450 
lately difcovered by Mr. Harding, which 
? 
he finds, in every refpect, to refemble the 
ether two which were firft feen by M. 
Piazzi and Olbers; fo that he fays the 
Ceres, Pallas, and Juno, are certainly 
three individuais of the fame {pecies. 
- The telefcope that fhews the diameter 
of one-fourth of a fecond of a degree, will 
mot determine-whether the difk of thefe 
afteroids is real or fpuricus. .A diftinct 
magnifying power of more than fix hun- 
éred has been applied to Ceres, Pallas, 
and Juno, but without fucceds. Every 
method tried upon thefe bodies, proves 
their refemblance to very fmall ftars. ¢* Tt 
will appear,”’ fays the learned aftronomer, 
<¢that when I ufed the name (afteroid) 
to denote the condition of Ceres and Pallas, 
the definition I then gave of this term, 
will equally exprefs the nature of Juno, 
which, by its fimilar fituation between 
Mars and Jupiter, as well as by the fmall- 
nefs of its diik, added to the confiderable 
inclination and excentricity of its orbit, de- 
parts from the general condition of planets. 
The propriety, therefore, of ufing the 
fame appellation for the lately-difcovered 
celeftial body cannot be doubted. 
Had Juno prefented us with a link of a 
chain uniting it to thofe great bodies, 
whofe rank in the folar fyftem I have alfo 
defined by fome approximation of a mo- 
tion in the zodiac, or by a magnitude not 
very different from a planetary one, it 
might have been an inducement for us to 
fafpend our judgment with refpect to claf- 
fification ; but the fpecific difference be- 
tween planets and afteroids appears now 
by the addition of a third individual of the 
latter {pecies, to be more fully eftablifhed, 
and that circumftance, in my opinion, has 
added more to the ornament of cur fy{tem 
than the difcovery of another planet could 
have done. 
Sir JosEPH Banxs has-laid be‘ore the 
Royal Society Mr. PicoTt’s Invefligation 
_of allthe Changes of the variable Star, that 
he difcovered as fuch in 1795, in Sobiefki’s 
fhieid. From long continued obfervations 
it appears that its rotation on its axis was 
eftimated in 1796, at 623 days from a 
mean of fix obfervations of its greateft and 
leaft brightnefs. Since that period, Mr. 
Pigott has made a great number of other 
-obfervations, fome of which commenced 
with the full brightnefs, and others with 
the leaft brightnels of the ftar: according 
to the frff tet of obfervations, the mean 
rotation was 63 days, according to thie 
fecond, it was 593. / mean of thefe 
two means being 614, agrees with the firft 
deductions to within 345 a coincidence 
Proceedings of Learned Societies. 
[June I, 
which he could not have éxpedcied to hap- 
pen.- He then proceeds to mention other 
changes that he perceived, and puts them 
down in a table. 
From the above and other obfervations ,. 
made with a great care and aceuracy, Mr. 
Pigot conciudes that the periodical returns 
of brightmefs are uncommonly flu&tuating, 
andthat the differencés between the extremes 
are very confiderable; to account for which, 
the following explanations and conjectures 
are given: 
1. That the bodies of the flars are 
dark and folid. 
2. Their real rotations on their axes are 
regular. 
3. The furrounding medium is by times 
enerating and abforbing its luminous 
particles in a manner fimilar to what 
has been lately illuf@rated by Dr. Her- 
fchel with regard to the fun’s atmo- 
{phere. 
4. That thefe luminous particles are 
but fparingly difperfed in the atmofphere 
{urrounding the variable ftar of Sobiefki. 
5. They may perhaps be confidered as 
{pots fomewhat circular, or of no great 
extent: for, z. even on its brighreft hemi- 
{phere, the duration of its full luftre is, on 
a mean, only 94 days.of the 62, or little 
more than one fixth of its circumference. 
2. They undergo perpetual changes which 
are vifible tous; and, 3. By the obferva- 
tions of increafe and decreafe of brightnefs, 
fome idea of the relative fituation or inter- 
vals between the bright parts may be ob- 
tained. 
Mr. Pigott, from obfervations and 
reafoning, is led to infer that there maybe ‘ 
primary wneniightened ftars that have ever 
remained in eternal darknefs: and he afks 
if it would be too daring or vifionary to 
fuppofe the number of thefe equal to thofe 
endowed with light, particularly when we 
contemplate the ample fet of bodies vifible 
only by reflected rays, that appertain to 
our fyf&em, fuch as planets, afteroids, 
comets, and fatellites. Do not thefe, 
he adds, lead us to fufpeé alio that the 
enlightened tiars ave thofe that havealready 
attained the higheft degree of perfeétion ? 
Granting, thercfore, that fuch multitudes 
do really exiit, clufters of them, by being 
collected together, as in the milky way, 
mu(t intercept all more diftant rays, and if, 
free from any intervening lights, they 
would appearas dark {paces in the heavens, 
fimilar to what has been obferved in the 
fouthern hemifphere. That fo few of 
thefe obfcure places are perceived, ‘may be 
attributed to their bemg obliterated by 
the pretence either of fome feattered flars, 
or 
