Optical telescope
The telescope is more a discovery of optical craftsmen than an invention of a scientist. The lens and the properties of refracting and reflecting light had been known since antiquity and theory on how they worked were developed by ancient Greek philosophers, preserved and expanded on in the medieval Islamic world, and had reached a significantly advanced state by the time of the telescope's invention in early modern Europe. But the most significant step cited in the invention of the telescope was the development of lens manufacture for spectacles, first in Venice and Florence in the thirteenth century, and later in the spectacle making centers in both the Netherlands and Germany. It is in the Netherlands in 1608 where the first recorded optical telescopes (refracting telescopes) appeared. The invention is credited to the spectacle makers Hans Lippershey and Zacharias Janssen in Middelburg, and the instrument-maker and optician Jacob Metius of Alkmaar.
Newton's reflector
Newton's third telescope was built in 1671-1672 by Newton and his "chamber fellow" at Trinity College John Wickins. He reported that Wickins did a better job of figuring the mirror than he had done on his second telescope. This is the telescope that he had by him when he was writing Opticks. The telescope appeared some time later in the shop of Heath and Wing instrument makers along with an instrument of Newtons belonging to Edmond Halley. It is most likely that the telescope had passed to Halley and then to Heath and Wing. This third telescope had the mirror damaged in 1694 by Newton while trying to clean it. It is thought that the mirror was later refigured by restorers accounting for its plugged eyepiece hole at an appropriate distance for a 6.25 inch focal length mirror and the new eyepiece position for the current mirror focal length of 8.5 inches. The current brass eyepiece is not original and was added later. This telescope was restored by Heath and Wing and presented to the Royal Society in 1766 as the telescope that Newton had made. At a later date a plaque was added to this telescope with the incorrect inscription claiming that it was his first telescope and made in 1671. This telescope probably includes the original mirrors, reground, part of the original base, the original support bar and possibly the original tube or parts of it.