Question

I am doing a project on Isaac Newton. Ive looked at his impact on the development of the telescope, in particular, the reflecting telescope. Ive researed this a bit and have found conflicting dates. Some sources say he built the first relflecting telescope in 1671 but others go as far as 1684. Can you define which year it actually was in and source it for me from somewhere reliable?

Answer 1

http://en.wikipedia.org/wiki/Reflecting_telescope

"Sir Isaac Newton is credited with constructing the first "practical" reflecting telescope after his own design in 1668.[1]"

The note [1] above refers to this book:
Reflecting Telescope Optics I, R. N. Wilson, A&A Library, Springer, 1996 (ISBN 0941-7834)

Also ---
http://brunelleschi.imss.fi.it/museum/esim.asp?c=200601
Scroll down to Newtonian telescope.

Answer 2

I'd be glad to. The Newtonian telescope was a great advance in telescope making and is still used today. It is easy to make with large apertures. It was very popular with amateur telescope builders for a long time. I also found (using Google) claims ranging from 1668 to 1689 for when he made his first reflecting telescope.

This quote, from
(Broken Link Removed) seems to be the most believable:
<<Reflecting telescope named after its inventor Isaac Newton (1643-1727), who built it in 1668 (a second copy, which survives, was presented to the Royal Society in 1672). The Newtonian telescope consists of a parabolic primary mirror, which serves as the objective, and a small plane elliptical mirror located on the optical axis and inclined at 45° to the axis. >>