Fact 1265 — Dalton and color vision

John Dalton had a color-vision deficiency himself and gave the first detailed account of it in a presentation in 1794; he published an expanded paper in 1798. He incorrectly explained his own vision by proposing an unusual tint in the eye’s vitreous humor. Only in 1995 did analysis of preserved eye tissue show that Dalton had deuteranopia, a form of red-green color blindness. The illustration is symbolic, not an accurate simulation of his vision, and is AI-generated.