Miscellanies. 391 



M. Gambey, in 1 829, by the city of Geneva. They were a fortnight on 

 the route from Paris, and arrived in perfect order. They have been 

 well adjusted, with the assistance of the maker, in the observatory ; 

 the transit instrument, in the principal hall of the ground floor, and 

 the equatorial in the eastern tower under a hemispherical cupola with 

 moveable roof. They are the admiration of all who have seen them, 

 from the the beauty of their execution, their free and easy motion, 

 and the security of their position. — Bib. Univ. Mai, 1832. 



3. Medal for discovery of Comets. — The king of Denmark, to 

 whom astronomy is under numerous obligations, offers a gold medal, 

 of the weight of twenty ducats, to any one who shall have found the 

 first comet whose revolution is not yet known, and which is not visible 

 to the naked eye. The discoverer must give immediate informa- 

 tion to the counsellor of state, Schumacher. The medal will be de- 

 creed six months after the discovery, to give time for verification and 

 determination of just claims. — Idem. 



4. Maximum density of Water. — M. Stampfes, professor of the 

 Polytechnic Institute of Vienna, has recently published a very de- 

 tailed memoir on the absolute weight of water at different tempera- 

 tures. His results do not entirely agree with those of prior enquir- 

 ers. He places the maximum density at the temperature of 3°. 75 

 Centigrade = 38°. 75 Fahrenheit. — Annalen der Physik, Vol. xxi. 

 page 75. 



5. On the simultaneous motions of a pendulum and the surround- 

 ing air. — A memoir on this subject was read by M. Poisson to the 

 Academy of Sciences of Paris on the 22d of August, 1831. It 

 was drawn up by this great geometer in consequence of the work of 

 M. Bessel, on the same subject, in which this illustrious astronomer 

 was the first to show the inaccuracy of the common rule by which 

 the oscillations of a pendulum are reduced to a vacuum from those 

 observed in the open air. It had in fact been supposed till then, 

 that the loss of weight which a pendulum sustains, when plunged in 

 a fluid, is the same, whether the body is at rest or in motion. Ex- 

 perience proves the contrary, and the theory of the motion of fluids 

 has also led M. Poisson to demonstrate that the result ought to be 

 different. It is the friction of the air which occasions the successive 

 diminution of the amplitude of the oscillations. This diminution 



