Births on April 21

Charles Barrois, French geologist and palaeontologist (d. 1939)

Charles Eugene Barrois (21 August 1851 – 5 November 1939) was a French geologist and palaeontologist.

12 Feb

Australian gold rushes
Edward Hargraves announces he has found gold in Bathurst, New South Wales, Australia, starting the Australian gold rushes.
11 Mar

Giuseppe Verdi
The first performance of Rigoletto by Giuseppe Verdi takes place in Venice.
21 May

Colombia
Slavery is abolished in Colombia, South America.
5 Jun

Uncle Tom's Cabin
Harriet Beecher Stowe's anti-slavery serial, Uncle Tom's Cabin, or Life Among the Lowly, starts a ten-month run in the National Era abolitionist newspaper.
24 Oct

Umbriel (moon)
William Lassell discovers the moons Umbriel, and Ariel, orbiting Uranus.