366 ; Dr. Herschel on the 
combinations of which the* above quantities are a mean do 
not differ much among themfelves ; it may therefore be ex- 
pected that thefe periods will come very near the truth ; and, 
indeed, I have for many months paft been ufed to calculate 
the places of the fatellites by them, and have hitherto always 
found them in the fituations where thefe computations gave 
me realon to expeCt to fee them. 
The epochae, from which aftronomers may calculate the pa- 
fitions of thefe fatellites, are QCtober 19, 1787; for the turft 
19 b. ii 7 28" ; and for the fecond 17 h. 22 7 40". They 
were at thofe times 76° 43' north- following the planet-; 
which, as will be fhewn in the fequel, is the place of the 
greateff elongation of the fecond fatellite; where, confe.- 
quently, its real angular lituation is the fame as the apparent 
one. And I have brought the fir ft fatellite to the fame place, 
as hitherto there has not been time to dilcriminate the lituation 
of its orbit from that of the fecond. 
The next thing to be determined in the elements of thefe 
fatellites is their diftance from the planet; and as we know 
that, when the periodical times are given, it is fufficient to 
have the diftance of one fatellite in order to find that of any 
other, I confined my attention to the difeovery of the diftance 
of the fecond. As foon as 1 attempted meal u res, it appeared, 
that the orbit of this fatellite was feemingly elliptical; it be- 
came therefore neceffary, in order to alcertain its greateff 
elongation, to repeat thefe meafures in all convenient fitua- 
tions; the refult of which was, that on the i8th of March, 
at 8 h. 2' $o // , I found the fatellite at the diftance of 46 // ,46 ; 
this being the largeft of all the meafures 1 have had an opportu- 
nity of taking, hence, by computation, it appears, that the 
7 fatellite’s 
