440 Report of the Committee appointed [June, 



Article VII. 



Report of the Committee appointed h>j the Council of the Astrono- 

 mical Society, for the Purpose of examining the Telescope con- 

 structed by Mr. Tulley, by Order of the Council. (Communi- 

 cated by the Council of the Astronomical Society.) 



YoxiR Committee in making this report, before entering on the 

 immediate subject of it, think it will not be unsatisfactory to 

 the Council if they recapitulate briefly the circumstances, 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 communication 

 ■was made to the Council of the Society, by M. Reynier, of Neuf- 

 chatel, 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 twelve inches and upwards — and claiming for him a 

 priority of invention before his former employers Messrs. Fraun- 

 hofer and Utzschneider of Benedictsbeurn, in case of dispute. 



The extreme difliculty experienced by our artists in procuring 

 discs of flint glass of even very moderate dimensions, had long 

 been severely felt, and the first prospect of an opening aftbrded 

 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 invention of the 

 process, they contented themselves with inviting M. Guinand 

 to submit specimens of his performance for examination, 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 

 authorise a judgment as to the quahty 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. DoUond reported 

 as favourably as the trifling magnitude of the specimen would 

 permit. The inquiries of the Council too were answered in 9, 

 manner hardly more satisfactory, M. Guinand appearing chiefly 

 desirous of disposing of his stock of discs on hand, and that a 

 very limited one, at a tariff annexed, and of obtaining a pecu- 



