This page has been validated.
120
Life and Works
tonian telescopes of Short, and the small achromatics of Dollond.[1]
We have seen, in what goes before, how his patient zeal had succeeded in improving upon these. There was no delay, and no rest. Steadily the art of making reflectors was urged forward, until he had finally in his hands the forty-foot telescope.
It must be admitted that this was the limit to which the manufacture of powerful telescopes could be pushed in his generation. The optical and mechanical difficulties which prevented a farther advance required time for their solution; and, indeed, some of these difficulties are scarcely solved at this day. It may fairly be said that no reflector larger than three feet in aperture has yet realized our expectations.
- ↑ James Short, F.R.S. (1710–1768), and John Dollond, F.R.S. (1706–1761), were the most celebrated makers of telescopes of their day. The six-foot Newtonian reflectors of Short (aperture 9·4 inches), and the forty-six-inch achromatics of Dollond (aperture 3·6 inches), were highly esteemed. The Royal Observatory of Greenwich possessed, in 1765, one of each class. In a comparative trial of Short's telescope, at Greenwich, and one of Herschel's first telescopes, the latter was adjudged greatly superior.
