ciple on a large scale. Apparently the way here also was barred against progress. All attempts to manufacture discs of pure flint glass larger than seven inches in diameter failed. Up to that point the achromatic refracting telescope was a great success. For seventy years good specimens of considerable size were exceedingly rare, and even in 1830 a disc of eleven inches and seven-tenths in diameter cost £1000.[1] An obscure musician, considering it probably impracticable to extend the range of Dollond's telescope, or impressed by the name and authority of Newton, was amusing himself, in 1772, if hard and continuous work can be called amusement, with casting and grinding mirrors, with mounting telescopes, and with studying the heavens in Bath, the gayest and idlest city in England. The people who formed the Literary Society of the town, who met to read papers on scientific subjects, and some of whom were members of the Royal Society of London, did not even know him. They were pigmies; a giant was among them, of whose existence and works they were not aware.
The courage of this musician was extraordinary. In the very year in which he removed to Bath, Messier, an eminent French astronomer, warned the Royal Society of London that progress in astronomy could be hoped for only from refractors. His words are: "It were to be wished that astronomers might be accommodated with achromatic telescopes of the most perfect construction, as such are the only instruments whereby a great knowledge of the celestial bodies can
- ↑ Herschel sometimes used a 312-feet achromatic or refracting telescope and a single eye-lens to confirm apparently the evidence of his 20-feet or 7-feet reflectors.
