1000000030

toXI, X, IX,

&e.

in Ihe forenoon, or aS

15, 30,

41,

!hllS,

\Ve

have fiñifhed our declining dial

and in fo

Oe.

dcgrces of IheequalOr pafs under the brazcnmeridi· dOlng, we made four dlals,

viz.

an al Ihefe hours refpelQil'ely; and Ihe degrecs Ihen cUIl A nunh dial, declining ea!lward by the fame numo

in Ihe quadraOl

Ihe firn meridian, are Ihe refpeaive ber of d<grees.

A nonh dial, declining Ihefame numo

dinances of Ihe f"renoon hours frnm XII on Ihe

pl.ne

of ber wel!.

3· .

A lomh dial, declining eal!. And, 4, a

Ihe dial.- - Then, for Ihe

afl~rnoon

hOllrs, lurn Ihe foulh dialdechnmg wd!. Ooly, placiog Ihe proper numo

quadranl of altilude rounJ Ihe zenilh IInlil il comes lOIhe ba of hours, and Ihe lIile or gnomon refpellively, upon

degree in Ihehorizon oppofile

Ihal where it was placed eachplane. For (as aboye OIenlioncd) in Ihe foulh.wdl

hefore: namely, as far(rOIll Ihe IVen poi Ol of Ihehorizon plane, Ihe fubllilJr.line falls among Ihe afterooon houu'

IOIVards Ihefomh, as it was fel al firll from Ihé eafl point and ill lbe I(¡uth

e.fI

, of Ihe fame declinalion, among

Ih~

lowards Ihe nonh; and luro Ihe globe w..¡hvard on its forenoonhours, al equal dillances from XII. and fo, in

axis, until lhe firfl merioian comes tO Ihe brazen meruli, n all the morning hours

lhewefl

declin~r,

will be like Ihe

again, and Ihe hour·index

XII :

Ihen, Ctlnlinue lO turo afltrooon IhJU rS on Ihe eall decliner : Ihe foulh·eall de·

the globe weflward, and as Ihe index poillts

the after· ciiner wil! produce the nonh·wefl decliner ; and theCouth.

noon hours 1,

!l,

111,

Oe.

or as

15 ,3°,

45,

(oe.

de· IVeitdeclintr, lhenonh ealldecliner, by onlyeXlending the

~rees

the equalor paCs uoder Ihe brazen meridian, the hour.lmcs, IIde and fubllile, quite through the center:

firflmeridian will cut the qu.dranl of altilude in the re· Ihe

a~1S

of Ihe lIile (or edge that ealls Ihe fhadow oUlhe

fpcllive number of degrees from Ihe zenith that each of huur uf Ihe day) bdog in all dills \Vhalever parallel to

Ihefe hours is from

XII

on Ihe dial.--And nOle, Ihal IheaXIs

Ihe \Vo"d, and confequently puiming towards

when Ihe firfi meridian

go~s

011'

the quadrant at the hori· the nonh pole

01'

the heaven in nonh latitudes, aod tOo

zon in the forenoon , the hour·index (he\Vs Ihe timewhen wud the Cuuth pole iu foulhlaliludes.

Ihe fun will come upon this dial : 'and \Vhen it goes 01F

Hut b,caufe every one who wuuld like to

m.ke

a dial,

Ihe quadrant inIhe aClerneon, the index will poine tOIhe may perhaps not be provldcd wilh aglobetO .lIiflhim, and

lime whenthe fu n goes 01F the dial.

may prob,loly nOI underlland the

metll~d

oC doing it by

Having thus Cound all the hour diflances

Crom

XII,

lay logart:nmic caleulalion; IVe lIlall IhelV holV

perlormil

them down upon your dial plane, either by dividing a fe· by the plain dialling lmes. or Cc. le

laliludesand hours;

micirde into tlVO quadrantsof 90 degrees eacn (beginning fuch as thofeon the top of Plale LXX, and which may be

al the hour·line of

XII)

or by Ihe line

chords, as a·

~ad

on C,ales commonly fold by Ihe malhcnldtical inllru·

bove dire/led.

memmakers.

In all dedining dials, the line on which the flile or

Tlus is the eafiefl of aH mechanical methods, and by

f nomon flands (comlllouly called

the'¡ubJlildi,,~)

makes much the ben, when the lines are truly divided : and not

3nangle with the tlVelve o'clock line, ao<l faHs among Ihe onlythe half hours and quancrs may-be laid down by al!

{orenoonhour.lines, if the dial declines towards the eall ; of them, but every fifth minule by mOll, and every lingle

and among the aCternoon hour·lines, IVhen the dial de

minule by Ihole where the line of hours js a IOOt in

elines towards Ihe wen ; that is, tOtheleCt haodfrom Ihe length.

twelve o'clock line in the former cafe, and to the right

Hal'ingdrawn your dooble meridian line

ed,

(Plate

hand fromit in the lamr.

LXIX.lig. 5.),on the plane inlended

Cor

ahorizontal dial,

To find the dillance

the fubfl ile from the twelve and crofitd it at right angb by tlu; fix o'dock line

o'clock line ; if your dial declines from Ihe fouth IOIVard

(45

in fig.

31.)

lake Ihe latilude

your place \Vilh Ihe

Ihe earl, couo! the oegrees of Ihal declmation in the ho·

compan~s,

in Ihe Ccale of latiludes, aud

Cet

ti,",

eNlcnt

rizon Crom the eafl poinl toward the nonh, and bring the from

10 _,

and Crom

Ihe lix o'dockline: thcn,

lowerend

the quadranlof altitude tOIhat drgree of de· taklog Ihe whole fix hours belween Ihe poinls of the como

elination where the reckoning ends: then, turo the globe palfes in the Icale of hours, with th' l

e~l,m

fel one

COOI

until the firfl meridianCUtSthe horizon in thelike number iti the 'point

and let Iheother fOOl Cal! whm il \Vdl up·

degrees, eounled fromthe fouth poinl toward theeafl; on the mertdian hne

ed,

as at

Do the fame

Crom

3nd the quadrant and firrl meridian IVill then

croCs

one a· to

and draw Ihe righl lines

and

/b,

each

\Vhicb

nOlher at righl angks, and Ihe number

degrees of Ihe \Vil! be equal in lenglh tO the whole fcale of hours. This

quadrant, which are intercepled between the fir flmeridi· done, fwing one COOt

the compalfes in Ihe beginning

ao and the zenith, is equal to the diflanee of Ihe Cubllile of Il,e fcale at XII, and emndiog the other tOm h huur

line Crom the twclve o'clock line; and

th~

number of de· on Ihe Ide, lay (¡IP Ihefe eXlents from

tO,

Cor

tHe af·

grees

thefirfl meridian, IVhieh are inlereepled

b~lween

afternoonhours, and Cro'OI

Ifor

thoCe

the Corenoon:

Ihe quadrant '.nd lhe nonh pole, is equal

the elel'auon this wIII diVide Ihe lines

.no

in the

CarnemannCT.as

of the flile above the plane of the dial.

Ihe hour·fcale is divided al

1,2,3,

4, aud 6; on whlch

If the dialdeclines wellIVa¡d froOl theCouth, count tha! the quarters may alCo be laid down, if required. Tite?,

declinalion fromIhe eafl point of Ihe horilOn tOIVards the laylOg a ruler ou

th~

poinl

draIV the firil five hours ID

fouth, and bring the

~uadraO!

altilude to Ihe deRrce in . the afternoon, Cro:n thal point, throllgh the do:!

the

Ihe horizon at whicl, the reckoning ends; both for linding numeral ligurcs

1, 2,

on the IlOe

d~ ;

and conu'

Ihe forenoon hours, and oiflance of Ihe fubllde from Ihe oue the

hn~s

of 1111

~od

Ihrough Ihe C('nter

Ihe

meridi.n: and lot Ihe afternoon hoors, bring the qua· otlter fiJe of the. dial, lor Ihe llke huurs of the ml,r01l1g:

draot tO the oppofite degree io the honzon, n.IOIel)', as Car whieh dOlle, l,¡y lhe rultr on Ihe poinl

aoJ draw Ir.e

from the well towards the nonh, and then promd in al!

1.11

live huurs in Ihe foreooon tbrough Ihe dOls 5, 4,

reCpells as aboye.