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

The Sundial Primer Index

DeltaCad Sundial Macros - Peter Mayer

Peter Mayer wrote a number of DeltaCad macros that will draw sundials that indicate clock time. There are a total of 4 macros that will be discussed and you can get them all here.

Merchant Dial

The sundials drawn by these macros are based on the design developed by mathematician Charles J. Merchant. It is an equatorial sundial that can be adjusted for longitude and the Equation of Time and will therefore indicate clock time. The four sundials that can be generated are set up for different longitude ranges.

  • Merchant Card Dial-Europe-summer: European Summer - Longitude range 0 to 75
  • Merchant Card Dial-North-summer: US Northern Hemisphere Summer - Longitude range 60 to 130
  • Merchant Card Dial-South-summer: Southern Hemisphere Summer/Northern Hemisphere Winter - Longitude range 105 to 165
  • Merchant Card Dial-South-winter: Southern Hemisphere Winter/Northern Hemisphere Summer - Longitude range 105 to 165

No user inputs are required to generate this sundial. Figure 1 illustrates the sundial drawn with the "Merchant Card Dial-South-summer" macro.

Figure 1: Merchant Dial

Figure 1: Merchant Dial

An excellent description of this sundial and how to build and use it appeared in the March 1964 issue of Scientific American. You can get this article here

The following photographs are of a Merchant Dial created by Peter Mayer following the instructions given in the article. Figure 2 shows the parts required to assemble the sundial.

Figure 2: Merchant Dial Components

Figure 2: Merchant Dial Components

Figure 3 shows the completed sundial ready for use. This sundial is very easy to make and fun to use.

Figure 3: Merchant Dial Model

Figure 3: Merchant Dial Model