352 M. Utzschneider 07i M. GuinancVs Glass for Telescopes. 



I do not wish to occupy the public attention about my own 

 affairs ; but I am nevertheless obliged, by the interest which 

 is attached to this singular discovery, to state some particulars 

 relative to the residence of M. Guinand in my glass-house at 

 Benedictbeurn. I have already spoken of it in 1 826, in my Z///e 

 ojFraunhofcr: but it is necessary to recur to it again, in order 

 to refute the reports which are circulated injurious not only to 

 my establishment, but also to the memory of Fraunhofer. 



Before M.Pierre Louis Guinand entered my service, I made 

 him communicate to me every thing he knew, up to that time, 

 as to the art of making glass: I also obtained from him a de- 

 scription of the small castings made by him since 1775: and 

 I was convinced that his efforts would not have been attended 

 with any advantage either to science, or to his own interests. 

 M. Guinand renewed unsuccessfully his attempts, but was not 

 the less received by me. His efforts directed me in the path 

 which he ought to have pursued to obtain his object: and 

 I therefore resolved to continue to work with him, after a set- 

 tled plan, and to take advantage of every moment of leisure 

 I could spare fi'om my public duties to assist at his castings. 

 We obtained some pieces of flint glass, with which we made 

 object glasses for instruments forming in the manufactories of 

 Reichenbach, Utzschneider and Liebherr. Our labours were 

 only discontinued when I attended my public duties: I then 

 charged M. Fraunhofer with the direction of the castings which 

 were undertaken at my expense : and this excellent optician 

 always gave me a written report of the experiments and castings 

 that he had made. 



M. Guinand announced to me, on December 6, 1823, that 

 domestic affairs required his presence at Brennets : in fact, 

 he left me some time after, and never returned again to Bene- 

 dictbeurn. 



The description of the castings of M. Guinand, written with 

 his own hand, and still in my possession, proves that in 1805 

 he could not then make perfect flint glass: and that he would 

 not have succeeded but for the experiments made with me at 

 Benedictbeurn, and at my expense. Still the glass of the last 

 casting, which was made at the commencement of the year 

 1814, was not equal in quality to that which Fraunhofer made 

 at a later period. 



The flint glass for the object glass of the Dorpat telescope 

 lioas not cast till fotir years after the departure of M. Guinand, 

 in the thirty-third casting of December 18, 1817; as may be 

 seen by M. Fraunhofer's journal: and it was I who furnished 

 the principal materials for this and the thirty-second casting. 



On the llth of January 1816, M. P. L. Guinand wrote to 



me 



