Astronomical Society, 305 



fiant gas in being condensable by chlorine, but consumes more 

 oxygen and gives more carbonic acid, by combustion, and has a 

 higher specific gravity than olefiant gas, aild even than atmosphe- 

 ric air. Whether this ingredient be strictly i gas, permanent at 

 all temperatures, or a mixture of olefiant gas with some new gas, 

 constituted of hydrogen and charcoal in different proportions 

 from what are found in the known compounds of those elements, 

 or merely the vapour of a volatile oil, he leaves to be decided by 

 future experiments. 



March 8. — At this meeting was read a paper on the length of 

 the seconds pendulum in diiferent latitudes. — By Capt. Sabine. 



15. — Observations on Naphthalin. — By Dr. Kid. 



21. — A paper by Mr. Herschel, on the aberration of compound 

 lenses ; also 



A paper on the skeleton of the Dugong. — By Sir E. Home ; 

 and 



A paper by Sir Humphry Davy, on the Papyri of Hercula- 

 neum. 



ASTRONOMICAL SOCIETY OF LONDON. 



April 13. — A letter was read from M. Nicollet of Paris, com- 

 municating the elements of the late comet, as deduced from the 

 observations of MM. Bouvard, Arago, and himself, from Jan. 21 

 to March I. And he adds, that on account of the small perihe- 

 lion distance, the motion of the comet will accelerate, and soon 

 become visible again in the morning before suiu-ise. 



A letter was also read from Dr. Olbers of Bremen, respecting 

 the same comet ; giving the elements as deduced from his own 

 observations, and from the observations of Professors Nicolai of 

 Manheim, Encke of Seeberg, and Staudt of Gottingen. Dr. Ol- 

 bers likewise states that he observed tlie remarkable luminous 

 appearance on the dark limb of the moon on the 5th of February 

 last, as mentioned by Capt. Kater in his paper read before the 

 Royal Society. But he adds, that he cannot yet bring himself 

 to believe in the existence of any fiery volcano in the moon, and 

 thinks that the appearance is to be satisfactorily accounted for 

 in another nianncr, and more consistent with what we know of 

 the physical construction of the moon. The luminous appear- 

 ance seemed to be situated in or near the spot called Aristar- 

 chus, witli the general appearance of which Dr. Olbers was 

 ))erfectly acquainted. But this pha;nomcnon prcsentcil quite a 

 different aspect. 



A paper was next read — " On the do.scri|)tion of a repealing 

 instrument upon a new construction ; I)y G. DoUond, Esq." : 

 w'herein tlic author particularizes several improvements adopted 

 in the construction of this instrument j and which promise to be 



Vol. 57. No. 27G. /liiiU 1821. Q q not 



