HF The History of Photography 600pág

Heliography 57
---
thin layer spread on a glass plate, on which Niepce superimposed an engraving made
transparent by oiling. When exposed to light for 2 or 3 hours the bitumen under the
white parts of the engraving became hard, whilst that under the dark lines remained
soluble and could be washed away with a solvent consisting of oil of lavender and
white petroleum (turpentine). The resulting picture was unalterable by light. One
can well understand the joy of the two brothers at this turn of events.
I have read and re-read with admiration [wrote Claude on 19 July 1822] the
interesting details you kindly transmitted to me; I thought I saw you, as well as
my dear sister [-in-law] and my dear nephew, attentive and following with your
eyes the admirable work of light; and I thought I myself saw a 'point de vue' which
I had great pleasure in remembering. How I desire, my dear fellow, that an experiment
so beautiful and interesting for you and for science may have a complete and
definite result.
On the strength of the italicized passage the French historian Georges Potonniee
was quite positive that Niepce had also succeeded in taking a view from nature
(point de vue) at the time he copied the engraving of the Pope. This caused him to
date the invention of photography 1822, and to have a monument erected to Niepce Pl 18
at Saint-Loup-de-Varennes. But Potonniee was wrong. Claude, remembering the
paper views which Nicephore had sent him six years previously, hoped that he
would soon be able to take landscapes as good as the engraving of the Pope-for
views from nature were the ultimate goal. Probably Nicephore had mentioned in
his (lost) letter something about this; otherwise why should Claude say 'I thought
I myself saw a view which I had great pleasure in remembering'? Even though this
sentence is ambiguous and capable of misinterpretation, later letters from Claude
make it clear beyond a shadow of doubt that Nicephore did not take a permanent
view from nature before 1824 at the earliest.
Niepce presented the heliograph of Pius VII to his cousin, General Poncet, who
happened to visit Gras at the time. The general was so full of enthusiasm that he
carried it with him everywhere to show to his friends, until one day a clumsy admirer
dropped and smashed it.
In the following years Niepce copied several engravings in a similar way to that
of the Pope, with the difference that he now employed metal-chiefly zinc and
pewter-instead of glass, for they were intended to be etched and printed from.
Several of these plates, as well as the original oiled engravings, are preserved at the
Musee Denon in Chalon-sur-Saone. The most successful heliograph is a copy of an
engraving of Cardinal d' Amboise, Minister of Louis XII. In the summer or autumn
of 1826 Niepce made two copies of this engraving on pewter, and in February 1827
he sent them, with three other heliographs, to the Parisian engraver Lemaitre, who
re-etched them with stronger acid and pulled one print from each.4 No handwork
was done on them. Of these two plates, one was brought by Niepce to London in
September 1827, with two proofs. This plate and one print are in the Science Museum,
London; the other print is in the Gernsheim Collection. The second plate of Pl 19
the Cardinal is in the Museum at Chalan, which also possesses a third, rather poor,
plate-poor because it is over-etched, and the prints pulled from it are in consequence
far too contrasty compared with the two other proofs. There exists no documentary
evidence about this third plate; it might have been over-etched by Niepce himself
in a first trial before entrusting the other two to the professional skill of Lemaitre ;
but it is more likely that Jules Chevrier, curator of the Chalan Museum, tampered
with it in 1864 when he had several prints pulled, of which one is at the Museum in