Daguerreotype
Arago announces Daguerre's photographic process to the French Academy of Sciences
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Original prompt & settings (JSON) ↗The Academy heard that Daguerre could preserve the image. It was told almost nothing about how he did it.
Monday, 7 January 1839, at the Academy of Sciences
At the Academy of Sciences in Paris on Monday, 7 January 1839, François Arago verbally introduced Louis Daguerre's discovery for permanently fixing camera-obscura images. The commonly listed date of 9 January is wrong; the Academy's own proceedings identify the session as the 7th.
Arago described the extraordinary precision and fine detail of the images. He did not reveal the chemical recipe.
An announcement, not a disclosure
Arago was the Academy's perpetual secretary as well as a legislator, and he was pushing a plan for the French state to buy the process and make it public. On 7 January both the purchase and the technical disclosure were unfinished business.
He likened the invention to an artificial retina that retained what it saw. The working procedure was not laid before the Academy until 19 August 1839.
Eighteen days to a rival claim
On 25 January, still without knowing Daguerre's technical details, William Henry Fox Talbot publicly presented his own photogenic drawings and asserted priority for his work.
What Daguerre had was a single direct-positive image on a silver-plated copper sheet, not a reproducible negative. The earliest daguerreotypes needed exposures of roughly three to fifteen minutes.
Sources
Researched 23 Aug 2026 7 sources 2 audit passes Date corrected
How this was checked
Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →
Date corrected. The research places this at 1839-01-07.
What the sources leave uncertain
- The listed date, 9 January, is wrong. The Academy's own proceedings identify the session as Monday, 7 January 1839.
- The 7 January announcement must not be confused with the 19 August joint meeting at which the working process was fully disclosed.
- A newspaper preview appeared on 6 January, which may explain occasional one-day discrepancies in secondary accounts.
Checked against
- Comptes rendus hebdomadaires des séances de l'Académie des sciences, volume 8 (1839)
- Histoire(s) de la photographie — Académie des sciences
- Photography timeline — French Ministry of Culture
- French daguerreotypes — Musée d'Orsay
- Daguerre and the Invention of Photography — Metropolitan Museum of Art
- Niépce–Daguerre association agreement — Musée Nicéphore Niépce
- The Daguerreotype Medium — Library of Congress