Astronomical Observatory, 375 



bastion, at the N. W. extremity of the 'city ; and it enjoys 

 on all sides a clear and delightful horizon. Its isolated sit- 

 uation secures it from all agitation arising from the motion 

 of wheels, and the ground, on which it stands, though 

 made, has had the consolidation of 200 years, and possess- 

 es sufficient firmness for the masonry, especially as it repo- 

 ses on a bed of sandstone. The observatory is a regular 

 octagon, 63 French feet in circumference. It is exactly 

 oriente ; its entrance is on the east, and opposite to it is a 

 niche, which includes a moveable stair case, and accommo- 

 dations for books. The S E., S W., N E., and N W 

 faces have large windows, before which, within, are stone 

 brackets, which have no communication with the building. 

 Two similar brackets are placed at each extremity of the 

 meridian. Each of these brackets as well as the two stone 

 columns which support the trunnions of the transit instru- 

 ments, repose upon massive masonry,as does also the pedes- 

 tal of the clock. The upper demi-circumference of the meri- 

 dian, is exposed when the shutters are opened. The floor is 

 raised two feet above the outside level, so that the air may 

 pass freely under it. The two floors are eleven feet apart, 

 and above is a wooden capula, so solid that very sensible 

 levels, placed upon brackets provided for them, remain 

 perfectly at rest during many series of delicate observations 

 of the heights of the sun or stars, taken with the circle of 

 Borda. This observatory is already furnished, — 1st with a 

 transit instrument, by Ramsden, of three feet focus. Its 

 vertical movement is extremely easy. It is at rest in eve- 

 ry position, its axis passing through the center of gravity of 

 the system, its equilibrium is perfect. The meridional po- 

 sition of this telescope is verified by an object erected on 

 the Gourten, a mountain distant 12,000 feet, when it is 

 placed at an angle of 4°.23 with the horizon. 2d. The 

 great azimuth circle of Ramsden three feet in diameter. 

 This is placed between the two columns of thet ransit tel- 

 escope. A description of this instrument may be seen 

 in the Philosophical Transactions, vol. 80th, and in 

 Adams' Essays. It arrived at Bern, from London, in 1797, 

 and escaped, as by a miracle, in 1798. 3. The clock, an 

 excellent instrument by Wulliamy, a skillful Swiss art- 

 ist in London. It has a compensation pendulum. It is 

 kept to Siderial time. 4th. The great circle of BordOi 



