Mathematician, born in Hertfordshire, SE England, UK. He developed many improvements to the Gregorian reflecting telescope, making it into an accurate instrument for use in astronomy. He also designed a double-reflecting quadrant which became the basis for the sextant.
John Hadley (April 16, 1682 Bloomsbury, London – February 14, 1744, East Barnet, Hertfordshire) English inventor of the sextant, around 1730.
An American, Thomas Godfrey, independently invented the sextant at approximately the same time.
Hadley also improved the reflector telescope, building the first Gregorian telescope in 1721.
Mons Hadley and Rima Hadley on the Moon are named after him.
He is the older brother of George Hadley (meteorologogist).
User Comments Add a comment…