Functional description

On a Bernhardt precision sundial, the time is read from an engraved number ring. The time can be read on the scale optionally in MET or MEST.

The shadow is no longer cast by a skinny rod but by a thick roller that creates a broad shadow with two shadow limits. The time is read at the intersection of the advancing shadow limit to the number ring. The other limit is not considered.

While the sun dips deeper each day from summer solstice to winter solstice, the sun beam scans the shadowcaster from the top downwards. Thus, each day, a different height of the shadowcaster generates the shadow that strikes the number ring. Each height of the shadowcaster, therefore, represents a certain day.

The shadowcaster is held at this height stronger or weaker correspondingly to the time equation applicable to this day. The shadow on the number ring is thereby automatically moved ahead or behind by as many minutes as prescribed by the time equation.

Once the sun has reached its deepest level at the winter solstice, the shadowcaster is substituted by a second one that now, on the basis of another curvature, compensates the error when the sun begins to ascend.