92 
* comet, as his most favorite problem. And although some 
six years elapsed before he found it within his power to 
begin the long-desired research, he then prosecuted it with 
an earnestness which showed no loss of interest or of en- 
thusiasm. 
In December, 1849, he published the first part of this 
masterly discussion of the Orbit of the Great Comet of 
1845,—an investigation begun only a few months before, 
but hastened for the sake of an early contribution to the 
Astronomical Journal. This paper occupied a part of eight 
numbers, the conclusion appearing in July, 1852. It seems 
to me safe to say that the orbit of no comet of long period 
has been more thoroughly and exhaustively treated than this. 
All observations of the comet, of whatever kind, whether 
before published or obtained from the manuscripts of astron- 
omers, were subjected to rigorous scrutiny, and were wil- 
nowed with a painstaking fidelity which would have sur- 
passed the patience of most men. Especially were the 
very important sextant-observations, made in the daytime 
on the 28th of February by Captain Crarke, at Portland, 
Maine, and by Mr. Bownrrne, at Chihuahua, discussed with 
extreme care, and made, after sundry corrections, to exert 
an important influence upon the resultant orbit. 
First forming normal places by the aid of one of the ap- 
proximate parabolas at hand, Husparp computed elliptic 
elements by the ordinary Gaussian method, and thus ob- 
tained new normals. Determining for these the coefficients 
of the variations of the elements relatively to the varia- 
tions of the geocentric co-ordinates, — and, for the sake of 
control, both by Besset’s method and by that of GoxrTze, 
he deduced the variations required for satisfying the new 
normals, and thus arrived at a second set of elements. 
Repeating the process, and computing ten new equations 
