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ments in European culture as a whole. It was only the
confl uence of these developments in the early nineteenth
century that made photography conceivable and perhaps
even inevitable. They included general shifts in Euro-
pean society, such as the advent of the Industrial Revolu-
tion and consumer capitalism, as well as more particular
changes in scientifi c thinking and technology that led to
new theories of light and optics and the production of
more refi ned chemicals and improved lenses. But this
signifi cant historical moment was also accompanied by
revolutionary changes in the experience of time, space
and subjectivity that were equally important to what
might be called photography’s conditions of possibil-
ity. It was the representational demands accompanying
these changes that encouraged experimenters to imagine
bringing together the basic components, some of them
available for some time before 1839, that eventually
constituted a workable photographic apparatus. The
advent of photography, therefore, was a complex his-
torical event involving social, cultural and technological
changes in about equal measure.
The two most important technical components of
the photographic apparatus were the camera and light-
sensitive chemicals. The photographic camera was a
modifi ed version of the camera obscura, an instrument
that had been used in one form or another by European
artists since at least the sixteenth century. Originally
comprised of a darkened room into which light was
allowed to enter through a small hole in one wall, the
camera obscura eventually became a portable box with
a lens at one end and a ground glass sheet at the other. A
skilled draftsman could trace an exact copy of the image
focused on the glass by the light that has passed through
the lens (an improved lens for this purpose was designed
by William Wollaston in 1812, and Niépce and Daguerre
experimented with a number of different versions in the
1820s). Although moving, reversed and upside-down,
this projected image was regarded as a faithful facsimile
of the outside world because the light which formed it
had passed through the lens and into the camera ac-
cording to the objective geometric laws of perspective,
itself an invention of the fi fteenth century. By the time
of photography’s conception, the camera obscura was
one of a number of mechanical instruments—another
was the camera lucida, a three-sided glass prism on a
retractable stand patented by Wollaston in 1806—em-
ployed by artists in an effort to produce more accurate
drawings than could be made by the unaided human
hand. However such instruments still required some skill
to operate successfully. As Talbot famously recalled in
1844, he tried to use both the instruments just described
while drawing at Lake Como in Italy in 1833, but the
results were “melancholy to behold.” It was then, he
says, that an idea occurred to him: “how charming it
would be if it were possible to cause these natural im-
ages to imprint themselves durably, and remain fi xed
upon the paper!”
The realisation of this idea required Talbot to apply
what was already common knowledge amongst those
like himself who studied chemistry and physics; namely,
that light had a discernable chemical effect on certain
silver salts, causing them to oxidise and change colour.
This reaction had been noted by the German natural
philosopher Johann Heinrich Schulze as early as 1727
and his experiments, which included making stenciled
words appear in purple against his white solution of car-
bonate of silver, were repeated and confi rmed by others.
Swedish chemist Carl Wilhelm Scheele, for example,
undertook experiments on the action of light upon silver
chloride and published his fi ndings in 1777, and these
were subsequently translated into German, English and
French. Swiss librarian Jean Senebier published further
experiments along these lines in 1782, timing the effects
of different coloured light on chloride of silver. Light
was also a subject of much discussion in the period, with
the corpuscular theory of light proposed by Newton in
the eighteenth century being gradually replaced by the
wave theory developed by Thomas Young in England
and Augustin Fresnel in France. In 1803 Young, a
colleague of Humphry Davy’s, even conducted some
photographic experiments with light by projecting
microscopic images on to a sheet of paper soaked in
silver nitrate. Both Scheele and Senebier were among
those referred to in the essay by Davy that is generally
considered to be the fi rst publication specifi cally about
photography.
This essay, appearing in the Journals of the Royal
Institution of Great Britain in June of 1802, described
various experiments that Davy and his friend Thomas
Wedgwood had undertaken with white paper or leather
moistened with a solution of silver nitrate and exposed
to light. These experiments included attempts to produce
both contact prints and images formed in a camera
obscura.
White paper, or white leather, moistened with solution
of nitrate of silver, undergoes no change when kept in
a dark place; but, on being exposed to the day light,
it speedily changes colour, and, after passing through
different shades of grey and brown, becomes at length
nearly black...The condensation of these facts enables us
readily to understand the method by which the outlines
and shades of painting on glass may be copied, or profi les
of fi gures procured, by the agency of light...The images
formed by means of a camera obscura, have been found
to be too faint to produce, in any moderate time, an ef-
fect upon the nitrate of silver. To copy these images, was
the fi rst object of Mr Wedgwood, in his researches on
the subject, and for this purpose he fi rst used the nitrate
of silver, which was mentioned to him by a friend, as a
substance very sensible to the infl uence of light; but all
his numerous experiments as to their primary end proved