358 Dr. Herschel’s observations of the satellites 
when the orbits of the satellites were contracted into a 
line, which might be examined with greater facility than a 
more expanded space ; and where even the very situation of 
a star in this given direction, rather than in the numberless 
others, in which it might be placed, must be a presumption of 
its being a satellite, provided its distance at the same time 
should not exceed a certain probable limit. 
An interior satellite. 
The supposed interior satellite observed January 18, 1790, 
could not be a star, whose existence was doubtful, as it had light 
enough for an estimation of its distance in diameters of the 
planet ; its absence, however, not having been noticed the 
19th of January, although great attention has been shown to 
ascertain the sidereal nature of another supposed satellite, 
observed at the same time with the former, leaves the obser- 
vation of the eighteenth unsupported. 
The observation of the 4th of March 1794, which has been 
supposed to relate to an interior satellite, is by the identifying 
method proved to belong to the second satellite ; and its ob- 
served absence on the 5th from the place where it was the 
4th, being thus verified and accounted for, shows that great 
confidence may be placed on such observations. 
The observation of an interior satellite of the 27th of March, 
i794)> is without a subsequent observation ; but then it has 
already been noticed in remark III, that an interior satellite 
cannot be seen two successive days, when its orbit is already 
contracted, as it was on the day of observation. 
