378 Astronomical Society. 
which have led to it, by way of presenting in one view the 
history of the telescope in question. ‘ 
So long ago as the 29th of September 1821, a communica- 
tion was made to the Council of the Society, by M. Reynier, 
of Neufchatel in Switzerland, on the part of an artist of the 
name of Guinand, resident in that neighbourhood, stating him 
to be in possession of a process for making discs of flint glass, 
fit to be employed in the construction of object-glasses for 
achromatic telescopes, and free from the defects which have 
hitherto given so much annoyance to opticians—and of any 
required size even as far as 12 inches and upwards—and 
claiming for him a priority of invention before his former em- 
ployers Messrs. Fraunhofer and Utzschneider of Benedicts- 
beurn, in case of dispute. 
The extreme difficulty experienced by our artists in pro- 
curing discs of flint glass of even very moderate dimensions, 
had long been severely felt, and the first prospect of an open- 
ing afforded for the cessation of this inconvenience, which bore 
so heavily on the progress of practical astronomy, could not but 
excite the attention of the Council. Declining, however, to 
constitute themselves judges in any dispute respecting the in- 
vention of the process, they contented themselves with inviting 
M. Guinand to submit specimens of his performance for ex- 
amination, and making such further inquiries as to his prices 
and his ability to furnish a regular supply, as the nature of the 
case and the wants of British artists appeared to call for. 
This invitation was at first, however, very unsatisfactorily 
complied with, the specimen sent being merely sufficient to au- 
thorize a judgementvas to the quality of the glass with respect 
to refractive and dispersive power, but too small to justify any 
conclusion as to the real merit of the process by which it had 
been made. The principal was a disc of about two inches in 
diameter, of which an object-glass was immediately constructed 
by Mr. Tulley, and of which that artist and Mr. Dollond re- 
ported as favourably as the trifling magnitude of the specimen 
would permit. The inquiries of the Council too were an- 
swered in a manner hardly more satisfactory, M. Guinand 
appearing chiefly desirous of disposing of his stock of dises on 
hand, and that a very limited one, at a tarif annexed, and of 
obtaining a pecuniary compensation for his secret, rather than 
of continuing the manufacture. A Committee was therefore 
appointed, consisting of Messrs. Gilbert, Herschel, and Pear- 
son, to examine the telescope, and thereon to report on the 
propriety of purchasing a larger specimen for further trial. 
The report of this Committee will be found on the books of 
the Society. (A copy is subjoined.) 
A copy 
