Capricorn: Dec.22-Jan.29 The Sundial Primer
created by Carl Sabanski
Capricorn: Dec.22-Jan.29

The Sundial Primer Index

DeltaCad Sundial Macros - Valentin Hristov - Horizontal Double Box Altitude Sundial

This macro draws a sundial that indicates the time using the sun's altitude (elevation, height). The sundial consists of two boxes with a common gnomon. One box is used to indicate the time in the morning and the other in the afternoon.

Horizontal Double Box Altitude Sundial - sddboxh

This box sundial is generated after the user enters the "Latitude", "Longitude" and "Central meridian" of the sundial's location as shown in Figure 1. A "Place" descriptor can also be included. Hour lines intervals of 15 and 30 minutes and one hour are available. The hour lines can be adjusted for longitude and the Equation of Time. Daylight Saving Time can be selected or not and this determines if a second set of hour numbers is applied for DST. The "Height of the gnomon" and the "Width of one box" can be defined. Note that it is suggested the width of one box should be at least twice the height of the gnomon to allow flat folding of the whole construction, however smaller ratios can also be entered. Note that if you change both parameters simultaneously bur keep their ratio the same, then the result will be the same drawing but the size of the fonts will be different.

Figure 1 - Horizontal Double Box Altitude Sundial Macro

Figure 1 - Horizontal Double Box Altitude Sundial Macro

The sundial drawn with this macro is shown in Figure 2. 

Figure 2 - Horizontal Double Box Altitude Sundial

Figure 2 - Horizontal Double Box Altitude Sundial

Two sets of hour lines are drawn, one for the morning hours and one for the afternoon hours. The morning and afternoon hour lines are located in separate boxes with the gnomon separating the two. Unfortunately, close to local noon the change in altitude is very small and it is practically impossible to determine the time with reasonable accuracy. There are two sets of hour numbers. The blue indicate standard time and the red indicate Daylight Saving Time if "Yes" is selected. If Daylight Saving Time is not selected all the numbers are blue and only standard time is indicated.  Rotate the horizontal box until the red morning or afternoon arrow in the middle points to the sun (the arrow follows the azimuth of the sun). A convenient way to do this is to watch when the short sides of the box cast no shadows. The long common edge at the centre of the two boxes is then the shadow casting edge or style.

Figure 3 shows a photo of the completed sundial. Both sundials are the same except the bottom one is printed on 8-1/2" by 11" paper and the top one on 11" by 17" paper.

Figure 3 - Horizontal Double Box Altitude Sundial Model

Figure 3 - Horizontal Double Box Altitude Sundial Model

The third dimension of the box is calculated in such a way that an A4 (297/210) sheet of paper will be fully used when printing. If you want to use the entire area with different paper formats (11/8.5, 17/11, etc.), then you should edit the lines 298-300 in the macro file with any ASCII text editor, leaving uncommented ( i.e. without ' ) the line with the desired format. The following shows the lines you are looking for, with the A4 format selected.

A=297/210 (A4)

'A=11/8.5 (Letter)

'A=17/11 (Tabloid)