Two Satellites of the Georgian Planets 129 
their orbits till I can bring fome of my micrometers to bear 
upon them ; which, thefe laft nights, I have in vain attempted, 
their light being fo feeble as not to Suffer the lead; illumina- 
tion, and that of the planet not being ftrong enough to render 
the lmall filk-worm’s threads of my delicate micrometers vifi- 
ble. I have, nevertheless,, feveral refources in view, and do 
not defpair of Succeeding pretty well in the end. 
W. HERSCHEL. 
Slough, near Windfor, 
February it, 1787. 
f 
Vol. LXXVII. 
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