1000000030

4ij

II'al1:on

r01\~\en~r',

,n.i eoolinlles ,ill an

~qu.II

;:y

in the

:HlU"(I,hcr,s IS

:t~.lin

H,,'td ; anJ dut,

itn~.I ,d

..ldyup'

on tl,í,. a ne',V Irr..llion rak-s place.

¡.l'hat

r~rulJio,\

may(ul>(,!t hWI'ixt tIVO

bodi~s

\\ hieh

h.lve never n!'Jlua:!)'

b :~u

attr.lled, provlded thtir at·

mp(phms be qu.dly

deor~.

Tlllt

th~

d,llaoee tOwhich hoiies

rcrdl,d is

allVays io proponir'o tOIhe IIrene"h of lhc

~ka,

I';ilythey

eont:tio. ThlS f••

firll (uggelled the ootiooo ao elec·

trometer, or a maehioe fur me.(uriog Ihe diC,,":nl de ·

glees of ekarieity.

O[ E/dlri../

11IJ,hina

and Atfara/ul.

i"'provemeol of

d~ariell

onchines

hl~

kepl pace

ith lhe improvements io the (eicoee. \Vhile na·

thing more

th~n

cleaneal attra.'lion and repullion

IV.,

known, every ph:::nJmenoo mighl be exhibited by

m~ao,

of a pi:ee of an,uer, (,aliog wax, or gl.(s, ",hteh the

philo("pher rubbeJ

ag~ion

his COAt, and pre!eoled 10 bits

of paper, fearhm,

~nd

other lieht budies.

1'0 give a grealer denree o( fria ,oo tO cldlrie (ub·

Ih nees.

0110

Gueriekc aod Mr Hawkcíbee eonori"rd 10

whid (ulphor ?od gla(s in a (pherieal (orm. The hIn

eoodutlors \\'ere oOlhing mJre th, n hrmpeo.enrds (up–

port,d by

filk~o

lioes. In place of thde, bars of mCldl.

or guo barreis, were (000 (ubllituted; aod a rubua

IVas emrloyed ro (upplylhe place of a human hand. The

di(eovtty of the Leyden borrle, (ro be a(twvards de·

ferihed) occafiooed more additioos 10 lhe eleélrie.1ap'

paratus; and t!te di(eomics o( Dr Fraoklio have made

proponional additions

oecdr~ry.

No philofopher

c~o

nolV ue (atisfied, i( he be OOt lule tO(upply a eooduaor

from the c1ouds, as well as (rom the (,iaion o( his gl.(,

210bes or tubes.

Ahhough globes or eylioders are nolV o( rhe mon ex–

tcofive ufe in el,arical experiments, gb s tubes are ftill

mon coovenient (or (evml purpof.:s; rhey fhould be a·

bout Ibree f,et loog, aod as wide as a perlon can eonve·

Dieorly gra(p,

(Piare

LXXIII. fig,

la.)

The

lhicl,nc~s

of the gla(s is not mamial ; perhaps tbe lhiooer tbcy are

the beBer, if they can brar fufficitnl friélioo.

The befl rubber (or a (moolh gl.(s is rhe rour.h fide

~Iaek

oiled filk, e(peei.lly IVhen

Irlll, amalgam o(

mercury or orber melal is put upon it.

GI'("globe, are io geoeral prc(mble 10 cylioders .

The elobe fhould have it, oeck ioclo(ed in a pretty deep

bra(, cap, ending io

dilmd urim, of about hal( ao

ioeh bload, if the elobebe a large ooe.

hos oot beco

delermined what kind o( gla(s is the befl ; but 11101 is

eommooly u(cd, I'cr!..ps globcs o( tlVelve or thirleeo

¡oches diamelcr

are

lhe ben fize.

Th, ben ruuum lor globes

are

made o( red b:lfil lI,in5,·

panieulady the oeck·pm o( them. where the grain is

more opeo, aod lhe (urface (omelVh"t rongha. Th.1I

Ihe

rubber may prefs ,the globe equally, ir IhoulJ be pllt

upoo a plale of met.1 beol 10 the Ihape of the gl ,u(', ar.d

lIuff~d

Wilh anv lhiog that is

clly ("fl: b..n is I:o.,d;

aod I( lhe

nuffio~

be a condu{l(,r, as flax, it will ue

b~l

te, rhao i( ir be

non.CI

"dua('r, as Ildir 01' ivoull. It

fI'(lIIld ren u?on a (priog. 10 favour any iucclu.'¡iry

there

m~y

io Ihe (ormo:

Ih~ ~Iobe,

here Ih"uld

no lI,al

cclg~s

a:t~lcs

a;'''",1

ti"

rtl:.b,,; fv, tI,"t.

l'Iol,ld Indke lht il,lul"...n o(

iodl llll'l.

1:)'

lh,' in·

fulltion of lhc r:obbu

r \

ny , lttlnc.d t

~r'

Iim

'oH

m,IY

rel (orOle~

wi:h the rIVu(old valitly nr

,'ti/IV!

and

,l(,

¡fit'r,

aOlI a contillOor be nude 10

gll'C

",d r. ke fire

rl.'afurc. This ir,(ulaoi"n is bdl

1II,.~e

nte~os

bako',i wuod, 10 lhe (urm of

1'1",', fire or fiJi ioehe,

io diameta .

fig.

2 )

inl"phl,,1

llVCUI the OI.r.llic

p.trt of llae ruhhtr antl the

lIee!

fpnng

,,1 fuppt,m

il. Wheo p"liti\'e eh'!ri,il)' is IIHroded ro be

r"",ltlCe~ ,

a ehain

(n,

fi~.

: .) OIul! eonne{l the

ru~ulT ~irh

Ihe fillOr ; bUI, when

neg~ti\'e

ckf.ricity IS ",anted, rhe

eham OIun be removed, and

huu~

up"o

lh~

eommon

e(¡oduaor, while anorher prime eendutlor OIul! be coo–

ncaed ..itll .lhe ,ubbcr; which wlll lhercfore ue cleari.

fied negari,·cly.

The uefl Illelhod o( eollclling rhe e1,,'!rie fire (10m the

globe (cl'm, to ue by Ihree or fUllr poiRled wires,

(111,

fie.

2.)

two or thrce ir:ches

Itng,

h.lOglng lightly

upun Ihe globe, aod (ufpended 00

opeo mmllic

ri"p.

The prime conrlullor fhoultl he fixed very ncady:

Whmver

lhe fize of lhe r"ime eoodullor, the eXtre·

mily of it, or tI,a, par! wbi, h is mull remOle (rom rhe

~Iouc,

lllOU!d be mllch

larf.cr

and ruuoder thao tllé rel!,

(f.

lig.

2 ) ;

(or the effort of the

eb~l "c

maller r.

Jly Ofi' IS al"'IYs gre.ltell al the gre.ltdl dinanee f, om tI!C

gloloe.

The elearician fhould

provided ",irh

ETAl L

Ro os

(/ ,

fig.

t.)

10 lake (parks from hlS eondullor (or

various u(es. Th& IItould have knous, largcr or fin. II.,

io prol,onion 10 t!le

eurv~ture

of the euoduaor. If the

koou ue 100 (mall, ir \Vdl OOt di(eharge the

eondu,~"r

ooee, but by degrces, aod \Vith

Idi (eulible

efi~él ;

\\'h~rm

the

IF:,k

L(.{\ve

uroad

furfae~s

is t111ek .od

IIrong.

The 01011 (ormidable pan of an ekllrical apparalU!

coofins i" rhe

'OATFO GLASS

rhal is ufed fpr the

Ley·

den eXl'c:imeot. The

f~rnt

o( lhe piale is imrnarcrial

\Vilh "i'peél ro lhe

rhue~.;

aod. for differenl experimlntsl

both plam of

~Lt!s,

aod j:trs of variuus

(Url115

and

(¡us,

mun be u(ed. For eommon u(es, tbe

01011

eommodioul

form is lhal of a

j.tr

wide as a pedon eao eon\'eniendy

hold in hls

h.nJ

gr.¡(ping. and as lall as il will 1I.0d

wilhout aoy d.lnger of falliog; perhaps abour

iuehes

io diamclcr. and

inches io

hei~ht.

The mourh I"ould

be prctly Opeo. th.r ir may be lhe more eooveoienrly

coated 00 the infide, as \Vell as the oUlfiJ" wilh linfoil.

cuofid"rable variel y of Ilrrfe j:¡rs m.lYhe (cco io lhe

ve I'I.Ire,

fig,

e,j,

j, .1.

he mcrhud of ctlJtioll is I}luch PI elerablc ro thal of

pUlli"g W.Her or ur:tfi.C"a,·ings inlOrhe jars, whieh uOlh

m,k" lhem

ht.IV

""d

lilcelVil, i"cap.ble o( being io.

nrted. \\

hich is reql!ifilO

ti!

10y r,xr(·rimenll. Br,I(S'

dlll!. hOlVe\'n ,

Iradon fho"

Ver)' eon\'cnieol (or

(11,. 11

p~IIJI,. Th~

liofud ",ay b: p,1I

eilher Wilh

p' ¡¡ !, gu,"

IV.II

·:r, or be<s·

"'.x

eO.1I Ihe inr.Jes of

\'dfds

~hich

ha!'e

o~rrolV

""ollrlll, Iltooolk o tlle inliJe

\Vlllt gUIlt

",,,1('1,

and lhrn 1"""

(¡m,c

~r.I(~

dull "peo il '

Enoll~h

",ill n" k iO OI.,ke .10

c~(" '\'Ilrn~

g,' od ro:lliog.

l"~

etloJlrutt:o;: 01' ao lU l'TK ICA L

r.\1

TER Y,

Dumbcr