Photo (2013) Willy Leenders

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Grimbergen (near Brussels)

In the village of Humbeek where Kerkstraat and Rumuoldusstraat fit together
Vertical sundial on a cylinder
Year: 2013 (inaugurated on October 5, 2013)
Design: architects Crepain Binst Architecture Antwerp
Calculation: Willy Leenders (hour and date line pattern and flow chart for programming the laser beam)
Production: Humbeek Sas Events, chaired by André Lombaerts


The sundial is placed in Humbeek to commemorate the celebration of 1,000 years of this village . In a book from 1760 university professor William Lepage , born in Humbeek, wrote a book on arithmetic and geometry, applied in particular on the ways to make sundials

The sundial is a cylindrical column of opal glass 3.60 meters high on a metal support 0,70 m high. The diameter of the cylinder is 1.80 meters .

In the middle of the upper surface of clear glass is located - invisible to the visitor - a sphere of 10 cm diameter. The shadow of the sphere falls on the inside of the cylinder and can be seen through the opalescent glass on the outside. There the shadow gives an indication of the time and the date.

There are hour lines for each full hour. Some curved lines are date lines for the beginning of the seasons, spring, summer, autumn and winter. At these beginning dates the shadow follows the corresponding date line from morning to evening. On dates between, the shade is located between the date lines.

The hour and date lines in the lower half of the cylinder are provided for overnight. From sunset to sunrise a programmed laser beam from the bottom of the cylinder takes over the indication of time and date.

All time indications are shown in local solar time.

In the evening and at night the white opal column is enchantingly illuminated .