1000000031

72 / 868

!VI E q H A N 1 e s. 55
be found to m('!\Ie along with the fdOle velocity as al lirn:
which nl~WS, dllt {he po\\'cr required to dr;¡w lhe c:tr-
1'la5!.c is dll lhe [..me, whcthcr lhe grcat or f.nal1 whccJ~
.are foremaH i and thererore lhe great wheels do nal help
io Ihe leal! 10 pufh on Ihe f",all whecls io Ihe road.
H. ng Ihe fc. le lO Ihe fore cord, and place Ihe fore
wh!els (\Vhich are the fmall anes) in (wo holes, CUt three
cighth-paru of <In inch deep ioto lhe board; lhen pnt a
weight of 32 ounees ioto lhe c:uriagc, over lhe fore -axJe.
2nd an equal weisht over lhe hind ane: this done, pm
44 aunees ioto the rcale, which will be juO: fufficicnt to
draw out the fore -wheels: bUI ir tbis weight be takeo out
oC lhe rcale, aod one of 16 ounees pUl ¡ntO ils place, jf
.he hind·wheeh are placed in Ihe holes, Ihe 16 ounces
weight will draw thcm out; which is Hale more than a
third pan of \l/har was neeeífary to draw out the fore·
wheels. This fllews, thal the I:trger the wheeJs are, lhe
icfs power will dr¡w lhe carriage, efpeciaJly on rough
ground.
PUL 61 ounees o\'er tbe axle of ,he hind·wheels, and
32 over lhe axle of the fore ones, in the ea.rriage ; ~nd
place lhe fore·wheels io the holes: tben, pUl 38 ounces
into lhe feale, whieh will jufi draw out the fore· wheels ;
.od when the hiod ooes come to Ihe hole, Ihey will ftod
but very Iittle refiaaoce, beeaufe Ihey fiok bUI a little w.y
into ¡t.
BUl lhift lhe weighu in lhe earriage, by pUlting the
32 ounees upon the hind axle, and lhe 64 ounees upon the
fore one ; and place the fore whee)s in lhe holes ; lhen, ir
76 ounees be put inlo the fcale, it will be found no more
than fufficient to draw OUt there wheels; which is double
the power required tOdraw them OUt, when the líchter
part of the load \Vas pUL upon them: which is a plain de–
monaration of Ihe ab(urdily of putting Ihe heaviea pa"
of the lo. d io the fore part of the wageon.
Every one knows whal an outcry was made by (he ge·
neralit y. jf not lhe whale body. of the carriers, ag~infl:
(he ~road-wh~el aél; aod how baTd it was lOperruade
them to comply witb if, even though lhe government al–
lowed them' to draw with more horfes, ~nd carry grejuer
·Joad,. than ufual. Their principal objeétion was, lhat
as a broad whecl mun touch the grollnd io a nreat many
,more po:nls than a narrow wheel, the friétion mull of
courfe be jufl: fa much lhe greater; and confequently,
there mull be fa many more horres lhan ufuJl, ca draw
Ihe \V.ggoo. lt is believed Ih.1 Ihe m. jority of people w<re
.of the filme opio¡oo, not eonfidering, that if Ihe whole
weight of the waggon and load in it bears upoo a gre:\t
many points, Cull.ins a proportionabl y dee..e of
.weight and fríélton, lhao when it bears only upon rl; few
points; fo thal what is wanling in onc, is in the
'Vlher; and therefore \ViII be jull equ. 1 under e'!ual .de·
grees of weighl, as may be fhewn by the follo",in;: pbio
'and eafy experimento
L et ooe end 01 • piece of packthrc.d be f. fleJletl 10 a
brick, ~nc1 the other cnd 10 a COOlmOIl feale.: for holdir.g
weighls: tllt:o, having J~id the briC'k ed~ewifc on a lable,
anct Icc the fcal~ hang unfler lhe ed~e of lhe tabJc, pUl 3S
·m\1ch weiJ~hl into Ihe fc:\Je :\s wiIl jull dr:\w lhe hrick a–
long lhe table. Theo takinc baek lhe brick la its for–
mer r i.lec, lay it n." on the lable! .od lcave it lO be ../l.
eel upon by lhe f...me wcicht in the [c;¡).! :t before, which
will uraw ít along ',\lith di: fame eolfe as when it I.y up·
011 its edge. In the form er cafe, tht brick mey be con–
fiJt'fcd as a narrow wll~cl 00 the gl'ound j and in th:
htttr, as a bro:¡d whecl. And fince (he brick is ctrawn
alo~lg with equal e<\fC', whether its bro:td tide or narro,",
cdge touehes ,he table, il fuews that a broad wheel might
b: drawn along the ground with th~ fame e:afe as a nar–
row ooe (fuppofioe them <qually heavy) e.~ though Ihey
fl,ould drag, and nOI roll, •• they eo ~olg.
As narrow wheels ~re always linkiog ioto the ground.
cfpecially when Ihe heaviea pa" of the load lies upon
them, they O1l1H be cO!lfidcred as going eonllantly up hil!,
even on leve1 ground; ólnd their muU fufiain ,a
gre'l deaJ of friBioo by rubbiog agaioll Ihe fides of .lhe
TUtS made by lhem. But both thef~ inconveniencies are
avoidcd by broad wheels; which, inflead of cuníng and
ploughing up the roads, roll them finooth, and harden
thero; as expcrieoce te(lifies in pJ:\ces where they have
been ufed, efpecially "ither on \Vettin, or C.ody ero.uod :
though after all ,;1 mua be eonfdr. d, that they will 001 do
io f1 ilf clayey crofs· becauCe they would (oon ga–
,her up as much clayas would be almoa equal 10 -he
weighl of an ordioary load .
If Ihe whecls were .Iwdys 10 go upoo Cmooth and leve!
,grouod, the b, fl way would be 10 n., ke the Cpokcs pe~,pendicular
te tbe ~avts; lbat ¡s, tO Iland at rig!H ar.gle:
to che a)\les; becaufe lhey would thtn bCólr (he weight
of the load perpeodicubrly, which is Ihe arongea way
for wood. BUl beeaufe che ground ¡, geoer~lIy uoeven.
one wheel often falls into a cavity Or rut when the other
does not; and chen it bears much mort of the weight tban
the other ,does: in which cafe, concave or dilhing wheels
are beft j becaufe wheo ooe r.tll, into a rut,. and lhe other
keeps upon high grouod, Ihe fpokes become perpendicu–
Jar in the rut, and therefore have ,be greaten rlrength
whe" tbe obliquity of the load Ihrow, moa of its we;ght
upoo them; whillt thofe 00 Ihe high grouod have lefs"
weight to bear, .and therefore need nOl be at thei r fuli
flrc'oglh. So that the ufual (vay of makine Ihe \Vheel.
Concave is by much the bell.
The aKles of the \Oheels ought 10 be perf<tlly araighl,
Ih. I the rims of the \vheel, !nay be parallel tO eaeh oth«;
for the" they will OlOVe e.fieíl, becaufe they will be at
liberty to go 00 arai&ht forewards. Buc in the ufual
way of prJtlice, lhe axlc:s ate bent downward at their
ends; \\ hich brinns lhe fides of rhe wheels neXI the
ground nearer to one another than their oppofire or high–
tr fid:!s are: :lI1d this oot only makcs lhe whcels ;'0 drag
Gdewife as they ~o ~Iong, ancl git'"cs th: load a much
r.rcaler powcr of cruO¡;ng thcm tha.n whcn (hey are r;¡ral–
Id lOeaeh other, hm alrQ endolngC'rs the ovenurniog- of
the carri:\ge wheo ,my wheel fal), into a hale or rut; or
whcn lhe carriace go('s in a rOtld which has one fiete lowcr
than Ihe oll>er, as .Iong the fide of a hill . Th us (in
the hiod view of , \\'aggon or ca ,, ) let AE aod BY (Ii~.
5·) o':!' t1tt! gre~t whecls rarallcl tu c:\ch olher, 00 t h~~i r
{lr,li~IH :\:de K, and HeI the carri:1gc load~d with he;n',·
r.(lod~ from e lo G. ' -hco, flS lh~ carri~tie &OCS On i~\
l!le ~hliq\\c road , the rentlc of nra\ ity of lhe wholo!
machin. a:ld 10,<1 will be at e (fee p. 3S. col. J, ) aoJ. the
!m: