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History of Sundials

Why the Sun Dial keeps time

Developing and Making Sundials

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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 12

AC, draw lines parallel to BE, which will be the required hour lines. FIGURE z shows the hour lines transferred to the sundial plate, and the proper way of numbering them. The position of the sundial when in use. Hour Limitations It is necessary to show on this sundial only those hours between 6 a.m. and 6 p.m., because the plane of the sundial, if produced, would cut the east and west points of the horizon. At 6 in the morning and 6 in the afternoon the shadow cast by the gnomon is infinite in length; therefore the 6 a.m. and 6 p.m. lines cannot be placed upon this sundial. Setting the Sundial When setting the sundial elevate the plate above the horizon, at an angle equal to the latitude of the place, as shown in Fig. 3; then turn the sundial so that the 12 o'clock or substyle line lies in the plane of the meridian. If this is done correctly, the style will then point to the celestial pole. THE DECLINING SUNDIALS; Declining sundials are vertical sundials so-called because they do not face the cardinal points of the compass. There are four types of declining sundials: Those facing the south and declining toward the east or west; and those facing the north and declining toward the east or west.

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