On this day in 1839 the French government bought Louis Daguerre’s photographic process and gave it to the world, free, “for the glory of France.” François Arago stood up before a packed joint session of the Académie des Sciences and the Académie des Beaux-Arts in Paris and explained it, step by step. (England got a patent-shaped exception; Daguerre had quietly filed one in London five days earlier. Engineers and lawyers have always kept different calendars.)
Here’s the clever bit: a silvered copper plate, made light-sensitive with iodine vapour, exposed for several minutes, developed over warm mercury, and fixed in a bath of salt water. Fussy, poisonous, and miraculous — and every image was a one-off, because there was no negative.
The picture below is Daguerre’s own Boulevard du Temple, made in 1838. The street was busy; the exposure was so long that the traffic simply vanished. One man stopped for a shoeshine long enough to be recorded — very likely the first person ever photographed. He never knew.
Ripple from my desk: within a year of this announcement John William Draper in New York pointed a daguerreotype plate at the Moon and got the first detailed picture of another world — March 1840, a twenty-minute exposure. The Moon, as ever, held perfectly still for it.
One man held still for the whole exposure and walked into history. Patience is a skill, folks. Scouts never write it on the card and it wins more games than the arm.