310 Mr. Schroeter/s Observations 
that it actually has an atmosphere of no small extent, was the 
striking diminution of light which I noticed on the planet in its 
various phases from its exterior limb towards the interior edge 
of its illuminated surface, and especially near the latter*: and 
this appearance it was which induced me to make farther ob- 
servations on the subject, especially as I found that the phee- 
nomenon recurred as often as I looked at the planet with an 
Herschellean four and seven-feet reflector, armed with the 
higher magnifying powers. 
The great number of observations I have now made on this 
object, for a series of years, being upon the whole very similar 
in their nature and results, it would no doubt be not only te- 
dious, but also superfluous, to describe them here at length : 
but the following general remarks it may be necessary to 
premise, in order to obviate all misapprehension, and the false 
conclusions that might be deduced from hasty and inaccurate 
observations. 
In fig. i. Tab. VI. which I have annexed for the sake of 
greater perspicuity, the light appears strongest at the out- 
ward limb a , b, c, from whence it decreases gradually, and in 
a regular progression towards the interior edge or terminator, 
and this not only towards its middle d, e, but also near the 
two cusps f g, h i, the light becoming so dim immediately at 
this border g, f, d, e , h, i, that it commonly loses itself in a 
faint bluish grey, forming a very indefinite ragged margin, 
scarce discernible with the best telescopes, and which, in se- 
veral of the phases, resembles the interior uneven border of 
the moon, as it appears to the naked eye, or to a power mag- 
nifying from i to 4 times. The following circumstances must 
necessarily be attended to respecting these observations. 
