the
back of the style is hollowed as shown. The upper edges which
cast the shadows must be sharp and straight, and for this size
dial (10 in. in diameter) they should be about 7-1/2 in. long.

To layout the hour circle, draw two parallel lines AB and CD,
Fig. 2, which will represent the base in length and thickness.
Draw two semi-circles, using the points A and C as centers,
with a radius of 5 in. The points of intersection with the lines
AB and CD will be the 12 o'clock marks. A line EF drawn
through the points A and C, and perpendicular to the base or
style, and intersecting the semicircles, gives the 6 o'clock
points. The point marked X is to be used as the center of the
dial. The intermediate hour and half-hour lines can be plotted
by using table No. 2 for given latitudes, placing them to the
right or left of the 12-o'clock points. For latitudes not given,
interpolate in the same manner as for the height of the style.
The

Table NO. 2.
Chords in inches for a 10 in. circle Sundial.

Lat HOURS OF DAY
12-30 1 1-30 2 2-30 3 3-30 4 4-30 5 5-30
11-30 11 10-30 10 9-30 9 8-30 8 7-30 7 6-30
20 .28 .56 .87 1.19 1.57 1.99 2.49 3.11 3.87 4.82 5.93
30 .33 .66 1.02 1.40 1.82 2.30 2.85 3.49 4.26 5.14 6.10
35 .38 .76 1.16 1.59 2.06 2.57 3.16 3.81 4.55 5.37 6.23
40 .42 .85 1.30 1.77 2.27 2.82 3.42 4.07 4.79 5.55 6.32
45 .46 .94 1.42 1.93 2.46 3.03 3.64 4.29 4.97 5.68 6.39
50 .50 1.01 1.53 2.06 2.68 3.21 3.82 4.46 5.12 5.79 6.46
55 .54 1.08 1.63 2.19 2.77 3.37 3.98 4.60 5.24 5.87 6.49
60 .57 1.14 1.71 2.30 2.89 3.49 4.10 4.72 5.34 5.93 6.52

1/4-hour and the 5 and 10-minute divisions may be spaced with the'
eye or they may be computed.

When placing the dial in position, care must be taken to get it
perfectly level and have the style at right angles to the dial
face, with its sloping side pointing to the North Pole. An
ordinary compass, after allowing for the declination, will enable
one to set the dial, or it may be set by placing it as near north
and south as one may judge and comparing with a watch set at
standard time. The dial time and the watch time should agree after
the watch has been corrected for the equation of time from table
No. 3, and for the difference between standard and local time,
changing the position of the dial until an agreement is reached.
Sun time and standard time agree only four times a y