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 year, April 16, June 15, Sept. 2 and Dec. 25, and on these dates the dial needs no correction.  The corrections for the various days of the month can be taken from Table 3.  The + means that the clock is faster, and the means that the dial is faster than the sun.  Still another correction must be made which is constant for each given locality.  Standard time is the correct time for longitude 750 New York, 900 Chicago, 1050 Denver and 1200 for San Francisco.  Ascertain in degrees of longitude how far your dial is east or west of the nearest standard meridian and divide this by 15, reducing the answer to minutes and seconds, which will be the correction in minutes and seconds of time.  If the dial is east of the meridian chosen, then the watch is slower; if west, it will be faster.  This correction can be added to the values in table No. 3, making each value slower when it is east of the standard meridian and faster when it is west.

The style or gnomon with its base can be made in cement and set on a cement pedestal which has sufficient base placed in the ground to make it solid.

The design of the sundial is left to the ingenuity of the maker.  —­Contributed by J. E. Mitchell, Sioux City, Iowa.

Table No. 3

Corrections in minutes to change. 
Sun time to local mean time,- add those marked + subtract those
Marked — from Sundial lime.