256 Lieut. Zahrtmann on the Mathematical 



among them of good quality. M. Jecker manufactures more 

 instruments for the navy than any other artist : but this I sup- 

 pose may be attiibuted to his moderate prices, for he sells a 

 reflecting circle 10 inches in diameter for 400 francs, while 

 M. Lenoir charges 430, and M. Gambey 500 ; M. Jecker al- 

 ways makes use of the dividing machine of Ramsden. His 

 residence is at No. 32, Rue de Bondy. 



M. Richer is dead, and his son does not appear to have any 

 intention of continuing the establishment. He was possessed 

 of considerable merit, and invented a machine for calculating 

 the distances of the moon from the stars; several of the in- 

 struments which M. Freycinet employed in his voyage round 

 the world, and with which he was much pleased, were of his 

 construction. His son, the present M. Richer, lives at the 

 Rue Harlais aux Marais. 



INI. Lerebours is a man of more than 60 years of age, and is 

 esteemed the first optician in France ; his workshop has pro- 

 duced several excellent instruments, of which the most im- 

 portant is a telescope, the object-glass of which is nine inches 

 diameter, which he has constructed for the observatory. 

 He sent a quantity of object-glasses of different dimensions to 

 the observatory, in order to be examined, and the greater 

 number of them were found very good ; he is a member of 

 the Legion of Honour, and artist to the Board of Longitude. 

 He resides on le Pont Neuf, at the corner of the Quai de 

 l'Horloge. 



M. Cauchoix, who is nearly 50 years old, is regarded as 

 possessing a more complete knowledge of his art than M. Lere- 

 bours, though he has not brought it so much into exercise : he 

 has constructed a telescope of 1 1 inches aperture, the largest 

 which has ever been made in France; and likewise a stand of a 

 very ingenious construction to support a telescope. M. Cau- 

 choix lives Quai Voltaire, opposite the Pont Royal. 



Among the other opticians of Paris, I shall notice only 

 M. Soleil, who has distinguished himself by his activity in the 

 execution of Untitles a echelon, which are used for light-houses: 

 but though he has received great assistance from the glass- 

 houses, and from M. Fresnel, who furnished him with better 

 tools than those which he possessed, yet they still appear ca- 

 pable of considerable impi'ovement. M. Soleil lives at No. 21, 

 Passage Feydeau, and his manufactory is France Nouvelle, 

 No. 21, Rue de Poissonnieres, near the Barriere Poissonniere. 



As I have never seen a large optical workshop, I am unable 

 to give an opinion respecting them: but M. Thiele, who came 

 to Paris after having worked a year with M. Frauenhofer, was 

 quite astonished at the mechanical poverty which he observed 



in 



