C 133 3 
VI. On the periodical Changes of Brightness of two fixed Stars. 
. By Edward Pigott, Esq. Communicated by Sir Henry C. 
Englefield, Bart. F.R.S. 
Read January 12, 1797. 
Bath, August, 1796. 
Although those far distant suns, the fixed stars, have baffled 
all investigation with regard to our knowledge of their dis- 
tance, magnitudes, and attractions ; we have, nevertheless, by 
determining their periodical changes of light, established a 
strong affinity between them and our sun ; and among such 
an inconceivable number, we may expect to find some with 
periods of rotation much longer and shorter than those we are 
already acquainted with, and with changes perhaps even suf- 
ficiently rapid to afford a ready means for determining accu- 
rately differences of terrestrial longitudes. This would be a 
most satisfactory, useful, and profitable discovery, and may be 
the lot of those who have but a slight knowledge of astronomy, 
provided that with great exactness, and a good memory, a con- 
stant look out be given. The discoveries which at present I 
have the honour of laying before the Society, are the periodical 
changes of brightness of two stars, one in Sobieskis Shield , 
the other in the Northern Crown. 
The constellation of Sobieskis Shield consists of a very few 
stars, and was formed by Hevelius, in honour of a king of Po- 
land ; the variable star that now appears in it was, doubtless, 
not noticed by him, as he has set down stars near it, which 
are by times much less conspicuous. It has nearly the same 
right ascension as the star l, and is about one degree more 
