September 2012 page 20
Mike Cowham

The Planispheric Nocturnal

This article describes the planispheric nocturnal, an instrument for telling time at night by aligning a rotating star chart with actual stars. It functions as an alternative to a traditional nocturnal and can be found on the reverse of some quadrants, offering timekeeping to within 15 minutes without requiring Equation of Time correction.
Dialling Tools, How Sundials Work, Dials: Nocturnals

March 2011 page 11
Tony Moss

Accurate Division Without the Use of a Dividing Engine

The author explores methods for accurately dividing sundial scales without modern dividing engines. He proposes a compact, semi-mechanical system using pivot pins and a straightedge, designed to fit on a bench, and notes its superiority over Ramsden's engine in terms of user comfort.
Construction Projects, Dialling Tools, Sundial Design & Layout

March 2011 page 34
Mike Cowham

A Sun Simulator for Moyse’s Hall Museum, Bury St Edmunds

This article describes the creation of a motorised sun simulator for a museum exhibition, designed to demonstrate how sundials work by speeding up daylight duration. It features three lights for different seasons and allows visitors to test card sundial kits.
Construction Projects, Dialling Tools, How Sundials Work

June 2011 page 8
Michael Lowne
John Davis

A Horizontal Quadrant of 1658 by Henry Sutton; Part 1

This article describes a unique 17th-century horizontal quadrant by Henry Sutton, detailing its stereographic projection, various scales for altitude, azimuth, time, and astronomical functions. It explains how the instrument, acting as a mechanical analogue computer, finds time from the sun's altitude.
Dialling Tools, Dials: Horizontal, Historical Dials, Mathematics of Dialling

June 2011 page 20
Malcolm Barnfield

The Sundial Goes to War: Part 1

This article explores the military use of solar compasses, particularly during World War II, for navigation in unmapped desert terrains. It describes several models, including the Burt, Abrams, Cole Universal, Bagnold, and Union Observatory sun compasses, highlighting their principles and operational advantages.
Dials: Analemmatic, Dials: Portable, Dialling Tools, Historical Dials

September 2011 page 34
William Watson
Michael Lowne

Simple Instrument for Finding a Meridian Line

William Watson describes a new instrument for finding a meridian line to aid in sundial making, using two tubes aligned with Polaris and Capella. Michael Lowne comments on the necessity of accounting for Polaris's displacement from the true pole and the stars' right ascension difference for correct alignment, noting potential inaccuracies in Watson's original design and challenges in its use.
How Sundials Work, Mathematics of Dialling, Dialling Tools

March 2010 page 24
John Davis

Thomas Tuttell’s Playing Cards

Discusses two sets of playing cards published in 1701 by instrument maker Thomas Tuttell, which functioned as a trade catalogue. The cards illustrate instruments like elliptical dials, dialling globes, and projections of the sphere used in dialling.
Dialling Tools, Historical Dials

June 2010 page 42
Michael Maltin

A Simple Meridian Instrument

This article describes a DIY instrument for establishing a meridian line, developed for aligning large sundials. It uses two mirrors set at right angles to each other to project a spot of sunlight that remains directly beneath the sun horizontally, regardless of the instrument's heading. The device, a variant of a corner reflector, allows for precise tracking of the sun's path along the horizon.
DIY Sundial Projects, Dialling Tools, Sundial Design & Layout

June 2010 page 43
Doug Bateman

Meridian Mirrors

This article presents an alternative construction for Michael Maltin's meridian instrument, which uses two orthogonal mirrors to establish a meridian line. The author describes using an engineering V-block as a ready-made 90-degree angle, adding small mirrors and a spirit level for accurate setup. It discusses refinements like front-silvered mirrors and a hinge for precise spot overlap, highlighting its simplicity and accuracy for determining the sun's azimuth.
DIY Sundial Projects, Dialling Tools, Sundial Design & Layout

September 2010 page 35
Maurice Kenn
Roger Bowling

Readers’ Letters

This section contains two letters: Maurice J. Kenn congratulates Michael Maltin on his 'Novel Meridian Finder' and discusses the dipleidoscope; Roger Bowling queries if anyone has seen Haidinger’s brushes and the perception of polarised light.
How Sundials Work, Dialling Tools

March 2008 page 14
Mike Cowham

Finding the Sun’s Position in the Zodiac

This article explains how to use Solar Course diagrams found on historical instruments, such as an Edmund Culpeper universal equinoctial ring dial and Italian quadrants, to determine the sun's position in the Zodiac. It details calculation methods, including adjustments for Old Style and New Style calendars, and notes rare instances of early Gregorian calendar pre-emption.
Dialling Tools, Historical Dials, How Sundials Work, Mathematics of Dialling

March 2008 page 43
John Davis

Pat Briggs’ Meccano Models

Showcases Pat Briggs' Meccano models, ranging from simple equatorial dials to complex planetaria and astronomical clocks. It highlights his ingenious mechanisms, including a universal joint for shadow tracking, an Equation of Time clock, and a 'Meccano Analemmagraph' for drawing the analemma, using cunningly-designed gear ratios.
Dials: Equatorial, Equation of Time, Dialling Tools, DIY Sundial Projects

September 2008 page 130
Tony Ashmore

Astrolabes, Part 5 - Other astrolabe related instruments

This part of the Astrolabes series covers instruments related to, but distinct from, planispheric astrolabes. It discusses the rare spherical and linear astrolabes, monumental and domestic astrolabe clocks, mariner's astrolabes (not true astrolabes), and various types of quadrants, including horary and astrolabe quadrants, detailing their history and use.
Dials: Astrolabe, Dialling Tools, Historical Dials, How Sundials Work

December 2008 page 166
Malcolm Barnfield

Timbouctou Sine Quadrant

This article details the reproduction of a sine quadrant from a preserved Timbouctou manuscript for a documentary film. It describes the instrument's function in solving trigonometric problems without manual calculation, like determining unequal hours, and its historical context as a teaching tool in Islamic astronomy. The author discusses the challenges of interpretation and the modern construction using laser-cut perspex.
Construction Projects, Dialling Tools, Historical Dials, Mathematics of Dialling

December 2008 page 188
John Davis

John Blagrave

This short note features an illustration from John Blagrave's "The Mathematical Jewel" showing a diallist determining wall declination. It briefly mentions Blagrave's life in Reading and the various tools depicted in the drawing, such as a square, plumb-bob, and simple theodolites.
Dialling Tools

March 2007 page 24
Chris Lusby Taylor

A universal Italian and Babylonian hour accessory

This paper introduces a simple accessory, a three-quarters CD, that can be used with existing horizontal sundials to signify Italian and Babylonian hours. It explains how these hour systems differ from conventional timekeeping and how the accessory allows us to read these hours, using the shadow of the CD.
Dials: Horizontal, How Sundials Work, Dialling Tools, DIY Sundial Projects

March 2007 page 27
John Davis

Extract from Joseph Moxon’s ‘Mechanick Exercises’

John Davis presents an extract from Joseph Moxon's 1678 book, 'Mechanick Exercises,' detailing a method for laying moldings on round brass pieces without a lathe, invented after the Fire of London. This technique is suggested to have been used for horizontal sundials, offering insight into 17th-century sundial making practices and Moxon's ingenuity.
Dialling Tools, Historical Dials

September 2007 page 118
Mike Cowham

How Big—How High?

This article presents practical, simple methods for measuring the height and size of sundials, especially those high on church towers. It describes using a homemade shadow square for height, relating dial dimensions to known object sizes from photographs, and employing a marked tripod. Computer software techniques for perspective correction are also discussed to improve accuracy.
Construction Projects, Dialling Tools

September 2007 page 137
Tony Belk

Declination Lines Detailed

This article offers detailed methods for drawing declination lines on planar sundials using polar and Cartesian coordinates, or a graphical protractor, all based on the dial's style height and nodus distance. It also provides formulas for calculating hour line angles for various dial types and a simple method to check existing dials for accuracy.
Construction Projects, Dialling Tools, Mathematics of Dialling, Sundial Design & Layout

December 2007 page 151
J. P. Lester

Newbury Meeting 2007

This report summarises the British Sundial Society's Newbury meeting, which began with a tribute to the late Dr. Margaret Stanier. Presentations included stained-glass sundials, mounting a vertical sundial with a TV bracket, mathematical proofs for hour lines, a schools programme for dialling, universal equinoctial ring dials, dipleidoscopes, dials with vertical gnomons, and hemispherical dials.
Dialling Tools, How Sundials Work, Sundial Design & Layout, The BSS and Members

February 2006 page 3
Mike Cowham

A Bird’s Eye View

This piece addresses the challenges of photographing high-mounted or horizontal sundials. The author presents a practical solution involving an elevated digital camera on an extended tripod with a remote shutter release, enabling bird's eye views while ensuring the photographer's safety and optimal framing without including themselves in the shot.
Dialling Tools, DIY Sundial Projects

September 2006 page 142
Tony Belk

Simple Delineation of Vertical Declining Dials

This article introduces a user-friendly method for delineating vertical declining sundials using bespoke slide rule-like calculators. These tools determine equivalent latitude and longitude, simplifying the process by eliminating complex trigonometry. The article explains how to use these calculators with standard dialling scales to accurately plot hour and sub-style lines.
Dialling Tools, Dials: Vertical, Mathematics of Dialling, Sundial Design & Layout

December 2006 page 167
Allan A. Mills

Hooke’s Joint, Sundials and the Sundial-Clock

Allan Mills explores Robert Hooke's "Sundial Delineator," an instrument using a cross-shaped interior member (similar to a Hooke's joint) to simulate gnomon shadow motion for sundial delineation. The article details how Hooke's joint can be applied to delineate sundials and, when driven by a clock, create a "sundial-clock," explaining the underlying mathematical principles.
Sundial Design & Layout, Dialling Tools, Historical Dials

June 2005 page 63
Patrick Powers

Reader’s Letter

Letter recommending WinEphem software for calculating moon transit times useful for moondials. Notes features such as rise/set/transit data and accuracy for dialling purposes.
Dialling Tools, Dials: Nocturnals

March 2004 page 38
Doug Bateman

Finding North with a Magnetic Compass - The Accuracies Achievable

This article details the practical limitations and achievable accuracies when using a magnetic compass to determine true north, especially for diallists. It explains how Earth's magnetic field variations, crustal and external influences, and man-made objects affect compass readings, and provides methods, including online tools, for accurate magnetic variation calculation to assist sundial alignment.
Dialling Tools

June 2004 page 47
Mike Cowham

Magnetic Azimuth Dials

Historical and technical discussion of magnetic azimuth dials from the 17th century, including Dieppe ivory examples, London surveying instruments, and design considerations for modern reconstructions.
Dialling Tools, Dials: Unusual, Historical Dials

June 2004 page 69
Patrick Powers

Reflections on True North, Large Dials and the Apparent Sun

Discussion on the challenges of aligning large sundials to true north, focussing on accuracy and discrepancies in tools to calculate solar azimuth
Dialling Tools, Sundial Design & Layout

September 2003 page 91
Mike Cowham

Fakes and Forgeries (or How to identify an imitation dial)

This article discusses how to recognise fake or imitation sundials. It provides a list of points to consider, such as the material used, how the markings were applied (engraved, punched, or etched), and the presence of suspicious mottoes or dates. The author also suggests tools for investigation and discusses common errors made by both forgers and legitimate makers.
Dialling Tools, Historical Dials

March 2002 page 35
Mike Cowham

The Horary Quadrant

Overview of the design and historical use of various horary quadrants.
Dialling Tools, Historical Dials

June 2002 page 74
A. F. Baigent

The Declination and Possible Reclination or Inclination of a Wall

Discussion of geometric methods for determining wall orientation for accurate dial design.
Dialling Tools

June 2002 page 81
Maurice Kenn

John Harrison's Unusual and Unique Magnetic Compass

Examines a rare compass designed by Harrison, with discussion of its function and potential sundial applications.
Dialling Tools, Dials: Portable

June 2001 page 56
John Davis

A Pocket Gnomon Protractor

John Davis introduces his design for a flexible, wallet-sized gnomon protractor, aimed at overcoming difficulties in measuring gnomon angles on buttressed sundials. The device expands the scale for better precision within typical UK angles and can be photocopied by readers to create their own. He details its construction from laminated paper and auxiliary scales.
DIY Sundial Projects, Dialling Tools

June 2001 page 83
W.S. Maddux

Finding a North-South Line

W.S. Maddux describes precise techniques for accurately establishing a true north-south line, essential for sundial installation. He outlines two methods using a plumb line and its shadow: one for general alignment and another for achieving high precision, detailing practical steps for observing and marking the meridian.
Dialling Tools, Sundial Design & Layout

October 2000 page 115
Andrew James

Photographing Sundials

Practical guide to photographing various types of sundials, including exposure, lenses, framing, and lighting for effective recording and archival use.
Dialling Tools

February 1999 page 9
Maurice Kenn

Astro-Compass or Heliochronometer

This article references the Gibbs Universal Heliochronometer, patented in 1906, and its presence at the 1998 BSS Conference. It suggests converting existing Astro-Compasses into heliochronometers by adding self-adhesive hour-labels, providing an affordable way to indicate local sun time with reasonable accuracy.
Dialling Tools, DIY Sundial Projects, Dials: Heliochronometer

February 1999 page 33

Readers' Letters

This section contains diverse reader correspondence, including a tribute to Charles Aked, discussions on the Equation of Time and Bernhardt dials, explanations of the Lluc sundial in Mallorca, a comparison of Eureka compass cards, reflections on restoration, and a submission on 'Tipple Times'.
Dials: Unusual, Equation of Time, Dialling Tools, The BSS and Members

June 1999 page 62
Allan A. Mills

Noon Marks and the Projection of the Analemma, with some New Versions of these Old Instruments

This article explores noon marks and the analemma, detailing how the sun's daily and annual motion is used to determine local noon and time of year. It discusses simple horizontal and vertical noon marks, the use of aperture gnomons, and the historical and modern application of the analemma for time correction. New designs for polar and vertical analemmatic noon marks, including sculptural forms, are also presented.
Dialling Tools, Dials: Noon Lines, Equation of Time, Sundial Design & Layout

June 1999 page 96
David A. Young

Vertical Dials - A Method of Estimating Their Declination

This technical article presents a method for estimating the declination of vertical sundials, particularly useful for dials high on buildings. Rather than measure the 'substyle distance' (angle between the gnomon and the noon line) one reads off the 'time' on the dial the gnomon is pointing to. This can be looked up in a precalculated table for a given latitude to give the degrees of declination of the dial.
Dialling Tools, Dials: Vertical, Mathematics of Dialling

October 1999 page 144
John Davis

A Lightweight Laser Trigon for Lay-out of Sundial Lines

This article describes the design and construction of a lightweight laser trigon for accurately laying out sundial lines. Inspired by difficulties with traditional string methods, the author developed a compact perspex instrument that uses a laser pointer to project declination and hour lines onto any dial surface. The design addresses issues of gnomon flexing and portability, and uniquely proposes linking the trigon's axes to trace analemmas mechanically, offering a universal tool for precise dial delineation.
DIY Sundial Projects, Dialling Tools

June 1998 page 37
John Davis

A Test Table for Horizontal Dials

This article describes how to build a simple, portable test table for horizontal sundials using a photographic tripod. The table allows for fine adjustments to be made to test dials for different latitudes without needing to find a perfectly horizontal surface.
DIY Sundial Projects, Dialling Tools

October 1998 page 10
John Moir
Peter Ransom

The Newbury Meeting 20 June 1998

This report summarises the BSS Newbury meeting on the eve of the Summer Solstice. It covers talks on Hampshire sundials, raised horizontal dials, astro-compass conversions, and a sun compass. The event also featured an exhibition of various sundials and computer programs, highlighting members' ingenuity and the collaborative spirit of the society.
DIY Sundial Projects, Dialling Tools, Historical Dials, The BSS and Members

October 1998 page 24

Readers' Letters

This section features a collection of correspondence from readers covering diverse topics. These include the origin of Bernhardt Dials, methods for finding the meridian, updates on Newbury BSS meetings, a problematic sundial in Lluc, Mallorca, discussions on the 'Eureka' credit card compass, and inquiries about spherical and 'problematic' Italian dials.
Dialling Tools, Dials: Unusual, Historical Dials, The BSS and Members

January 1997 page 37
J. T. R. C. Schepman

How to Determine Time by Moonlight

A method for telling time using moonlight and sundial principles. Explains necessary calculations, lunar phases, and adjustments for accuracy.
Dialling Tools, How Sundials Work

April 1997 page 33
Piers Nicholson

Sundials on the Internet

An overview of the emerging presence of sundial resources and communities online, highlighting websites, digital tools, and opportunities for dial enthusiasts to connect.
Dialling Tools

July 1997 page 9
Peter Lamont

QBASIC Sundial Programs SUNDL1, 2 & 3

This article describes three QBASIC computer programs for designing sundials. The programs can be used for plotting horizontal garden dials and various types of vertical wall dials.
Dialling Tools, Sundial Design & Layout

July 1997 page 13
Edmundo G.A. Marianeshi
Nicola Severino

The Floating Gnomon

Describes the making of an unusual device for regulating watches following a design from 1895. It finds solar noon, by measuring the times the sun is at the same elevation just before and after noon, using a sighting mechanism floating in a can of water to ensure it is horizontal.
Dials: Unusual, Dialling Tools, DIY Sundial Projects

July 1997 page 18
G.N. Thorne

D.I.Y. Dialling Scales

Guide to producing printed dialling scales using spreadsheet calculations and desktop publishing, enabling accurate layout of sundials.
DIY Sundial Projects, Dialling Tools, Mathematics of Dialling

October 1997 page 3
Peter Lamont

Marking Time

This article describes the "XY method", a practical process for marking time divisions on sundials. It details how to calculate shadow angles from first principles for various dial types and then plot them directly along rectangular borders using a graduated straightedge, acting as an "Add-on" to computer design programs. The method was adapted for complex declining/proclining dials and can also be applied to circular or octagonal dials.
Dialling Tools, Mathematics of Dialling, Sundial Design & Layout

June 1996 page 16
John Moore

Portable Dials - Accessories

Examines the features and design variations of historical portable sundials, discussing integrated instruments, storage cases, and accessories like compasses and perpetual calendars.
Dialling Tools, Dials: Portable, Historical Dials

October 1996 page 26
David A. Young

Sundial Constructor

A description of a software program developed to assist in sundial design and layout, explaining its capabilities and potential benefits to amateur and professional diallists.
Dialling Tools

October 1996 page 52

Sundials the Easy Way

Describes a set of dialling scales produced by Lindisfarne Sundials (a version of the Serle Ruler) to allow the easy laying out of sundials without calculations or measurements of angles.
Sundial Design & Layout, Dialling Tools, DIY Sundial Projects

February 1995 page 51
Ray Ashley

Declination Finder

Introduction to a simple tool or method for determining the declination of a sundial wall, enhancing the accuracy of vertical dial construction.
Dialling Tools

June 1995 page 32
René R.-J. Rohr

On Lunar Nomograms

A mathematical examination of lunar nomograms and their use in timekeeping, possibly as an analytical or design tool involving the moon's cycles.
Dialling Tools, Mathematics of Dialling

October 1994 page 18
Fred Sawyer

A Universal Nomographic Sundial

This article introduces a new sundial design that combines the simplicity of a Capuchin dial with the universality of a Regiomontanus dial through the use of nomograms. It explains the principles of subtraction and multiplication nomograms, demonstrating how they are integrated into the dial's coordinate system to calculate solar declination and latitude. The article details how to read the time by aligning a thread and bead, and notes its ability to show sunrise/sunset times and day length. The design aims for an acceptably accurate, universal dial that is easier to construct than other universal types.
DIY Sundial Projects, Dialling Tools, Mathematics of Dialling

October 1994 page 35

Computer Program

This section provides an update on the availability of the British Sundial Society's (BSS) sundial program. It announces that the 5¼" disc version is no longer available, but the 3½" discs can still be purchased from the editor, with profits supporting BSS funds. The program runs on IBM compatible systems and requires a graphic adapter for drawing. It also mentions a simpler program by Mr. David Young and another by Mr. H.C. Parr (no longer available in disc form), and suggests the future formation of a group to address specialized aspects of dialling and pool ideas for computer use among members.
Dialling Tools, The BSS and Members

February 1993 page 32

The Equation of Time - Nonomoil

This tongue-in-cheek article introduces 'Nonomoil,' a new product designed to simplify sundial readings by reducing the friction of the shadow on the sundial surface, thus avoiding the discrepancies between sundial time and Greenwich Mean Time. It explains how this annual treatment enhances accuracy and avoids sarcastic comments from onlookers unfamiliar with the Equation of Time.
Dialling Tools, Equation of Time, How Sundials Work

June 1993 page 21
Charles K. Aked

High Noon

This article discusses historical methods for determining exact noon, crucial for regulating early mechanical clocks. It highlights the challenges of precise noon observation with traditional sundials and describes the Dipleidoscope, an ingenious optical instrument invented by James Mackenzie Bloxham and later patented by Dent. This device used prisms or mirrors to achieve accurate noon determination through the visual coincidence of two sun images.
Dialling Tools

October 1993 page 13
Michael Hickman

Shepherds and Spreadsheets

This article explores using spreadsheet programs to design and create shepherds' dials, simplifying the complex calculations and plotting involved. It details the process of determining the sun's altitude using a mathematical formula and setting up a spreadsheet to generate the necessary data for plotting hour lines on a cylindrical dial, facilitating DIY dial construction.
DIY Sundial Projects, Dialling Tools, Dials: Cylindrical, Mathematics of Dialling

February 1992 page 18
Michael Lowne

Sundial Alignment by the use of the Pole Star

The article proposes an improved method for aligning a sundial gnomon using Polaris, building on previous discussions by Mills and Taylor. It suggests a sighting device made from sheet metal with an eye aperture and a circular target. The method relies on knowing Polaris's angular distance from the true pole and its position relative to the star Beta Ursa Minor (f3 UMi), aiming for an accuracy within 0.25 degrees by aligning Polaris on the target edge opposite f3 UMi.
Construction Projects, Dialling Tools, Mathematics of Dialling

February 1992 page 22
Allan A. Mills

A Sundial Delineator

This article introduces a portable sundial delineator that simulates the sun's movement using a point-source lamp to project shadows. It allows for plotting hour lines on any surface, including irregular ones, by setting the gnomon at the correct latitude and revolving the lamp at 15-degree intervals. The device, suitable as a teaching aid, can also simulate declination for "dial furniture" like equinoxes and solstices by adjusting the lamp's height.
Dialling Tools, Sundial Design & Layout

June 1992 page 3
Christopher Daniel

The Sundial at Sea

This lecture explores the practical aspects of 16th and 17th-century navigation, highlighting the crucial role of sundials and similar instruments for determining time at sea. Mariners used celestial observations for latitude, magnetic compasses for direction, and various tools like traverse boards, sand-glasses, nocturnals, astrolabes, and cross-staves for navigation and timekeeping.
Dialling Tools, Dials: Portable, Historical Dials, Dials: Nocturnals

October 1992 page 28
Noel C. Ta'Bois

Sundial Line Drawing Jig

This article describes a Meccano jig designed by Noel Ta'Bois for drawing hour and declination lines on sundial plates of any shape, including curved surfaces. The instrument features a telescopic arm, set by calibrated dials for latitude, declination, and hour angle, which is extended to mark the shadow position of the nodus. It eliminates the need for complex calculations, making it useful for irregular surfaces.
Dialling Tools, Mathematics of Dialling, Sundial Design & Layout

October 1992 page 36
Fer J. de Vries

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

February 1991 page 10
Allan A. Mills

Aligning the Gnomon.

Addresses the critical step of setting up an equal-hour sundial and suggests that aligning by observing Polaris, the pole star, can be a quicker and more accurate method. Simple tools like a peep-sight or telescope can be used for this purpose.
How Sundials Work, Dialling Tools

July 1991 page 1

Dialogue - Der Zonnewijzerkring, La Busca de Paper, Austrian Sundials, Der Sternbote

This section compiles news and updates from various sundial societies. It covers new bulletin issues from De Zonnewijzerkring (Dutch) and La Busca de Paper (Catalan), including mathematical dialling, celestial mechanics, and specific sundial descriptions. It also announces the founding of an Austrian Sundial Society and details a rare sun chronometer in Baden, Vienna, designed by Gibbs.
Book Reviews, Dialling Tools, Dials: Heliochronometer, The BSS and Members

July 1991 page 22
Fer J. de Vries

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

July 1991 page 38
Hector Parr

Sundial Calculations for Computer Programming

This article presents the theoretical basis for a computer program designed to calculate hour lines for various northern hemisphere sundials (direct, declining, vertical, reclining, inclining). It outlines using spherical trigonometry formulas to determine dial plane elements and hour line angles. The author emphasizes robust programming to handle issues like division by zero and inverse trigonometric ambiguities, providing simplified BBC Basic and design guidance.
Dialling Tools, Mathematics of Dialling, Sundial Design & Layout

October 1991 page 36
Hector Parr

Computer Program Listing

This section provides a listing of a BASIC computer program by H.C. Parr for calculating sundial hour lines, intended to accompany a previous article. The program is designed to save time and prevent errors in sundial computations. Details for obtaining the program on a 5 1/4 inch disk and information about inputting latitude, reclining angle, and declination are included.
Dialling Tools, Mathematics of Dialling