THE MANUFACTURE OF TELESCOPES. 379 



than half a century ago, the English Board of Longitude 

 offered a considerable reward for bringing the art of 

 making flint-glass for optical purposes to the requisite 

 perfection, but it led to no important discoveries. The 

 Academy of Sciences at Paris, offered prizes in vain for 

 this object ; and it remained for a man, not distinguished 

 by education, nor a glass-maker by trade, M. Guinand, 

 of Switzerland, to have the honor of arriving at the solu- 

 tion of the difficulty. 



Guinand was born at Brenets, near Neufchatel, and 

 was a workman in the clock and watch trade. Having 

 been permitted to inspect an achromatic telescope, he de- 

 termined to make one for himself, but could find no glass 

 suitable for this purpose in Switzerland. He obtained 

 some flint-glass from England, but this was not always 

 perfectly pure. He melted it anew, but did not obtain 

 satisfactory glass. He then erected on the river Doubs, 

 near Brenets, an establishment in which he constructed, 

 with his own hands, a very large furnace, and commenced 

 the manufacture of glass, and finally succeeded in obtain- 

 ing pieces large enough for telescopes. He visited Paris 

 in 1798, and exhibited discs of from four to six inches in 

 diameter. He afterward discovered a method of soften- 

 ing pieces of perfectly pure glass, for the purpose of 

 giving them the form of a disc. In the year 1805, Gui- 

 nand was invited by Eeichenbach to assist him in his 

 optical establishment which he had founded at Benedict- 

 burn, about 40 miles from Munich. Here he remained 

 nine years, but always in a subordinate capacity. In 



