Goodyear discovered the process first but did not patent it until 1844; Hancock examined a Goodyear sample, independently worked out the same process, and patented it in Britain weeks before Goodyear's own British filing. Neither side has ever produced evidence settling whether Hancock copied or independently rediscovered the process.
What would resolve this Documentary evidence of exactly what Hancock learned from the Goodyear sample he examined, if any, versus what he derived independently, would settle whether his 1843 patent was an independent rediscovery or a derivative of Goodyear's work.
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