Satellites of the Planet Saturn . 429 
put down in the notes, that it may be compared with the 
obferved one. 
To facilitate this comparifon, I have delineated a fcheme 
wherein the orbits of the iatellites are drawn in their due pro- 
portion. A few words will explain the conftruftion and ufe of 
this figure, which, notwithftanding its fimplicity, is yet amply 
fufficient to afcertain the accuracy of every obfervation. 
In each of the orbits, by way of marking them, is placed 
the fateliite to which it belongs, as it appeared to be fituated 
the 1 8th of October, 1789. The graduated circle is of ufe to 
find, by means of the tables, the apparent place of a fateliite 
for any given time ; or, the apparent lituation of the fame 
fateliite being given, its real Saturnicentric place may be de- 
duced from it. In the center of the fcheme is the planet Sa- 
turn, and its ring, exprelied by a line which reprefents the 
direction of its an fie ; or the ring itfelf, as it appeared in my 
telefcopes during the months of July, Auguft, September, 
Q&ober, and November, 1789. The five lines which are 
carried on parallel to each other ferve to convey the meafure 
of the planet, and its ring, to the orbits, of the fatellites, as 
will be feen in feveral inftances that occur hereafter. 
The graduated circle is divided into degrees, and begins to 
count from that part of every fatellite’s orbit beyond the pla- 
net, which is intercepted by a plane palling from the eye of 
the obferver, at redlangles to the ring, through the center of 
Saturn. Hence it follows, that the point of zero, or 360 de- 
grees, is the fame with the geocentric place of the planet in 
thofe four parts of the orbit of the fateliite where the eye 
is in the plane of the ring, and where it appears the moll 
open ; and that, in other places, it may be had by folving one 
fpherical triangle. This is to be underftood as relating only to 
* See Tab. XIX. fig. 1. 
the 
