Account of a RemarJmhle Comet, 391 
the planetary orbits, they have acquired, as objects of terror, a 
degree of importance which they could not have commanded as 
objects of science. 
As the comet of 1682 is the only unequivocal instance in which 
these bodies have re-visited our system, astronomers have expe- 
rienced no inconsiderable difficulty in assigning some reasonable 
attributes to these mysterious strangers. Under such circum- 
stances, the discovery of a comet which has returned five times, 
which never ranges beyond the orbit of Jupiter, and which may 
therefore be regarded as forming part of our own system, is an 
event peculiarly interesting to astronomers. Its short period of 
little more than years, and its mean distance from the sun, 
which is not much greater than twice that of the Earth, connect 
it in a particular manner with the part of the system in which 
we are placed ; and when we consider, that in the performance 
of its triennial rounds, it crosses the orbit of the Earth more than 
sixty times in the course of a century, we cannot but consider 
the probability of a collision as greatly increased. 
This remarkable comet was discovered at Marseilles by M. 
Pons on the 26th November 1818, in the constellation Pegasus. 
It was easily seen through a night telescope, and had a diame- 
ter of from five to six minutes. The parabolic elements which 
were computed for it by M. Bouvard, did not represent the ob- 
servations with sufficient accuracy. The difference between the 
theory and observation, was reduced from 3' to by the el- 
liptical elements computed by M. Enke, Joint Director of the 
Observatory of Seeberg, which we published in p. 200. of our 
last Number. 
As this comet had a short period of little more than 3| years, 
or 1202.54 days, astronomers naturally conjectured that it must 
have been repeatedly observed ; and they soon found that it 
had a considerable resemblance to the comets of 1786, 1795 
1801, and 1805. Dr Maskelyne had observed it on the 20th, 
21st and 24th November, and compared it with three small stars 
of the 7th and 8th magnitude, whose positions are unfortunately 
not known. 
The following elements of its orbit as calculated from the ob- 
servations made in 1795, 1805, and 18||, have such a singular 
* Dr Olliers of Bremen suggested that the comet of 1 795 was the same as that 
ofJ818. 
