A quick sundial design using a computer is a snap. Scant keystrokes suffice to conjure up a complete drawing.
How different things were a few centuries ago. Still, tools did exist for rapid drafting. Here is a graph for horizontal sundials between 30 and 60 degrees latitude.
The next figure shows how to use the graph to find afternoon hour lines for a sundial for 50 degrees south.
Mirroring the pattern downward yields morning lines.
The figures above were inspired by the example of Regiomontanus from his Der Deutsche Kalender des Johannes Regiomontan, published in 1474. His graph, restricted to latitudes between 36 and 56 degrees, is shown below *.
It is remarkable that Regiomontanus, too, drew his graph for sundials on southern latitudes, far from usual at the time. Or was it a mistake?
It really does not matter much. The hour lines remain the same, only the numbering should be fitted to the correct latitude.
Fer de Vries
* From a 1937 facsimile.
English translation: RH