en.wikipedia.org/wiki/Robert_Hooke
1 correction found
Hooke was dissatisfied with refracting telescopes so he built the first practical Gregorian telescope that used a silvered glass mirror.
This is incorrect because Hooke's Gregorian telescope was built in the 1670s, but silver-on-glass telescope mirrors were not introduced for astronomy until the 1850s. Early reflecting telescopes used speculum-metal mirrors, not silvered glass.
Full reasoning
The article combines two different historical facts into one incorrect claim.
- The History of Science Museum at Oxford says James Gregory designed the Gregorian telescope in 1663, and that Robert Hooke helped build it 10 years later—i.e. in the 1670s.
- But the British Astronomical Association explains that since the invention of the reflecting telescope in the 17th century, mirrors had been made of speculum metal, and that silver-on-glass mirrors were not good enough for astronomical purposes until the 1850s. The same source says the first telescope with a silver-on-glass mirror was built in France by J. B. L. Foucault in 1857.
So Hooke may well have built the first practical Gregorian telescope, but it could not have used a silvered-glass mirror. That technology postdates Hooke by almost two centuries.
2 sources
- Gregorian Telescope | History of Science Museum
James Gregory ... designed the original in 1663 CE ... it wasn't until 10 years later that he was able to recruit Robert Hooke to help him build it.
- Meeting of the Historical Section - British Astronomical Association
Since the invention of the reflecting telescope in the 17th century, mirrors had been made of speculum metal ... it was not until the 1850s that a sufficiently fine and stable silver deposit could be produced that was good enough for astronomical purposes. The first telescope with a silver-on-glass mirror was built in France by J. B. L. Foucault in 1857.