1000000031

ter foltc'.Vs

the:

pinon of a commCln pU'''llp

\\'h~n

r~; (j'd

the pump.barrd' ;

~nd

thlS,

a\.·cl)rr!ln~

¡lUIl!!,

11\)I1C!

Ly tutti"n.

HUI 10

l'efUle ~th:,¡t

enonC("IU$ UO; IOI1,

Il't tho!

ai.:, be

pump~d

out of

tilo:

recr ivt r

A /J.

~nd

then

"ti

lhl!

quiCktihoc:r in

(he

tUDe \ViII falJ

d o\...

ilS

Qwn we'ght

10("

t~f'

j.u:

tlod

CitnnOl

f\,tiJlO

r,¡i(ed

olle

h.ur

's bre04.Jlh in

lhe

luce

workin~

the Iyrin¡;e , which

rhcws,

th:\t

[uaioll

had no hand in ra,ling ,he cpllck(,¡ver: 'lOd, to prove that

is done by prelrure,

l ~t

lhe

air ioto

lhe Teceiver

by rhe

toek 4 (Iig. 8.) and ito .élioo upoo ,ho

furf.ee

of ,he q"iek–

(¡¡ver-in lhe jar will faile

¡OtO

lhe

tub~.

although °lhe

pilloD of the fy!inge continues mtltionlefs.

the

lube

Iba",

ioehes high, ,he quickfilver will rife io it

't:ry

n~ar

high

fiands at that time

the baromeler,

I\ad, if ,he fyringe ha.

f,ilall hale, as

oear.,he top cf

ir, and lhe pifian be drawo up auove that hale, the air

wdl

tulb .,h rough ,he hale ioto ,he (yringe aod tube, aod ,he

~uickfilv~r

will immediately falldowñ iolO ,he jaro

rf,his

gart

the apparatus be air tight. the quick!ilver may be

p'ump~d

up iOlo the tube to the rame he[ght tll3l i, Oaod.

the barometer; but it

\ViII

no higher, becaufc: lheo

\he weight of the column in (he lube is Ihe Colme as the

weight of a column af air of .be fa me tbiekners with the

quickGlver, aod reachi ng from

{he

earth tO lh!!

rop

(he

atnlorphere,

Haviag placed the jar

(fig.

16.)

wi,b fome quick–

~hcr

iD il. 00

the ·pump·plate,

in lhe!aH expenment,

~over

wit~ tl~e

rt:ceivcr

then pufh lhe open end of (he

¡1.ls-

,ube

,hrough ,he collar of lea,hers in ,he ·brars oeek

(j.

(",hieh il fi,s f,? as ' o be air-tirih,) almon dowo

,he

'luiekfi!ver io ,he

iar.

Theo ."haull the air out of

,h~

re·

ctivct, and it will alfo 'come out of lhe rube. becaure the

tube is clofe' at tOpo ''1heo ,h e gauge

Ihe"'. ,h.t the

r.eceiv~r

¡s· well

exhauHed. pUOl down the tube, fa as tO

ip1n~erfe

lower

~nd

ioto the: quick!ilver in thejar

Now,

~Ithough

,he tllbe be exhau(led of ai r, oooe of the qUlck–

f~ver

will rife lnto it, becaufe there is

n.o

ai r It ft in [he re–

t¡eiver

prefs upon ¡ts furface io (he

jaro

B ut let the air

ip.to

Ihe recei\'er

the cock

and the quickGlver will im·

Qledía.tcJy rife

the robe; aD(f (hnd as high in

it,

as il was

p"umped up in ,he

1. (1

e~perimcot.

, Bo,h thcCe experimeoto Ibtw, ,hdl ,he quiekfil ver is

("p–

poned in the baromett r by

lhé

prdlure of [he air on In

(urface in lhe box, in which lhe! opeo end of the tube is

l"aced : and lh3t' the more denfe and heavy (he air ¡s, the

~igher

does rhe quickiiJver rife; aod, on the conl

ruy,

the

~hinner

and

li~hlt:r th~

::tir ¡s, the mOre wiH the quickGlver

f~II.

For, ir ,he h.odle

be ,urned ever ro lillle, it rake.

1.onte

alr out of

ch~

receiver. by raifing one or oeher

the

piCl(los in in barre! : apcf conrequently, {hat which remains

i.;.O

the rc.ceive; is fo much the. rarer, and has fo much the

Jc(~

fpring and

~eigh (

and thercupon, the quickGlver foll!s.

h11e in the

tub~ ;

bUl upon turn;"g the coek, and

re· ¡.¡d~

Initting the air

joro

the recci"er, jt

b~comes

as wcighty as

before. and the quickíilver rifes

a~~i o

the

f¿mc

h~'ght.

- Thus \Ve

f~e

lhe reafon why the qui ck!iJver

lhe baro·

meter

(;.tlls

~~rol

e rain or (n

\1.' ,

and ri

r~s.

before fair wea–

\hcr

for, in the former caCe, lhe air;! 100 lhin

amI hght

bear up the ,'apollTs, and in the Jalter too dt'nfC!

and

bta.y

let

,h""

f.II

N .

J).

ln all mercurial exptd:nenls with the air-p'lmp,

a Ihon pipe muH uc fcrew cd into lhe hale

fo as to rife

..baut ao ioch .bove ¡he ph,e, to rre,eut tbe quiekúlver

(n\1Il gettir.g ¡nto {he air.pip"!' and

b"rrc:l~,

in r .. re

í\Oy

fh'~ulo

be arcidt:nt;.¡ lIy

fp.lc

over lhe j!l. r

[(Ir

once gClS

i~lto

lhe pip..!s

b.lrrels. jt fpoib

lbtm,

by h.lofcnillg lhe

(olda,

~nrl

corrodlOg

the br ..

fs .

Trike

lh~

tube

OOJ[

of d.e recc;vcr. and pl1t olle end

of a Uil of di Y haze!.branch, abom;'ln ¡neh long, tight io–

ta lhe hCJle. ancl lhe other t.'nd

IIgl11

in~o

hale:. quite! lhrough

the

b~ttom

Im..1I woodcn cup : lhen pour fume quick.

hlvcr Into lht:

CUP,'

and exhauH lhe receiver

~i r ;

alld

lhe

prdfu rc o( lht: oll1w;¡rd air, O" [he !tlffacl! or lhe q.u:ckIiJ.

ver

will fo rce it th

rou~h

che pores of the haze1, from

whcncc it \ViII defcend in a beau tl(uJ (hower ioto

cup placed

under the receiver tO cateh it.

Pu, a wire through the collar of leathers io the top of

lhe

receiver, and

fix a

bit of <try lVood on the end

lhe

\Vire wilhin . rhe

reeei"e~;

then exhiiUn the air,

~nd

pufh

the \Vire down , fa as to immerfe lhe wood into a jd( of quick–

lilver on [he

p~mp ·

pI.He:

[hls dO"le, Jet in the alr; and up'

taking the \OJood out of lhe jar, and fplilting ¡t, its llores

w"l be fouod full of.q uiekfilver, whi.h ,he force of the air,

upon being Jet i010 th e receiver, drove. i"to [he

woou.

10 .

Join ,he t,.,o bufs hemilpherical eups

and

(fia.

J7 .)

together,

·with

a wet leather b.elween

lh~m,

havlngOa

h? le .io ,he m,ddle of i,; tbeo ferew the eod

of ,he ·pipe

loto the phlte of the .pump at

aod turn the cock

fo ..s the: pipe lDay be apeo all th e way into the cavity of the

hemlfphc:res; lhen txhaufi: lhe air out of them, and turo

(he cock

quarter round, which wilfnlut the pipe

e D ,

and

keep out lhe alr. This done, unfcrew the pipe al

{rom

the

pump,

and ferew the

piece

Fh'upon it at

and. let

two (lroog meo

'o puU ,he hemilpheres .Iuoder by the

riogs

and

\Vh,_h ,ney will fiod h"d 'o do; for if the

dlAmc:.ter of the

hemirph~res

be four ¡nches, they

wiJl

prdl~d

togeloc:r by the eXltl nal

air

with a force equal to

,88

pounds . And to Ibcw thal i, is ,he prefi"ure of the

ai"

that ke.eps the:.m together, hang them

tilner of the rings

upon ,he hook

of ,he \Vire io ,he Ieedver

JI.[

(6g.

8.)

and Ilpon exhaufhog the air out of (he reeeiver, they

will

fall .fuoder of ,hemrtfve•.

1' ,

.Plaee

rmaU reeeiver

(fig .

8.)

oear ,he hale

the pump. plate, and cover bOlh it and

{be

hoJe with the

re~

ceiver

lJtl;

and [uro [he \Vire fa by the! top

that its hook

may take huJd of the Jitde reeeivcr by

rillg at

tOP,

al_o

lowing that recelver

Ildnd WilJl ies own weighc on the

plate o Then,

~pon

work'illg the ptlmp, the air wiIJ come

ou, of bo,h ree<lvers; bu, ,he I.rge ooe

/l'I

\ViII be forcibly

hel.d d own tO

lhe

pump by

{he

preffüre of lhe external air;.

whiltl the fm all one

having no air tO prcfs upon it,

\Vi II

continue Joofe, anel mily be drawn

4I.nd

let do",!n at pIca–

fure , by the \Vire

SUl, upon leuing il quile down tQ

(he plate, alld ad01itting

lhe

c\ir iOlo the recei. er

by the

eoek~,

,he air will pre Cs. fa Ilroogly upoo ,he fmall reeei.

ver

as to (ix it down to

the

p)olle; and at lhe

ram

e time(

by couDterbal:tncing lhe outward pr..:-Ifure on the lolrge re..

ceiver

it will become

loofe~

This experiment evideot.,

(ht:w~ ,

thal the receivers Qre heId down by prelTure, Ind

not

futlion, for lhe internal receiver continueci looro

whilt~

the operator was pu.nping, and lhe external one

W:t9

held dowo; but

"le

forme r bécame

hfl

immediately, by let–

ting

Ihe air upon

¡t.

SerelV ,he end

(fig.

18.)

of {he

br.rs

pipe

ABF

¡OlO Ihe hole of Ihe pump-plate, aod turo the cock

llOli l

the r ipe be open; tueo put a

wel

!ta\her upon ,he pl"e

cd.

whu:n .•