Completed in 1721, John Hadley an English mathematician and astronomer was the first to create a parabolic mirror for a Gregorian reflector with virtually no spherical aberration. Despite having ground the surface by trial and error with continuous testing, his 6 inch mirror telescope with a focal length of 6ft performed as well as the much larger refractors of the day such as Huygens 123 ft focal length instrument.To use simply upload and rez to your sim
If you have any questions, then contact Skipper Abel in Second Life and please see accompanying CC licence, or visit SpaceportUK in Second Life, enjoy.
