14-i Mr. P r gott’s Investigation of the Changes 
suggesting previously a few plausible conjectures, and some 
inferences arising from the observations themselves, 
ist. That the body of the stars are dark and solid, 
sd. Their real rotations on their axes are regular. 
3d. That the surrounding medium is by times generating 
and absorbing its luminous particles in a manner nearly similar 
to what has been lately so ingeniously illustrated by the great 
investigator of the heavens, Dr. Herschel, with regard to the 
sun's atmosphere. 
4th. That these luminous particles are but sparingly dispersed 
in the atmosphere surrounding the variable star of Sobieski, 
appears from the star being occasionally diminished to the 6.7 
magnitude, and much less. July 4, 1799, it was of the 7th; 
September 15, 1798, and August 9, 1803, of the gth, if not 
invisible. (See Table VII. ) Does not this indicate a very small 
portion of light on its darkened hemisphere ? 
5th. And may we not with much plausibility consider them 
as spots, somewhat circular, or of no great extent ? for even on 
its brightest hemisphere the duration of its full lustre is, on a 
mean, only 9^ days of the 6 2, or about one-sixth and \ of its 
circumference. (See Table VIII. page 140.) The dimensions 
therefore of the parts enlightened seem much circumscribed, 
and can be tolerably estimated, and consequently may be re- 
presented very small, particularly if the powerful effect of a 
little light and the length of time a bright spot is remaining in 
view be taken into consideration. 
6th. And a further ground of presumption that those principal 
bright parts are but slight patches is, that they undergo perpe- 
tual changes , and also that such changes are very visible to us, 
for most probably they would be imperceptible, were not the 
