no 
MOTION. 
phenomena of falling bodies, and determined the law of 
their motions. He was followed in this theory by New¬ 
ton, and his dodtrines are juftly refpedted to this day. 
That great man confidered, however, that bodies thrown 
perpendicularly upward, merely defcribe in rifing and 
railing the fame ltraight line. He was one of the moll 
powerful advocates of the two-fold motions of the earth 5 
yet he never confidered bodies, adted upon by a tem¬ 
porary and relative projedtile force, as hill fubjedt to the 
abfolute two-fold motions of the earth and atmofphere. 
Hence he confidered the force which returned the body 
to the earth as equal in fmall diftances to the weight of 
the body, and as adting in right lines from the centre of 
the earth. In this notion he was borne out by the belief 
in all kinds of fympathies and emanations which cha¬ 
racterized his age, as well as that of Newton ; and to thefe 
fuperftitions may, doubtlefs, be referred the doctrine of 
an emanating gravity. It appears, however, that, as a 
body fubjedt to the novel force of an upright projedtile, 
does not, in truth, defcribe a perpendicular line, but two 
Tides of an exceedingly obtufe triangle ; no force is requi- 
fite to defied! it to the earth but the exceedingly fmall 
one, which creates the nafcent defledtion. Hence, as the 
angle of defledtion required to carry a body through the 
firft inch is not the 2000th part of a degree, the defledtive 
force need not be more than the 120,000th part of the 
permanent momentum of the body created by the orbi¬ 
cular force; and confequently no difficulty arifes in re¬ 
ferring the finall defledtive force to the combinations of 
the great motions of our planet. 
Suppofe E, fig. 2, to be the earth; A B a portion of its 
orbit; F a place on the earth’s furface ; C a ftratum of 
the atmofphere which a projedtile has reached; ah a pa¬ 
rallel of the orbit, and D E a tangent of the atmofphere. 
Then it is evident that, whether the earth is turning 
from D towards E, or from E towards D, a defledtion, 
from the orbicular motion to the rotary, would take 
place, meafured by fuch an angle as D C a, or b C E; in 
either cafe creating a diredtion of force oppofed to that 
in the orbit, and producing a refiftance in the next fu- 
perior atmofphere, and creating a defledtion downward 
fully equal to the known phenomena, which requires for 
the firft defledtion but an infinitely fmall portion of an 
angle of 20 feconds. 
It is alfo evident that the common rotary motion of the 
earth and atmofphere would confer a greater velocity on 
the circle C than the circle F, and fo in every circle from 
C to F, the fpaces defcribed being as the fquares of the 
radii, or as the fquares of the diftances from E. To confer, 
however, an equal momentum on the mafs, it is necef- 
fary that the denfities from C to E fhould be inverfely 
as the velocity, or inverfely as the fpaces, or inverfely as 
the fquares of the radii. 
Moreover, as by the phenomena the momenta in every 
concentric ftratum or circle of rotation are known to be 
equal, fo any mafs of equal denfity would in different 
circles, or at different diftances, be carried or impelled in 
the vortex by the circumambient media, or incumbent 
bodies, through fpaces, which would be to each other, 
inverfely as the Jquares of the difiance from the centre, and 
direaly as the refiftance of the medium in ichich they move. 
Confequently, the coliifion of the bodies or mafies of 
different denfities, in the terreftrial fyftem, will force 01 
•urge the heavy bodies towards the centre, and of courfe, 
alfo, the light ones towards the circumference—circum- 
Itances which we know accord with the phenomena of all 
fluid bodies, and of all fixed bodies, when deprived of 
competent fupport, and of all bodies moved out of their 
ftation by mufcular or explofive force, and left without 
lupport. 
The following illuftrations and obfervations may tend 
to make thefe principles perfectly clear, and to remove all 
doubts : 
1. The projedtile at its apex, when deprived of the pro¬ 
jedtile force, is ftill immerfed within the atmofphere, and 
is carried, or urged, by the atmofphere, in the diredtion 
of the circular rotation of the atmofphere. 
2. That circular rotation then produces, or folicits to 
produce, (with a force proportioned to the relative den¬ 
fities of the atmofphere and projedtile,) a defledtion of 
the faid projedtile from the right iine of the orbicular 
motion, into the diredtion of the circular motion at the 
place of contadt. 
3. If the denfity of the projedtile were equal to the den¬ 
fity of the atmofphere, then the projedtile would float in 
the atmofphere, and be carried round the earth in the 
circular vortex of the earth, like the atmofphere itfelf. 
4. If it were denfer than the atmofphere, then the rotary 
momentum of the lighter atmofphere being lefs than the 
rotary momentum of the projedtile, refiftance would be 
generated equal to the difference of their rotary momenta; 
and a defledtion of the denfer body, by the lighter atmof¬ 
phere, into a fmaller circle of rotation, would take place 
till it reached a competent balls on the earth. 
5. If the projedtile were lighter than the atmofphere, 
then the momentum of the circumjacent atmofphere 
would be greater than that of the projedtile, and the pro¬ 
jedtile would, in confequence, be forced upwards into a 
larger rotary circuit, till its rotary momentum equalled 
that of the circumjacent atmofphere. 
6. In media of uniform denfity, as in water, the pro¬ 
jedtile, if heavier, finks to the bottom; if lighter, floats 
on the top, equalizing its momentum by prefenting a 
portion of its mafs within the air; or, if of the lame 
weight, floats indifferently within the fluid. 
7. As the defledtive force is continually operating 
during the fall, and as every uniformly-continued force 
generates a conftantly-accelerated motion, fo as bodies 
fall by the adtion of a. continued defledtive force, they 
are neceflarily accelerated during their fall, till they reft 
on the fixed parts of the earth. But, as is found by ex¬ 
periment, the increafed refiftance of the air, arifing from 
the increafed motion, will occafion a balance of the two 
forces, and an equable motion during part of the fall. 
8. Combining the time of falling, the fpaces as deter¬ 
mined by Galileo, and by alleged experiments, with the 
adtual bafes, generated by the orbicular motion, the fol¬ 
lowing will be the elements of bodies falling in times 
between four feconds and the tenth of a fecond : 
Seconds. 
Feet. 
Safe . 
4 - - 
- 25 6 - 
!■ 400,000 
3 
144 
300,000 
2 ~ 
- 64 - 
- • 200,000 
2 
l6 
100,000 
.5 
4 - 
50,000 
>2S 
1 
25,000 
‘I 
- * - 
10,000 
9. As every fucceflive circle, from the centre to the 
utmoll bounds of the atmofphere, in performing the 
■diurnal rotation, contains bodies of fuch denfity, that the 
denfity multiplied by the motion is equal ; fo no body of 
undue denfity would remain in a circle of rotation which 
created in it too great or too fmall a relative momentum, 
provided, as in fluids, the parts were free to move one 
among another; and, if they were not free to move, as.in 
fixed organizations, then they would exhibit the pheno¬ 
mena of preflure, or would appear, in regard to other 
bodies, to folicit to afcei.d or defeend, as the cafe might 
be. Probably to this conflidt of light and heavy bodies, 
to the generation of light bodies in undue politions, and 
to the varied adtion of fixed and fluid matter, may be re¬ 
ferred molt of the phenomena of terreftrial organizations ; 
and, as the whole grows out of the two-fold motion of 
the earth, fo we thus refer the origin of all things, and 
phenomena to the agency of motion. 
It follows-, therefore, that the velocity of all the parts 
and dependencies of tiie earth being alike, the momentum 
of every part is diredt.y as its quantity of matter; con- 
lequentiy, momentum is weight; and the velocity of 100,000 
feet per fecond in the diredtion of the tangents of the 
1 orbit 
