Work of our members

This is a round granite sundial of 60 cm (2 ft) diameter for local apparent time.
The outer ring carries this motto:

Of which we are unaware appears as a shadow without.
Of which we became aware appears as a light within.

The ring between motto and hour lines shows the difference between civil time and local apparent time for the first of each sign of the zodiac.
Between Cancer and Leo, for example, is the number 47
This signifies that on the first of Leo, 21 July, civil (winter) time equals indicated local apparent time plus 47 minutes. The addition of another hour gives us summer, or daylight saving, time.

Date curves for the start of the winter, summer, and spring/autumn are provided.
A small (imaginary) globe with tropics serves as the indicator. A line from the indicator through the tropics intersects the 12 o’clock line at the appropriate date curve.
The accompanying figure shows this construction in blue lines.
When we rotate this construction about the style, the intersections of the blue lines with the sundial face trace out the date curves.
In gnomonics, the construction is known as a trigon. Its use can be extended to any desired date curve.

Gnomon indicator with imaginary globe

Design:
Hendrik Hollander

Location of the sundial:
Nes aan de Amstel
Southeast of Amstelveen
North Holland
The Netherlands

Hendrik Hollander