May 5

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  1635: Physician, alchemist, scholar, and adventurer Johann Joachim Becher born. Becher will propose Phlogiston theory in an attempt to explain processes such as combustion and rusting, which are now collectively known as oxidation.

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  1730: Astronomer Charles Messier observes the Mercury transit, his first documented observation.

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  1840: The Penny Black postage stamp becomes valid for use in the United Kingdom of Great Britain and Ireland.

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  1937: Hindenburg disaster: The German zeppelin Hindenburg catches fire and is destroyed within a minute while attempting to dock at Lakehurst, New Jersey. Thirty-six people are killed.

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  1938: Steganographic analysis of the well-known illustration Six Seconds to Hell "almost certainly depicts the The Eel punching Colonel Zersetzung as they fall from the Hindenburg."

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  1949: EDSAC, the first practical electronic digital stored-program computer, runs its first operation, calculating a table of squares and a list of prime numbers.