John Hadley was an English mathematician and instrument maker who served as vice president of the Royal Society. In 1730 he invented the reflecting octant, the direct ancestor of the sextant, independently of the American instrument maker Thomas Godfrey, who built a working octant on the same double reflection principle at approximately the same time, so credit for the invention is shared between them. Hadley also ground and figured the first successful parabolic mirrors for reflecting telescopes, demonstrating a Newtonian telescope to the Royal Society in 1721.
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Birth DateSourced to the subject's own account Death DateSourced to the subject's own account FieldSourced to the subject's own accountMathematics, scientific instrument making, astronomy 1 John Hadley
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Hadley's 1730 reflecting octant, developed independently of Thomas Godfrey's parallel invention, is the direct ancestor of the sextant.
Source John Hadley (Wikipedia)
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1. John Hadley (Wikipedia)
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In 1730 Hadley invented the reflecting octant. An American, Thomas Godfrey, independently invented the octant at approximately the same time.
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