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On This Day

  • 11-18-1812

    Jean Victor Poncelet (1788-1867), a military engineer, was captured while Napoleon's army was retreating from Moscow. He profited from this enforced leisure (until his release in June 1814) by resuming his study of mathematics. While in Russia, he did important work on projective geometry.

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    Jean Victor Poncelet
    Projective Geometry
  • 11-18-1883

    The telegraphic signals sent out daily at noon from the Naval Observatory at Washington, D.C., were changed to standard time, a system adopted on the initiative of the American Railway Association. Standard time was suggested for the U.S. in 1869 by Charles Ferdinand Dowd, a schoolmaster from Saratoga, N.Y., but was not adopted then. He suggested dividing the continent into four time zones each one hour or fifteen degrees of longitude wide. Standard Railroad Time had four time zones, Eastern, Central, Western, and Pacific. Congress made these official in 1918. Some citizens grumbled about "railroad tyranny" and tampering with "God's time."

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    Naval Observatory
    Standard Time in the US
  • 11-18-1962

    Niels Bohr died in Copenhagen, Denmark. The famous physicist studied atomic structure and radiation.

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    Niels Bohr