850 Analysis of 'Scientific Books and Memoirs. 



of his, M. Recordon, having gone to England, where he took a patent for 

 his invention of self-winding watches, which were then in great request, 

 brought him, from that country, some flint-glass ; and though the speci- 

 men was much striated, he manufactured from it some good achromatic 

 glasses. Having obtained supplies of this material on various occasions, 

 and having seen other glasses besides those of M. Jaquet Droz, he easily 

 ascertained that flint-glass, which is not. extremely defective, is rarely to 

 be met with. Convinced of the impossibility of procuring it of that quali- 

 ty which he wished, and having become skilled in the art of fusion, he 

 melted in his blast-furnace the fragments of this flint-glass ; no satisfac- 

 tory result was obtained, but he discovered, from some particles of lead, 

 which re-appeared during the process, that this metal was a constituent in 

 the composition of flint-glass. At the time of this first experiment, he 

 had attained his 35th year. The ardent desire to obtain some of this glass 

 then induced him to collect such notions of chemistry as might be useful 

 to him; and, from 1784 to 1790, he employed a part of his evenings in 

 different experiments, melting, at each time, in his blast-furnace, three 

 or four pounds of glass; in every experiment he took care to note down 

 the substances and proportions of his combinations, the time of their 

 fusion, and the degree of heat to which he had subjected them ; so that, 

 by an examination of the results, he endeavoured to discover the causes 

 which had rendered his products defective. While occupied in these re- 

 searches, he derived a strong incentive to perseverance, from the prizes 

 which he understood to have been offered for this desideratum by differ- 

 ent academies. At a later period he also learned the almost total impossibi- 

 lity of procuring flint-glass exempt from stria?, which impressed him with 

 the importance of the discovery at which he was aiming. 



Having relinquished, at the age of forty, the trade of watch-case-maker 

 for that of maker of bells for repeaters, at that time very lucrative, (since 

 he could make as many as twenty-four in a day, for which he was paid five 

 francs each ;) he resolved to prosecute his experiments on a more extend- 

 ed scale. Having purchased a piece of ground on the banks of the river 

 Doubs, near Brenets, where his establishment is at present situated, he 

 constructed a furnace capable of melting two hundred weight of glass, and 

 he settled there with his family, in order to dedicate his leisure to new ex- 

 periments. 



His perseverance, however, had to overcome many untoward accidents. 

 At one time, his furnace threatened to burst while heating, and he was ob- 

 liged to rebuild it with materials procured from abroad ; at another time, 

 he noticed an essential defect in its construction, which obliged him to 

 suspend the melting ; sometimes his crucibles, which he had procured at 

 great expence, or manufactured himself, cracked without his being able to 

 discover the cause, and the vitreous matter was lost. These fruitless at- 

 tempts discouraged him on some occasions, but on others, excited him so 

 as to deprive him of rest, and he meditated day and night on the probable 

 causes of the accidents, and on the means of obviating them. At length, 

 however, he obtained a lump of glass, of about two hundred weight ; hav- 

 ing sawed this lump vertically, he polished one of the sections, in order to 



