In what year did Charles goodyear invent vulcanized rubber?

Most textbooks point out that Charles Goodyear (1800-1860) invented vulcanisation of rubber as used today by the addition of sulfur in high heat. Depending on what you read, the Goodyear story is one of either pure luck or careful research. Goodyear insisted that it was the latter, though many contemporaneous accounts indicate the former.

Goodyear claimed that he discovered vulcanization in 1839, but did not patent the invention until June 15, 1844, and did not write the story of the discovery until 1853 in his autobiographical book Gum-Elastica. Meanwhile, Thomas Hancock (1786-1865), a scientist and engineer, patented the process in the UK on November 21, 1843, eight weeks before Goodyear applied for his own UK patent.

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