370 JD r. Herschel on the 
me to attempt as many meafures as pofiible, that I might be 
enabled to come at the proportion of the axes of the apparent 
elliplis ; and thence argue its lituation. But here I met with 
difficulties that were indeed almoft infurmountable. The un- 
common faintnefs of the fatellites ; the fmallnefs of the angles 
to be meafured with micrometers which required light enough 
to fee the wires; the unwieldy fize of the inftrument, which, 
though very manageable, ftill demanded affiftant hands for its 
movements, and confequently took away a great (hare of my 
own directing power, a thing fo necefiary in delicate obferva- 
tions; the high magnifiers I was obliged to ufe by way of ren- 
dering the lpaces and angles to be meafured more confpicuous ; 
in fhort, every circumftance feemcd to confpire to make the 
cafe a delperate one. Add to this, that no meafure could pof- 
fibly fucceed which had not the moft beautiful fky in its fa- 
vour ; and we may eafily judge how fcarce the opportunities of 
taking fuch meafures mult be in the variable climate of this 
ifland. As far then as a fmall number of feleCt meafures will 
permit, which, out of about twenty-one that were taken, 
amounts only to five, I fhall enter into our prefent fubjeCt of 
the portion of the fecond fatellite's orbit. 
The following table contains in the fir ft column the correct 
mean time when the meafures w r ere taken. The fecond gives 
the quantity of thefe meafures. In the third column are the 
fame meafures reduced to the mean diftance of the Georgian 
planet from the earth. The fourth contains the calculated 
pofitions of the fatellite as' it would have appeared to be fitua- 
ted if it had moved in a circular orbit at rectangles to the vifual 
ray ; and the degrees are numbered from the firft obfervation 
fuppofed to have been at zero, and are carried round the circle 
from right to left. 
March 
