. motion o f the earth about its axis,' and alfo the variation
/o f fegfons a^ifing; from jit-Sïinotioàv about ,the -
fupppijf}gj;fte hip tpjmove fiï thevecjjpjtiçsinjiea<3» o^the
. earth, which wfil pot alter any o f th«fa^pearaaoes^M^Q,1
n e a c h * t h e r e is a circular, fiat* piece- oBwop.d^the'
plane o f which gaffes through the penter^ 61^ ^q^gfpbe,
marked the days o f the month, .a n d jp ^
fefponding _to-them the figns o f the .ecliptic, * wh*er,e^the~
fun is on thoie'fiays; /the points o f the -compafs' arè^âHo
put upon the fame .^iece.>Xî^hi^;is *câ|lécl: iftie horizon ;
at^Hghf angles to .which; tthere, is -a circular piece= b f
brafs, on which thé ; globe hangs, called the brazen meridian
5 it is fupported at the Ioweft,point-on a roller,
oh which it turns ip, its own-plane, and paffesj;hroügh
the horizon in two^gró’öves eu f fpr ^ h ^ ^ rp o fe ; on this
circle the globe is fuppprted Iby the • extremities o f its
axis ; and the axis paffes through the brazen-meridian,
and carries an index round, with it over a ( circular plate
^ which is divided into hours, SCGi ''Qireach "giqbé/mere
are -two circles,- one' jeprefentihg the ecliptic? ?the
^HaraSters'©f the hgnshipon it,'an d the other the- equator.
~ T o each o f thefe circles, on the celeftial globe, IJj
'condaries are drawn to every io or 15 degrees"; blit on
the terreftrial globe, they are drawn only to the equator.
/There is ■‘alfo a?fiat piece oFbrafs, called the quadrant o f
altitude, which is occalionally fixed-to thé brazen menU
dian in its zénith,-by à hut, and the lower end is put between
the globe and the -horizon, and can be .turned
round to any point ; • i t is dfvided-into degrees,, &c.~by
which the altitudes o f objects above the horizon may be
found, and'fhéirà^tmuths determined, From^üé^qint
o f the brazen meridian correfgondingto the equator, the
^degrees begin, and are continued" Both ways up to o o f
at each pole ; but for the other femieircle o f the brazen
meridian/ the. degrees-b'^gin a t the goles, and 'are continued
up 'to;ÿoç 'a t tlie equator. Oü: .thé' hpifzón, the
degrees1 begin a t thé éaft' and weft points’,.arldhte continued
both' ways to 90*,' "of to- the. uprth ahd ’fouth
points.1' T h e ecliptic and equltor begin thrirdègreés at
one o f their, interfe&ioos,' qafled ariesÿ)and they are conS
tinued round the fame way1 to 360°; alfg^thë former is
divided into, and marked with» tne&welve iigns ; and the.
la tte r« divided from th^ fame^point, into 24 hours,
jüpon the foot o f th e globe there‘ is often put a cora-
pafs, by which the- brazen - ^ i^ ia ii .m a Y be fet/ north
and fouth*
On tjpe life pf the T erre s t ria l Globe,
f a d I P Datituclèfcif aPlace.
Bring the place under that femieircle o f the brazen
meriqian where the divifions begin at the equafqr, and
pbferve what degree the place is under, a n d i f is the la-
titttde required. .
"zoB.-' To rtSify thèjGldbvtô the Latitude ó f a-Plpce»..
Elevate the pole above the horizon till its altitude,
obferved on the brazenr merioiap,. be equal tq the latitude
o f the place, and it is then fa id to be' rectified tet
/^^Ja^ltpde» -and it fo far: ftands! righ t, .-for thé folütîo» ’
*è£^all .problems, .for.that latitude;
.-‘ l!:WM$t " ToJind'thÓlïMigitudeqf;â \Plàchfront Greghwiàhu'
7';’^rBring^he‘place! to the. graduated edge o f the brazeiV
meridian, and obfervë the point o f 'the| equator , which .
dies''wilder ‘it, and the diftance o f that point from thé
. point where the meridian o f Greenwich cuts the equator,
is the longitude 1 equiiedr/ +
■ 2 io. Given the,., hatitude and Longitude, o f a Plate, to-
f a d where ihepldce is. H :
Bring the. given degree o f longitude to the brazen*
meridian, and then under the given, ^egreef a latitude*
Lpp'dh thàtrmëridian,. you have the ’pace. ^equir|i|/J
rT2 i i^ When it is No.on at any Place Ay pofad the Hour
ita n y other Place B .
B r in g ;A to the meridian, and fet the index to 'X I I ;
Æhen turn tdie .glhhévtill BXcomës^ under *the mqridian,
and theihdex^ -will fhow the, hour-- -at-1B . t * I f it, be .; not-
iiooii at A , fet the index to the hour,, aftdfproceeil asbé-
I fore, and you get the correijicmdin^hour at Bi
I Bring A to the ^ e r i|iite ta i^ ^ ew it^ q u 'a d ra n t -o f
•altitude over it, and carry it to B , and you get themum-
her o f .degrees-, between i l and B , , which multiply- b y
6çj2, ïhe miles in one_degree, and you get the diftance
required.
HH '23 Toxjfnd the Bearing bj B'fnom A.
Re ftify ftherglobe fort-hë d’atitude o f A ; aridb rifigA
to the meridian, andftx. thé" cmâdraùt of!:altitudé tq ;A 5-
then direót the quadrant -to B , ^and|tKe/p,oint ,,where it
I éiits^ thè horizon {hqwsThe h ^ f in g ré^^ ’ ;
214. A t any. Hour o f 'the Day at By to find the:Bfnce A*
tô buhibh the, S un is zièrïicah'.
* S Find the H -the - ecliptic, and bring it to.
the brazen-meridian, and you find its^d’eclination on the
meridian ; then- bring B 'to the meridian,! and* fet the. iff-
d ex'to thegrvea hour, and-turn thé%îofeé til^th^indéx
comes to X I I at hbon/and the place unde*"- the fun’ s
declination upon the meridian;,-is that required.. M
215. To Jma'tal any Dc^ andHoury th&-.Places\%uhere
the Sun 'is, rifing, felting, or on the Meridian ; plfo, thofé.
Places which are .'enlightened, and where thç Twilight >*>
beginning and ending. ,•
- Fi-nd-- (by. art. x214; )-the .place to .which tbifu-n is vertical
at/the givên- hour; and:bring’ thé fame to.themeri-
#ia>b, ''and reftify the globe tq a-latitude, equal to the
féh,8 d'eefination*. I Then tojaB thofe' 'places undélfTthe (
Wejlërn■ -femicircle o f tHe horizon,-the"'fu-njis.r//7w^; to
thofe under the eajlern femieircle, the fun is Jetting; and
tó thdfe under the mridiàn,, it. is noonw
A lfo , all' places above th e horizon, are enlightened, and
all thofe below.are in the dark hemifpEere.
L a ftlyj in all thofe places l§ ° . below the weftern horizon,
the twilight is juft beginning in the morning, and in-
1 1
tTioft t8? UJ91Ï the c (îein haiizon; it ls ji’.l ending in
the-evening. - ,
2 16. 0 find all the' Places to-which sa lLunar Pcliffe is
'evifible' at any Irflant.- ' •
Find the place’ to 'wh ich'th’e fun is vèrtieal at any .
time, and bring that plncé to the zenith, and,the e'eMipie]
will be vifible to all the hemifpherc 7mrZ?r-th-e. horizon, '
- beèaufe the moóh.' is then-.oppqftte to the £nn.
:/ On
2 17 . 2"o find the Sun's right Afienfwn and Declination.
I . Bring the tuijT., . 'tliL ](1 ,i^pn
Jncrùlian, a i t ' hd i n t c meridjan, -mie^Le-..
elination ; and the degree f t the equatoi .vk eh ij Lilt by
the meridian, is the n ^ L & ijefiioi
2 18. Given the right dfeetfion and Declination o f anhea-
FbitvBrfrig“ the gitell âaéênffiin eö^iê'equ®-
te)r, to thé>bVj^Mi mti di ib,' and the degree <; Trite'-meridian
.corràÿonéütgÿfte thé declination, ^>ôin'ts"out tTie
place required. I "
zto. . Gkien tSe Latitude gT a Placcfithc B a y and Hour,
to fixid the Àlülude and Amplitude ofi a given heavenly Body.
. Ihedtify.the .globed (by art- 2c8.)->t/^he.lat;tbd£,of the
lace,, and Jitfing the iu^’ s place hi the ecllptic-:|o* the
rajren meridian, and fet the index tó X I I ; then turn
the globe till thé index points to, the given hour, and in
that pofit^o'4'the globe reprefents thqiproper iituation o f
all the heavenly bodies, jnf bôipeâ, ta th e meridian and
horizon. .Then fix the quadrant o f altitude to .the
zenith, an.il direftûts graduated edge to the place o f the
T o d y , tand ittffipws jshe altitude o f the body ; and the
degree jwh^rf), it, cuts, the horizpn, fhows-its atnpbtodè.
I f the body b,e .the moon o f a planet,; afterlhaving, found
its place, you ma y pu t a finall patch to denote its place.
oez'QsISi; (is • before, to f i t the Globe fa that the Stars
Upon it may correjpond to their Situations in the Heavens.
T he globe being fixed as^jrr thé .'la il'â ra â^ .b y means
o f the ' compafs' let the brafs/,iiiei|SaB;B;e fé t in the meridian
o f the plate, with the hoTtii pole to the north ;
then wîll'all .the ftars upon tiïé globe’correrpond. tó their
placesïSirhe heaVehsj'fo that an eye at thejeenter ,of the
globe would refer every ftar On its fnrfacel tO:the'place'of
the ftar in fhfc KeàVens. B y coi . the
ftars in thé Heavens with their place's on the globe1,^ypii
will eàfilÿ get acquainted: with the ftars.
, 221. STofind the.fime.;uwen anyof the heavenly Bodies^
rife] fit* or come to the, Meridian ; alfo, their Azimuth at rifi'VS
or fi>ti”g- | ; .
R ed ify the globe to the latiCude o f the place, and
bring the, fun’ s place in the ecliptic to the meridian, and
fet the index to X I I . as in art. 219. Then turn the globe
till the given body comes to the eaftempa rtof the horizon.,;
and; the index ftio.ws .the time, o f its filing; and the
arc’ o f the horizon between, the body and the north or
foutli points, will give its azimuthi Bring thé body to
it-he^meridian, and the index (hows the time o f its coming
to it. BringrthO'body to the weftern horizon, and the
index.jhows the. time .of its fetting ; and tile arc o f the
horiàon ihetween
"will give its You may-thus find the time o f
the fun S' rifing arid; fetting. I f you turn the globe
about its^axis, àllfhofe liars which dp not defeend below
thé b;o,ip£anj rieyef fet i:at that place;; ând thofe which
^o - db'cwe' it, lleveé. rife. / .
222. To explain, in general, the /tlle.fatmti‘ o f the Lengths
ofi the, Days, and .Difference o f the Seafint. . ' ‘ (
» Put patches upon the edfptic from a ties both ways
to the tropics,;and|det.jthem f eptefent fo many different
fituations o f tlîcifcn ; andfhen the globe being re&ified
to the latitude o f the place (by art;: 2o8i), torn it about-
and ypp w S . fee, for r,iorth Jatitadfe; I t hat as the patches
approach the tropic o f caricerihli&jcojréfponding diurnal
.ares ^ wiih mereafe-J ^.’^ /Is the patches approach the
tropic o f caprice 1 d, the diurnal arcs' will decreafe ; alfp,'
tV- former arcs are gréîjter than a.femieircle, and the-
latter lefs; and the patch in the equator will deferibe a
femieircle above the horizon. When,therefore the fu^-
is in the equator, the days and,nights are equal as he
■ advaiaces'to wards the t:ropic.ofcancer,thedaysinçrçâfé,-
the night,s decreafe, till he^comes.' to, the tropic,
where the days are fopnd.tP: hé. longcft, and the nights
Ihortefi: ; then, as lie approaches the equator, the length
pi* the days.diminillies and that o f the nights increafes, and
when, the fun comes to the equator, the lengths» o f ; the1
days and mights are equal; Then ^as he advances towards
capricorn, the days contiiiué to diriiiniih and the
ri.ights-increafe till that tropic; where the days,
■ areiftiorteft and the nightsarejongeft.; àndthen as hpj ap-
proaches the equator^ the days iricreafe and the nights* di-
minifti ; and when he.comes.to .theiequator, the days and
nights are equal. Arid wha^â^o|)MhMÛCÀ<I^..t|||a.'
..Æé fun is in thé equator, days and nights, are equal. T o *
riniiphaKtant at the-polfe; the fun. will*appear to be half
a year above thé,1 hdÈizôhV.TÙnd h a lf ayeaishélow. T o an-
inhabitaiit a t theequator.'lHe, clays an el nights .will appear
to -be always equal ;!l alfo, all the heavenly bodies
will be found to be as long above1‘the horizon-as below.
A t 1 the 'arctic - circle, the lçagcit day will be . found
to be 24 hours, arid tlie fóhgeft.nigliL 24 hours ; this apt
pears b y rectifying the globe to that latitude, and ob-
ferving the patches at tlie'tropics p f canccrarid’pf capri-1
corn. . L a llly , it will be found that- «ill places enjoy
equally the:fab in' icfpeft to time, and are equally deprived*
of it, the length', o f the days, at cine time o f the
year.*-bairg;çfound; exàiîüy ‘equal- to ’ the length o f the
nights at the ‘pppöfi.té féàfbri, f This appears by getting
patches upon the àdlîpjaèmtopppfitè points o f it.
223., Tsfind the Latitude and Longitude ofafiiven Stary
alfo* the Dyiance o f isuo'Siars.
■ Bring the folftitial col rire to 'the meridian, and fix
the quadrant o f 1 altifrid'ebovier the pole o f the ecliptic ;
then turn the quadrant over the1 -given -ftar; 'and the- arc
contained