Births on June 12

Zygmunt Janiszewski, Polish mathematician and academic (d. 1920)

Zygmunt Janiszewski (12 July 1888 – 3 January 1920) was a Polish mathematician.

16 May

Electric power transmission
Nikola Tesla delivers a lecture describing the equipment which will allow efficient generation and use of alternating currents to transmit electric power over long distances.
31 Aug

Jack the Ripper
Mary Ann Nichols is murdered. She is the first of Jack the Ripper's confirmed victims.
4 Sep

Kodak
George Eastman registers the trademark Kodak and receives a patent for his camera that uses roll film.
8 Sep

Annie Chapman
In London, the body of Jack the Ripper's second murder victim, Annie Chapman, is found.
30 Sep

Elizabeth Stride
Jack the Ripper kills his third and fourth victims, Elizabeth Stride and Catherine Eddowes.