598 P L A 
fhould exift within the planet itfelf, and grow out of ac¬ 
cidents arifing from its general motion. Whatever varies 
the rotation of the axis of motion (that is, of the mafs,) 
round the axis of the real matter in a planet, would ne- 
ceflarily vary its rotary impulfe, increafe or diminifh its 
centrifugal force, and give a variation to the length of the 
radius vedlor; and hence the elliptical form of the orbits of 
the planets. 
The maffes of each planet would be kept together, and 
accidental difturbances in the arrangement of the parts 
would be reftored, by the fubjeftion of each part to the 
paramount motions of the whole ; and the medium of l'pace, 
whatever it may be, would thus be an adling caufe of 
motion, like a current of the fea, and not a means of re¬ 
finance, as has been miftakenly fuppofed. 
There would be no occult principle of attraction or 
gravitation concerned in any part of the phenomena; 
but the whole would be a neceflary refult of the known 
laws of motion, at once fubordinate, analogical, harmo¬ 
nious, and fit. The phenomena of the univerfe are the 
refults of a fyftem of motion producing motion; and of 
motion generated by motion. By this agency a ftone is 
propelled to a planet by the motions of the planet ; a 
planet is carried round the fun by the motions of the fun ; 
a fecondary is carried round a primary by the joint 
motions of the fun and primary ; and the motions of the 
fun are, perhaps, caufed by the motions of fyftems of funs ; 
while the motions of thofe fyftems may again be caufed 
by other fuperior motions ! In fliort, all nature confifts 
of a feries of included motions produced by the motions 
of fuperior bodies and fyftems, till we afcend to the firft 
term in the feries—an infcrutable Cause of Causes. 
The general mathematical laws would be the fame 
as thofe heretofore determined, though the refults would 
be produced by different trains of reafoning. The data 
would, however, be more precife and analogical, and the 
deductions therefore more fatisfaCtory. 
I infer, generally, that motion is the primary and 
proximate caufe of all phenomena; that it operates 
in a defcending feries from the rotation of the fun round 
the fulcrum of the folar fyftem, to the fall of an apple to 
the earth ; that, as transferred through all nature from 
its fource, motion ferves as the efficient caufe of every 
fpecies of vitality, of every organic arrangement, and of 
all thofe accidents of body heretofore afcribed to gravita¬ 
tion; and I venture further to fuggeft, as a theological 
deduCiion, quite as probable as the doCtrine of the New¬ 
tonians, which afcribes their gravitating or projeCtile 
force to the immediate agency of the Deity, that motion, 
as a great fecondary caufe, may be regarded, in its uniform 
operation from the great to the lmall, as the hand of 
Omnipotence; while, as a principle of caufation, it 
neceffarily involves the attribute of omnipresence. 
Monthly Mag. OCh 1817. 
Sir Richard Phillips is not the only man who has 
doubted whether the Newtonian fyftem of aftronomy be 
in reality the fyftem of Nature. Arguing againft the 
opinion that the earth is perpetually revolving around 
the fun as an axis, St. Pierre, in his Studies of Nature, 
fays, “The liability of the earth may be prefumed from 
this circumftance, that the diftance of the liars never 
changes with refpeCl to us, which mud perceptibly take 
place if we performed every year, as is alleged, a round 
of fixty-four millions of leagues in diameter through the 
heavens; for in a fpace fo vail we mull, of necelfity, draw 
nigher to fome and remove from others. Sixty-four mil¬ 
lions of leagues, we are told, dwindle to a point in the 
heavens compared to the diftance of the liars. I am 
much in doubt as to the truth of this. The Sun, which 
is a million times greater than the Earth, prefents an ap¬ 
parent diameter of only fix inches, at the diftance of 
thirty-two millions of leagues from us. If this diftance 
reduces to a diameter fo fmall a body fo immenfe, it is 
impoffible to doubt that double the diftance, namely, 
fixty-four millions of leagues, would diminifh it Hill 
NET. 
more, and reduce it perhaps to the apparent magnitude 
of a liar; and it is far from being impoffible that, on 
being thus diminifhed, and on our Hill removing fixty- 
four millions of leagues further, he would entirely difap- 
pear ! How comes it to pafs, then, that when the earth 
approaches or removes to this diftance from the liars in 
the firmament, in performing its annual circle, no one 
of thofe liars increafes or diminiffies in magnitude with 
refpeft to us ?” 
That the planets are opaque bodies, like our earth, is 
thought probable for the following reafons. 1. Since in 
Venus, Mercury, and Mars, only that part of the difk 
illuminated by the Sun is found to Ihine ; and again, 
Venus and Mercury, when between the Earth and the 
Sun, appear like dark fpots or maculae on the Sun’s difk ; 
it is evident, that Mars, Venus, and Mercury, are opaque 
bodies, illuminated with the borrowed light of the Sun. 
And the fame appears of Jupiter, from its being void of 
light in that part to which the lhadow of the fatellites 
reaches, as well as in that part turned from the fun ; and 
that his fatellites are opaque, and reflect the fun’s light, 
is abundantly Ihown. Again, fince Saturn, with his ring 
and fatellites, only yield a faint light, fainter confiderably 
than that of the fixed liars, (though thefe are vaftly more 
remote,) and than that of the reft of the planets ; it is 
pad doubt that he too with his attendants are opaque 
bodies. 2. Since the Sun’s light is not tranfmitted 
through Mercury and Venus,, wdien placed againft him, it 
is plain they are denfe opaque bodies; which is likewife 
evident of Jupiter, from his hiding the fatellites in his 
lhadow; and therefore, by analogy, the fame may be con¬ 
cluded of Saturn. 3. From the variable fpots of Venus, 
Mars, and Jupiter, it is evident thefe planets have a 
changeable atmofphere; which changeable atmofphere 
may, by a like argument, be inferred of the fatellites of 
Jupiter; and therefore, by fimilitude, the fame may be 
concluded of the other planets. 4. In like manner, from 
the mountains obferved in Venus and the Moon, the 
fame may be fuppofed in the other planets. 5. Since, 
then, Saturn, Jupiter, and the fatellites of both, Mars, 
Venus, and Mercury, are opaque bodies Ihining with the 
Sun’s borrowed light, are furnilhed with mountains, and 
encompafled with a changeable atmofphere ; they have, 
it is concluded, waters, feas, &c. as well as dry land, and 
are bodies like the Moon, and therefore like the Earth. 
And hence it feems alfo highly probable, that the other 
planets have their inhabitants as well as our earth. 
As to the Sun itfelf, Mr. Arago, of the Academy of 
Sciences, Paris, lately communicated to that body, 
the refults of feveral curious experiments which he 
had made upon the polarization of light. From thefe 
experiments he confiders himfelf authorized to believe 
that the luminous part of the Sun is nothing elfe than a 
gafeous fubftance in combuftion like the flame of candles. 
It is well known that this was fufpefled by the celebrated 
Dr. Herfchell. 
Many are of opinion that comets are inhabited alfo. 
The great viciffitudes of climates is the chief objedlion 
that has been made to this opinion. This objection 
is founded upon a propofition advanced by philofophers 
(Sir Ifaac Newton amongll the reft), that the heat of 
every planet in our fyftem is inverfely as the fquare of its 
diftance from the fun. This propofition is by others faid 
to be contrary to experiment. Were heat a certain body 
proceeding immediately from the fun, the quantity of 
heat in any fpace would be inverfely as the fquare of its 
diftance from the fun. But there is much reafon for 
thinking that heat does not come from the fun. We 
perceive that light comes from the fun. We alfo perceive 
that heat is produced in the bodies on which the rays of 
the fun’s light fall; hence we are apt to confound light 
and heat together, though it is demonltrable that light 
is not heat, and that heat is not light. Experience 
teaches us that different quantities of heat are produced 
by the fame caufe, according to the medium on which it 
operates j 
