7 The 100 Most Influential Inventors of All Time 7he called heliography (sundrawing), with a camera. He
recorded a view from his workroom window on paper
sensitized with silver chloride but was only partially able
to fix the image. Next he tried various types of supports
for the light-sensitive material bitumen of Judea, a kind
of asphalt, which hardens on exposure to light. Using this
material he succeeded in 1822 in obtaining a photographic
copy of an engraving superimposed on glass. In 1826/27,
using a camera, he made a view from his workroom on a
pewter plate, this being the first permanently fixed image
from nature. Metal had the advantage of being unbreakable
and was better suited to the subsequent etching process
to produce a printing plate, which was Niépce’s final
aim. In 1826, he had produced another heliograph, a
reproduction of an engraved portrait, which was etched
by the Parisian engraver Augustin-François Lemaître,
who pulled two prints. Thus Niépce not only solved the
problem of reproducing nature by light, but he invented
the first photomechanical reproduction process. While
on a visit to England in 1827, Niépce addressed a memo-
randum on his invention to the Royal Society, London,
but his insistence on keeping the method secret prevented
the matter from being investigated.
Unable to reduce the very long exposure times by
either chemical or optical means, Niépce in 1829 finally
gave in to the repeated overtures of Louis-Jacques-Mandé
Daguerre, a Parisian painter, for a partnership to perfect
and exploit heliography. Niépce died without seeing any
further advance, but, building on his knowledge, and
working with his materials, Daguerre eventually succeeded
in greatly reducing the exposure time through his dis-
covery of a chemical process for development of (making
visible) the latent (invisible) image formed upon brief
exposure.