104 
and leaves us ready for the new investigations which its 
return eighteen months hence will require. . 
Another extended investigation by Husparp is that upon 
the Fourth Comet of 1825. Hansen had long ago found 
that the observations before and after perihelion seemed 
better reconciled by an ellipse than by a parabola; and 
Hvupearp undertook the collection and discussion of all the 
observations in the hope of some definite determination of 
the major axis. This investigation occupied much of his 
time at irregular intervals for five or six years, and was 
finally published in the spring of 1859. In this, as in most 
of these cometary investigations, a leading object was to 
learn whether the motions of the comets, distinguished by 
their magnitude or varying aspect, or by any other striking 
peculiarity, would prove in all cases amenable to the law of 
gravitation alone. In the case of the comet of 1825, no 
special fact of general interest was elicited; but negative 
results, though less interesting, are attained with no less 
labor and skill than positive ones, and are often scarcely 
less important. Suffice it to say of this memoir, that it is 
complete, and apparently exhaustive ; that the elliptic char- 
acter of the comet is fully demonstrated, although its periodic 
time must be exceedingly long; and the material deducible 
from past observation lies ready for the hands of the future 
investigator. 
I have now spoken, Gentlemen, at sufficient length of the 
larger and more extended memoirs of our departed col- 
league, and have described their characteristic features. Of 
his minor contributions to astronomy I need say no more 
than that they resembled the larger ones in thoroughness 
and neatness of conception. The columns of the Astronomi- 
cal Journal, and the pages ‘of the Washington Observations, 
are full of them:— elements and ephemerides of many 4 
