Virginia Argus. [volume] (Richmond, Va.) 1796-1816, 1809-05-23

small arches, the velocity of the upper point !
may be a miilian OF times greater than the
velocity OF the under po.Di. This-ao doubt
will appear incredible to many VINO even
doubted that the upper POM of vince.
goes switter than the under point To be |
told; that for certain, altnons,h very small
space, the upper point ola wheel may NOV.
a million OF times swItter, than its CORES
bonding under point. Yet the assertion is
a correct one, and l am also wa, ranted in
he same conclusion by a paper which
nave seen, on this subject, by professor
Blackburn of w .lhainsburg, gentleman
whose mathematical talen,s hold in the
highest respect
tne under point, therefore when in con-
tact with the ground may be considered as
stationary, and its velocity gradually TO in
Crease until 1t reaches the horizontal line
when 1t becomes equal TO thai of ITS oppo-
site point.
Whea the upper and lower points had
each described thirty degrees, found that
the velocity OF the upper point was To that
OF the under point as SLY to 758 when they
had moved over forty five degrees their velo
Cities were 10 each other as 1858 TO 1867
and when they had described all arch of
SIXTY degrees they were in the prsport ON
OF 10 600 to 5404
the earth round the SUI. On the 21s, March
he sun entered Aries; ther efore the earth
vas IN the opposite point of Libra; and a.
the earth revo,ves round its axis from west
20 east, all those points in the Hemisphere
next the sun Will move lower than the pon'
of the opposite Hemisphere wherefor c
the gravity of matter VIII be most and the
centrifugal force least at noon, on the 21st
OF March. Again OIL the 22l OF September
the SUN enters Libra, and the eartns arts :;
therefore the gravity ofmatter will be most
and the centrifugal force least At mid llghi
On the 22d of September or at noon OH that
day, the gravity OF mater viii. be least and
the centrifugal force greatest. The reason
OF tn" will readily appear from examining
the second and third coroliories in my last
essay.
wherefore il appears that from the 21st
LOT March until the 22d OF September
that particular moment when gravity is
most has variation of a few minu, { S later
every twenty four hours, aud in like man.
ner II has similar variation from the 22d
OF september until The 2lss CT March.
10 Calculate the PARTICULAR hour when
garyity is most for every day in the year
several circumstances must BE- taken nto
consideration, viz, the INCLINATION OF the
AXIS OF the Earth to its orbit her irregular
progressive motion, and ,lle particular
species or Cycioid which the Earth Ges-
criDes. these wouiG lead to calculations
which my present time does NOT permit.
But to compare the eiisct, which the Earth,
rotation has upoa The tides with the elect
which the noon produces, it is requisite
that these calculations should FIRST DE made,
and table constructed, showing the pre-
portion between the velocity OF tue points
OF the opposite Hemisphere of the Earh
tor every day and hoar in the year.
In the same manner also a. SIC isaac
Newton has calculated Prop Xxx, Book 81
OF the PrincipiaJ the length OF tue Pendu.
um for the several degrees of Latitude
from the Poles to the Equator; ana the
weight OF bodies for these Latitudes so
likewise Table may be constructed, ex.
hibitng the length of the Pendulum and
the weights OF Bodies, Tor every hour aud
minute ct the day throughout the year.
1t has been frequently observed that tho
best Penduiums have varied in the 81
hours OF the earths rotation but the cause
has always been attributed to change of
temperature in the atmosphere, and uot to
a Change OF gravity in matter.
The atmosphere is AFFECTED by the earth 81
rotation In two ways. IL is affected i'm thet
same manner as the Tides by the gravity
OF the matter which composes 1t, ALWAYS
changing 1T is also affected by the acton |
of light (Which may be considered fluid |
upon its rotatory motion since this mott
on Is different in the opposite paris OF the |
atmosphere. i cannot explain this better
than by quoting the ennnciatlop Of the sad |
prop. of the '2d book and the first coroIlary
of Ncwton's Pr,ncipa
Prop. SD. If a solid sphere, in AN uni. |
form and infinite fiud, revolves about an
axis, gwen IN position tn au uniform mo. |
lion, and the Sud be forced round by on |
~ this impulse of the sphere and every !
part OF the fluid perseyeres uniformly in !
Is motion 4 say that the periodic times |
OF the paris OF tie flad are as the squares |
OF their distances from The centre of the
sphere.
Cor. 1st. Hence the angular motions of |
the parts OF the Sud about the axis of the |
globe are reciprOcaliy as the squares of |
the distances from The centre OF the globe. |
and the absolute velccIties are reciprocal
ly as the same squares applied to the dis
tances frofn the axis
An ingenious writer in the last Visitor.
affirms that the problem respecting the
wheel is nothing new, aud refers 70 the
articles Routemcrf, Roue, RoHe q.IriS.ole,
'Cycloide, Irochoide in the French Ency