SUNDIAL SECTIONS:

Sundials Home

History of Sundials

Why the Sun Dial keeps time

Developing and Making Sundials

Sundial Materials

Sundial Hour Lines Lay out

Sundial "Furniture"

Declination Lines of Sundials

Portable Sundials

Interesting Sundials of the World

LAYING OUT THE SUNDIAL HOUR LINES - Page 5

Draw lines from A through the points found on KL, LM, and MH. Also draw lines from A through the points L and M. These will be the required hour lines. The hours may be divided into halves, quarters, and so on, by further subdividing the arcs TV, PQ, and SR, into the desired number of parts. FIGURE 2 shows the hour lines transferred to the sundial plate, and the way in which they should be numbered. FIGURE 3 shows the position of the sundial when in use. Hour Limitations This sundial will show the time from sunrise to sunset, in the latitude for which it is constructed, throughout the year. Setting the Sundial To set the sundial, first place it in position and carefully level it. Then turn it, so that the style points to the celestial pole and the 12 o'clock line lies in the plane of the meridian. See also Section V. Note: When the hour lines are transferred to the sundial plate, allowance must be made for the width of the gnomon. This holds true for all sundials. It has been exaggerated in Figure 2. Thus BB and AA represent the width of the style. Also note that the 7 and 8 hour lines in the evening do not converge in the same point as the afternoon hours, but on the opposite side of the gnomon where the morning hours converge, because they are the prolongation of the same hours in the morning. The same is true of the 4 and 5 hours in the morning.

  more on laying out sundial hour lines...