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of heliography, along with Daguerre’s improvements
to the camera obscura. By this date, Niépce had begun
using iodine vapors to darken the light parts of camera
images produced on silver plates, thereby restoring the
normal relationship between light and dark that had
been reversed in images in his earlier process. Daguerre
preferred the quality of the original (“negative”) image
obtained on bitumen, and together they invented a new
process that rendered a single, unique image, the phy-
sautotype. This process, based on the photosensitivity
of the residue from oil of lavender dissolved in alco-
hol, resulted in an image that, like the daguerreotype,
appeared either positive or negative depending on the
angle of refl ected light. After Niépce’s death on July
5, 1833, Daguerre remained determined to perfect a
process that would render a similar, unique image. He
returned to the use of iodine, no longer as a darkening
agent, but because of its photosensitivity when applied
to silver plates as a vapor. This discovery led Daguerre
to the invention of the daguerreotype process, in which
mercury fumes brought out the latent image in the silver
iodide on plates exposed to light in a camera.
Daguerre probably produced his fi rst successful da-
guerreotypes as early as 1834 and announced his inven-
tion in the Journal des artistes on September 27, 1835.
Daguerre had signed a new contract on May 9, 1835
with Niépce’s son, Isidore. The new contract changed
the name of the partnership from “Niépce-Daguerre” to
“Daguerre and Isidore Niépce,” in light of Daguerre’s
recognition of the chemical bases of the daguerreotype.
A fi nal contract was signed on June 13, 1837, naming
Daguerre as the sole inventor of the new process, which
was announced by the politician and scientist, François
Arago, on January 7, 1839. Arago formally divulged the
process to a joint meeting of the Académie des Sciences
and Académie des beaux-arts on August 19, 1839, after
King Louis-Philippe signed the law granting lifetime
pensions to Daguerre and Isidore Niépce on August 7.
Following Arago’s announcement, Daguerre sent da-
guerreotypes to Ludwig I of Bavaria (Munich, Fotomu-
seum, Münchner Stadtmuseum), Ferdinand I of Austria,
Nikolaus I of Russia, Friedrich Wilhelm III of Prussia,
the Austrian chancellor Klemens Metternich (Prague,
National Technical Museum), and Austrian ambassador
to France A.G. Aponyi (Budapest, Museum of Science).
Daguerre also offered daguerreotypes to Arago (Perpig-
nan, Musée Hyacinthe Rigaud) and Alphonse de Cailleux
(Paris, Société française de photographie).
Arago’s announcement of Daguerre’s invention in
January 1839 provoked numerous claims of priority for
other photographic processes, the most notable of which
came from a member of the Royal Society of London,
William Henry Fox Talbot. Talbot, a scholar known for
his work in mathematics, presented examples of his
photogenic drawings to the Royal Society on January
25, 1839, followed by a formal paper explaining his
process on January 31. Talbot had fi rst considered the
possibility of fi xing the images of the camera obscura
in 1833. In 1834, he had developed both a form of
cliché-verre, in which drawings scratched onto var-
nished glass plates were printed by contact onto silver
paper, and photogenic drawings, in which the shadows
of objects were imprinted through direct contact onto
paper sensitized with silver nitrate. Talbot produced
his fi rst images in a camera in 1835, although these,
like the contact images, had reversed light and dark
areas. While he had already conceived of the idea of
restoring the image to its proper disposition through a
second contact printing, he did not pursue the idea of
printing multiple positives from the initial paper print
until the fall of 1840. At that time he began producing
multiples by using the initial photogenic drawing image
produced in the camera as a photographic negative, from
which to make a positive image by taking a fresh piece
of photogenic drawing and exposing it in contact with
that negative. Until then, he was still attempting to meet
the challenge posed by Daguerre, of producing a single
image in which lights and darks could be perceived in
their natural disposition.
Talbot’s photographic process was not the only one in
competition with the daguerreotype in 1839. The English
physicist and astronomer John Herschel also invented
several independent processes, including the cyanotype,
and presented his paper on photography to the Royal
Society on March 14, 1839. He is best known today,
however, for having coined the term “photography”
and for introducing sodium thiosulphate, or “hypo,” as
a fi xing agent. Hercules Florence, a French immigrant
living in Brazil, claimed to have captured images in
a camera obscura by 1833, although he presented his
fi ndings only in October of 1839. Hippolyte Bayard, a
French civil servant, invented an original process within
the fi rst few months of 1839 that rendered direct posi-
tives on paper. Although he received little support from
Arago, Bayard’s process received a favorable report in
Paris from the Académie des beaux-arts, as did those of
Talbot and an English engraver, James Tibbits Willmore.
Willmore’s process of “photogenic engraving,” which
was similar to Talbot’s cliché-verre, was presented to
the Académie des beaux-arts in April of 1839. In August
of the same year, a French painter and drawing instruc-
tor, Auguste Berry, presented Arago with yet another
photo-based process of producing multiples of original
drawings. Such artistic applications were not pursued
by the Académie des sciences, which rather supported
Alfred Donné’s use of the daguerreotype as an engrav-
ing plate for images taken through a microscope. Apart
from Donné and the photoengraving process Hippolyte
Fizeau used to print some of the plates of Nicolas
Marie Lerebours’ Excursions daguerriennes in 1841,