April 11

Are You Sure ... (April 11)

• ... that clockmaker Jean-André Lepaute (23 November 1720 – 11 April 1789) introduced numerous improvements in clockmaking, notably his pin-wheel escapement, and his clockworks in which the gears are all in the horizontal plane?

• ... that physicist and academic Macedonio Melloni (11 April 1798 – 11 August 1854) demonstrated that radiant heat has physical properties similar to those of light?

• ... that physicist and academic Ukichiro Nakaya (4 July 1900 – 11 April 1962) contributed to glaciology and low-temperature sciences, and that Nakaya created the first artificial snowflakes?

Screenshot: Are You Sure (April 11, 2021)

On This Day in History and Fiction

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  1789: Clockmaker Jean-André Lepaute dies. He was an innovator, introducing numerous improvements in clockmaking, especially his pin-wheel escapement, and his clockworks in which the gears are all in the horizontal plane.

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  1798: Physicist and academic Macedonio Melloni born. Melloni will demonstrate that radiant heat has physical properties similar to those of light.

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  1914: Mathematician Dorothy Lewis Bernstein born. She will be the first woman to be elected president of the Mathematics Association of America.

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  1962: Physicist and academic Ukichiro Nakaya dies. He created the first artificial snowflakes.

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  1980: Viking program: After operating on the surface of Mars for 1316 days (1281 sols), the Viking 2 lander is turned off when its batteries fail.

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  2017: Dennis Paulson calls for a moment of silence in recognition of the thirty-seventh anniversary of NASA switching off the Viking 2 spacecraft.