John Hadley

About

Brtish mathematician who invented the octant, an early version of the sextant navigational tool. He also was known for making Gregorian telescopes with accurately shaped mirrors.

Before Fame

He joined the Royal Society in 1717 and ascended to its leadership role 11 years later.

Trivia

Together with two of his brothers he developed a tool to help ship navigators determine their position at sea and avoid dangerous waters.

Family Life

He grew up in an aristocratic family; his father served as high sheriff of the region.

Associated With

He built some of the earliest telescopes from Isaac Newton's designs.