of the variable Star in Sobieski's Shield. 
141 
SECOND PART. 
FontainbleaUj 1803. 
These essential variations of the star being thus settled with 
considerable precision, we may proceed to examine some of 
its other phenomena, particularly one common to most of the 
variables, as likewise in some degree to our sun, viz. that the 
times of their periodical returns of brightness are, in general, 
irregular, a circumstance I apprehend sufficiently interesting 
to engage our attention, at least I have ever thought so, and 
was thereby induced a few years past to make a succession of 
observations on one of them, in hopes of finding in what 
manner such irregularities took place, or at least to leave to 
future astronomers determinations, that might lead them to 
form some ultimate opinion thereon. I therefore chose for 
that purpose the star in Sobieski's shield, on account of the 
time of its revolution on its axis being comparatively of a 
moderate length, viz. 6 2 days, and shall here have the honour 
of laying before the Society the appearances that occurred, 
point out the various results deduced from the observations, 
and attempt to explain them. The two following Tables are the 
observed middle times of its full and least brightness, with de- 
ductions of the star's apparent rotation from single intervals , 
which in the present examination can alone be admitted, be- 
cause a mean taken of two or several would in general make 
such irregularities disappear, by the long and the short ones 
compensating each other. The remarks for the present need 
not be attended to, as they are chiefly to explain the reliance 
that may be put on some of the observations. 
