*Cet auteur est chargé de recherche au CNRS et est maintenant professeur!..........
1-que cela en devient ridicule !
2-Vincent était l'opticien fabricant de Daguerre, ce dernier n'avait pas la possibilité de polir ses lentilles.Vincent Chevalier réalisait aussi des optiques pour le Diorama.
Dans une lettre provenant du laboratoire de Petiot-Groffier., Richebourg écrit à ce dernier: " Suivant ma promesse, je joints mon portrait fait l'après-midi le jeudi 1er juillet 1841, en 7 minutes, par un temps trop clair pour me permettre d'ouvrir les yeux....."
Ce qui contredit l'hypothèse de J L Marignier. Si V Chevalier avait mis au point le 6 pouces de Daguerre, le portrait s'obtenait dans les conditions mentionnées par Richebourg en une durée inférieure à 2 minutes.
3-Lire les commentaires de Charles Chevalier comparant l'objectif de Daguerre à celui de Wollaston.
4-Non pas parce qu'elle nous convient, mais qu'elle correspond aux faits observés.
5-références sur J B Biot: les ouvrages sur la physique, et surtout le 2ième tome de son traité sur l'astronomie, pages 34 à 110.
6- J L Marignier nous écrivait le 26 septembre 1990, alors que nous nous interrogions sur les présentations de ses recherches: " vous déformez les résultats de mes recherches en me faisant dire l'inverse de ce qu'ils prouvent d'une manière poutant si éclatante ..... Pour ma part, je ne suis ni dans le camp de Niépce ni dans le camp de Daguerre......je désire que mes recherches et résultats expérimentaux parlent d'eux-mêmes et que leurs conclusions s'imposent..(souligné dans la lettre)"
Let us keep in mind that Jean-Louis Marignier is in close connection with the family of one of the inventor of photography.
For us, this isn't what should be expected as a proof of objectivity.
The fact that Jean-Louis Marignier referred to a renowned expert is something open to debate: how does a researcher come to be acknowledged as an expert (1)?
We should not give credence to an expert who always takes refuge behind an institution to shun discussion and thus be able to spread information out of any supervision.
The text we're dealing with specifies that "there are too many incompatibilities left which are inconsistent with what we know of Niepce's research". "Thus, to the best of our current knowledge, we can't, at present, be quite positive that Niepce owned that chamber". That's how the authors see it but it's their own view: this understanding of the documents known at present and the use they make of it can't be the only reference.
How poorly Jean-Louis Marignier argued was a surprise to us as something more organized was expected from a scientist! No answer point by point to our arguments could be read. To have a valuation done you need an open debate and sound arguments. Contrary to Jean-Louis Marignier's method, we'll answer taking up arguments point by point.
Niepce used oil paper from the start. We can't imagine him being content with such a rudimentary method during all his researches. Besides, when he describes his chamber (plate IV in his opuscule), Daguerre does refer to a ground glass. As for Isidore, when listing his arguments against an improvement by Daguerre, he doesn't mention a ground glass (page 41 in his pamphlet), which enables us to think its use obvious and thus keep quiet about Daguerre's contribution.
In 1861, Jules Chevrier mentioned he had found five or six chambers. In his letters, Daguerre wrote of "differently sized boxes", just like the one used to show the famous "Laid table". These different boxes are obviously missing from Chevrier's list. One should wonder about Nicephore's methods when testing the use of lenses with such varied focal lengths, a work done on commission for Chevrier.
First of all, let us draw your attention to the fact that Nicephore Niepce is mentioned.
In 1840, Petiot-Groffier and Niepce de St Victor had superior means at their disposal.
These authors also write: "Bills are piece of evidence that, as early as 1840, he ordered his chambers, his lenses and photography material at Vincent Chevalier's at a time when this optician was trying to improve Daguerre's chamber, especially by reducing the size of the picture, in order to reduce the time of exposure".
This unwarranted poorly argued and false hypothesis (as regards to the end result) shows that they aim at denying any invention by Daguerre which only reinforce and strengthen our first comments.
In his correspondence, Daguerre write he has invented the 6 inches lens.
If Vincent Chevalier had perfected this lens, he would have to take part in Daguerre's experimental tests.
But neither Vincent Chevalier (2) nor Richebourg his pupil said they had been involved in and Charles Chevalier (3) has been so critical of Daguerre's lens that we can consider such an assumption as crazy. This author is plainly and logically of Isidore Niepce's opinion.
The assessment (4) of Daguerre's experimental method by J B Biot who carried out research on the theoretical optic similar to that of the physicist Gauss an did measures in the same field with the optician Cauchois, is more surely that of a well-informed and renowned expert.
We refer to Jean-Louis Marignier, as Pierre-Yves Mahé hasn't published (to the best of our knowledge) any articles or works on the subject.
See on that subject JB Biot's works and Daguerre's lens.
1- This author supervises research at the CNRS &endash;National organisation for scientific research-
It becomes utterly ridiculous!
2-Vincent was the optician working for Daguerre as the latter couldn't polish his lenses. Vincent Chevalier also made optical for the Diorama.
3-Read Charles Chevalier's remarks comparing Daguerre's lens to that of Wollaston.
4-Not because it suits us well but because it meets with observed facts.
5-References: JB Biot's works on physics &endash;especially his treatise on astronomy- second part (pages 34 to 110).
6-JL Marignier we wrote September 26, 1990, when we questioned the presentation of his research: "you distort the results of my research in making me say the opposite of what they show in a way poutant so bright. .... for my part, I am not in the camp or in the camp Niepce Daguerre ...... I want my research and experimental results speak for themselves and their conclusions can be drawn .. (underlined in the letter) "
nous remercions Annick Pourny pour cette traduction, responsabilité du texte J Roquencourt.