July 1997
Page 40

De Boerenring

The article describes the mathematics and construction of an altitude ring dial, including diagrams for delineation and discussion of its limitations.
Construction Projects, Dials: Portable, Mathematics of Dialling

Fer J. de Vries

October 1993
Page 12

A Triple-Sundial

This article describes a unique sundial designed with three styles intersecting at a single point, allowing for the reading of various lines on the dial plane, including azimuth and astrological houses. An example dial is illustrated, delineated for latitude 52° with inclination and declination of 45°, demonstrating how different styles can indicate solar time or other phenomena.
Dials: Unusual, Sundial Design & Layout

Fer J. de Vries

October 1993
Page 40

Bifilar Gnomonics

This article presents a general method to transform a 'normal' sundial layout into a bifilar sundial, suitable for all flat dials, not limited to equiangular hour lines. It explains how to calculate thread heights for the resulting sundial drawing.
Dials: Bifilar, Mathematics of Dialling, Sundial Design & Layout

Fer J. de Vries

October 1992
Page 36

Computer Program for Dial Calculations

This entry announces the availability of a computer program by Mr Fer de Vries for sundial calculations, sold to BSS members with proceeds benefiting the Society. Compatible with IBM systems and requiring a graphic adapter for drawing, it comes with explanatory text and is available on disc. An older, simpler program by Mr H.C. Parr is no longer available but its listing can be found in a previous Bulletin issue.
Dialling Tools, Mathematics of Dialling

Fer J. de Vries

July 1991
Page 22

A Glass Dodecahedron

This note introduces F.J. de Vries' new computer program for designing a three-dimensional dodecahedron multi-faced sundial, imagined as made of glass to display various dial lines. The ZONWPLT program interfaces with ACAD to convert dial designs and generate complex geometric models. The article details the computational process, noting the time and files required for the example dodecahedron, and mentions de Vries' subsequent astrolabe program project.
Construction Projects, Dialling Tools, Dials: Multi Faced, Sundial Design & Layout

Fer J. de Vries

October 1991
Page 28

A Sundial for the Blind

Gerard Sonius developed a sundial for the blind, located at the Bartimeus blind institution in Zeist, Netherlands. This equatorial rotating dial features figures in relief and an electronic device that emits a sound when pointing to the sun. Marks for summer and winter time allow blind users to determine the time in 5-minute intervals, with explanations provided in Braille and print.
Dials: Equatorial, Dials: Unusual, Sundial Design & Layout

Fer J. de Vries

June 1990
Page 5

Letters and Comments from Members

This section features a letter from F. J. de Vries, offering a simplified single shift method for calculating declining/reclining sundials, to which George Higgs provides a magnanimous reply. It also includes various comments from members regarding the Bulletin's quality and content.
Mathematics of Dialling

Fer J. de Vries
George R. Higgs