created by Carl Sabanski
"Dialling Guides" - Horizontal Shadow Plane Sundial
The purpose of the "Dialling Guides" is to provide an easy method for laying out the hour lines for a number of horizontal shadow plane sundials located at various latitudes in either the Northern or Southern Hemispheres. The shadow plane sundials presented here are designed to be used as interactive sundials. Figure 1 is an illustration of a typical "Dialling Guide". It is designed to show local apparent or solar time.
Figure 1: "Dialling Guide" (CAD)
Figure 2 shows a horizontal shadow plane sundial similar to what you can build. This one is in the Northern Hemisphere.
Figure 2: Shadow Plane Sundial (CAD)
There are a total of 81 "Dialling Guides" that cover the range of latitudes from 25° to 65° inclusive in increments of 0.5°. Each "Dialling Guide" illustrates how to lay out the hour lines in minimum time increments of 5 minutes. As the sundials are intended for people there is information available to construct sundials with east-west widths of 1 and 3 metres. The smaller "Dialling Guide" can be used to build a model while the larger one can be used to build a sundial of any size and shape you like.
To obtain the design information for your shadow plane sundial just find a "Dialling Guide" close to your latitude in the following table and you will be good to go. Don't forget the instructions.
If you see what might be a problem with any of the "Dialling Guides" please let me know. Thank you.