DIAL 
toIG; then ra a rulerto A aa h, and G, and 
_again to A and d, and H, draw the right lines AV, ATV, 
AVITI, and A VIIL. aftly, i x an oblique ind:x 
AD, making an angle D with a meridian line in the 
plane of the meridian, equal to the elevation of the equator 5 
or the perpendicular index in C, equal to 3; or, inftead 
of an index, a triangular plate ED A, on the meridian line 
EA, perpendicular to a plane of the dia 
V, AVI, be the hours of the fore- 
AVI, A VII, and A VILL, thofe of the af- 
; and ac cordingly wil be pointed out by the fha- 
w of the feveral indexes. 
and the triangle A 
urned about its pole A, til AE fal direGly on A XIL 
aaa a 3 itis evident, a no la ereby had, only 
obferving what has been faid aie eine the hours, 
Lo draw a vertical north or fouth Dia Sead aici 
Thefe only differ from the horizontal dial, t the 
angle CA B is equal to the complement of the “ievation of 
the pole of the place ; 
ing the ye las the 
of the pole of the 
r the method of defe: “ing pen dial by a ‘globe, aa by 
dialling aes fee peg es 
Diat, Eaff, or ere& direG e. ae 
the p: ‘ane of the meridian ie 
Since the fun illumines - eine of the meridian 
-looking eaftward, ae noon, an eaft dial can only fhew 
— hours till twelve o’clock. 
Diar, To defcribe an eaft. On the eaftern fide of the a 
ete meridian draw aright line AB (Plate Il. fig. 16 2 
parallel to the horizon, and to this join AK, making with 
Buss, is that drawn on 
> 
fa) 
fa) 
into four quadrants. 
‘Each of thefe quadrants fubdivide i ie fix equal parts. And 
from the centre D through the feveral divifions draw the 
right lines DIV, DV, DVI, DVII, DVIII, DIX, 
x Laftly, in D ereé& a ftyle equal to the radius 
E, perpendicular t to the plane; or, on two Jittle pieces 
a as lente in 5 rt and equal to “its fame radius 
E, ae par C. 
Thus will a in ndex ms she feveral hours projet a fhadow 
to the refpective hour-lines IV IV, VV, Cs 
Diat, Weft, ot ered dire weft Diab, j is that defcribed on 
the ion fide of the meridian. 
As the fun only illumines that fide of the plane of pe 
‘meridtan looking to the weft after noon, a weft dial ca 
only fhew the hours from noen to night. 
ees luigi joimed with an eaft dial, fhews all hours 
of th 
Niven To draw awef. The conftru@ion is perfe&ily the 
fame as sen of an eaft dial, only or its fituation is invert- 
e hours are written according nh 
cribed on a plane paffing through 
the poles of the world, ate the eaft and weit points of the 
horizon. It is of two kinds, the firft [eek up towards 
the zenith, and called upper; the latter down to the nadir, 
called lower. 
The polz ar ore therefore, is eee - the horizon in an 
o the elevation of the 
- i) paffes through 
rant of the equator 
is intercepted between it and the meridians confequently the 
upper furface is diese by fun from fix in the morning 
to fix at night 3 and the lower from fun’s rife to fix ia 
the morning, and from fix in the evening to fun-fet. A 
lower polar dial, bac fhews the ae of the morning 
o’clock, and that of the evening, from 
n aig , the hours from fix in the 
( fig. i. ) parallel to the horizon ; 
meveable, find the meridian line C E. 
two equal parts, and through C draw a right line F G paral. 
lelto AB. Then from the centre D, with the interval 
D E, defcribe a quadrant, which divide into fix equal parts ; 
and from the fame centre D, through the feveral points of di- 
vifion, draw right lines, D 1, DIT, D I1I, DIV, D d 
ae intervals a I, cm E TI, E IV, EV, fet off the con- 
IX, VII], and VII. From the 
i, At i, &c. raife perpendiculars meeting 
Gin the correfpondent points. Laftly, in D 
erect a perpendicular ftyle equal to E, or on two equal 
pieces, E and C, fix a crofs iron r 
Then will XII XIJ, II, I1 il, “TT Ill, &c. be hour- 
lines, to be pointed out at the proper times by the fhadow 
of the indices. 
fete ba an cia polar, only differs in fituation, and t 
of ing the hours, . eaft and weft “dite 
joined together in the line of fix : 
L, @ lower polar, is had ee bones out the hours of 
the (econ IX, X, and XI, and thofe of the afternoon, 
I, and III, with the noon-hour XII, itfelf ; and only 
leaving the hours VII and VIII of the morning, and | 
and V in me evenin 
dE D C. touching the edge 
then nace the top of the gnomon at G the centre of the 
vertical fouth dial, defcribe it on the board E DC. efides, 
on a circular plate I K defcribe an equinoGtial ae = re 
a flit ¢ din the XIT o’clock line, = 
ot 
‘centre, put it on the gnomon F G, as far as the hit will namie, 
The fame gnomon will fhew the fame hour on each of thofe 
w all the primary Diavs on o fame block or poft.— 
I, Let ‘te plane A » (fig nthe proper pofition 
of the block, be fuppofed fore ontle and thereon defcribe 
hs dial. See Horizontal Diat 
. Draw the right lines EM and F 7 parallel to DC, 
hick, accordingly, in the proper pofition of the block, will 
e parallel to the horizon: then let the 
. Let Lay oppofite plane, A DE, make w a 
= M, equal to the ‘elevation of the equator; and 
on this draw an upper equinoGial dial. 
4. Let the plane, K LHI, make with FL an angle 
H LF, equal to the elevation of the equator; and on this 
infcribe a lower equinoAial dial. 
5+ Let the oppofite plane, F G, make with F L an angle 
FL, alae a the elevation of the pole; and here drawa 
lower ae 
7. On the p ML F defcribe a weft dial; and on 
the oppofite eae an eaft dial. 
Tf, 
