Ophthalmology

Near the end of this list, French names a condition after a man from Manchester. Le daltonisme is colour blindness, and the name inside it is John Dalton, the chemist of atomic theory, who read a paper on his own defective colour vision to a Manchester society in 1794. He could not tell a scarlet coat from a green leaf, and he supposed the cause was a blue liquid inside his eye; he left instructions for his eyes to be examined after his death, and they were. French built a noun on the man and then an adjective, il est daltonien, une vision daltonienne, and both are ordinary words that no French speaker hears as a surname any more. Spanish, Italian and Portuguese did the same. English is the odd one out: the language of the man himself says « colour blindness », a plain compound anybody can assemble, and leaves « daltonism » to dictionaries. So the memory hook here runs backwards. The French term is made out of English, the English term is not, and a reader who starts from « colour » will never arrive at le daltonisme.