Rotation of the Planet Saturn upon its Axis. 65 
meridian at the time of observation, and by the figure we find 
it to be a very marked place. 
A strong evidence of the rotation is the position H 149, ob- 
served Dec. 4, contrasted with the place F 278, which had 
been viewed in the early part of the same evening. The cal- 
culation here completely supports the suspicion which is ex- 
pressed in the observation, 44 that the side which presented 
44 itself then was not the same which had been seen in the be- 
44 ginning of the evening.” 
The observations of Dec. 6, are of the most decisive nature ; 
as will clearly appear by viewing the calculated positions L M 
N O P Q R S T, and comparing them with the descriptions 
belonging to them, that have been given in the observations. 
For, here the revolving belts were successively seen, in all 
their various tints, and the last position T was marked down 
as leaving no doubt of the evident rotation. By the calcula- 
tion it appears that the belts had moved over 32 9 degrees, in 
the course of this evening's observation. 
When the positions c, d, are compared, which were observed 
Dec. 16, we see that the southmost belt had acquired an addi- 
tional brightness, as the observation expresses. It may not be 
amiss to remark upon this occasion, that brightness relates to 
clearness, distinctness, and easiness of vision ; in opposition to 
faintness and confused outlines ; therefore, the belt being 
brighter here, denotes its being more strongly marked by a 
deeper tint of dusky yellow, and by clearer divisions ; so as to 
be easier perceived. 
Dec. 19 furnishes a good instance of the exactness of our 
period ; as the calculated position g perfectly justifies the sur- 
mise which is expressed in the observation. 
mpccxciv. K 
