i8(> Dr. Herschei/s Method of observing the 
tude we have dignified by the name of sun, to-morrow may 
slowly begin to undergo a gradual decay of brightness, like 
0 Leonis, a. Ceti, « Draconis, (J'Ursae majoris, and many other 
diminishing stars that will be mentioned in my catalogues. 
It may suddenly increase, like the wonderful star in the back 
of Cassiopea’s chair, and the no less remarkable one in the 
foot of Serpentarius ; or gradually come on like (3 Geminorum, 
Ceti, £ Sagittarii, and many other increasing stars, for which 
1 also refer to my catalogues. And lastly, it may turn into a 
periodical one of 25 days duration, as Algol is one of 3 days, 
8 Cephei of 3, p Lyras of 6, v\ Antinoi of 7 days, and as many 
others are of various periods. 
Now, if by a proper attention to this subject, and by fre- 
quently comparing the real state of the heavens with such 
catalogues of brightness as mine, it should be found that all, 
or many of the stars which we now have reason to suspect to 
be changeable, are indeed subject to an alteration in their 
lustre, it will much lessen the confidence we have hitherto 
placed upon the permanency of the equal emission of light of 
our sun. Many phenomena in natural history seem to point 
out some past changes in our climates. Perhaps the easiest 
way of accounting for them may be to surmise that our sun 
has been formerly sometimes more and sometimes less bright 
than it is at present. At all events, it will be highly pre- 
sumptuous to lay any great stress upon the stability of the 
present order of things ; and many hitherto unaccountable 
varieties that happen in our seasons, such as a general seve- 
rity or mildness of uncommon winters or burning summers, 
may possibly meet with an easy solution in the real inequality 
of the sun's rays. 
