Who is the most ancient mathematician of which we have a photograph? (or, in the same vein, what is the oldest photograph of a mathematician) A quick search on MacTutor History of Mathematics gives Binet (b.1786) as a pretender with Cauchy (b.1789) coming close...

4$\begingroup$ This is a fairly arbitrary question of little research interest, but I imagine it is of some interest to the audience here. The word "photo" gets used somewhat flexibly in English so you might want to specify if you mean "likeness recorded on photographic paper via an early camera" or something more flexible, like "likeness recorded in a painting or sketch" or the most flexible "likeness recorded by an artist that imagined what the person looked like". $\endgroup$– Ryan BudneyNov 13, 2014 at 20:32

9$\begingroup$ But I believe that there are more mathematicians with some interesest in photography than viceversa. $\endgroup$– Jimmy DilliesNov 13, 2014 at 20:43

8$\begingroup$ At least as far as videos go, there are some old mathematicians here: youtube.com/watch?v=D7Kz_Le7BOc Around the 33 minute mark you can see David Hilbert shoveling snow. $\endgroup$– Alex R.Nov 13, 2014 at 20:49

9$\begingroup$ This is a wrong site for such questions. Try History of Math and Sciences. They like to discuss such questions:) $\endgroup$– Alexandre EremenkoNov 13, 2014 at 22:18

5$\begingroup$ I personally find the question quite interesting to appear on this site. $\endgroup$– Filippo Alberto EdoardoNov 14, 2014 at 8:24
1 Answer
Most ancient: Wikipedia has a daguerreotype of Gauss (1777–1855) on his deathbed. Or possibly Farkas Bolyai (1775–1856) in what look like similar circumstances.
Less ancient, but allegedly photographed earlier: Googling "daguerreotype mathematician" gives
• c. 1840, 1840: Augustus De Morgan (1806–1871)
• c. 1842–1843: Ada Lovelace (1815–1852)
• c. 1843: Friedrich Wilhelm Bessel (1784–1846)
• c. 1843: Joseph Plateau (1801–1883)
• c. 1843, 1847–1851: Charles Babbage (1791–1871)
• c. 1844: William Henry Fox Talbot (1800–1877)
• c. 1845: François Arago (1786–1853)
• c. 1845: William Rowan Hamilton (1805–1865) (per frontispiece)
• c. 1846: William Thomson (1824–1907)
• c. 1846: John Couch Adams (1819–1892)
• c. 1847: Hermann von Helmholtz (1821–1894)
• c. 1848: John Herschel (1792–1871).

$\begingroup$ Wait a minute, how do Binet and Cauchy fit into this chronology? $\endgroup$ Apr 13, 2018 at 8:05

$\begingroup$ According to wikipedia (fr), Cauchy's picture was taken soon before his death (1857). Isn't Binet a psychologist? $\endgroup$ Apr 13, 2018 at 15:12

3$\begingroup$ There's more than one Binet. The relevant one here must be Jacques Philippe Marie Binet (18761856), as in the CauchyBinet formula for $\det(AB)$, not Alfred Binet (18571911) as in the StanfordBinet intelligence scales. $\endgroup$ Nov 6, 2021 at 23:40

1$\begingroup$ Typo alert – Binet did not die $20$ years before he was born. $\endgroup$ Nov 7, 2021 at 0:58

$\begingroup$ The link for Joseph Plateau seems to be dead, but there are some versions archived in the Wayback Machine. $\endgroup$ Nov 7, 2021 at 4:52