ASTRONOMY. 
354 
the great number of fmall telefcopic comets that have been 
observed ; and to tiie far greater number that (bill are pro¬ 
bably much too (mall for being noticed by our mod dili¬ 
gent fearchers after them. This throws a myftery over 
their deltinatioft, which feems to place them in the allego¬ 
rical view of tool?, probably defigned for fome falutary 
purpofes to be wrought by them ; and, whether the refto- 
ration of what is loft to the Sun by the emiflion of light, 
the poflibiliry of which we have been mentioning above, 
may not be -one of thefe purpofes, I (hall not prefume to 
determine. The motion of the comet difcovered by Mr. 
Meftier in June, 1770, plainly indicated how much its or¬ 
bit ivai liable to be changed, by the perturbations of the 
planets ; from w hich, and the little agreement that can be 
found between the elements of the orbits of all the comets 
that have been obferved, it appears clearly that they may 
be directed to carry their falutary influence to any part of 
the heavens. 
“ My hypothefis, however, fays Dr. Herfchel, does 
not lay me under any obligation to explain how the Sun 
can fuftain the wafte of light, nor to (hew that it will fuf- 
tain it for ever ; and I fhould alio remark, that, as in the 
analogy of generating clouds I merely allude to their pro- 
dutftion as owing to a decompoiition of lome of the elaftic 
fluids of our atmofphere, that analogy, w hich firmly refts 
upon the faff, will not be lefs to my purpofe, to whatever 
caufe thefe clouds may owe their origin. It is the fame 
with the lucid clouds, if I may fo call them, of the Sun. 
They plainly exift, becaufe vve fee them ; the manner of 
their being generated may remain an hypothefis; and 
mine, till a better can be propofed, may (land good ; but 
whether it does or not, the confequences I am going to 
draw from what lias been faid will not be aff'effed by it. 
“ Before I proceed, I lliall only point out that accord¬ 
ing to the above theory, a dark (pot in the Sun is a place 
in its atmof phere which happens to be free from luminous 
decompolitions ; and that faculae are, on the contrary, 
more copious mixtures of fuch fluids as decompofe each 
other. The penumbra which attends the fpots, being ge¬ 
nerally deprelfed more or lefs to about half way between 
the folid body of the Sun and the upper part of thofe re¬ 
gions in which luminous decompofltions take place, mud 
of courfe be fainter than other parts. No fpot favourable 
for taking meafures having lately been on the Sun, 1 can 
only judge from former appearances, that the regions in 
which the luminous folar clouds are formed, adding there¬ 
to the elevation of the faculae, cannot be lefs than 1843, 
nor much more than 2765, miles in depth. It is true that 
in our atmofphere the extent of the clouds is limited to a 
very narrow compafs ; but we ought rather to compare 
the folar ones to the luminous decompofltions which take 
place in our aurora borealis , or luminous arches, which 
extend much farther than the cloudy regions. The den- 
fity of the luminous folar clouds, though very great, may 
not be exceedingly more fo than that of our aurora borealis. 
For, if we confider what would be the brilliancy of a fpace 
two or three thoufand miles deep, filled with fuch corruf- 
cations as we fee now and then in our atmofphere, tlieir 
apparent intenfity, when viewed at the diftance of the Sun, 
might not be much inferior to that of the lucid folar fluid. 
“From the luminous atmofphere of the Sun I proceed 
to its opaque body, which by calculation from the power 
it exerts upon the planets we know to be of great folidity ; 
and from the phenomena of the dark fpots, many of which, 
probably on account of their high lituations, have been 
repeatedly feen, and otherwife denote inequalities in their 
level, we furmife that its furface is diverfified with moun¬ 
tains and vallies. 
“What lias been faid enables 11s to come to fome very 
important conclufions, by remarking, that this way of 
conlidering the Sun and its atmofphere, removes the great 
< 3 iffimilarity we have hitherto been ufed to find between its 
condition and that of the reft of the great bodies of the 
folar fyftem. The Sun, viewed in this light, appears to 
be notlung elfe than a very eminent, large, and lucid, pla- 
net, evidently the firft, or in ftriiftnefs of fpeaking the 
only primary one, of our fyftem ; all others being truly 
fecondary to it. Its fimilarity to the other globes of the 
folar fyftem with regard to its folidity, its atmofphere, and 
its diverfified furface ; the rotation upon its axis, and the 
fall of heavy bodies, leads us on to fuppofe that it is moft 
probably alfo inhabitated, like the reft of the planets, by 
beings whole organs are adapted to the peculiar circum- 
ftances of that vaft globe. 
“Whatever fanciful poets might fay, in making the Sun 
the abode of blelfed fpirits, or angry nioralifts devife, in 
pointing it out as a fit place for the punilhment of the 
wicked, it does not appear that they had any other foun¬ 
dation tor their aifertions than mere opinion and vague fur- 
mile ; but fays Dr. Herfchel, I think my felt authorized, 
upon aftronomical principles, to propol'e the Sun as an in¬ 
habitable world, and am perfuaded that the foregoing ob- 
fervations, with the conclufions 1 have drawn from them, 
are fully (efficient to anfvver every objection that may be 
made againft it. It may, however, not be amifs to re¬ 
move a certain difficulty, which arifes from the effect of 
the Sun’s rays upon our globe. The heat which is here* 
at the diftance of ninety-live millions of miles, produced 
by thefe rays, is fo confiderable, that it may be objected, 
that the furface of the globe of the Sun itfelf muft be 
lcorched up beyond all conception. This may be very 
fubftantially anfwered by many proofs drawn from natural 
philofophy, which (hew that heat is produced by the Sun’s 
rays only when they aft upon a calorific medium ; they 
are the caufe of the produftion of heat, by uniting with 
the matter of fire, which is contained in the fubftances- 
that are heated : as the collifion of flint and fteel will in¬ 
flame a magazine of gunpowder, by putting all the latent 
fire it contains into aftion. But an inftance or two of the; 
manner in which the folar rays produce their effect, will 
bring this home to our mod common experience. 
“ On the tops of mountains of a-fuffleient height, at an? 
altitude where clouds can very feldom reach, to flicker 
them from the direft rays of the Sun, we always find re¬ 
gions of ice and fnovv. Now if the folar rays themfelves- 
conveyed all the heat we find on this globe, it ought to be 
hotteft where their courfe is leaft interrupted. Again,, 
our aeronauts all confirm the coldnefs of the upper regions 
of the atmofphere ; and fince, therefore, even on our 
Earth the heat of any fituation depends upon the aptnefs 
of the medium to yield to the impreflion of the- folar rays* 
we have only to admit, that on the Sun itfelf, the elaftic 
fluids compofing its atmofphere, and the matter on its 
furface, are of fuch a nature as not to be capable of any 
exceflive affection from its own rays ; and indeed, this 
feems to be proved by the copious emiffion of them ; for 
if the elaftic fluids of the atmofphere, or the matter con¬ 
tained on the furface of the Sun, were of fuch a nature as 
to admit of an eafy chemical combination witli its rays', 
their emiflion would be much impeded. Another well- 
known fact is, that the folar focus of the largeft lens* 
thrown into the air, will occafion no fenfible heat in the 
place where it has been kept for a confiderable time, al¬ 
though its power of exciting combuftion, when proper 
bodies are expofed, fhould be fuffleient to fufe the mod 
refractory fubftances.” From thefe, and the foregoing ar¬ 
guments, Dr. Herfchel finally concludes, that the Sun is 
a planet, abundantly ftored with inhabitants. 
As to the figure of the Sun, this, like the planets, is not 
perfedtly globular, but fpheroidical, being higher about 
the equator than at the poles. The reafon of which is 
this:- the Sun has a motion about his own axis; and there¬ 
fore the folar matter will have an endeavour to recede 
from the axis, and that with the greater force as their 
diftances from it, or the circles they move in, are greater: 
but the equator is the greateft circle; and the reft, towards 
the poles, continually decreafe ; therefore the folar mat¬ 
ter, though at firft in a fpherical form, will endeavour to 
recede from the centre of the equator farther than from 
the centres of the parallels. Confequently, fince the gra- 
