Natural Fhilosophy — Astronomy, i99 
has been conducted are given in the Ccmnoissance des Term 
for 18S1, p. 219. which has lately appeared; but the details of 
the calculus by which he obtained them, will, we suppose, be 
published in the Memoirs of the Institute. 
S, Repeating Circle . — In the observations made last year by 
the French and English astronomers, at Dunkirk, the former dis- 
covered a constant error of about two seconds in the deter- 
mination of the latitude by the repeating circle, and found that it 
differed in kind, according as the stars observed were on the 
north or south side of the zenith. The true latitude w as obtain- 
ed by taking a mean between the tv/o results, as was ascertain- 
ed by its agreeing exactly with the latitude found by the Eng- 
lish astronomers, who used their incomparable instrument, the 
zenith sector made by Ramsden. ■ 
4. First Comet 0/I8I8. — ^This comet, which was discovered by 
M. Pons at Marseilles, on the 26th December 1817, was not seen 
at Paris till the 29th March 1818. From the observations made 
in these two places, M. Nicollet has computed the following pa^ 
rabolic elements of its orbit : 
Passage of the perihelion, mean time at Paris, 1818, Feb. 26. 0' 
Perihelion distance, - 1.19878 
Inclination of its orbit, - - 89° 47' 27'^ 
Longitude of ascending node, - 70 21 10 
Longitude of perihelion upon the orbit, 182 56 52 
Heliocentric motion, - - Direct. 
This comet is a very remarkable one, from the singular incli- 
nation of its orbit, which is greater than that of any other that 
has been observed, being only 12' S3" from being perpendicular 
to the ecliptic. 
5. Second Comet ^1818. — ^I. Pons of Marseilles, one of the 
most active of our modern astronomical observers, discovered 
another new comet, in the constellation Pegasus, on the 26th 
November 1818. The following are the results wdiich he obtained. 
R. Ascen. South Declin. 
Nov. SO. 175^37' mean time 179° 38' 29^7' 
Dec. 1. 17 57 180 39 28 47 
This comet, which may be seen through a night telescope, 
has . a diameter of from dye to six minutes. 
