MOTTO N. 
108 
pendulums be let fall from equal heights, fo as to {trike 
full on each other; if thofe pendulums be of lead, or foft 
clay, they will lofe all, or almoft all, their motion; and, if 
they be of any elaftic matter, they will only retain fo 
much motion -as they receive from their elaftic power.” 
If it be aflced, how it happens, that motion, being thus 
continually loft, ihould be continually renewed again ; 
the fame author adds, that it is renewed from fome active 
principles, “ fuch as the caufe of gravity, whereby the 
planets and comets preferve their motions in their orbits, 
and all bodies acquire a great degree of motion in falling; 
and the caufe of fermentation, whereby the heart and 
blood of animals preferve a perpetual warmth and mo¬ 
tion; the inner parts of the earth are kept continually 
warmed ; many bodies burn and ftiine ; and the fun him- 
felf burns and fliines, and with his light warms and chears 
all things(as alfo from the caufe of elafticity, by which 
bodies reftore themfelves into their former figures,) “ for 
we find but little motion in the world, except what plainly 
flows, either from thefe adtive principles, or from the 
command of the wilier.” The prefervation of the fame 
quantity of motion in the univerfe, was a principle laid 
down univerfally by Des Cartes; but has been found falfe, 
and holds true only in the fame direction, which is thus 
exprefled by fir Ifaac Newton: “ the quantity of motion, 
which is colledted by taking the fum of the motions di- 
redted towards the fame parts, and the difference of thofe 
that are directed to contrary parts, fuff'er no change from 
the adtion of bodies among themfelves.” Princip. lib. i. 
Motion, we have obferved, is the fubjedt of mecha¬ 
nics ; and mechanics is the bafis of all natural philofophy, 
which hence becomes denominated mechanical. In eftedt, 
all the phenomena of nature, all the changes that hap¬ 
pen in the fyftem of bodies, are owing to motion; and 
are directed according to its laws. Hence, the modern 
pliilofophers have applied themfelves with peculiar ar¬ 
dour to confider the dodtrine of motion; to inveftigate 
the properties, laws, &c. of it; by obfervation, experi¬ 
ment, and the ufe of geometry. And to this we owe the 
great advantages of the modern philofophy above that of 
the ancients, who w'ere extremely regardlefs of motion, 
notwithftanding that they feemed fo fenfible of its im¬ 
portance, that they defined nature by the firft principle 
of motion, and reft of the fubftance in which it is. 
Among all the ancients there is nothing extant on mo¬ 
tion, excepting fome things in Archimedes’s books “De 
iEquiponderantibus.” To Galileo a great part of the 
dodtrine of motion is owing; he firft difcovered the ge¬ 
neral law's of motion, and particularly of the defcent of 
heavy bodies, both at liberty and on inclined planes ; the 
laws of the motion of projectiles; the vibrations of pen¬ 
dulums, and ftretched chords, with the theory of refin¬ 
ances, &c. which were things of w'hich the ancients had 
little notion. His difciple Torricelli polilhed and im¬ 
proved the difcoveries of his mafter; and added to them 
divers experiments concerning the force of percuflion, 
and the equilibrium of fluids. Mr. Huygens improved 
very confiderably on the dodtrine of the pendulum ; and 
both he and Borelli on the force of percuflion. Laftly, 
Newton, Leibnitz, Varignon, Mariotte, See. have brought 
the dodtrine of motion {till much nearer to perfedtion. The 
general laws of motion were firft brought into a fyftem, 
and analytically demonftrated together, by Dr. Wallis, fir 
Chriftopher Wren, and Mr. Huygens, all much about the 
fame time : the firft in bodies not elaftic, and the two laft 
in elaftic bodies. Laftly, the whole dodtrine of motion, 
including all the difcoveries both of the ancients and 
moderns on that head, was given by Dr. Wallis in his 
“ Mechanica, five de Motu,” publilhed in 1670. See the 
article Mechanics, vol. xiv. p. 626 Sc feq. 
The Laws of Motion, and the dedudtions from them, 
as expounded to us by thofe high authorities, have been 
given under our article Mechanics, vol. xiv. p. 626 
& feq. But we have lately met with a curious eflay in 
the Monthly Magazine, (by fir Richard Phillips,) which 
makes fome bold attacks upon the Newtonian theory of 
the influence of gravitation, or attradlion, upon motion ; 
which we {hall lay before our readers without giving any 
opinion upon the fubjedt ourfelves, as otherwife we mult 
enter into a difeuflion far exceeding our limits. 
The writer fets out with obferving, very properly, that 
it is the proper objedt and end of philofophy to invefti¬ 
gate the mechanifm of caufes, and the means by which 
they produce natural phenomena. For this purpofe, ob- 
fervers regifter fadts, and pliilofophers infer the caufes 
from the phenomena by a logical procefs of indudtion. 
“ The defign of the prefent eifay is to determine the 
caufes of ali thofe phenomena, on which philolophical 
obfervers have hitherto conferred the name of gravitation 
or attradlion, and which is vulgarly defignated by the 
name of weight .—Owing to what caufe or caufes does a 
body fall to the earth ? Why does a projedtile return to 
the earth ? Thefe are the queftions which it is here pro- 
poled to anfwer. 
The Newtonians, and all the modern fchools of phi- 
lofophy, have been unable to folve thefe problems ; or, 
finding themfelves unable, they have been unwilling to 
dilcufs them, or even tolerate their difeuflion : while the 
theologians have been deftrous of referring this power to 
the proximate agency of the Deity. It is, however, the 
duty of genuine pliilofophers to perfevere in fpite of 
difficulties and oblcurities; and of wufe theologians, to 
exalt their notions of the Deity by contemplating the 
fublime and Ample mechanifm of fecondary caufes. 
In the prefent cafe, the phenomena confift in the ap¬ 
parent influence of one body upon another, though they 
are not in contadl, and though no vifible mechanical 
agency appears to exift between them ; and in their ap¬ 
proach to each other by certain laws of accelerated mo¬ 
tion, as a refult of apparently continued and reiterated 
forces. 
What, however, are the circumftances in which the 
bodies fo adting upon each other are placed, as in the 
cafe of a {tone projedted from, or falling to, the earth? 
The earth is a globe of heterogeneous materials, moving 
round the fun in every year, at fuch diftance, that its 
mean rate of motion, in round numbers, is 100,000 feet 
in a fecond of time; and the ftone moves with the earth 
in the fame orbit, partaking conjointly with it of the fame 
mean motion of 100,000 feet in every fecond. Nor will 
any one doubt that, at the time the earth and atmofphere 
are performing this orbicular motion, they are alfo per¬ 
forming a rotary motion in every twenty-four hours, 
which rotary motion carries bodies on the earth’s furface 
through a fpace, at the equator, of 1250 feet in a fecond, 
or one-eightieth of the orbicular motion. The whole 
earth, then, with all bodies upon the earth, and the at¬ 
mofphere, are fubjedt to thefe combined motions and 
forces ; and, in this paflive ftate, the queftions are, By 
what law or laws the heterogeneous particulars are kept 
together; and how, if the pofitions are difturbed, thofe 
poiitions are reftored ? 
Suppofe A, fig. 1, of the annexed Engraving, to be a 
place on the earth’s furface, from which, by mufcular or 
explofive force, a ftone is projedted towards D, at 16 feet 
and an inch above A. Suppofe that a fecond of time 
elapfes while the ftone is afeending from A to D; then it 
is evident that the point A will in that fecond be carried 
forward, by the orbicular motion of the earth, 100,000 feet, 
or to C ; that is to fay, the point A will move 100,000 feet 
while the ball is afeending 16 feet and an inch; confie- 
quently the ball will, in truth, not afeend in fpace from 
A to D, but will be carried in an oblique line from 
A to E, moving upwards as it proceeds. The two forces 
—that which carries it from A to C, and that which 
carries it towards D,— are as 100,000 to 16.^, or as 
6000 to 1 nearly. 
The ftone having arrived at E, it is then known, by the 
phenomenon, to fall to the earth in a fecond of time; yet 
it does not fall through E C, but, while falling, is carried, 
by 
