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 Before
mentioning the stages that led to the development of photography, there is
one amazing, quite uncanny prediction made by a man called de la Roche
(1729- 1774) in a work called Giphantie. In this imaginary tale, it was
possible to capture images from nature, on a canvas which had been coated
with a sticky substance. This surface, so the tale goes, would not only
provide a mirror image on the sticky canvas, but would remain on it. After
it had been dried in the dark the image would remain permanent. The author
would not have known how prophetic this tale would be, only a few decades
after his death.
There are two distinct scientific processes that combine to make photography
possible. It is somewhat surprising that photography was not invented
earlier than the 1830s, because these processes had been known for quite
some time. It was not until the two distinct scientific processes had been
put together that photography came into being.
The first of these processes was optical. The Camera Obscura (dark room) had
been in existence for at least four hundred years. There is a drawing, dated
1519, of a Camera Obscura by Leonardo da Vinci; about this same period its
use as an aid to drawing was being advocated.
The second process was chemical. For hundreds of years before photography
was invented, people had been aware, for example, that some colours are
bleached in the sun, but they had made little distinction between heat, air
and light.
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