Aatrcmmiy. 175^ 
; The following are the elements of other astronomers 
Prof. Encke Prof, Nicolai of . H. Von Sta;jidt ; 
of Seeberg. Manheim. of Gottingen, 
Passage of Perihelion, Mar. 21. 405 Mar. 21. 6016 . Mar. 21. 6026 
Longitude of Perihelion, 239° 20' 45^' 239° 34' 5" 239° 36': 0" 
Long. Perihelion distance, 8.95966 8.96466 8.9641627 
Long, of Node, - 48° 34' 37" 48° 43' 34" 48° 45' 44" 
Inclination of Orbit, 74 5 0 73 23 15 73 16 33 
The following interesting observations on the comet were made 
by Mr J. F. W. Herschel with the 7 and 10 feet reflector at 
Slough. With neither of these could he discover any central 
star-like point, such as he had distinctly seen in the comet of 1819. 
It seemed a mere misty mass. The tail was about S long, and 
seemed to be somewhat less bright along its axis. The head 
seemed rather obscure, and appeared to have lateral portions of 
light, which seemed to go off at a greater angle than the tail. — 
See Memoirs of the Astronomical Society^ vol. i. p. 154. 156, 157. 
6. Supposed Volcanoes in the Moon. — The luminous appear- 
ance in the moon, which Captain Kater and Mr Dunlop ob- 
served on the 5th February 1821, and which Captain Kater 
considered as a lunar volcano, was observed by Dr Olbers, who 
thinks that there are no volcanoes in the moon, and that this phe- 
nomenon is capable of another explanation. It was situated, he 
observes, either in or near the spot marked Aristarchus, which is 
always enlightened by the earth, or the dark portion of the 
moon when three or four days old, and is distinguishable from 
all the other spots in the moon by its brightness. The lumi- 
nous appearance, however, on the 5th of February was entirely 
different from the usual appearance of Aristarchus, and appear- 
ed with a five feet achromatic telescope like a star of the 6th 
magnitude. 
Professor Struve of Dorpat observed the very same phenome- 
non on the 27th January 1822; He describes it as a point near 
Aristarchus, resembling a star of the 8th magnitude, and is of 
the same opinion with Dr Olbers that it is not a volcano. 
The same phenomenon was seen in Aristarchus on the 4th 
and 5th May 1821 by Mr Ward at Tam worth, and by Mr 
Bailey. Hevelius describes the spot called Aristarchus under 
the name of Mons Porphyrites^ and describes it as aut ex rupe 
rubra^ aut sabulo^ sive terra rubicunda constare^ aut prorsus 
