Template:Selected anniversaries/January 9
1799: Mathematician, philosopher, theologian, and humanitarian Maria Gaetana Agnesi dies. She is credited with writing the first book discussing both differential and integral calculus.
1848: Astronomer Caroline Herschel dies. She discovered several comets, including the periodic comet 35P/Herschel-Rigollet, which bears her name.
1894: New England Telephone and Telegraph installs the first battery-operated telephone switchboard in Lexington, Massachusetts. (Shown here: another telephone exchange circa 1900.)
1916: Mathematician and entomologist Peter Twinn born. During the Second World War, he will be the first professional mathematician recruited by the British Government Code and Cypher School.
1918: Scientist, inventor, and educator Charles-Émile Reynaud dies. He invented the Praxinoscope (an improved zoetrope) and was responsible for the first projected animated films.
1923: Engineer, inventor, and pilot Juan de la Cierva makes the first autogyro flight.
1942: Mathematician and cryptologist Jerzy Różycki dies. Różycki worked at breaking German Enigma-machine ciphers before and during World War II.
1955: Premiere of Yeast of Eden, an American period drama film about a wayward young baker (James Dean) who, while seeking his own identity, vies for the yeast of his deeply religious father against his favored brother, thus retelling the story of Cain and Abel.
1989: Mathematician Marshall Harvey Stone dies. He contributed to real analysis, functional analysis, topology, and the study of Boolean algebra structures.