Scientists
John Hadley
Citation Formats
General Reference
APA Style
BibTeX
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.
Facts
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 Cross-Tradition Connections
Invented
Hadley's 1730 reflecting octant, developed independently of Thomas Godfrey's parallel invention, is the direct ancestor of the sextant.
Sources
1. John Hadley (Wikipedia)
WikipediaWork sectionQuote, Work section
In 1730 Hadley invented the reflecting octant. An American, Thomas Godfrey, independently invented the octant at approximately the same time.
Reader Challenges (0 open reader challenges)
No disputes yet. Spotted an error or a better source? Open the first one.
Sign in to dispute this or suggest a correction.
View At A Past Year
The atlas records no dated fact of its own for this entry, so there is no other year to choose.