on the plate, which exhibits no visible
mark of the effect, it renders the process very difficult and uncertain, and is an
unavoidable cause of occasional failures. I have discovered that before the
plates have been exposed to the light the vapours of mercury have not chemi-
cally operated upon their surfaces, and this has led me to think, that in
producing the vapors of mercury in the camera obscura itself during the
operation of the light upon the plate, these vapours, instead of injuring the
operation, would only act the very moment that the light fell upon the plate.
By experience I have found that the effects of the mercury upon those parts of
the plate that have been operated upon by the light are more perfect when
that effect is made to take place immediately under the influence of light.
After having thus explained the principles of my discovery, I now proceed to
the description of the alterations I have made in the construction of some parts
of the apparatus employed in the daguerreotype process. In the first place, I
do away with the detached mercury box heretofore used, and, in the second
place, I adapt to my camera obscura a cup containing mercury, which, by
means of a spirit lamp applied under it, spreads the vapours of the mercury
throughout the camera obscura. When the mercury has attained the proper
temperature I open the aperture of the object glass, and the operation com-
mences. Now, in order to watch the effect I apply the eye to an opening or
tube made in the side of the camera, through which I can see the image on
the plate within, which is to be lighted by a lantern throwing the light upon
the plate through an aperture in the side of the camera, in which is placed
a piece of red or orange colored glass. As soon as I see that the
simultaneous effect of light and mercury has operated sufficiently, and that the
image is brought out, I shut the object glass of the camera and take out the

page_text: plate, which shews the image in all its perfections and quite finished, requiring
only the washing process. I have said that the light which enables the opera-
tive to see the plate in the camera obscura during the process is passed through
a piece of red or orange colored glass (yellow and green might also be
employed). And to explain the reason of the fact that light passing through
such media does not injure the effect of the light reflected by the image upon
the sensitive plate, I have only to state that these colors appear to have no
photogenic effect in the daguerreotype process; the plate may therefore be
exposed to such colored rays without any injury. In fact, these rays, acting
all over the surface of the plate, appear to render it more sensitive to the effect
of the light; so that, instead of losing any advantage by lighting my plate
with a red or orange color in order to watch the process, I accelerate the
operation.
In reference to the third part of my Invention, I may state that when the
daguerreotype process was originally applied to portrait taking it was
necessary to place behind. the sitter some plain backgrounds of neutral tints
in order that the outlines of the figures should be delineated and brought out.
I have now improved this by applying behind the sitter some backgrounds of
painted scenery representing landscapes, interiors of apartments, and other
representations adapted to the taste and habits of the sitter or to his profession.
The advantages of such background scenes is obvious, for they give to the
portrait an effect quite pictorial. Besides, I can at will place the sitter,
according to the colour of his dress, complexion, or hair, cither against a dark
or a light part of the subject painted upon the background scene. I can also
vary the scenery by the combination of several backgrounds, shifting one upon
the other like theatrical decorations, and by placing, nearly on the same planc
where the sitter is, such subjects as could not be correctly introduced in a
daguerreotype portrait, as the daguerreotype. process does not represent the
correct images of any objects but those placed nearly at the same focus.
With reference to the fourth head of my Invention, the employment of
artificial light in the absence of daylight, it is to be observed that, whichever of
the three modes of illumination above described be employed, a reflecting
mirror of a concave form must be adapted behind the light; and I hold it an
especial condition or essential feature of my Invention that the burner or
burners, or the alinentary tube which conveys the combustible gas or the
supporter of combustion, shall be placed in the axis of the reflecting mirror, or
that such tubes shall be placed round it parallel to the axis of the mirror, in
such manner that their jets (falling upon the body of coal or refractory material
held in front by means of a platina or iron wire, by which it is attached to the

page_text: burner) shall illuminate its surface precisely opposite the centre of the curve.
It must be the same also with regard to the flame produced from carburetted
gas burning with oxygen. This flame must issue forth from a tube placed in
the axis of the reflector. In those cases only where a flame is produced by
the combustion of carburetted liquids with oxygen, I make use of a vertical
burner, which must stand in front of the reflector in a line with its axis. I
sometimes produce the illuminating flames by means of carburetted gases
obtained from sea coal and from fatty substances made to pass through a
vessel containing an essential oil of a highly volatile nature, and which vessel
stands in water constantly boiling. By these means the essential oil will be
mixed with the burning gas, so that at the moment of its combustion with the
oxygen it produces the most brilliant light possible. In the case of carburetted
liquids being employed, I should construct the burner of tubes placed side by
side, cach fixed in the centre of a wick, the end being plunged in an essential
oil mixed in equal portions with spirits of wine or naptha.
Having thus described the details of my Invention, I have only to add that
I claim the improvements in the process or means of an apparatus for obtaining
images or representations of nature or art, as set out under the five heads
above recited, and more fully explained in the subsequent parts of this
Specification.
In witness whereof, I, the said Antoine Jean Francois Claudet, have
hereunto set my hand and seal, this Eighteenth day of June, in the
year of our Lord One thousand eight hundred and forty-two.