1000000030

.thread is a

r:n~JI

plumnoet

~od

00 the middle of il a

fnll11

be.lu

for

Ihewin~ d.~

ho\\r of the day.

'1'0 reélify Ihis dial, fet the thread in the Oil right a·

~aioll

Ihe day of Ihe mond., aod (lwch the

thr~ad

from

the d.,), of Ihe moath 01'er Ihe aognlar poinl \Vh"re Ihe

curl'c·lto,s tlhel :11

XI!;

Ih~o

Olírt Ihe bead 10 Ihal poiot

011

the :hrcJu,

ami

Ih~

dial wíll be reé\ified.

1'0

hnu Ihe hour of Ihe day, raife Ihe gnomon (no

nt.\tter how lI\\\ch or ho\V lillle) anJ hold Ihe edge of

Ih~

IItal neXI tll! gooowo 10IVards the fno, fo as Ihe up·

rcrmoll

ed~e

of the Ol"do\V of the goomoo may jutl eo·

\'«

Ihe

Ib~.I'1'U1-lill(;

aod Ihe bead lhen playiog free ly

oa Ihe f.\Ce of Ihe dial, by Ihe weighl of the plummet,

will OlelV tbe time of the day among the hour·lioes, as

it is forenoon or afleroooo.

To ¡ind the time of [un· rifing aod fClliog, move Ihe

thread amoog 'the hour.lioes , uotil it either eovers fome

one of them, or lies parallel bctlViKI ally IWO.; aod then

it \ViII cut the time of fuo.rifiog among the foreooon

hours, aod of fuo.feHiog among thc

~fleroooll

hours,

for thal day of the year 10 which Ihe Ihread is fet in

the [cale of monlhs.

find the fun's declination, nrelch Ihe Ihrcad from

lhe day of Ihe month over the angular point at XII,

ano il lVill cut the fun's declinalion, as it is oonh or

fouth, for Ihat day, in the proper

fc~le.

•

T hen feniog ooe fool of the compall'es io Ihe

poiol

e¡¡teod the other 10

aod deferibe Ihe are

for the tropic o[W : Wilh Ihe Came eXleot, fet·

liog ooe

COOI

defcnbe the are

AEO

for Ihe Iropie

Eii.

NexI fmiog ooe fool io Ihe poiot

aod ex·

teoding Ihe olher to

deferibe Ihe are

ACJ

for Ihe be·

giooings of Ihe figns

:::z

aod

aod wilh Ihe fame ex–

t~lIt,

Cetting one foot io the poiot

deferibe Ihe arc

for lhe begiooiogs of Ihe figos

aod

6(..

Set ooe

fool in Ihe poiol

aod haviog exteoded the olher to

dcferibe Ihe are

(or Ihe begiooiogs of the figos

aod

nl ;

and \Vith the fame eKteot, fet 00 fOOI io ", aod

defcribe lhe are

}{j'd

for the beginoiogs of Ihe figos

and

nJt.

Then fwiog ooe fool .in the POiOl

¡od ex·

lendiog the other

deCeribe Ihe curve

for!he

begiooiogs of "(' and

:Q:;

aod the figns

will

be lioi!hed.

This dooe, laya ruler from the poinl ,10ver Ihe fun's

declioatioo in the

~rch

RST;

aod where the ruler eulS

Ihe line

FDe,

make marks ; and place the days of !he

moolbs right agaioH Ihefe marks, io Ihemaooer fhewo by

fig.

Latlly, drawthe fhadow·lioeP

~parallel

to tbe oc·

cult lioe

;

make the gnomoo, aod Cet the hours tO.lheír

refpeélive lincs, as in fig.

and Ihe di.! will be fiol!hed,

There are feveral kiods of dials, IVhieh ate called

univerfa/,

becaul'e they

f~rve

[or all latÍtudes, Of thefe,

thl! bel! is Mr Pardie's, (Plate LXX. fig.

4.)

whieh eoo–

fins of linee priocipal parts; the firl! whereof is called

Ihe horizootal plaoe

(A) ,

becaufe io praéliee il

mu~

parallel to the horizoo. In Ihis plaoe is fixed ao upnght

pio, whieh enters ioto the edge of the [eeood par!

BD,

called the meridiooal plaoe; which is made of tWO

pieces, Ihe 10IVe(l whereof

(B)

is called the

quadr~ot,

be–

eaufe it eoolaios a quarter of a circle, divided lOtO

degrees; and il is ooly iOlo Ihis part, nen

Ihat the

pio eolers. The other pieee is a femicircle

(D)

adju(l.

ed lO the

quadr~nl,

aod lurniog in il by a groove, for

raifiog or

d~preffiog

the diameter

of lhe femieirde,

whieh diameler is called Ihe axis of Ihe ionromenl. The

third pieee is a eircle

(e) ,

divided 00 both fides

i~to 2~

equal pans, \Vhieh are the houn . This cirele IS put

upoo Ihe meridiooal plaoe [o, that Ihe axis

may

be perpeodicular to the eircle, aod the point

be the

commoo eeotre of the circle, femicirde, and quadraot,

The (lraighl edge of the feruicircle is chamfered on

bOlh fides to a fharp edge, \Vhieh pa/fes through the ceo'

tre of the eircle. On one fide of the chaOlfered part,

the fidl fix months of the year are laid down, aceordiog

to the fun's

declin~lioo

for Iheir refpeélive days,

aod.oo

To 6nd 00 what days the fun enlers the figos: when

the bead, as aboye reé\ifled, mOI'es aloog aoy of the

eurve·lioes whieh

h~ve

the figns of lhe zoJiac marked up'

oo.thcal, the fuo eOlm Ihofe figos 00 the days pointed

OUI by lhe

thre~d

in the [cale of momhs.

The eoo(lruaion of this dial is very eafy, efpeeially

if the reader compares it aJl aloog Wilh fig.

as he

reads the fuJlo\Ving explanatioo of that fignre.

Draw the oeeull lioe, (Plate LXX. fig.

9.)

parallel

to the tep of Ihe eard, aod erofs il at right aogles wilh

lhe Gx o'dock lioe

ECD;

lhen upon

as a ceotre,

IV';"

Ihe radius

CA,

defcribe the femicircle

AEL,

and

diride it iOlO

equal pans (begiooiog al

Ar,

Al,

&c. aod from Ihefe poiols of divifion draw the

hour·Jioes r,

/ ,

u, v,

'W ,

aod x, all parallel to the

fi x o'clock line

If eaeh pan of the femicircle' be

fubdi"ided iOlo four eqllal pans, they will give the half·

hour lioes aod qUHlers, as io lig.

DralV the righl–

Jine

AS Do,

makiog the aogle

SAB

equal 10 the latÍ·

tude of your place.·

poo the cenlre

defcribe the

areh

RSr,

aod fet 011' upoo il the ares

aod

sr ,

eaeh equal

23'~

degrees, for the fuo's greatelt declina·

lioo; aod divide theminto

23';'

equal parrs,

in fig.

Through Ihe ioterfdlioo

of the lioes

ECD

aod

ADo,

draIV lite right lioe

FDe

at righl aogles to

,1Do.

Lay

a ruler

the poiots

aod

and sraw the line

ARF

throllgh

13{

degrees of fouth declioatioo io the are

SR ;

"nd then I,'yiog the ruler to Ihe points

and

draw

the lioe

re;

throu~h

1 }

degrees of oOrlh declioalion

in Ihe are

sr:

0,,11

Ihe lines

ARF

~nd

Are

eUI Ihe

linc

(){;

io the proper length for the feale of months.

Upu"

I~e

centre

with the r.dius

DE,

dcferibe the

b ,lÍeirek

roe;

IVhieh di, ide 'OtO fix

e~u:tI

pans,

Fm,

" . ,

&e. ar," from lhefe poiots of divifioo Qmv

thz right lin':\

mf,

IR,

aoo

ql,

eaeh rarallcl to

lhe other olher fide Ihe la(l fix months. And agalOl[

me days on \Vhich lhe fuo enters the figns, there are

nraighl líoes dra\Vn upon the [eOlicirele, \Vith Ihe eha·

raélcrs of Ihe figos marked upon Ihem. Therc is ablaek

lioe drawo aloog Ihe middle of Ihe upright edge ?f I!IC

quadrant, over \Vhieh haogs a Ihread

(H ),

lVuh

lIS

plummet

(/ ),

for levelling Ihe io(lrumeot.

From

theIwenty.third of September to thetI"eolielh ofMareh,

the upper furface of Ihe eircle mun IOlleh bOlbthe eeotre

of Ihe Cemicirele,

~od

lhe líoe of "(' aod

.f1, :

and

from the tlVentitlh 0f March

the twenty.third of

Sep'

tember, Ihe lower

furf.ce

of the eirele muH loueh Ibal

centre aoJ li oe.