Professor Moser of Königsberg has discovered that all bodies, even
in the dark, throw out invisible rays; and that these bodies, when
placed at a small distance from polished surfaces of all kinds, depict
themselves upon such surfaces in forms which remain invisible till
they are developed by the human breath or by the vapours of mercury or
iodine. Even if the sun’s image is made to pass over a plate of glass,
the light tread of its rays will leave behind it an invisible track,
which the human breath will instantly reveal.
Among the early attempts to take pictures by the rays of the sun
was a very interesting and successful experiment made by Dr. Thomas
Young. In 1802, when Mr. Wedgewood was “making profiles by the
agency of light,” and Sir Humphry Davy was “copying on prepared
paper the images of small objects produced by means of the solar
microscope,” Dr. Young was taking photographs upon paper dipped in
a solution of nitrate of silver, of the coloured rings observed
by Newton; and his experiments clearly proved that the agent was
not the luminous rays in the sun’s light, but the invisible or
chemical rays beyond the violet. This experiment is described in
the Bakerian Lecture, 1803.
Niepce (says Mr. Hunt) pursued a physical investigation of the
curious change, and found that all bodies were influenced by this
principle radiated from the sun. Daguerre[14] produced effects from
the solar pencil which no artist could approach; and Talbot and
others extended the application. Herschel took up the inquiry; and
he, with his usual power of inductive search and of philosophical
deduction, presented the world with a class of discoveries which
showed how vast a field of investigation was opening for the
younger races of mankind.
The first attempts in photography, which were made at the
instigation of M. Arago, by order of the French Government, to
copy the Egyptian tombs and temples and the remains of the Aztecs
in Central America, were failures. Although the photographers
employed succeeded to admiration, in Paris, in producing pictures
in a few minutes, they found often that an exposure of an hour
was insufficient under the bright and glowing illumination of a
southern sky.