1000000030

806

H Y D R O S T A T

lhe tllbes, Or, i( ,,JI the tubes exeept A, or

~oy

other

ooe, \\'ere

t~kco

alVar, aod a larse lube cqu,,J in

di~me

ter to lhe

\\'hol~

tOp

were plaeed upon it,

~nd

ce–

menreu

it; and theni( IVater lVere poul ed iolO the rube

th~t

lVas left in cither of the holes , it 1V0uld

~fcend

through all the refl of the I,oles, ulltil it fill,d rhe large

tube tOthe

f.me

height that it flaods in the fm,lI one,

.frer

fullieicot quaotity had beco poured ioto it : IVhieh

(helVs, that the top

lVas preflcd upward by lhe water

Iloder it. and before any hole lVas

m.de

io it. Wilh a

force eqllll ro that wherewith it is nolV prefled dOlVnwa,d

by the

wei~ht

o( all the lVater above it in the great tube.

And thercfore. the reaaion o( the óxed top

mufl be

as great. in preffiog the lVater downward upon the [¡Oto

t01l1

ce,

as the whole prefl"ure o( the water In the great

IlIbe would have been. i( Ihe 10p had been laken away.

aod the water in Ihat lube Itft

prt rs direaly upon Ihe

waler in Ibe eavity

BDtlf.

Thr hydroJla,ic

b,II'WI,

RHAPS

Ihe bdl maehine in Ihe world (or demonnra–

liog the upwar,: I'refl"ure of fluids.

the

hydroll~lie

bel·

lows

(6g .

7.)

whi:h eoofins oflwo Ihick

oval

boards.

eaeh aboul 16 ioches broad. and 18 ioehes loog.

coveml

",ith leaher. to opeo aod fhut like a cOOlmoo bellows.

bUI witbout vdlves; ooly a pipe

about three feel high,

is fixed iolO Ihe bellows at

Let fome water be pour–

ed iolO the pipe at

whieh will ruo iOlo the bellows.

aod [eparate the boards

linle. Then lay timeweighls

eaeh weighiog 100 pouods. upoo the upper

board ; :nd pour more water inlO the pipe

ll.

whieh.will

ruo iOlo the bellows. aod raife up the board wilh all the

wcights upoo it; and if the pipe be kept full, uotillhe

weights are rai(eu as high as the lealher whieh

eovers

the

bellows will allow Ihem. Ihe water will remaio in the

pipe! a'nu fuppon

.11

lhe weighls. even though it OlOuld

weigh 00 more lh:ro a

qu~mr

of a pound. and they 300

pouods: 001' will all lhcir fo rce be

~ble

tOeaufe them to

~ef,eod

and force the Water out at the rop of the pipe.

The rea(oo of this will be made evident. by confieler·

ing what hns been al ready

f.id

of the r<felr oflhe prenitre

of fluids of

equ~1

heights withou t aoy regard 10 rheir

qu~ority.

For. if a hole be made io Ihe upper board.

and a tube be pUl inro ir. Ihe warer will rife io the tube

10 the fame height Ihat it does io the pipe; aod woulJ

rife as

hi~h

(by fuppl ying the pipe) in as maoy lub:s as

rhe board eould eootain holes. Now. fuppofe ollly one hole

tobe made iD any part of the boa,d. of ao equal diameter

with the bore of thepipe B; and that rhe pipe holds

ju{~

qua,ter of a pouod of water; if a perfoo clars his finger

npon rhe hole. and Ihe pipe be filled with water, he

will fiod his nnger [O be f'r,fI"ed upward with a force e–

qual tOa quarter of a pouod. And as Ihe faole preflore

¡,

equal upon all equal pHIS of Ihe boad.

e.eh p.rt

",hofe arca is equ:d

rhe area oflhe whole. ",ill be prer.

red

upward wilh a force equ:u to that of a quarter of a

pouod : rhe fom of

~II

whieh prefl"ures

.gain(~

the uoder

flde of ao oval

bo~rd

r6 ioehes broad. 20d

ineh,s

long, will amount tO 300 pounds; aod thercfore fo mueh

weif(ht will be raifed up aod fupported by

quarter of a

pOllDuof Waler in lhe pipe,

Heo~e.

if aman fl aods upon rhe upper board. aod

b!ows 'oto the bello'Ns through the pipe

Ire will raife

h"ufdf upward upon the board : aod 'the .fmalla Ihe

bore of the pipe is. Ilre calier he will

be 'abl~

tO r.ife hilO'

reir. . Aod üleo, by

c1aFpi~g

his finger ' poo the top of

the p'pe. he can (upPOrl.

h,~nrelf

as long .s he plcalcs ;

prov,ded the bellows be atr·ught, fo as oot tolofe what is

blown ioto ir.

. U

poo this principie of Ihe upward prcfl"ure of flu ids.

~,ec~

of lead may be mace to fwim io water. by immer.

(,ng It to a proper depth, aod keepiog the warer from get–

lineabove it. Let

(fig.

8.)

be a glafs tube. open. t

both eods. aod EFG a

pieee of lead. exaa ly fiued

Ihe lower eoo of the tube, oot 10

wirhin ir. but

for il to flaod upon; with

IVet leather betlVeeo rhe

lead aod lube to make clore work. Let this leadeo

bouom be half ao ineh lhiek. aod held clofe to the tube

by pulling rhe packtlrread IHL uplVard at L with ooe

hand, whilfl Ihe (ube is held io rhe other by the upper

end

lo this

r.¡u~lion.

let the tube be immerfed iD

water io the glafs veflel AB. 10 the depth of fix inehes

b~low

the furfaee of the water at

aod theo. Ihe leaden

bouom EFG will be pluoged to the depth of fomelVh. r

more thao eleveo times its owo thiekoefs : holdiog ,he

tube at that deplh. you may let go the th read at

L ;

aod

the lead will OOt fall from the lube. bur will be kept ro

it by the uplVar.d prcfl"ure of the water below il, oeeafiooed

by the heigh t of Ihe water at

above

rhe level of the

lead. For as lead is 1r.33 times as hcavy as its bulk

o( water, aod is io Ihis experiOleot immerfcJ to

dcprll

fomewh atmore thao 11.33 times its thickoefs. aod 00 wa·

ter getting into the tubebetweeo it aod rhe lead, the (olurno

of wdter

EahcG

below the lead is

prefl"~d

uplVard

.~gainfl

it by the water KDEGL

all

around the lube; whieb

water being a liule more thao

11.

times as Itigh as

Ihe

I.ad

is rhiek. is fuffiei<n t

balaoee and fuppon rhe

Iead al the depth

KE.

If a lirtle water be poureu into

the tube upoo the leau. it will inemfe the \Veighl upon

Ihe eolumo of water under ¡he lead, aod eaufe tite lead to

f:.1I

froOl the tube to the bOIlOOl of the glrtfs !'(Ir.I, wltae

it willlie io rhe (ituatioD

bd.

Oro if Ihe tllbe be raif,u

a liule io the water. the lead will fall by ils O. o ",(itht,

whieh \ViII theo be too great for the prcfl"ure of Ihe wa–

ter around Ihe lube upon the, eolumn of w.ter bclow ir.

Let tIVO pieees of wood be plaioe'd quite /Iat. fo as no

water Olay gel in betweeo thern \\ heo Ihey are pUl roge–

Iher: let one of the pieees. as

hd.

be eement,d tOthe

bonom of the

1,.{[e1

(fig.

8.)

~lId

the other pieee be

laid fl,t aod clofe upon ir. ano held down ro it by a nick,

whilll water is pour,d iOlo Ihe venel : thep rrmo!'e tloe

fl iek. aod the upper picee of wood \ViII nOI rife froOl t!le

10IVer ooe: for, as the uppcr one is prcfl"l'd down bo,h

by its owo w,ighl and Ihe weight of all Ihe

"'~Ier

Ol'er ir. \VI,illl lhe eootrary prrfl"u,e of Ihe water is kept

off hy the wood under it. ir will lie as n'¡l as a

lio.oe

\Vould do in ils piare. But if il be raifed cver

('o

lillle al

any

ed&~,

fome warer will then

g~t

uod" ir ; IVhirh be·

ing ac1cd uponby the watH

~bove.

will imrneJi:udyrrcfs

il uplVard; aoo as it is liglt¡¡r Ih.1O irs bulk of w.ter,

it will rife. ao'J ·/Ioll UpOIl Ihe furf.lee of rhe water.

Allllui,1s

w~iCh

jull as mueh in th,ir 0'.\'0 elcmenl "

they