Work of our members

The sundial described here is a simple flat one, mounted at a height of about 2,5 metres on the wall of our kitchen which is oriented almost to the south. The panel measures 20 by 17 cm. The time scale is in intervals of 10 minutes.

The panel is a plate of brown trespa - an artificial material for outdoor work. On this brown background the hour lines and the figures and letters are painted green and yellow. Thus the sundial is in colours which we also meet in the garden: the brownish soil, green foliage and yellow flowers.

In preparative work it appeared that also on such a brown background the shadow of the stile is fairly well visible. In the course of years the trespa will fade a little and its surface will become more dull. By this the legibility will improve at last.

The hour lines and their frame are shallow grooves filled with green paint.
The figures and letters are realized according to the early matrix printing technique: pits in a 7*5 matrix pattern. These pits are filled with yellow paint.

The thickness of the trespa panel is six millimetres. By this it is possible to give some information on its edges. These texts are not striking because they are coloured black.

On the left edge is written:
A VD B          MEI 2003
These are the initials of the maker and the date of production. In between is left some space for further information, if desired.

The right edge shows the data:

These are the geographic longitude and latitude and the declination and inclination of the sundial, all given in decimal degrees.

On the lower edge is given the instruction:
MEZT = MEZT* + (-E)
MEZT is the daylight saving time (DST) for the Central European time zone.

The sundial shows the non-equated MEZT, indicated by the symbol MEZT* . To get MEZT from MEZT* the time equation E must be subtracted from it. This is rather confusing, because E can be positive as well as negative. Adding is easier than subtracting. That is the reason why the time equation is given as a graph of minus E. Then MEZT is acquired by simple mental arithmetic, according to the instruction given above.

It is impossible to give a full explanation of this graph on this little sundial. The user is supposed to know something about the matter. From the fact that the extreme values of E are about plus and minus 15 minutes (s)he can understand that the vertical rows of points in the graph of -E represent intervals of 5 minutes. These rows also mark the months of the year, from January to December. The values of -E are given at intervals of about 10 days.

Ton van den Beld.