Some Account of the late M. Guinand. 353 



M. Guinand, having visited Paris in 1798 or 1799, presented to the 

 late M. de Lalande several disks of from four to six inches of the glass 

 which he obtained in sawing his blocks, (not having at this period thought 

 of the expedient of remelting them ;) that celebrated astronomer advised 

 him to work them up himself, so as to demonstrate the goodness of his 

 glass. M. Guinand followed this advice, and while continuing his manu- 

 facture of bells for repeaters, he pursued for several years the making of 

 glass and the working of lenses ; he constructed achromatic telescopes, 

 some of which had object-glasses of four or five inches, free from striae ; 

 and having purchased a small water-mill at Brenets, he adapted it to the 

 polishing of his glass. 



Though his success was not publicly known, yet he was visited by seve- 

 ral men of science. Having in this way become acquainted with Captain 

 Grouner, of Berne, the latter had occasion when in Bavaria to speak of the la- 

 bours of M. Guinand, and, a short time afterwards, in 1804, he asked him, 

 on the part of M. Fraunhofer, the director of the celebrated establish- 

 ment of Benedictbauern, for some specimens of his glass. M. Fraunhofer, 

 after examining them, and requesting several disks of the glass, was so 

 well satisfied with them as to repair to Brenets, a distance of 260 miles, 

 where he engaged M. Guinand to go into Bavaria. Having arrived in 1805, 

 he determined to settle there ; and during a residence of nine years he was 

 almost solely occupied in the manufacture of glass. 



After having discontinued for several years subsequent to his return all 

 his optical labours, his taste for the pursuit revived, and from that time 

 he was alternately occupied with the manufacture of glass and the construc- 

 tion of telescopes. 



Among the opticians who have used this glass may be mentioned M. 

 Lerebours, a French artist, who, during a visit to Brenets in 1820, obtain- 

 ed all the glass which M. Guinand then had, and was so well satisfied 

 with it that he requested a fresh supply, and made overtures for obtaining 

 the process. We may also mention M. Cauchoix, who, in a notice rela- 

 tive to the telescopes in the last exhibition at the Louvre, has spoken high- 

 ly of the flint-glass of which they are constructed. When the Bibliotluque 

 Universelle announced the formation of the Astronomical Society of Lon- 

 don in 1821, M. Guinand was requested to present to them a sample 

 of his glass, upon which they made a report as favourable as the small size 

 of the specimen could warrant ; they also offered to make another, on disks 

 of a larger dimension. M. Guinand accepted the offer, and they have 

 now in progress a disk of seven inches." 



• Among the telescopes made by M. Guinand after his return to Switzerland, 

 there are several of remarkable magnitude and effect ; in general the greater part ap- 

 pear to advantage on a comparison with English telescopes; a merit which is owing 

 in an especial manner to the quality of the glass. But the most singular circum- 

 stance is, that they have been constructed by an old man of seventy-six years of age, 

 who himself manufactured the flint and crown glass, after having made with his own 

 hands his vitrifying furnace and his crucibles, who, without any, mathematical 



VOL. II. NO. II. APRIL 1825. A a 



