Template:Selected anniversaries/January 30
1619: Mathematician and cardinal Michelangelo Ricci born. Ricci will play a significant part in the theoretical debates and experiments that lead up to Torricelli's discovery of atmospheric pressure and invention of the mercury barometer.
1661: Oliver Cromwell, Lord Protector of the Commonwealth of England, is ritually executed more than two years after his death, on the 12th anniversary of the execution of the monarch he himself deposed.
1736: inventor, engineer, and chemist James Watt born. He will make major improvements to the steam engine.
1830: In a letter to Laplace, Carl Friedrich Gauss writes about a "curious problem" that he had been working on for twelve years. He gives the limiting value of the frequency of distribution of positive integers in the continued fraction of a random number (now called the Gauss-Kuzmin Distribution) as log2(1+x) . Gauss then asks if Laplace can offer help in finding the error term.
1975: The Monitor National Marine Sanctuary is established as the first United States National Marine Sanctuary.
1998: Mathematician Samuel Eilenberg dies. He co-founded category theory with Saunders Mac Lane, and proposed the Eilenberg swindle (a construction applying the telescoping cancellation idea to projective modules).
2022: Premiere of Rise of the Variants, the third film in Planet of the COVID global health catastrophe media franchise about a world in which humans and COVID clash for control.