11 
remarkable appearance. On the broad south belt three spots 
were distinctly visible, and at the same time three satellites 
appeared off the disc. The first spot in the order of transit 
was very black — this was the shadow of the third satellite. 
The next spot was brown in colour when contrasted with 
the belt — this was the third satellite ; and the third spot, 
which was the shadow of the fourth satellite, was very dark 
and well defined. At this time the fourth satellite appeared 
very faint in comparison with the first satellite, which was 
just below it. The second satellite, which was on the west 
edge of the planet, was soon eclipsed, and attention was 
entirely directed to the fourth satellite, which was the next 
to transit. As this satellite entered on the disc it was 
visibly brighter than the planet ; after a short time it dis- 
appeared, and then, to my surprise, it became visible again 
as a dark spot, and at intervals it was as black as its own 
shadow. The alteration in the colour of this satellite during 
its transit has been noticed by several observers, but I was 
not prepared for such a complete change . from a bright 
object to one as black almost at times as an ink spot. 
During these observations the first satellite had entered on 
the disc of the planet, and when it was about half its dia- 
meter on the planet it appeared to me to be in contact with 
its own shadow. After a short time I could only distinguish 
the first satellite at intervals, closely following its own 
shadow. Before the third satellite passed off the disc it 
became nearly invisible, and when close to the edge of the 
disc it appeared brighter than the surface of the planet. 
The fourth satellite was not observed at the end of its 
transit. 
Mr. Robert Worthington, F.R.A.S., observed some of the 
phenomena with me, and remarked at the time that he did 
not recollect having seen Jupiter so sharply defined as on 
that evening. The bays and various markings on the belts 
were most beautifully distinct. 
