HOROLOGY, 297 
TABLE. 
Equation' 
in Deg. 
correfted. 
fVV. 
— E. 
in 
Time. 
Sun's 
Long. 
Sun’s 
Decl. N. 
Sun’s 
I-ong. 
Equat 
in 
Time. 
4 -W. 
on -E. 
in Deg. 
corrected. 
Equation 
in Deg. 
correifted 
4-w. 
-E. 
in 
Time. 
Sun’s 
Long. 
Sim’ 
Decl. 
S 
S. 
Sun’s 
Long. 
Equat 
in 
Time. 
+w. 
on p 
in Deg. 
corre&ed. 
0 
r 
n 
1 
// 
s. 
O 
/ 
O / •! 
s. 0 
/ 
/ 
II 
O / II 
O 
/ 
// 
I II 
s. 
0 
/ 
O 
/ 
// 
s. 
O 
/ 
I u 
O 
1 II 
+ 0 
16 
44 
+ 1 
33 
3 
O 
C 
23 28 15 
2 30 
0 
+ 3 
13 
+ 0 16 44 
—I 
54 
35 
—7 37 
6 
0 
c 
O 
O 
0 
11 
30 
c 
+ 7 36 
+ 3 
54 0 
49 
29 
3 
35 
I I 
C 
23 
19 
0 
— I 
12 
— 16 34 
2 
7 
14 
8 29 
2 
32 
I 
2 7 
28 
8 22 
2 
5 2 9 
1 
ID 
28 
5 
4 
39 
5 C 
22 
IO 
IC 
2 
46 
38 29 
2 
39 
55 
9 20 
5 
2 
2 
24 5 » 
9 8 
2 
16 57 
I 
20 
4 
5 43 
3 
*5 
5 1 
Zl 
2 4 
9 
3 
3 1 
49 29 
2 
32 
18 
10 10 
7 
35 
3 
22 
2 5 
9 5 ° 
2 
27 19 
I 
2+ 
19 
5 
59 
4 
O 
4 
20 
I 29 
2 C 
3 
54 
54 59 
2 
44 
22 
10 59 
IO 
5 
4 
«9 
55 
10 33 
2 
37 53 
1 
25 
34 
6 
2 
5 
1 C 
x 9 
24 4< 
4 
2 
57 12 
2 
55 
35 
11 45 
12 
40 
5 
17 
20 
II II 
2 
47 5 
I 
2 3 
5 f ' 
5 
53 
9 
5 
18 
20 
5 ? 
3 
59 
56 5- 
3 
6 
15 
12 29 
35 
15 
6 
>4 45 
11 49 
2 
56 18 
I 
20 
5 
5 
35 
12 
4 r 
>7 
17 
15 
3 4 ° 
54 3 1 
3 
l6 
3 
13 10 
‘7 
5 
7 
12 
IC 
12 25 
3 
4 57 
I 
14 
5 
5 
9 
l6 
9 
16 
33 
5 1 
3 
33 
50 42 
3 
25 
31 
13 5 ° 
20 
29 
8 
9 
31 
12 57 
3 
12 41 
I 
7 
22 
4 
39 
19 
20 
tS 
IO 
3 i 
3 
5 
44 4 C 
3 
33 
7 
14 2 3 
23 
3 
9 
6 
57 
13 2 5 
3 
18 45 
I 
O 
49 
4 
5 
22 
35 
14 
7 
25 
2 
38 
38 19 
3 
40 
8 
14 54 
2 5 
53 
IO 
4 
9 
13 5 i 
3 
z 4 35 
So 
25 
3 
27 
25 
3 fc 
33 
4 
24 
2 
6 
30 42 
3 
46 
2 
15 21 
6 
28 
2 9 
11 
11 
I 
21 
14 II 
3 
28 51 
40 
22 
2 
4 < 
4 
28 
3 c 
12 
I I 
3 ° 
I 
29 
21 46 
3 
5 ° 
53 
IS 44 
7 
I 
3 ° 
12 
IO 
28 
30 
14 27 
3 
32 1 
29 
22 
1 
59 
5 
1 
21 
II 
0 28 
29 
0 
4.8 
11 48 
3 
53 
51 
16 0 
4 
24 
33 
25 
36 
14 3 8 
3 
34 37 
17 
44 
1 
12 
4 
s 
IO 
25 
5 > 
—0 
10 
— 2 28 
3 
55 
26 
16 11 
7 
2 5 
14 
22 
35 
14 42 
3 
33 57 
+ 
5 
26 
+2 
22 
6 
57 
9 
23 
3 
+0 
34 
+ 8 24 
3 
55 
14 
16 14 
IO 
3 J 
15 
19 
2 9 
14 40 
3 
32 31 
— 
6 
4 1 
—0 
l? 
9 
3 i 
8 
20 
29 
I 
16 
18 49 
3 
52 
53 
j 6 9 
13 
5 ' 
16 
l6 
9 
14 28 
3 
28 38 
29 
36 
! 1 
J 9 
12 
IC 
7 
17 
5 ° 
2 
3 
3 ° 3 i 
3 
*8 
18 
15 54 
J 7 
15 
17 
12 
45 
14 8 
3 
22 46 
32 
49 
2 
12 
14 
45 
6 
15 
x 5 
2 
49 
42 I 
3 
40 
27 
15 2 7 
20 
55 
l 8 
9 
5 
13 37 
3 
14 2 7 
46 
34 
3 
7 
17 
20 
5 
12 
40 
3 
38 
54 J 8 
3 
29 
45 
14 47 
2 4 45 
39 
5 
>5 
12 51 
3 
2 17 
59 
5 i 
4 
0 
19 
55 
4 
IO 
5 
4 
25 
t 6 6 
3 
33 
5 ° 
13 45 
7 29 
20 
20 
IO 
O 40 
II 40 
2 
44 28 
I 
13 
37 
4 
55 
22 
25 
3 
7 
3 5 
5 
75 
1 18 38 
2 
53 
0 
12 21 
5 
4 
9 
21 
9 
2 5 
5 1 
IO IO 
2 
22 24 
I 
27 
27 
5 
5 ° 
24 
s 8 
2 
5 
2 
6 
J 
I 30 I I 
2 
22 
20 
10 14 
IO 
IO 
22 
19 
5 ° 
7 57 
I 
5 ° 34 . 
I 
40 
44 
6 
43 
27 
28 
I 
2 
32 
6 
5 C - 
I 42 2 9 
I 
22 
53 
6 0 
19 
O 
23 
II 
c 
+ 4 8 
+ 
57 i° ; 
-I 
54 
15 
—7 
37 
5 
30 
O 
The Equinoxes. 
4-7 
3 6 
+' 54 0 
— 
l6 
3 ° 
— I 12 
8 
30 
c 
23 
28 
15 
9 
O 
0 
— I 12 
— 
16 3o[ 
This Table being provided, it will be found moft con¬ 
venient to lay down a plan for general ufe, thus: On a 
metal plate, or a Iheet of fine pafteboard, draw a ftraight 
line. In the middle of that line, raife a perpendicular, 
of the length you choofe for the fize of your dial. Twelve 
inches feems to be a molt convenient one. With that 
length as radius, either by calculation or. with a feftor 
and compafi'es,. lay off the tangent of every degree along 
the original line, from each fide of the middle, till you 
come to 23 0 28' 15", whofe tangent mull be laid down 
xipon it likewife. The middle point is here intended to 
correfpond with the equinoxes, while each of the others 
anfwers to a degree of declination north or fouth.—See 
Plate III- Pig. 9. 
You are then, with the fame radius as before, to lay 
eff, for the equation of time, the tangents of fo many de¬ 
grees, minutes, and feconds, at right angles on either fide 
of the line at the centre of it, as you find in the outer- 
moll columns of the Table at the equinoxes; laying that 
which you find in the Table on what you deiign for 
the weflern fide of your meridian line, which will be for 
March ; and the equation marked —, on the eaftern fide, 
for September; and making a dot at each. In the fame 
manner you proceed at each degree of declination; taking 
the fecant of that degree (or the dillance from the farther 
end of the perpendicular to the end of the tangent of 
that degree) for your radius ; and laying off its refpec- 
tive equation from the Table accordingly, at right angles 
to the meridian line; and marking its place by a clot. 
Through thefe dots, you- then draw the curve formed by 
them ; and mark the months, in which the curve on the 
one or the other fide of the meridian is to be obferved. 
This laying down on your plan requires to be executed 
with great care ; becauie it is the foundation of the whole. 
But, when it is once, done, the points are eafily trans¬ 
ferred from it to any number of dials of the lame radius. 
In order to draw the curve with a Heady hand, it will be 
found convenient to form a pair of rulers l'uited to the 
curve of each half-year from folllice to folftice; by which, 
after laying down a few of the principal points, and 
placing the rules carefully, you llrike each half of the 
curve on the dial itfelf with cafe, 
Vol. X, No. 661, 
With thefe data, for a dial of 12 inches radius,, provide- 
a box (fig. 10,) in the form of'an equilateral triangle, 
each of whofe fides are 14I inches clear within, and about 
5 inches broad. On one of them pafte a paper perfeftly 
fmooth. Let the angle oppofite to this fide be cut fo far 
down as to receive a brafs plate, whofe inner furface may 
be exaftly 12 inches from the centre of the paper op- 
pofed to it. In the middle of that brafs plate, let there, 
be a very linall hole A, jull to admit a ray of light (cham¬ 
fered all round, to an angle of 6o degrees at lealt, lb as to 
be very thin at the edge next to the inner furface of the 
brafs), and mark the point on the paper at which the 
hole is exactly at right angles oppofite to the furface j 
which, if your work be true, will be in the centre of your 
paper. Through that point, draw a ftraight line on the 
paper ,for a meridian line, parallel to the triangular fides ; 
and crofs it at that point, with another at right angles, 
for an equinoctial line. On the meridian line, transfer 
from your original plan fo many of the dots for declina¬ 
tion as you fee proper; and, on the equinoctial, the equa¬ 
tions at the equinoxes. Transfer likewife the dots for 
the equation at each folftice ; and fo many of the inter¬ 
mediate equations as may be neceffary for being certain 
of laying your rules properly.. Then,, with a lteel pen,, 
llrike the curves ; and infert the months in their refpec- 
tive places; but at fuch a dillance from the line itfelf, as 
to be clear of the fun’s image when it is near the curve. 
Thefe things wall require to be done before the box is 
finally put together, that they may be done with accuracy. 
And therefore it will be found moft convenient to have 
that fide fixed with fcrews. Another of the fides (viz. 
that neareft to the winter folftice, according as it is in¬ 
tended for north or fouth latitude) mull be made to open 
about § of its length; with a rule-joint and cheeks like 
the lid of a fmall camera obfcura, to keep off falfe light, 
and enable you to fee the image within. It is alfo to be 
obferved, that the angle B mull be equal to theJatitude 
of the place. 
Additions may be made to it, for elegance, or difference 
of adjullment; but this is the whole of the inftrument: 
which, if carefully conllrufted, and once rightly fixed in 
the meridian, inclined properly according to the latitude 
4 G- oil 
