1000000030

'lfard fronl us, llave noon, and every olher hOllr, an Imur

fooner Ihan

Im:e. They whofe meridi"n is Hleen

¿egrees well\Vard from us,

hav~

noon, and r"ery

ther hour, an hour laler than "'e have: and lo '-on

jn proporúon, reekoniDg one hour for every fifleen de–

gree!.

For Ihe ecliplic circle, figos, and degrees,

f~e

ASTRO'

NOMV ,

p. 435.

The

Iropio

are lelfer circles in the heaveD, parallel to

the equiooc'lial; one on eaeh fide of it, touching the e–

.cliplic in Ihe poiols of jts grealell declioatioo; fo Ihat

each tropic i! , ,{ degrees from tbe Equiooaial, ooe on

the oonh fide of it, and Ihe other

the fouth. The

nonhern tropic louches Ihe ecliptic al the begiooing of

Caoeer, the foutbero at the begiDoing of Capricoro; for

which reafoo Ibe former

called tbe

Iropie o[ Caneer,

. od the lauer the

lr6pie o[ Caprieorn.

The

p.lar eirel"

in the heaveo, are each

degrees

{rom Ihe poies, all arouod. That which goes round tbe

Jlonh pole, is caBed the

ar!lie eirelt.

The foulh polar

.circJe. is called the

an/arme eire/.,

from its being op–

pofite

Ihe araic.

The ecliptic, tropics, aod polar circles, are drawo up–

po the terrellrial globe, as well as upoo th;. ccldlial.

BUI Ihe ecliptic,

b~iog

a great fixed circle in the hea.ens,

caooot properly be faid tO beloog to the terrenrial globe;

aod is I"id dowo

UPOD

it ooly for me conveoiency of fol·

viog fume problems. So that, if this circle

the ter·

renrial globe was properly divided joto the months aod

days of the year, it would oot ooly fuit the globe bener,

but would alfo make the problems thereon much eaGer.

For Ihe earm's mOlion round its axis every

hours;

Íts

mOlion io the ecliptic rouod the fuo every year; aod

Ihe viciflitude oHeafoos; fee

A STR

oNOM

452.

DcJcription of tbe Terreflrinl G/ohe.

[See Plate

XLIV.

fig.

2.]

The equator, ecliptic,

~od

Iropics, polar circles, aod

meridiaos, are laid down upoo the ¡;Iobe in the manoer

already defclibed. T he ecliptic is dlvided into

figos,

aod eách Ggn iOlo

degrees. Each Iropic is

23{-

de–

grees from th: equator, aod each pol?r cirde

23t

degrees

from ils refpeaive pole. Cireles are drawn parallel to

the equator, at every tendegrees difl,nce from it

each

fide lO tRe poles: thefe cireles arecalled

paraJl,/¡ o[ la

Iilude.

large globes Ihere are cireles dra\Vo perpeo·

dicularly

thro~gh

every leoth degree of the equator,

interfeaiog each other at the poles : bUI

globes of

(Ir

uoder a foot diameter, they are ooly drawo through

every fifteeoth degree of the equalor ; thefe rireles

are geoerally callerl

lIIeridian!,

rometimes

eire/a

JMgilude,

aod at olher times

hour·circleJ.

The globe is

huo~

in a brafs.riog, called tbe

hrnun

múidiQ1J;

and turos upoo a wire io eace pale funk half

Ihicknefs into onefide of the meridian ring; by whieh

meaos,

Ihal

Gde of the riog di,'ide, Ihe ,globe ioto t\Vo

equal pam, called Ihe

eajlrrn

aod

'Wrjlml honijpheru ;

I S

Ihe equalor divides it inlo twa eqllal pms, called the

lIIm/¡ern

aod

fouth,rn hemifph(fIJ.

'fhe,riog is divided

iolO 360 equa l pHtS or degrees,

0 0

Ihe Cide

whwi~

Ihe

axis of Ihe globe turnl . One

h.df

of thefe

d~grees

are

Jlumbered, aod retku:1ed, (rom the equator to lhe roles,

where Ihey eod at

90:

their ufe is to fhe\V the l:tmudes

of places. The degrees

theolher half of themelidian

rins are numbtrcd from Ihe poles to the equRtOr, \\'here

lhey eod at

90:

iheir.ufe is

!he\V ho\V

elevale either

the nonh or foulh poie aboye the horizon, accordiog to

the lalitude of , oy giveo place, as it is north or foum

the equator.

Tile brazeo meri¿iao is let into two notGhes made io

a broad Hal rine, called the

'Woodrn horizon

; the

upp~r

furface of \Vhich divides tbe globe ioto t\Vo equal pam,

called the

up/w

aod

1O'W,r

h,mijphtrtJ.

Ooe ootch is

iD the oonh point of Ihe horizoo, and the other io

th~

foulh.

tbis horizoo are fe,'eral conceouic circles,

which cootaio the mOLlb aod days of the year, thefigos

aod degrees aofweriog to Ihe fu o's place for eaeh month

aod day, and Ihe

poinls of the complfs.-The gra–

duated fide of the brafs meridiaolies towards the eal! fide

of the horizoo, and fhould be geoerally kept towards the

perfon who works problems by Ihe glo!>es.

Thereisafmall

borar) eirclt,

fo fixed to the oonh parl

of lhe brazen meridian, thal Ibe wire io the oorth pole of

tbe globe is io theceotre of Ihat circle ; and on the wire i$

indt>t,

which.goes over all the

hours of the cirele,

as the globe is turoed rouod its aKis. Somelimes there

are two horary circles, ooe bwveeneach pole of lbe globc

and the brazeomeridiano

There is a Ihio nip of brafs, called the

qtladrant

1//–

tilud"

whieh is divided ioto

eqllal pans or degrees,

anfweriog exaalyto fo many degrees of the equator.

oec~fionally

fixed lO the uppermon poiot of the braze6

melidiao by a out aod rcre\V. The diviGons eod at

the

nut, aod the quadraot is turned round upoo it.

Tbe DeJcriptioll nnd Ufe oftbe Armillary Sphere.

[See Plate

LXXXVII. Fig.

l.]

exterior pans of this machioe aTe, acompages of

brafs rings, w.hich repréfent the pri ocipal circle6 of

Ih~

heareo,

viz.

T he eauionai.1

AA,

which is divided

into

360

degrees (beginning at its iDterfeaioo wilh

th~

ecliplic io Aries) lor fhewiog the fun's right afceoGoo in

degrees ; aod alfo iOlO

hours, for fhewiog his right a·

fceoGon in time.

The ecliptic

BO,

\\'Lich isdi"ided

iOlo

figos, and each Ggn iOlo

degrees, aod alfo ioto

the monlhs aod days of Ihe

ye~r ;

in fu eh amanner, thal

the degree or poim of theecliplic in which the fuo is,

any

gire~

day, nands over thal day in Ihccircleof mooda.

The tTopic of Cancer

CC,

touchiog the ecliptic at the

beginning of Caocer in

aod the Iropic of Capricorn

DD,

touching the ecliptic at Ihe beginoiog of CapricorR

in[; each

23t

degrees froOl the equinoaial circle.

The

ar.'lic cilde

and the

~otaraic

cirele

eaeh

23t

de·

gree, from its refpeaive pole at

and

The equi–

ooaial colul'c

CC,

p¡fliog through the oonh and foulh

poles of Ihe heaven

and

anJ through the equi–

noai.1poiots Aries and Libra, io Ihe cdiplic.

The

ful!litia l

eolUTe

"H,

palling through

Ihe

poi

of Ihe

h.al'

Cn,