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

HOW TO DESIGN AND MAKE A SUNDIAL - Page 6

Lay off five equal spaces on this line beginning at A, ending at C. Then join B and C with a straight line. Draw other lines parallel to BC through the points on AC and cutting AB. This is shown by the dash lines in the figure. Thus will the distance between the two given lines of latitude be divided into five equal spaces, each equal to one minute. The latitude may be easily obtained Fig. 18. Within a few seconds of arc by further subdividing the minute space into six equal parts of ten seconds each. The cross lies about half way between the line of 32'50" and the line of 33'00". Thus, the latitude at the cross is 42°-32'55". The longitude is 71033'45", which is found in a similar manner by using the vertical lines, subdividing the five minute interval into a sufficient number of spaces to obtain one minute intervals, and so on. The latitude must be found in order to lay out the hour lines. The longitude must be found if the sundial is to be used for standard time; to find the meridian; or to find the declination of a plane. When the hour lines have been laid out, place them roughly in the position you want them, on the full size sketch; then make a careful plan of the sundial plate and gnomon at full size, either on fairly heavy tracing (transparent) paper, or on a good sheet of white paper. This drawing is used to transfer the design to the sundial plate; or if you prefer, lay out the final plan on the sundial plate. It is better, however, to retain a careful paper copy of the hour lines and design, for reference. Those who have a mathematical bent will probably want to compute the hour lines. Computation is by far the best way to lay out any sundial, but the same accuracy can be obtained with a large, well made protractor. The protractor is an instrument used for laying off angles in degrees. If you do not already have one, an accurate ma-chine ruled protractor can be procured from drawing and engineers supply stores at a nominal sum of twenty to forty cents.

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