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

The Sundial Primer Index

DeltaCad Sundial Macros - Fer de Vries

Fer de Vries also wrote a DeltaCad macro that can be used to generate a graph of the Equation of Time between the years -3000 to 4000.

Equation of Time - eotgraph

This macro is very easy to use. Just enter a year.

Figure 1: Equation of Time Macro

Figure 1: Equation of Time Macro

Figure 2 displays the resulting graph for the Equation of Time. Because this is a CAD drawing you can include addition date and time intervals. The graph can also be mirrored along the 0 minute line if you want to use it on a solar time sundial to show how many minutes to add or subtract from the indicated time. The time values can also be adjusted to include the longitude correction. This graph is the start of a great piece of furniture for any sundial.  

Figure 2: Equation of Time Graph

Figure 2: Equation of Time Graph


 I have never written a macro before but I thought that perhaps I could modify one. I took Fer's "eotgraph" and created "eotgraph_mod", which is also included in the download file. All I did was provide the option to invert the graph of the Equation of Time so it does not need to be mirrored. Figure 3 shows the modification to the user interface for the macro. It even works!

Figure 3: Modified Equation of Time Macro

Figure 3: Modified Equation of Time Macro