1000000031

A N

e s.

,,'hich givC:$' each f\lrrow a filar? edge, and in the two

flones

thay

come, as it werc, againO one another Iike the

edges of a paír of (c¡{[us.: and fa

cut

the corn,

m:\ke

grind the eafier when

(alls upon the places betwecn

the furrows.

Therc

are cut tl¡e fame

way

in both {lones

when lhey lie upon their backs, which makes them run

crofs ways to e3eh otber wben the upper none is ioverted

turning its furrowed [yrface towards that of {he lower.

For,

lhe

fu rrow's of both flones

lay

{he fame way, a

great deal of

lhe

corn would be driven

oll ward

in the

lower (urrows, and fo come out from betwcen {he Hones

without ever beiog cut.

Whcn the fu rrows

bee.me

blunt and !hallo", by wear–

ing, the

rllnning

Clone mua be

taken

up,

and

both flones

ne\V dren with a chife! and hammer . And eveq time

the (lune i5 taken up, there mu(l be fome ullow put

rouno the Cpindle upon the buih, whieh will fooo be me!t–

cd by lhe heat that the fpindle acquires from its turning

and rubbing againll the bulb, and fo will get in betwixt

them: otherwiCe the bu!h would take fire in a very Iinle

time.

The bulb muCl embrace tile fpindle quite c1oCe, to p.e–

vent any fhake in the mOllon; which would make fome

pans of the (Iones grate and fire again(l caeh other ; whilll

other parts of them would be too far aCunder, aod by that

means rpoil lbe meal in grioding.

When~yer

the Cpindle wears the bulb fo as to begin to

fhake in it, the {lone muO: be taken up, and a chifel drove

ioto feveral pans of the bufh ; and when

is taken out,

wooden wedges mlla be driven ioto the holes ; by which

means the bulb will be made to embrace the fpindle c10fe

all afound it ag\lia.

doing this, great care mufl be

taken to drive equal wedges ioto the bufh onoppofite fides

of the fpindle; otherwife ir will be thrown out of the per·

pendicular, and fo

~ioder

the upper llone from beiog fet

parallel to the uoder one, which i5 abrolutely necefTary

for makinr, good work_ When any aecident of this kind

happens, the perpendicular pofition of the Cpindle mu(l be

r.norcd by adjuning the bridge-tree ST by proper wedge.

put between it and the brayer QR.

oft~n

happens, that the ryña is a liu le wrenched io

h ying clown lhe upper fione upon it; or is made to fink

a Jittle lower upon one fide of the fpindle than on the o·

ther: and this will cdufe one

ed~e

of the upp3r none

drag all . round upon the other, whil(l the

oppor.te

edge

will

not touch .

But this is

ea~ly

fet to rights .

by raifing the (lone

litde with a lever, aod putting bits

of papcr, cards, or thin chips, betwixt the rynd and lhe

Gone.

The di.meter of the upper fione is gcnerally .bout r.x

feet, the lowcr Ilone abont an ¡"ch more: and the upper

Clone when new contains about

'22{~

cubic

f~et,

which

\V~igh~

fOOlewhat more than

1900

pouñds. A flone_of

\hls d\amcter ollght never to

" O

more than 60 times

round in a

minute!;

for if

tur~5

fd,ll-.!r)

\ViII heat the

rneal.

The grinding r.lrface of the undcr nane is

liole con·

vcx

r~om

thc edg! to the centre, aod th:n of the. upp'!r

none: a little mfl re c

>nC-lve :

fo that th: y are ftrth d l

from

on~

aoother in the

mi~ldlc,

and ca ne gradud,lIy

maree to\,.'.uds lhe cdgt!s .

this m"

:d.ns

, the ..;orn

its firU entrance between the {lones is ooly

br~ifed;

but

as it goe5 farther on towards the circumferencc or edge,

jt is eut fmaller and Cm.lIer; and at lafl fincly ground

jull before

comes out from between them.

The w.n ee-wheel mull not be too large, ror if it be,.

its motion will be toO flow; nor toO liule, for then it

wiIl want powo!r. And for a milI to be in perfeétion, rhe

floats of the wheel ought to move Wilh a third pan of (he

velocity of the water, aod the !tone to tum rou\ld once in

a fecond of time.

Such a mili as Ihis, wirh a fall of water about 7{- feet.

will require about

hogíbeads every minute to lUro

t}¡:::

wheel wilh a third pan of the ?elo.;ity with which the

water falls, and to overcome lhe refifhnce ariGng from

the frittion of the geers and aurition of the fionés in grind·

ing the corn.

The greater fall the water has, the leCs quantity of

will

ferve to turo lhe milI. ·The water is kept up in 'the

mill ·d.m, and let out by a flu iee ealled the penCloek,

when the mili is to g.o.

W~en

the peoClock is drawn up

by means of a lever, it open' a

palf.ge

tI:.:ough which th.e–

water fiows

the wheel; and when the mili is to be UOpt,

the pen(loek is let down, whieh Clop. the water from fall.

jng opon the whee!_

A leC. quantity of water will turn an over!hot-mill

(where the whee! has bucket. in(lead of Hoat-boards)

thao a brea(l-mili where the fall of the water feldom ex–

eeeds half the height

of the wbeeL.

S o that , where

there is but a fmall quantity of water, and a (aJl great e–

oough for the wheel

lie under it, the bucket (or over...

!hOt) wheel is always ufed_ B ut where there is a large

body of water, with a little fall, the breafl or Hoat·board

wheel mull: take place. ' V'here the waterruns ooly upon

a linle declivity, it can aét but flowly urJOn the under

pan ofthe whee! at

in whieh caCe the motioo of the

whee! will be very Clow: and therefore, the Boats ought

to be very long, though not high, that. large body of

water may aét upon tbem; fo that what r.... wanting in ve.

locity may ue made up in power; and then the

cog~wheel

may have a ' greater nUClber of cogs in proportion

the

rounds in the trundle, in order to give_the milHlone a fuf–

ficient degree of velocity.

They who

h.ve

read what js faid in the firfl CetlioD,

eoncerning the aeceleration of bodies falling freely by the

po·.ver of gravity .é\ing eonn.ntly and uniformly upon

them, may perh. p••

fl<,

Why Ihould the motion of the

wheel be equable, and . not accelerated, fince the water

.fu

eonn.ntly and uniformly upon it ? T he plain anClVer

is. That

th~

velocity of the whce1 can never be fo great

as the vdoc'ty of the water that turos it; for, if it fhould

become ro grear, the power of the water wauld be quite

1011 upon the

wh~{"I,

aO,d

~hen

{Itere wonld be no propcr

force

avercome {he fnéhon of the geers and attritian of

the Clones. "rhoefore. t he velocity with which the wheel

begins to mov.e. \ViII ¡ncreare no long{'r than till its

momn¡-

111m

or f0rce

halan=ed by the refirbnce of the machioe.

ano then the whecl \ViII go on \Vith iln equablc motion:

[ Ifthe cog-whcd D -be madc ::Ibout

il1rh~s di.lIncter

with

rng~ ,

the u undle

fmall in proportian with

HdVCS, an Ilbe milllancs becach .1bout t \\lO fcel in

Jiam~tcr.

¡t:lJ

th~

wilol'.! \\'ork

be put

iot'J

ílrong

rramo! of w('od,