346 Dr. Herschel’s Observations of the 
are performed in the same time the satellites revolve in their 
orbits. 
In the following table are the calculated places of the satel- 
lites; the correct sidereal times, given with the observations, 
having been turned into mean time. 
Table of the Positions of the four Satellites of Jupiter at the Time 
of the Observations. 
Time or Observ. 
1 1 
1 'I 
1 HI 
Rv 
| Time of Observ. | 
1 1 11 
III | 
IV 
' 794 - t 
July i9 d 9" 21 
O 
12 7 
O 
34 6 
O 
'79 
0 
46 
1796. 
Aug. i8 d 
8 h 21' 
O O 
"5 
O 
0 
191 
July 21. 8. 57 | 
I 
1 1 
1 2 78 | « 9 ,! Se P t - , 5 - 
7 - +4 
36 1 328 
198 | 
July 26. 8. 56 j 
124 I 333 I 
169 j 205; i^ept. 21. 
7. 19 
'7 2 | 214 
>38 | 
210 
July 28. 8. 59 | 
1 ' 7 i 1 
| 176 | 270 | 248; ,Sept. 24. 
8. 38 
74 1 '63 
3°5 1 27s 
July 30. 10. 27 I 231 I 25 | 
'3 
| 29Z1 jSept. 30. 
7. 27 
206 | 46 
24+ 1 
36 
July 31. 8 40 | 
| 59 
| 1 1 8 | 
60 1 
1 3'2 
jOct. 15. 
7 - 44 
28 j 130 
1 
s 
Aug. I. 8. 56 | 
265 | 
1 221 1 
in 
1 33 + 
Oct. 15. 
10. 15 
49 1 
1 
Aug. 9. 8 42 j 
83 1 
1 3 '° 1 
152 | 
1 '38 
Oct. 16. 
10. 39 
256 | 243 
334 1 
1795 - 
iOct. 25. 
7 - 25 
261 | 72 
59 I 
Sept. 30. 7. 37 
294 
62 
219 
100 
Nov. 3. 
9. 0 
306 | 270 
' 5 ' 1 
58 
Oct. 2. 7. 32 | 341 | 
1 264 | 319 1 
>43 
1 
It will be necessary now to explain in what manner, with 
the assistance of this table, the observations of the brightness and 
magnitudes of the satellites have been reduced to the expressions 
they bear in the four circles of the figures contained in Tab. 
VIII. and IX. By way of uniformity I judged it would be best 
to reduce the estimations of magnitude to those of brightness ; 
as it may be justly supposed that when a satellite is at any given 
time larger in proportion to another than it was at another time, 
it will also be brighter, than it was at that other time, due re- 
gard being had to the light of the satellite to which its magni- 
