Fer De Vries wrote a series of BASIC macros for Delta Cad that produces a
design drawing and table of coordinates based on your input parameters,
latitude, longitude, size etc. These macros are available on the NASS
website, www.sundials.org The final one of the series "hor_analem3_v2.bas"
adds what Fer calls "Day Circles" to the analemmatic sundial design. These
circles that some people call "Lambert's Circles" go through the sunrise and
sunset points on the hour ellipse, the focus points of the ellipse and the
date on the zodiac table.
I have added a few lines of code to this macro to take the sunrise and
sunset points that Fer calculated and draw the straight lines through the
seasonal marker points that some people call Bailey Points. The drawing
produced with this macro demonstrates both concepts well and clearly shows
the difference. Fer suggested putting the Seasonal Marker lines on a
separate layer, like the Day Circle layer. He added this so you can now
turn on and off each of these layers while working in Delta Cad, (View, Set
Layers, View Layers etc). Several of the slides in my "seasonal Marker
"presentation were created using this macro.
The macro is small, ~13 kb so I have attached it for your use and enjoyment.
Again I hope that this note and attachment get through the size filter.
Don't worry if you get a virus warning on this macro. Just save it to your
disc before using it in Delta Cad.
Roger Bailey
Walking Shadow Designs
N51 W115
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