ASTRONOMY. - 335 
the diligence and accuracy of Copernicus in obferving the which was, in fouie meafure, contrary fo the natural' ten- 
heavens. But it ought to have formed none in favour of dency of the body, as when a (tone was thrown upwards, 
his hypothefis ; fince the fame obfervations, and the refiilt or horizontally. No violent motion could be lading; for, 
of the fame calculations, might have been accommodated being confhmtly weakened by the natural tendency of the 
to the fyftem of Ptolemy, without making any greater al- body, it would foon be deftroyed. The natural motion of 
teration in that fyflem than what Ptolemy had forefeen, and the Karth, as was evident in all its parts, was downwards, 
had even foretold (hould be made. It formed, however, a in a ftraight line to the centre, as that of fire and air was 
a prejudice in favour of both, and the learned began to upwards in a ftraight line from the centre, ft was the 
examine, with fame attention, an hypothefis which afford- heavens only that revolved naturally in a circle. Neither, 
ed the eafteft methods of calculation, and upon which the therefore, the fuppofed revolution of the Earth round its 
moft exaCt predictions had been made. The fupenor de¬ 
gree of coherence, which it beftowed upon the celeftial 
appearances, the (implicit)’ and uniformity which it intro¬ 
duced into the real directions and velocities of the planets, 
loon difpofed many aftronomers, firft to favour, and at laft 
to embrace, a fyftem which thus connected together fo 
happily the moft disjointed of thofe objects that chiefly 
occupied their thoughts. Nor can any thing more evi¬ 
dently demonftrate, how eafily the learned give up the evi¬ 
dence of their fenfes to preferve the coherence of the ideas 
of their imagination, than the readinefs with which this, 
the moft violent paradox in all philofophy, was adopted 
by many ingenious aftronomers, notw ithftanding its incon- 
fiftency with every fyftem of phyfics then known in the 
world, and notwithftanding the great number of other more 
real objections, to which, as Copernicus left it, this account 
of things was moft juftly expofed. 
It was adopted, how ever, nor can this be wondered at, 
by aftronomers only. The learned in all other fciences, 
continued to regard it with the fame contempt as the vul¬ 
gar. Even aftronomers were divided about its merit; and 
many of them rejected a doctrine, which not only contra¬ 
dicted the eftabliftied fyftem of natural philofophy, but 
which, confidered aftronomically only, feemed to labour 
under leveral difficulties. Some of the objections againlt 
the motion of the Earth, that were drawn from the preju¬ 
dices of fenfe, the patrons of this fyftem, indeed, ealily 
enough got over. They reprefented, that the Eartli might 
really be in motion, though, to its inhabitants, it feemed 
to be at reft; and that the Sun, and fixed (tars, might re¬ 
ally be at reft, though from the Earth they feemed to be 
in motion ; in the fame manner as a (hip, which fails thro’ 
a fmooth fea, feems to thole who are in it to be at reft, 
though really in motion; while the objeCts which (he paftes 
along feern to be in motion, though really at reft. 
But there were fonre other objections, which, though 
grounded upon the fame natural prejudices, they found it 
more difficult to get over. The Earth had always pre- 
fented itfelf to the fenfes, not only as at reft, but as inert, 
ponderous, and even averfe to motion. The imagination 
had always been accuftomed to conceive it as fuch, and 
fuffered the greateft violence, when obliged to purfue, 
and attend it, in that rapid motion which the fyftem of 
Copernicus beftowed upon it. To enforce their objection, 
the adverfaries of this hypothefis were at pains to calculate 
the extreme rapidity of this motion. They reprefented, 
that the circumference of the Earth had been computed to 
be above twenty-three thoufand miles: if the Earth, there¬ 
fore, was fuppofed to revolve every day round its axis, 
every point of it near the equator would pafs over above 
twenty-three thoufand miles in a day ; and confequently, 
near a thoufand miles in an hour, and about fixteen miles 
in a minute; a motion more rapid than that of a cannon¬ 
ball, or even than the fwifter progrefs of found. The 
rapidity of its periodical revolution was yet more violent 
than that of its diurnal rotation. How, therefore, could 
the imagination ever conceive fo ponderous a body to be 
naturally endowed with fo dreadful a movement ? The 
Peripatetic philofophy, the only philofophy then known 
in the world, (fill further confirmed this prejudice. That 
philofophy, by a very natural, though, perhaps, ground- 
Jefs difhnCIion, divided all motion into natural and violent. 
Natural motion w’as that which flowed from an innate ten¬ 
dency in the body, as when a done fell downwards: vio¬ 
lent motion that which arofe from external force, and 
own centre, nor that round the Sun, could be natural 
motions ; they nuift therefore be violent, and confequently 
could be of no long continuance. It was in vain that 
Copernicus replied, that gravity was, probably, nothing 
elfe belides a tendency in the different parts of the fame 
planet, to unite themfelves to one another; that this ten¬ 
dency took place, probably, in the parts of the other pla¬ 
nets, as well us in thofe of the Earth ; that it could very 
well be united with a circular motion ; that it might be 
equally natural to the whole body of the planet, and to 
every part of it ; that his adverfaries themfelves allowed, 
that a circular motion was natural to the heavens, whofs 
diurnal revolution was infinitely more rapid than even that 
motion which he had beftowed upon the Earth ; that, tlio’ 
a like motion was natural to the Earth, it would ftill ap¬ 
pear to be at reft to its inhabitants, and all the parts of 
it to tend in a ftraight line to the centre, in the fame 
manner as at prefent. But this anfwer, how fatisfaCfory 
foever it may appear to be now, neither did nor could ap- 
ear to be fatisfaftory then. By admitting the diftiuCtion 
etwixt natural and violent motions, it was founded upon 
the fame ignorance of mechanical principles with the ob¬ 
jection. The fyftetns of Ariftotle and Hipparchus fup¬ 
pofed, indeed, the diurnal motion of the heavenly bodies 
to be infinitely more rapid titan even that dreadful move¬ 
ment which Copernicus beftowed upon the Earth. But 
they fuppofed, at the fame time, that thofe bodies were 
objects of a quite different fpecies from any we are ac¬ 
quainted with near the fiirface of the Earth, and to which, 
therefore, it was lefs difficult to conceive that any ftort of 
motion might be natural. Thofe objects, belides, had ne¬ 
ver preftented themfelves to the fenfes, as moving other- 
wife, or with lefts rapidity, than thefe fyftetns reprefented 
them. The imagination, therefore, could feel no difficulty 
in following a reprefentation which the fenfes had render¬ 
ed quite familiar to it. But, when the planets came to be 
regarded as fo many Earths, the cafe was quite altered. 
The imagination had been accuftomed to conceive fuch 
objects as tending rather to reft than motion ; and this 
idea of their natural inertnefs, encumbered, if one may 
fay fo, and clogged its flight, whenever it endeavoured to 
purfue them in their periodical courfes, and to conceive 
them as continually rufhing through the celeftial fpaces 
with fuch violent and unremitting rapidity. 
Nor were the firft followers of Copernicus more fortu¬ 
nate in their anfwers to fome other objections, which were 
founded indeed in the fame ignorance of the laws of mo¬ 
tion, but which, at the fame time, were ncceffarily con¬ 
nected with that way of conceiving things, which then 
prevailed univerfally in the learned world. If the Eartli, 
it was laid, revolved fo rapidly from weft to ea(t, a per¬ 
petual wind would fet in from eaft to weft, more violent 
than what blows in the greateft hurricanes; a (tone thrown 
weftwards, would fly to a much greater diftance than one 
thrown eaftwards ; as what moved in a direction contrary 
to the motion of the Earth, would neceffarily pafs over a 
greater portion of its furface, than what, with the fame 
velocity, moved along with it. A ball, it was laid, drop¬ 
ped from the mart of a (hip under fail, does not fall pre- 
cifely at the foot of the maft, but behind it; and, in the 
fame manner, a done dropped from a high tower would 
not, upon the fuppofttion of the Earth’s motion, fall pre- 
cifely at the bottom of the tower, but weft of it, the Earth 
being, in the mean time, carried away eaftward from be¬ 
low it. It is amufing to obierve, by what fubtile and 
metaphylical 
