Astronomical and Nautical Collections. 97 
visit. Dr. Oxzers first pointed out to me that if it passed the 
perihelium later than the 10th of September, it will be visible to 
Europeans in August. From a cursory computation of the per- 
turbations, I find that its perihelium will be about Sept. 16.4, and 
its places will be nearly these: 
A.R. Decl. Log. Dist. 
1825 aatiy iF iets © = 
Aug. 1.6 82 31 32 1N 0.023 0.162 
6.6 90 23 32. 9 9.988 0.141 
11.6 99 1 3] 44 9.948 0.123 
16.6 108 19 30 36 9.903 0.107 
21.6. 118 9 28 37 9.852 0.097 
26.6 128 14 25 40 9.792 0.092 
31.6 138 23 21 46 9.724 0.093 
Its next return to the perihelium will be in Dec. 1828, or per= 
haps in the beginning of January 1829: and it will then be easily 
visible, unless its light should prove to be gradually dimi- 
nishing. 
In attempting to compute the perturbations, it becomes necessary 
to employ higher powers of the quantities concerned than those 
which are sufficient for the planets, and no precautions or suppo-. 
sitions respecting the masses of the disturbing bodies are capable 
of representing the successive revolutions from each other without 
errors of several degrees. For example, we represent the five 
perihelia of 1786, 1795, 1805, 1819, and 1822, most conveniently 
by taking the mass of Jupiter 71; less than that which is assigned 
by Laplace: but errors exceeding a whole day in the interval will 
still remain: and the middle three of the five considered alone 
afford still greater irregularities, although the actions of the planets 
which are neglected would have a very inconsiderable influence on 
this combination. 
Comprehending the effects of 8, 9, and ©, the best result is 
obtained by increasing the mass of Jupiter about 4: but the ele- 
ments thus corrected give the perihelium of 1786 two days too 
early, and that of 1822 a day and a half too late: nor will any 
Vou. XVII. H 
