C 2 93 3 
XIX. A series of observations of the satellites of the Georgian planet, 
including a passage through the node of their orbits ; with an 
introductory account of the telescopic apparatus that has been 
used on this occasion ; and a final exposition of some calculated 
particulars deduced from the observations. By William Her- 
schel, LL.D. F. R. S. 
Read June 8, 1815. 
The observations of the satellites of the Georgian planet, of 
which an account is given in this paper, are of such a nature 
that, in order to judge of them properly, and to make them 
useful to those who would continue them, it will be necessary 
to enter into some particulars relating to the telescopic powers 
required for critically viewing such difficult objects. 
The great distance of the Georgian planet renders an 
attempt to investigate the movements of its satellites a very 
arduous undertaking ; for their light, having to traverse a 
space of such vast extent before it can reach us, is so enfee- 
bled, and their apparent diameter so diminished, that an in- 
strument, to be prepared for viewing them, must be armed 
with the double power of magnifying and of penetrating into 
space. 
With regard to the first of these requisites, I have already 
shown in a former Paper,* that the magnifying power of my 
ten feet telescope, when no uncommon degree of light is 
* Phil. Trans, for 1805, page 31. 
