June 2012 page 17
John Foad

The Scoreboard Sundial

This article describes a unique direct south vertical slate sundial found in Wimborne Minster, made by clockmaker W.B. Kerridge. Its distinguishing feature is a system for displaying the Equation of Time and longitude correction using interchangeable 'FAST'/'SLOW' iron plates and possibly minute/second plates, resembling a cricket scoreboard, for public use.
Dials: Unusual, Dials: Vertical, Equation of Time, Historical Dials

June 2012 page 20
Julien King

Sundials in GCSE Astronomy

This article discusses the role of sundials in the GCSE Astronomy qualification as an introduction to 'sun time' versus 'clock time', the Equation of Time, and longitude effects. It highlights two popular Controlled Assessment tasks: using a shadow stick to determine local noon and longitude, and comparing sundial time with local mean time to assess accuracy.
How Sundials Work, Equation of Time

September 2012 page 16
Dennis Cowan

In the Footsteps of Thomas Ross. Part 2: The sundials at Craigiehall

This article details two sundials at Craigiehall: a 4-metre high obelisk dial, restored in 1965 after being found in fragments, and a horizontal brass dial by John England, dating from 1702-1714. The obelisk is unique due to an 18th-century globe base, while the horizontal dial features an Equation of Time table and armorial devices.
Dials: Multi Faced, Equation of Time, Historical Dials, Restoration projects

September 2012 page 33
Dennis Cowan

The Sundials of Gerald Laing

This article highlights the sundial works of pop artist Gerald Laing, known for at least four large sculptural pieces. These include two Scottish obelisk sundials, a 37ft market cross in Inverness, and "Axis Mundi" in Edinburgh, often featuring complex gnomonics and graphical representations of the Equation of Time.
Dials: Multi Faced, Sundial Design & Layout, Equation of Time, Dials: Scaphe

September 2012 page 46
Roger Bunce

An Equatorial Sundial with EoT Adjustment: Update

This article provides an update on an equatorial sundial design with Equation of Time adjustment, originally published in 2009. The Mk.2 version incorporates improvements for public use, focusing on weather protection, increased strength, and enhanced vandal resistance, developed in response to the Austrian Sundial Society's plans to install a version.
Dials: Equatorial, Construction Projects, Equation of Time

December 2012 page 30
Richard Cecil
Judy Cecil

Building A Sundial At Chestnut Cottage

This article details the construction of a large garden sundial at Chestnut Cottage, Essex, by Richard and Judy Cecil. It covers civil engineering aspects, from site surveys and drainage to concrete work, and the precise setting out of hour lines and the stainless steel gnomon, incorporating a polar version of the equation of time.
Sundial Design & Layout, Construction Projects, Equation of Time, DIY Sundial Projects

March 2011 page 16
Vicki DeKleer

Hop onto a Sundial for Your House!

This article provides instructions for making a simple, fun, and versatile horizontal sundial for educational purposes, particularly for young people. It explains how to determine the meridian line, layout the base, and incorporate an Equation of Time table for accurate civil time.
DIY Sundial Projects, Dials: Horizontal, Equation of Time, Sundial Design & Layout

March 2011 page 18
Jos Kint
Stan Ulens

Two Methods to Find the Eccentricity of the Earth’s Orbit from Measurements with a Sundial. Part 2—Observations and Calculations of e

This second part details observations and calculations to determine Earth's orbit eccentricity using a sundial. It applies Ptolemy's geometrical model and an algebraic approach based on the Equation of Time, finding surprisingly accurate results despite the sensitivity of initial conditions.
Equation of Time, How Sundials Work, Mathematics of Dialling

March 2011 page 32
V. N. Manimanis
D. Blatsis
E. Th. Theodossiou

Four Horizontal Sundials in Schools of Volos, Alonnisos and Stefanoviki

This article details the construction and placement of four horizontal sundials in Greek schoolyards between 1995 and 2008. It highlights student involvement, the evolution of precision in Equation of Time corrections, and the use of modern technology in their design and carving.
Dials: Horizontal, Construction Projects, Equation of Time, DIY Sundial Projects

June 2011 page 26
John Davis

The John Rowley Dial

This article details the rediscovery and reinstallation of a lost John Rowley azimuth and equation of time dial from Blenheim Palace. It describes its unique features, including the deep double-ogee rim and specific gnomon design, and its historical significance.
Dials: Unusual, Equation of Time, Historical Dials, Restoration projects

September 2011 page 23
John Davis

Daniel Delander Dial Recovered

This report details the recovery of a stolen large double horizontal dial by Daniel Delander from Stanford Hall, thanks to Polish dialling enthusiast Maciej Lose. The dial, catalogued as DH-17, SRN 3607, is a high-quality instrument with Equation of Time scales and geographical place names. The article also mentions Delander's apprenticeship under Thomas Tompion, suggesting close working relationships between notable clockmakers.
Equation of Time, Historical Dials, Dials: Double Horizontal

December 2011 page 16
Stefano Barbolini
Giovanni Garofalo
Guido Dresti
Rosario Mosello

The Sundial of the Certosa of Florence (Tuscany, Italy) Restored to Working Condition

This article details the restoration of a pinhole sundial at the Certosa of Florence. The meridian line served as a calendar and true local noon marker. Investigations revealed inconsistencies, leading to the conclusion that the dial correctly determined the spring equinox, vital for calculating Easter, reflecting its religious institution setting. Historical interventions, possibly by astronomer G.B. Donati, are also discussed.
Dials: Noon Lines, Equation of Time, Historical Dials, Restoration projects

December 2011 page 42
Frank King

Mind the Gap – Sundials and Leap Years

This article addresses the difficulties of accommodating leap years on sundial calendars, particularly when showing the equation of time or solar declination. It explains how to design scales for precise readings despite the difference between tropical and civil years, and discusses the historical debate around which day (24th or 29th February) is the "extra" leap day. Practical design solutions are proposed.
Equation of Time, How Sundials Work, Mathematics of Dialling, Sundial Design & Layout

March 2010 page 12
Doug Bateman

An Equatorial Analemmatic and Calendar Sundial, Alicante, Spain

Describes a modern, equatorial meantime sundial on the marina in Alicante, Spain, designed by Juan Vicente Pérez Ortiz. The dial features a 'cut-out' analemma shape and a slot for apparent time, and has scales for both local and time zone time.
Dials: Analemmatic, Dials: Equatorial, Equation of Time

March 2010 page 23
Eddie French

Holiday Sightings (2)

Features a vertical declining dial combined with a noon mark analemma on a church tower in Winterthur, Switzerland. The vertical dial is corrected for longitude, and the analemma is colour-coded for the two halves of the year.
Dials: Noon Lines, Dials: Vertical, Equation of Time

June 2010 page 7
Ortwin Feustel

A Vertical South Sundial Indicating the Equation of Time and its Terms

This paper describes a vertical sundial designed to indicate the Equation of Time (EoT) as a figure-of-eight curve, along with its anomalistic and tropical terms. It provides the mathematical formulae for calculating these values and their graphical representations as functions of time and the sun's declination.
Dials: Vertical, Mathematics of Dialling, Construction Projects, Equation of Time

September 2010 page 18
John Davis

A Benjamin Scott Horizontal Dial

This article describes a small horizontal dial by Benjamin Scott, believed to have been made for Lochnaw Castle, Scotland. It features transversals for minute resolution, an Equation of Time ring, and specific gnomon supporters, linking Scott to John Rowley and discussing its provenance.
Dials: Horizontal, Equation of Time, Historical Dials

September 2010 page 32
Stan Ulens
Jos Kint

Two Methods to Find the Eccentricity of the Earth’s Orbit From Measurements with a Sundial. Pt. 1: Theoretical Considerations

This article presents two theoretical methods to calculate the Earth's orbital eccentricity using sundial measurements. The first method uses the Ptolemaic geocentric model and season lengths; the second derives eccentricity from the Equation of Time by separating the part due to obliquity from the total.
Equation of Time, How Sundials Work, Mathematics of Dialling

December 2010 page 26
Christopher Daniel

Meridies Media—An Historical Essay. The direct vertical noon mark mean time sundial at Greenwich

This historical essay details the Meridies Media sundial designed by Dr Tadeusz Przypkowski for the Old Royal Observatory at Greenwich in 1967. It describes the dial's function using an analemma to indicate standard mean time, true noon, and date. The article recounts the author's involvement in its installation, the initial design error, and the eventual reconstruction of the wooden dial in 1969, which remained until 1991.
Dials: Noon Lines, Equation of Time, Historical Dials, Restoration projects

December 2010 page 44
Brian Albinson

New Dials (2)

This article describes a walk-on analemmatic sundial designed for Highlands School in North Vancouver, Canada, using 'Alemma' software. It features a double analemma design to provide direct mean time with minimal error, accommodating the equation of time correction. Parent volunteers built the dial, using plywood jigs and bronze survey markers for permanent reference.
Construction Projects, Dials: Analemmatic, Equation of Time, Sundial Design & Layout

March 2009 page 31
John Davis

An Unusual Equation of Time Display

This article describes a unique Equation of Time (EoT) chart found in Nottingham, featuring straight lines for EoT values in whole minutes plotted against a non-linear calendar date axis. Dated possibly to the 1830s or 1840s, it differs from typical "Watch Faster / Watch Slower" scales.
Mathematics of Dialling, Equation of Time, Historical Dials

March 2009 page 38
David Gauld

The Sundial at Glamis Castle

This article describes the magnificent 21-foot high Glamis Castle sundial in Scotland, tentatively dated around 1683. It is an elaborate obelisk dial featuring 84 time-recording faces, lion dials for cardinal points, and a complex \pineapple\ (stellar rhombicuboctahedron) with numerous declining and reclining faces. The article also discusses its Equation of Time inscription and possible mathematical contributions by James Gregory.
Dials: Multi Faced, Mathematics of Dialling, Sundial Design & Layout, Equation of Time, Historical Dials

June 2009 page 24
Roger Bunce

An equatorial sundial with EoT adjustment

Details the design and construction of an equatorial sundial that directly indicates clock time (UTC). It incorporates a mechanical cam to automatically apply the Equation of Time correction, and includes adjustments for latitude and longitude. An appendix explains how to design the cam.
Construction Projects, Dials: Equatorial, Equation of Time, Sundial Design & Layout

September 2009 page 26
Ortwin Feustel

A vertical sundial indicating the present ecliptic positions of the constellations

Describes the design and markings of a complex vertical sundial. In addition to time, the dial indicates the current ecliptic positions of the constellations using a Mercator projection. It also features longitude correction, an Equation of Time curve, declination lines, and functions as a nomogram for identifying constellations visible at night.
Dials: Vertical, Equation of Time, Mathematics of Dialling, Sundial Design & Layout

September 2009 page 46
Chris Lusby Taylor

The housewife’s trick

Re-evaluates A.P. Herbert's suggestion of turning a horizontal sundial to make it agree with mean time. While previously dismissed as inaccurate, this article presents a theoretical analysis and a practical implementation showing that, for UK latitudes, the 'trick' can keep the dial accurate to within a minute for most of the year.
Dials: Horizontal, Equation of Time, How Sundials Work, Mathematics of Dialling

December 2009 page 9
Peter Ransom

Postcard potpourri 14 - The Butter Cross, Witney, Oxfordshire

This piece analyses a vintage postcard of the Butter Cross in Witney. By comparing the time shown on the clock with the local solar time on the sundial, and accounting for British Summer Time and the equation of time, the author deduces the exact date the photograph was taken.
Equation of Time, Historical Dials, The BSS and Members

December 2009 page 28
Michael Lee

A universal heliochronometer

Details the design and construction of a modern, portable heliochronometer. The instrument, inspired by H.C. Armstead's 'Phoeboscope', uses a spot of light on an analemma to provide a numerical time readout. It can be adjusted for latitude, longitude, the equation of time, and summer time.
Construction Projects, Dials: Heliochronometer, Equation of Time

March 2008 page 2
Mike Cowham

The Clef-Callier and the Equation of Time

Describes an unusual 1842 pocket calendar device called the Clef-Callier, named after one of two Parisian clockmakers, which shows the Equation of Time for the 5th, 15th, and 25th day of each month. It also displays the month and date, with corrections generally within one minute of modern figures.
Dials: Portable, Equation of Time

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

March 2008 page 46
W. S. May

An Equatorial Mean Time Sundial

Describes the design and construction of an 18-inch brass equatorial mean time sundial, incorporating a mechanism to compensate for the Equation of Time. The article details the machining of a groove on a rotatable drum for EoT correction and the careful assembly and alignment of the time-ring and gnomon, calibrated to read GMT directly.
Construction Projects, DIY Sundial Projects, Dials: Equatorial, Equation of Time

June 2008 page 54
Robin M Catchpole

The Solar Pyramid

This article describes the design and astronomical calculations for the Solar Pyramid, a proposed large-scale art installation that will also function as the world's largest sundial. It details the design constraints, methods for reading time, and the accuracy of incorporating the Equation of Time over centuries.
Construction Projects, Equation of Time, Mathematics of Dialling, Sundial Design & Layout

September 2007 page 98
Graham Aldred

A Review of the Heliochronometers by Pilkington & Gibbs: Pt. 4. The Mechanical Equation Table

This article reviews Pilkington's Mechanical Equation Table a device for converting sundial time to mean time, detailing its two versions. It covers the design evolution, Pilkington's reluctant use of Gibbs' cam mechanism due to practical limitations, and their patent disputes.
Equation of Time, Dials: Heliochronometer

September 2007 page 116
Vicki de Kleer

A Rare Dial in the Far North: Sumburgh, Shetland Islands

This article details a rare 1890 brass sundial from the Sumburgh Hotel, Shetland. Commissioned by Laird John Bruce and made by C. Baker, it features a peripheral calendar combining longitude and equation of time corrections, plus unusual additional instructions. It is noted as the most northerly dial in the BSS Register.
Dials: Horizontal, Equation of Time, Historical Dials

September 2007 page 134
Fiona Vincent

Solar and Lunar Data

This entry provides a table of solar and lunar data for September, October, and November. It includes daily values for declination and transit times, as well as lunar quarter and new/full moon phases. This data is useful for sundial calibration and understanding celestial movements.
Equation of Time, How Sundials Work

February 2006 page 20
Hal Brandmaier
Tony Wood
Patrick Powers
Doug Bateman
Norman Darwood

Readers’ Letters

This section contains various reader contributions. Hal Brandmaier and Tony Wood discuss vector methods for sundial delineation. Patrick Powers and Douglas Bateman exchange views on a longitude error on the Kew Garden Cross Dial inscription. Norman Darwood briefly comments on the potential effects of changes in Earth's rotation on sundials.
Dials: Horizontal, Mathematics of Dialling, Equation of Time

February 2006 page 32

A New Shopping Centre Dial

This article describes a new large stainless steel equatorial sundial, shaped like a Viking longship, installed at the Westwood Cross shopping centre in Ramsgate. The dial also serves as public seating and features large Roman numerals and an Equation of Time graph, although the author notes some elementary numbering and calibration errors.
Dials: Equatorial, Sundial Design & Layout, Equation of Time

February 2006 page 48

A New ‘Rotary’ Dial For Ipswich

This article announces the installation of a new large stainless steel public sundial on Ipswich marina, sponsored by Rotary clubs to commemorate their centenary. Designed by Tony Moss, the horizontal dial features a massive gnomon, Rotary emblems, a British Summer Time scale, and an informative plaque with a combined longitude/Equation of Time correction graph.
Dials: Horizontal, Construction Projects, Equation of Time

June 2006 page 91
Graham Aldred

A Review of the Heliochronometers by Pilkington & Gibbs: Pt.1 - The Design and Accuracy of the Gibbs Helio-Chronometer

This first part of a review examines the design and accuracy of the Pilkington & Gibbs Helio-Chronometer, an equatorial sundial known for its mean time accuracy. It details the instrument's components, mounting assembly, sight screen system, and the mechanism for integrating the Equation of Time using a cam, and discusses factors affecting its long-term accuracy, such as wear and calibration.
Dials: Heliochronometer, Equation of Time, How Sundials Work, Sundial Design & Layout

September 2006 page 128
Graham Aldred

A Review of the Heliochronometers by Pilkington and Gibbs - Part 2, Procedures for setting up the Helio-Chronometer

This article provides comprehensive, practical procedures for calibrating and reinstalling Pilkington & Gibbs Helio-Chronometers. It covers essential steps such as precise levelling, accurate co-latitude setting, meridian alignment, and adjustments for the equation of time and longitude, offering detailed guidance for both Northern and Southern Hemisphere models, aimed at owners and restorers.
Dials: Heliochronometer, Equation of Time, Restoration projects, Sundial Design & Layout

December 2006 page 186
Graham Aldred

The Helio-Chronometers from Pilkington & Gibbs: Pt. 3

Graham Aldred reviews the Sol Horometer, William Pilkington's 1912 heliochronometer, developed to bypass George Gibbs's patent. It details Pilkington’s unique EoT adjustment mechanism, contrasting it with Gibbs's system, and discusses manufacturing, sighting, and pointer design. The article also compares its performance and rarity to the original Helio-Chronometer, noting the limited sales.
Sundial Design & Layout, Equation of Time, Historical Dials, Dials: Heliochronometer

March 2005 page 13
W. S. May

Equatorial Equinoctial Sundial

Details construction of a combined equatorial and equinoctial sundial using stacked car engine starter rings, cylindrical and brass components. Describes adjustable latitude setting and a novel gearing mechanism employing concentric eccentric spindles to apply the equation of time correction on two knobs, enabling mean time readings without manual calculation.
Dials: Equatorial, Construction Projects, Equation of Time

June 2005 page 66
John Davis

More on the Equation of Time on Sundials

Continues analysis of how the Equation of Time was represented on sundials, with historical examples and refinements in accuracy by 17th and 18th century astronomers.
Equation of Time, Historical Dials, Mathematics of Dialling

September 2005 page 91
Christopher Daniel

The Equation of Time: The Invention of the Analemma. A brief history of the subject - Part 1

This article traces the history and invention of the analemma, a 'figure-of-eight' shaped curve that corrects for the equation of time on a sundial. It discusses the contributions of Jean-Paul Grandjean de Fouchy and Johann Philipp von Wurzelbau, and notes that the analemma first appeared in English publications in 1889.
Equation of Time

December 2005 page 142
Christopher Daniel

The Equation of Time: The Invention of the Analemma. A brief history of the subject (Part II)

This part of the article discusses the history and application of the analemma in equinoctial sundials, particularly in Great Britain and the Netherlands. It details inventions by Major-General John Ryder Oliver, William Pilkington, and William Homan, and provides strong evidence suggesting Johann Philipp von Wurzelbau invented the analemma around 1716, predating Jean-Paul Grandjean de Fouchy.
How Sundials Work, Equation of Time, Historical Dials, Dials: Heliochronometer

March 2003 page 14

Book Review

Review of 'Time Lord: Sir Sandford Fleming and the Creation of Standard Time', examining the historical development of global standard time.
Book Reviews, Equation of Time

December 2003 page 135
John Davis

The Equation of Time as Shown on Sundials

A comprehensive study of how the Equation of Time has been represented on sundials from 1672 to the 20th century, analysing data sources, engraving methods, and dating implications.
Equation of Time

March 2002 page 17
John Foad

A Derivation of the Equation of Time

Accessible derivation of the EoT formula using orbital eccentricity and axial tilt, with historical and mathematical context.
Equation of Time, Mathematics of Dialling

March 2002 page 44

Wheel of Time

Describes a noon mark dial with a lens at the aperture, projecting a bright spot on an analemma inscribed on a semicircular scale.
Sundial Design & Layout, Construction Projects, Equation of Time, Dials: Noon Lines

June 2002 page 50
Tony Marsh

The Martian Analemma

An investigation into the analemma and equation of time as it would appear on Mars, using NASA data and proposing calendar models for Martian colonists.
Equation of Time

June 2001 page 60
Tony Kitto

Richard Towneley and the Equation of Natural Days

This article discusses the 17th-century work of Richard Towneley and John Flamsteed on the Equation of Time. It highlights their correspondence and experiments aimed at validating the Equation of Time and confirming the Earth's constant rotational speed, discussing earlier publications and the ongoing controversies surrounding this astronomical concept.
Equation of Time, Historical Dials, Mathematics of Dialling

June 2001 page 79
Mike Cowham

Dating a Sundial by Calendar Change

Mike Cowham explains how the historical change from the Julian to Gregorian calendars can serve as a dating aid for sundials. He outlines methods for identifying pre- and post-1752 dials based on calendar scales and Equation of Time tables, providing examples from historical quadrants and portable dials across Europe.
Equation of Time, Historical Dials

September 2001 page 113
Allan A. Mills

The Eye of Time

Describes a modern, three-dimensional noon mark sculpture in Portland stone, with analemma. It indicates both the instant of mean-time noon and the time of year by projecting a spot of sunlight onto an incised analemma. This design is believed to be the first of its kind that is 3-dimensional.
Dials: Noon Lines, Dials: Unusual, Equation of Time

September 2001 page 127
Herbert Wright

A Timepiece That Can't Go Wrong

Originally published in "The Countryman" in 1948, this article describes a highly accurate horizontal sundial built by the author while interned in a Japanese camp in China. Constructed from scrap materials using improvised tools and limited references, this unique dial provided correct clock time with built-in Equation of Time correction, serving as the camp's only reliable timepiece.
DIY Sundial Projects, Dials: Horizontal, Dials: Unusual, Equation of Time

December 2001 page 160
John Davis
Michael Lowne

The 'Bacon' Double Horizontal Sundials

This article investigates the 'Bacon' double horizontal dial, an intriguing 17th or early 18th-century brass instrument of unknown origin. Its unique Equation of Time table and stereographic grid are detailed. Analysis suggests it predates 1752 and aligns with Tompion's calculations. A modern replica, crafted using CAD and photolithography, is also described, featuring updated EoT values and modern heraldry, signed by its maker.
Construction Projects, Dials: Double Horizontal, Equation of Time, Historical Dials

December 2001 page 166
David Levitt

Three Jersey Sundials

This article details three interesting sundials on Jersey. St Brelade's Church features an 1837 south-facing vertical dial with a unique Equation of Time indicator. A circa 1825 vertical declining dial by Elias le Gros in St Helier's Royal Square is notable for its history of obliteration and restoration. The third is a possible medieval Mass Dial, a carved stone found partially buried, suggesting its age and raising questions about its original function.
Dials: Mass Dials, Dials: Vertical, Equation of Time, Historical Dials

December 2001 page 169
John Wall

Railway Time (2)

This article, the second part on railway-related sundials, describes two identical horizontal sundials commissioned in 1992. They commemorate the centenary of the Rochers de Naye mountain railway in Switzerland. These bronze dials feature a cogwheel design, an Equation of Time graph, and separate hour lines for summer and winter. The author notes that electric clocks are still preferred for official timekeeping, and clarifies the one-hour time zone difference between UK and Switzerland.
Dials: Horizontal, Equation of Time, Historical Dials

February 2000 page 49
Colin McVean

Albert and the Equation of Time

Humorous article on the variation between apparent time and mean time through the year
Equation of Time, Historical Dials

February 2000 page 51
John Singleton

A Horizontal Dial with Equation-of-Time Built In

Describes the construction and principle of a horizontal dial that incorporates the equation of time.
DIY Sundial Projects, Dials: Horizontal, Equation of Time

June 2000 page 101
Andree Chotkiewicz

An Educational Heliochronometer

Describes a portable device that demonstrates the equation of time and solar motion for educational use.
DIY Sundial Projects, Dials: Heliochronometer, Equation of Time

February 1999 page 8
Mike Isaacs

A Bernhardt Sundial in Israel

The author recounts discovering a Bernhardt dial at the Hebrew University in Rehovoth, Israel, in 1980. This memorial to Sir Hans Kronberger features special gnomon and dial shapes designed to provide directly read local mean time accurate to within a fraction of a minute.
Dials: Unusual, Equation of Time, Historical Dials

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

February 1999 page 37
Pat Briggs

The Sundial Clock

Describes a mechanical clock designed to display local solar time as well as Greenwich Mean Time. It uses two cranks to apply the Equation of Time correction, accurately accounting for the sun's uneven progress throughout the year, making it possible to read solar time even in overcast conditions.
Equation of Time, DIY Sundial Projects

February 1999 page 40
John Moir

Shadowy Secrets: The Lure of the Obscure (Part 2)

John Moir continues his exploration of hidden meanings and symbolism in sundials, presenting examples of 'false identity' dials like a bowl dial and a cat-shaped memorial. He delves into using logos, Morse code, and snooker ball colour codes, as well as analogies like railway lines and hair-lines, to enrich sundial design.
Dials: Unusual, Sundial Design & Layout, Equation of Time, Mottoes

February 1999 page 47
Mike Shaw

Journal Review

This review covers two issues of *Compendium*, the NASS journal. It highlights articles on a 'Witch's Sundial', various sundial designs (conical gnomon, Ptolemaic coordinates, cycloid gnomon, split analemma), and 'Sightings' features on notable dials, concluding with a report on the NASS Fourth Annual Conference.
Dials: Equatorial, Book Reviews, Sundial Design & Layout, Equation of Time

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 104
Ken Head

Derivations

This technical article provides formulas for the Equation of Time and the Sun's declination throughout the year, using the day number as a variable. The derived values are shown graphically and noted to be close to published tables, aiming to provide a clear understanding of these fundamental gnomonic concepts.
Equation of Time, Mathematics of Dialling

October 1999 page 108
Peter Ransom

Two Sun Dials in Andover, Hampshire

This article describes two sundials in Andover, Hampshire, both linked to William Hawkins Heath (1787-1861), a brewer and banker. One, dated 1846, is on London Street with the motto 'Respice Finem' and an equation of time table bears just the initials W.H.H. The second, dated 1833, is in poor condition on the Savoy Cinema (formerly Heath House) and bears his full name, solving the initials riddle. The article details Heath's family business and civic roles.
Dials: Vertical, Equation of Time, Historical Dials, Mottoes

October 1999 page 115
Alexander C. Scott

A Design for a Horizontal Sundial Adjustable by Rotation Around a Polar Axis

This article presents a design for a horizontal sundial adjustable for the Equation of Time and longitude by rotation around an axis parallel to the gnomon's style-edge. The design features a dial-face and gnomon-spine on a head, connected to a base with scales for longitude and a twelve-month Equation of Time adjustment. The offset bearing configuration and a Vernier-like scale simplify operations, allowing users to set the dial for different longitudes and regular Equation of Time corrections.
Dials: Horizontal, Equation of Time, Mathematics of Dialling, Sundial Design & Layout

October 1999 page 120
Allan A. Mills

Book Review

This review critiques 'The Inequalities of Sundial Time' by Dr. Eilon Saroka, describing it as peculiar and unique. It covers the book's extensive detail on astronomical deviations from perfect constancy, but notes that all the factors examined are irrelevant for sundial accuracy, except for atmospheric refraction. The reviewer criticizes the lack of index and modern references, suggesting the work be split into two monographs on Earth's motion inequalities and the Equation of Time/analemma.
Book Reviews, Equation of Time, Mathematics of Dialling

June 1998 page 16
Margaret Stanier

Bernhardt Dials

This article describes the distinctive equatorial sundials designed by modern German artist M. Bernhardt. These feature a polished aluminium gnomon pointing towards Polaris, and an hour scale calibrated for mean time, incorporating the equation-of-time correction within the gnomon's outline. Interchangeable gnomons allow for seasonal adjustments.
Dials: Equatorial, Dials: Heliochronometer, Dials: Unusual, Equation of Time, Sundial Design & Layout

October 1998 page 16
R. P. M. Holliday

Time's Tune on a Liquidambar Leaf

This article describes a unique sundial commission, featuring a gilded metal liquidambar leaf design. It incorporates an innovative equation-of-time correction system called 'Time's Tune,' which uses musical analogy to plot values on a treble clef. The dial provides a direct read-out of clock time with specific adjustments for longitude.
Construction Projects, Dials: Unusual, Equation of Time, Sundial Design & Layout

October 1998 page 27
A. F. Baigent

Gregory: The Gipsy Dial

This article describes the creation of "Gregory," a vertical direct south sundial designed specifically for young children and school use. Made from recycled metals, the dial features a gypsy face, with hair and eyebrows shaped to represent the equation of time. Its design aims to attract youngsters and serve as a teaching aid for time and longitude.
DIY Sundial Projects, Dials: Vertical, Equation of Time, Sundial Design & Layout

February 1995 page 39
Fred Sawyer

Of Analemmas, Mean Time and the Analemmatic Sundial – Part 2

Continued discussion on the analemma and its use in sundials, particularly analemmatic types, including the relation to mean solar time and design techniques.
Dials: Analemmatic, Equation of Time, Mathematics of Dialling

February 1994 page 24
Master Antonio de Nebrissa

A Table of Time Differences in Spanish Cities

Historical document listing time differences across Spanish cities for calendrical correction and dial calibration, translated and annotated.
Equation of Time

February 1994 page 30
Allan A. Mills

More About the Equation of Time and the Analemma

Further elaboration on the Equation of Time and the analemma's form, including seasonal impacts on sundial accuracy and diagrammatic explanation.
Equation of Time

February 1994 page 32
Allan A. Mills

The 'Equation of Time for the Moon'

Discusses the lunar equivalent of the solar Equation of Time and its practical application for estimating time by moonlight.
Equation of Time

February 1994 page 38
William Derham

Tables of Time Relating to Watchwork

Historic timekeeping tables by Derham related to mechanical watches and their relationship to solar time.
Equation of Time

June 1994 page 32
Giovanni Paltrinieri

The Meridian of the Basilica of San Petronio in Bologna - Part 1

Part one of a detailed study of the meridian line in San Petronio, a 17th-century astronomical installation in Bologna. The article outlines its construction, alignment, and function in tracking solar time and determining dates such as solstices, serving both scientific and liturgical purposes.
Dials: Noon Lines, Equation of Time, Historical Dials

October 1994 page 29
Girolamo Fantoni

The Gregorian Reformation of the Calendar

This article explains the historical context and mechanisms of the Gregorian calendar reform, initiated by Pope Gregory XIII in 1582 to correct discrepancies in the Julian calendar, particularly concerning the accurate determination of Easter. It traces the problem back to the Council of Nicea in AD 325 and the slight error in the solar year's length as calculated by Sosigenes. The reform involved dropping ten days and introducing a new leap year rule. The article also discusses the varying adoption rates across European countries, initial doubts within the Vatican (leading to the construction of a meridian line to verify accuracy), and briefly touches upon modern discussions regarding calendar improvements.
Equation of Time

February 1993 page 18
G. Camus
P. de Divonne
A. Gotteland
B. Taillez

The Meridians of St Sulpice Church, Paris, (Part 1)

This article describes two meridians in St Sulpice Church, Paris, by Henry Sully (1727) and Charles Le Monnier (1743). It discusses their purpose for time measurement and astronomical observations, detailing the historical context of time standardization and their architectural integration within the church.
Dials: Noon Lines, Equation of Time, Historical Dials, Sundial Design & Layout

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 11
G. Camus
P. de Divonne
A. Gotteland
B. Taillez

The Meridians of St Sulpice Church, Paris, (Part 2)

This is the second part of an article describing two meridians in St Sulpice Church, Paris, by Henry Sully and Charles Le Monnier. It details their purpose for time measurement and astronomical observations, discussing restoration efforts, challenges in conservation, and the historical context of time standardization. It also covers Le Monnier's observations and the meridian's condition through the French Revolution and later centuries.
Dials: Noon Lines, Equation of Time, Historical Dials

October 1993 page 8
David W. Hughes

An Introduction to the Equation of Time

This article explains the Equation of Time, the difference between local apparent solar time (sundial time) and mean solar time (clock time). It details the two astronomical reasons for this variation: Earth's elliptical orbit causing the Sun's speed to change, and the Sun's apparent motion along the ecliptic rather than the celestial equator.
Equation of Time, Mathematics of Dialling

June 1992 page 24
H. Christopher H. Armstead

The Phoeboscope

The phoeboscope is presented as a self-sufficient instrument combining time-keeping, meridian-finding, and calendrical functions by detecting solar declination. Designed during WWII as an improvement of the existing sun-compass, its adoption was frustratingly held up in bureaucracy until too late to be useful. It uses a lens to focus sunlight onto a shadow-plate engraved with an analemma, allowing accurate determination of time, meridian, and date anywhere in the world without a watch or almanac.
DIY Sundial Projects, Dials: Heliochronometer, Dials: Unusual, Equation of Time

October 1992 page 25
H. R. Mills

A Portable Polar Sundial

This article introduces a portable polar sundial design that overcomes the issue of an infinitely long dial face for extreme hour angles. It uses two end-styles, which cast shadows for forenoon and afternoon hours, respectively. The dial can be adjusted using a wedge to correct for the Equation of Time or longitude.
DIY Sundial Projects, Dials: Polar, Equation of Time, How Sundials Work

February 1991 page 3
David A. Young

Making a Start - the Equation of Time.

Explains the Equation of Time and how this variation became apparent with the development of accurate mechanical clocks.
Equation of Time

July 1991 page 5
James Richard

The Spherical Sundial as a Mean-Time Dial

Building on Peter Drinkwater's work, this article explores adapting a spherical sundial to indicate mean time for six months of the year, by offsetting the hour marks away from the equator. This is possible because the slanting terminator at different solar declinations, adjusted for corresponding equation of time, happen to fall very close to one of two circles (within 1.5 minutes). The author also discusses using surface texture, like paint brush marks, to significantly improve the dial's readability and precision.
DIY Sundial Projects, Dials: Unusual, Equation of Time, Sundial Design & Layout

July 1991 page 20
Robert Sagot

Equation of Time at Noon UT

This article, translated by Charles K. Aked, explains the equation of time and its importance for comparing sundial readings to legal time and for drawing analemmas. It outlines three calculation procedures: consulting ephemerides for meridian passage, calculating at 0h UT for precision, and using or constructing tables of mean values. A method for building updated tables is provided, ensuring sufficient precision for dialling needs.
Equation of Time, Mathematics of Dialling

July 1991 page 34
Fred Sawyer

An Equant Dial

This article introduces the equant dial, a horizontal sundial design inspired by Ptolemaic astronomy, addressing uneven hour spacing in classical dials. It describes how a specific curve is drawn on the dial face, against which an equi-spaced hour-line circle is rotated. This mechanism enables manual adjustments for the equation of time and other corrections, simplifying time reading on such a dial.
Dials: Horizontal, Equation of Time, Mathematics of Dialling, Sundial Design & Layout

October 1991 page 15
Pat Briggs

General Notes on Sundials (Hour Angle Types)

This note provides succinct facts about hour angle sundials. It covers topics such as local time variations, the twelve-hour day at equinoxes, dial portability, effects of rotation, limitations of different dial types, gnomon orientation, and the daily and annual changes in sunrise/sunset times and the Equation of Time.
Equation of Time, How Sundials Work

October 1991 page 29
H. R. Mills

Letters to the Editor

This section includes correspondence from H.R. Mills, who details his homemade "heliochronometer" sundial based on the Gibbs and Pilkington type. He also discusses A.P. Herbert's "Housewife's Trick," warning against adjusting sundials by twisting them in azimuth to correct for BST, as this introduces variable time errors.
DIY Sundial Projects, Dials: Heliochronometer, Equation of Time

October 1990 page 26
George P. Woodford

Q for Question

This article, presented in a question-and-answer format, describes a didactic hemispherical sundial that models the Earth's relationship to the sun. It explains how the shadow of a bead indicates date and time, distinguishes it from ancient Greek dials, and clarifies why it needs occasional adjustment about its axis to display clock time.
Dials: Hemispherical, Equation of Time, How Sundials Work

July 1989 page 12
Peter I. Drinkwater

Sun Time

Contrasts the "true" time indicated by sundials with the artificial time of clocks (GMT, BST) and advocates living in accordance with the sun's rhythm.
Equation of Time