and Astronomical Instrument Makers at Paris. 255 



of the axis. The telescope is by Lerebours; its length is 

 five feet, and the diameter of the aperture is 45 lines. The 

 axis, which is seven feet in length, appears to be less conical 

 than in the instruments of Reichenbach; but it is balanced by a 

 counterpoise, by which it is supported at the end upon two 

 wheels ; the instrument is in general perfectly balanced in all 

 its parts: the movement by the pendulum, which is communi- 

 cated by a screw, is sustained uninterruptedly during a period 

 of time rather longer than an hour; the level, or, more pro- 

 perly speaking, levels (for there are two) are constructed in 

 a particular manner, so as to suffer the axis to be levelled 

 independently of its form, being more or less perfectly cylin- 

 drical. This instrument, which was shown at the late exhi- 

 bition of French industry, is without doubt the best of the 

 kind that has ever been executed in France, and the other 

 artists of the exhibition have subscribed to that opinion 

 b}' attaching to it some lines in honour of M. Gambey. 

 M. Gambey has constructed for the observatory a magne- 

 tic declination circle, and a heliostat. As to his repeating 

 theodolites, of which I have already spoken to you, he has 

 hitherto made three : the first for the Polytechnic School ; the 

 second for M. Francceur ; and the third for England*. These 

 instruments give great satisfaction, and by M. Francoeur in 

 particular I have often heard them praised. The dividing in- 

 strument of M. Gambey's invention possesses the advantage 

 of not requiring the centering of the instrument that is di- 

 vided, — a process which he has hitherto kept quite secret. 

 M. Gambey obtained a gold medal at the exhibition of 1819. 

 His address is No. 52, Rue Fauxbourg St. Denis. 



The productions of M. Lenoir the elder are well known, 

 and he now actually works no longer. He is member of the 

 Legion of Honour, and artist to the Board ofLongitude; his son, 

 who is a man of about 4-0, directs the establishment at pre- 

 sent ; he works considerably, but it is rather for engineers and 

 mariners than for astronomers ; his nautical instruments ap- 

 pear well made. He lives at No. 340, Rue St. Honore. 



The age of M. Jecker is about 50 years. Fie is a native 

 of A.ix-la-Chapelle, and formerly worked at Ramsden's. 

 Though the exterior of his instruments is in general imper- 

 fectly finished, and though they possess a certain varnish, 

 yet I do not think that they are bad, at least there are some 



* [This last instrument was made expressly for Mr. F. Bail), under the 

 direction of M. Arago. The circles are only 10 inches in diameter, and 

 are divided so that 2 seconds are easily distinguishable with a vernier. 

 The execution of the various parts of the instrument does great credit to 

 this celebrated artist. — Edit.] 



among 



