1000000031

ph'c

(fee S .nd T ) í n ,he middle of eaeh bearer; ,hen

,hrough a Di, in ,he middle of ,he fquare ,op

3nd P)

of eaeh tOwer, and, going aver a fmíl ll pulley on

lhe

rop,

comes down ag::lin ¡he (ame way, 2nd is

L,n

fallened

,he urper end of ,he fock.. fix, in ,he middle of ,he .–

Lo. e-melllioned round plate_ Thefc plates S and T Iuve

e"eh

fouT

fo und holes near their edges

far

leuing

them

flide up and down upon lhe \Vires which mlke the comer

of each tower. The ball, and pi"e' being ,bu. eonneded

••eh by ilS particular line, it is pl. in, ,hat if the ball. be

dr;.¡wn outward, or towards the ends M and N of their

refpedive bearers, ,he round plates S and T will be drawn

up to ,he top of their refped iv. 'oIVers

and P .

There are (everal brafs weight!l, (ome of

tWO

ounees,

fome of 1hree, and fome of four, tO be oeeafiooally pu,

within {he

tOWeT

s O

~nd

P, upon lhe round

p]:nes

S and

T :

e.eh

weigh, having • round hole in the the ,middlt of

¡t,

for going uponathe Cockets or axes of [he pIares, and

from the edge to the hole, for allowing i, 'o be lIip'

over the forefaid line \Vhieh comes from e. eh ball 'o its

refpeéli,e plate.

The experiments to be made

this mí\chíne are,

T ake away

lhe

bea rer

rv1X.

and take the ivory ball

to which che lioe or

li1k

cord

i5 {aHened ac one end ;

and hi:!.ving made a loop

0 0

che ceher eod of the cord,

pu, tbe loop over • pio fix, in the eeOtre of the board

Theo, turning lhe wioch

to give lhe board a whirling

motion, you will fee ,ba! the ball does not immediately

begin

move

with

the board; but,

aceount of ¡ts

inaélivity, it endeavours tO comioue io the (late of

ren

which it was in befoTe.-Continue turniog, until lhe

board commuoicates

equal dfgree of motioo with íts

0\1.'0

tOthe ball ; and lheo lurniog

00,

you wiU perceive

lhat the ball

will

remain upon one pare of the board,

keep'ing che [ame velocity Wilh it, and having no relative

modon upon

as is che caCe Wilh every thing that lies

loofe upon tbe plane furfaee of ,be earth, \Vhieh having

the motion of lhe earth communicated to ¡t, never en–

dc:avours to remove (rom that place.

HUl

llop lhe board

fuddenly by band, and the ball will go on, and

eon,in~e

revolve upon lhe board, umil lhe fridion thereof fiops

hs motion : which Olews, lhat maner heing once put in–

to motion) \Vould conlinue to move ror ever,

it met

wi,h no

re~nance.

lik/l:

manoeT,

if a perCon fiaods

upright

in a

bOíu before it begins to mO\le, he can fia nd

lirm : but the moment the boat Cels off, he is io danger

of falling,towards that place which lhe bo;¡t dcparts from:

bccOlure, as maner, he has no natural

propen~ly

mO'ie.

Eut when he acquires the

mor

ion

Ihe

boal, le t it be

ever fo fwift, jf il be fmaolh and uniform, he

\ViII

Cland

upright and 6rm as ir he was

(he phio {hore :

¡¡nd

if the boat {lrike

ag.in

{l an, ob{laele, he will fall ' o–

wards lhac obClacle; on accounl of the

propcll~ l y

he has,

matter

to keep the motion whjch the: boat has put

him

inta.

::!.

TCtke

away Ihis halJ, and

put

lance r

CMd

it;

which nlíly be

put

down through 1he hollow axis

lhe

bearer

MX,

and whetd

aod

fix a

wt"ight tOche

er.d

of lhe cord helow

Ihe

mHhioe

whjch weight,

1<:.(1

liheny. \ViII draw the ball from the ,d"e

,he \\hirling-

board toj ts

CCD~re.

Draw off the ball a liule from ,he «nl re, 2nd turn ,he

winch; lhen the ball will go raund and ronod w:lh tne

board, .nd \ViII gradually lIy off fmher .nd f.rther from

lhe: centre, and r.!ire up lhe weigbt btlow lhe machine :

which {hews that all bodies rcvolving io cireles ha\'e

,endeney ' o

off from ,hefe eirele., .nd mu{l ha7e fome

power aéting upoo. them from the centre of motion, tO

keep Ihem from flying off.. StOp ,he machine, aod ,he

b..

Jl \Viii

continue to re\'oJve for Come time upon lhe board;

bU[ as lhe frid ioo gradually ftops

its

motÍon, the weight

aétiog upon it wiIl bring it ncarer and neao;er

the centre.

io every revolution, uncíl it brings it quite thither.

This O,e",., ,ha, if tbe planets me' wi,h any refinance iD

goiog round the fun, its altraélive power would hring

tbem nearer and oearer to it in efery revolulion, unti1

they fell into i,.

T ake hold of ,he eord belo\V ,he maehine wi,h one

hand, and with ,he o,her throw ,he ball upon the rouod

board as it were at right angles

(he card, by which

meaos

wilJ go rouad and Tound upon lhe hoard, Then;

obferving with "ha! veloeity i, moves, pull the eord be–

'!ow ,he maehine, whieh will bring ,he ball nearer 'o the

centre of lhe board, aod

you

will Cee that the oearer the

ball is

dra\Vn

tI.l:

cenlre, the faOer it will revolve ;

os ,hofe plane" IVhlCh are neareU ,he fun revolve fa{ler

thao IhoCe which are more remate; and not only

round fooner, becaufe ,hey deferihe fmaller eireles, but

even move fa{fer

every pan of their refpeétive

circle~e

T ake away ,his ball, and apply the bearer MX, whofe

CeDtre of motion is

in irs

middle at

'1JJ~

diretUy

over

the

centre of the \Vhirling: board

Th<n pUt

'wo

b.ll

(V and

of cqu. 1 IVdgh" upon ,heir beariog ",ires;

and b.ving fixed ,hem at <qua! dillane.. from their refpec–

tive centres of mOtioD

"lU

and

upon their filk cords, by

the fcrew,nuu , put equal weights

(he towers

ar.d

L aOly, pu, ,he eatgu, Ilriogs E and F upon ,he groo...

G 3nd H of ,he fm.1I \Vhed s.; wbich being of equa! di.–

meters, will give equal velocities tO the bearers above,

wben the \Vineh B is ,urned ; . nd ,he ball,

and V

\ViII Ay off ,ow.rds M and N, and will " ife lhe weights

the tDWers at the fame ioftant, T-his fhews, tbat wheR

bodies of equaJ quaotities of matter revolve

equa! cir–

eleswith equal velocities. their centrifugal

forces

are cqua);

5. T ake a\Vay ,hefe <qual halls, ant', in{lead of lhem,

pUt a hall of fix .ounees in,o ,he heare, MX', a' a fix,h

pan of the dillanct!."Wz (rom

ihe

centre, and put

ball

of one ounce ioto the

oppo~le

bearer, at

t~e

whole ¿i.

fiance

.9,

which is equal to

"l.UZ

from the centre of the

bcarer ; and

fix

lhe ball

theCe diflances

0 0

their cords,

by lhe fcrew-oms at top; tben the hall

which is fix

,ime,~,

heaoy... ,he ball V, "ill

a! only a fixth part

of the diltaoce from its CeDtre of motion ; and conCequette

will

revolve in a cir.cle

('Inly

fi xth P¡ut of lhe cir..

clJmfe rence

Ihe circle in wJlich

re\·oh'es. N ow,

Jet

any equa l wi!ights he ptH into Ihe towers, ar.d lhe machioe

be turneo

Ihe winch

which

(2S

the

catgtlt fi tinAis on

equal wheels belo,,) will eaufe the halls lO revolve iD

equal times

but V will move

fix ..

¡mes as {aft as U, be.

cauCe it re\'oh'es io

cireJe of

fix

times ils radius

and

bOlh the weighls in lhe towers \\-ill rife

once, T his

Ihews, ,hat Ihecentrjfug.1 fOlces of revoll'i"g bedi." (or

their