Work of our members

Sundial models

In order to gain a better insight into sundials, our member Jacob Borsje made, over the years, a number of models.
This page shows three of his models.

The first is a south dial on a cylinder made of sheet aluminium.
It is a nodus sundial. The index is the apex of a ‘triangle’ with two curved sides.

The second model is a sundial inside a cylinder made of a PVC drainage tube cut open.
The cylinder is horizontal and aligned east-west.
This is also a nodus sundial where the index is part of the cylinder surface.

The third model is a bifilar sundial on a south face.
In bifilar dials, the intersection of the shadow of crossed wires or edges is the readout point.
One of the ‘wires’ in this model is the curved edge of a prettily cut surface.

The bifilar sundial with two straight shadow casters was designed as late as around 1925 by Hugo Michnik of Germany.
Around 1978, Thijs de Vries of The Netherlands invented bifilar sundials with one curved wire.
Since then, bifilar dials with two curved wires have been developed.

All three models show local apparent time, and have date curves according to the signs of the zodiac.