The Netherlands' Sundial Society has been publishing its "Bulletin" for 40 years (1978 - 2017). It is continued under a new title: "Zon & Tijd". The new journal also serves the Sundial Society of Flanders, Belgium, which discontinued its journal "Zonnetijdingen".

A complimentary copy of "Zon & Tijd" is available here:

Bulletin 118,
 december 2015


Table with average values of solar declination and the equation of time, per day, prepared by Thibaud Taudin Chabot (pdf, 43 kB).


The software ZW2000-v2 for Windows was developed by Fer de Vries (zip-file, 1,0 MB).

ZW2000 calculates various types of lines for flat sundials, for any place on earth.

The line pattern will appear on your screen immediately.

The drawings may be saved as DXF and PLT files for further processing.

The program ZW2000 version 2.0 for Windows. Minimum screen resolution 800 x 600.

The program ZW2000 version 2.0 runs on 32 and 64 bit computers.

The program extracts to folder zw2000-v2.

The manual extracts to folder zw2000-v2/manual.

The manual is a .htm document. Start with zw2000.htm.

Note: Fer de Vries passed away in 2015. The software is not supported anymore.

The theory behind the ZW2000 program is described in the article: "A uniform method to compute flat sundials" (pdf, 130 KB).


The article "Construction of analemmatic sundials", by Fer de Vries (pdf, 400 KB).


The article "Construction of bifilar sundials", by Fer de Vries (pdf, 200 KB).


The article "Construction of hemispherium" by Fer de Vries (pdf, 190 KB).

The article "Equator Projection Sundials" by J.A.F. de Rijk  (J. Brit. Astron. Assoc. 1986, vol. 97) (pdf, 312 KB).


Fer's Legacy

Fer's Legacy is a treasure trove of 360 articles on every possible topic in gnomonics. From 2003 to 2012 our late honorary member Fer de Vries put three articles together each month, in three series: Sundial of the Month, Article of the Month and Work by Members. They were translated into English by Ruud Hooijenga.

The pages have been compressed into a zip-file, which can be downloaded below. After extraction, click the file 'FersLegacy.html'.

Note: Internet access is required in order to display the illustrations.

Download (520 KB).