100 
With this brief sketch of the history of our knowledge of 
Biela’s comet, I may, without entering into close detail, de- 
scribe Husparp’s labors and researches concerning it. His 
published Memoirs on this subject are three in number, in 
addition to sundry smaller communications on special points; 
such as one in which he corrected a serious error, which had 
found its way into the best European computations of the 
perturbations in 1845 — 6, and explained its’ probable origin; 
‘and a publication of the valuable manuscript observations 
made by Professor Cuaxis in Cambridge, England, during 
the same period, and “sent by this distinguished astronomer 
to Professor Hunparp for employment in his investigations: 
The first of these Memoirs is entitled, “On the Orbit of 
Biela’s Comet in 1845-6.” In this, as in every other me- 
moir of its author, the same searching thoroughness and 
scrupulous accuracy are manifest which I have recounted 
concerning his investigation on the comet of 1843. All 
known observations were employed, no appreciable refine- 
ment of method or computation was neglected ; and the ma- 
terials were so fully and completely discussed that it is im- 
probable that any results can ever be drawn from them 
which he did not himself deduce. The principal results of 
this memoir, in addition to the discussion of all the observa- 
tions, consisted in the definite determination of elements for 
each component, together with their variations for any vari- 
ation of the adopted mean motion ; and in the discovery that 
by far the greater part of the difference between the two 
orbits might be represented by a variation in the mean 
anomaly alone. The residual errors implied by this assump- 
tion are very small, much Jess than the errors of individual 
observations, and in no case exceeding 8”; but they are 
nevertheless too symmetric, and too large for his normal 
2A RS Sa eA ae 
