Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work.
Herschel originated the use of the Julian day system in astronomy. He named seven moons of Saturn and four moons of Uranus – the seventh planet, discovered by his father Sir William Herschel. He made many contributions to the science of photography, and investigated colour blindness and the chemical power of ultraviolet rays. His Preliminary Discourse (1831), which advocated an inductive approach to scientific experiment and theory-building, was an important contribution to the philosophy of science.
HistoryLayer draws the world as it was in any year from 123,000 BCE to
2026. Move the slider and the borders redraw for that year; the map
carries 23,890 events, 12,790 people, 837 wars and 13,183 cities, each
one readable in place. Signing in is optional and lets you keep what
you find.