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DECLINATION LINES OF SUNDIALS - Page 7

Declining sundials, where a horizontal sundial is inscribed about the substyle line. The height of the style for the reclining sundial is used as the height of the style for the auxiliary horizontal sundial. Then, the lines of declination constructed for the horizontal sundial will be the lines for the reclining sundial. The appearance of these lines on a direct east sundial reclining 25°, in latitude 37°N, is shown. The line SF is the substyle; F the foot of the perpendicular style; and N is the nodus. The horizontal line, AB, is drawn through the point where the equinoctial line cuts the 6 o'clock line and parallel to the 12 o'clock line, which on this sundial is parallel to the plane of the horizon. The horizontal line need not extend beyond the lines noting the greatest northern and southern declination of the sun. LINES OF DECLINATION ON EAST-WEST VERTICAL sundials The planes of these sundials lie parallel to the axis of the earth. The most satisfactory gnomon will be one shaped like a pin, the point or apex of which will serve as both style and nodus. The method for constructing the lines is the same for both sundials. The construction of the lines, described in detail, need only be shown for one of them, for example, the east vertical sundial. A direct east vertical sundial computed for latitude 40°N, with the lines of declination properly drawn upon it. The most suitable gnomon is also shown. The style and nodus are coincident at N; the height of the style is equal to the height of the perpendicular style, FN; the foot of the perpendicular style intersects the 6 o'clock line at F.

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