September 2012 page 8
Michael Lowne
John Davis

The Stereographic Projection and Quadrant by Henry Sutton

This article explores Henry Sutton's quadrant, which utilises a stereographic projection of the sky onto the equatorial plane, initially conceived by Thomas Harvey. It details the instrument's design, including scales for time-telling and other astronomical problems, and provides instructions for its use, such as finding the time at night using stars.
How Sundials Work, Mathematics of Dialling, Historical Dials

December 2012 page 11
Michael Lowne
Steven Woodbury

Readers’ Letters

This section features two letters: Michael Lowne corrects a misconception regarding the alignment of the Plough's pointer stars with the pole star for planispheric nocturnals, impacting time readings. Steven Woodbury provides observations and a solution for the Dutch Polyhedral Dial drawing, noting its equatorial and polar dials and non-latitude specificity.
Dials: Multi Faced, Dials: Nocturnals

December 2012 page 20
Michael Lowne

Window Reflections

This article investigates the cross-shaped reflections from double-glazed windows, attributing them to the concavity of the glass panes. Optical analysis reveals radial slope profiles and contour maps, showing a central depression. The phenomenon is likely caused by a partial vacuum inside the units, bending the glass inwards, forming distinct V-shaped patterns on narrow windows.
Dials: Reflected, 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

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

September 2011 page 37
Michael Lowne
Chris H. K. Williams
Peter I. Drinkwater
David A. Young

Readers’ Letters

This section compiles several letters from readers. Michael Lowne provides a complex formula for calculating shadow length from gnomon angle. Chris Williams praises Peter Drinkwater's article on scratch dials, linking them to medieval manuscripts. Peter Drinkwater responds on the transmission of scratch dial technology and the function of water clocks. David Young corrects a historical detail about BSS conference venues.
Dials: Mass Dials, Historical Dials, Mathematics of Dialling, The BSS and Members

September 2011 page 45
Michael Lowne
John Davis

A Horizontal Quadrant of 1658 by Henry Sutton. Pt. 2

This second part examines the scales and uses of a 1658 horizontal quadrant by Henry Sutton, collaborating with John Collins. It details the matched sine and tangent scales for astronomical calculations, star positions for night-time finding, calendar tables for moon age and high water, and shadow/quadrat scales for measuring building heights. It also provides biographies of Collins, Dary, and Sutton, highlighting their roles in 17th-century London's mathematical community.
How Sundials Work, Mathematics of Dialling, Historical Dials

March 2010 page 21
Alessandro Gunella
Michael Lowne
Tony Wood
Doug Bateman
Chris H. K. Williams

Readers’ Letters

A collection of letters from readers. Topics include a simpler graphical method for using the John Marke altitude dial, a discussion on the nomenclature of mass dials, the 'Sun Position Compass', and the historical connection between clockmakers and dialmakers.
Dials: Mass Dials, Dials: Portable, Mathematics of Dialling, The BSS and Members

June 2010 page 18
Michael Lowne
John Davis

The Horizontal Quadrant – Part 1, Introduction and Instruments

This paper introduces the horizontal quadrant, a less common but useful altitude sundial type, sharing its basic stereographic projection with the double horizontal dial. It discusses its history, including European precursors like Hartmann's compast and Apian's triens, and English developments by Delamain and Oughtred. The article describes the general form and known examples, detailing how it uses the sun's altitude to tell time.
How Sundials Work, Mathematics of Dialling, Historical Dials

September 2010 page 10
Michael Lowne
John Davis

The Horizontal Quadrant. Pt. 2: Use, and the Inverted Quadrant

This article details the use of horizontal quadrants for time-finding and surveying, including a rare 'inverted' variant. It describes how to determine time from solar altitude and declination, and from stars at night, discussing the historical accuracy and limitations of these instruments.
How Sundials Work, Mathematics of Dialling, Historical Dials, Dials: Nocturnals

December 2010 page 7
Frans W. Maes
Allan A. Mills
Michael Lowne

Readers’ Letters

This section includes letters from readers. Frans Maes describes a multi-faceted obelisk sundial in Schwäbisch Gmünd, Germany, similar to one previously discussed. Allan Mills and Michael Lowne provide detailed explanations and practical advice on how to observe the optical phenomenon known as 'Haidinger’s brush,' which appears due to polarized light in the blue sky.
Dials: Multi Faced, How Sundials Work

September 2009 page 2
Michael Lowne
John Davis

A universal altitude dial by John Marke

Describes a unique universal altitude dial made by John Marke, possibly for Robert Boyle, now in the London Science Museum. The article details the instrument's provenance, its physical characteristics, and its complex operation as a combined clinometer and sundial. It provides an in-depth analysis of the mathematical principles involved and its potential accuracy.
Dials: Portable, Dials: Unusual, Historical Dials, Mathematics of Dialling

September 2009 page 20
Michael Lowne

Reader’s letter

A letter responding to a previous article on Kircher’s 'Organum Heliocausticum'. The author argues that the instrument as depicted could not work because the focal length of the spherical lens is drawn incorrectly.
Dials: Unusual, How Sundials Work

March 2007 page 40
Michael Lowne

The self-setting property of dual sundials

This paper examines the self-setting property of dual sundials, typically consisting of a polar-gnomon dial and an analemmatic dial. It explains the astronomical parameters involved, how rotation affects time indications, and calculates the effectiveness of this alignment method at various latitudes and declinations. It also compares the traditional dual dial with an alternative Foster-Lambert reclining dial.
Dials: Foster-Lambert, Dials: Double Horizontal

September 2007 page 128
Michael Lowne
John Davis

Lines of Declination and Two Seventeenth Century Dials

This article explores declination lines on sundials as conic sections and details methods for their delineation. It examines two 17th-century horizontal dials by Isaac Symmes (Science Museum, Oxford), noting errors in their declination lines and the presence of seasonal hours and lunar volvelles. A new graphical method for drawing declination lines is also presented.
Historical Dials, How Sundials Work, Mathematics of Dialling, Sundial Design & Layout

February 2006 page 33
John Davis
Michael Lowne

Henry Wynne’s Double Horizontal Dials - Update

This update provides further information on Henry Wynne’s double horizontal dials, including new historical evidence for the Staunton Harold dial’s position from 19th-century maps and photographs. It also discusses the Wrest Park replica and criticises the National Trust’s decision to preserve a bent gnomon on the Powis Castle dial as part of its history.
Restoration projects, Historical Dials, Dials: Double Horizontal

March 2005 page 3
Michael Lowne

Moondials and the Moon

Explores principles and types of moondials, including tabular, volvelle, graphical and adjustable designs. Analyses moon’s orbital motion, parallax, illumination, and visual limitations under moonlight. Proposes improvements to enhance accuracy towards that of simple sundials, and presents prototype experimental dials demonstrating refined timekeeping performance.
Dials: Nocturnals

September 2005 page 104
Ken Head
Michael Lowne
Ian R. Butson
Graham Stapleton

Readers' Letters

Contains a series of letters from readers. Topics include a discussion on whether two shadows from the sun and moon can be seen simultaneously, a stained glass sundial in a church, and the origins of an equation of time table.

June 2003 page 47
John Davis
Michael Lowne

Henry Wynne's Double Horizontal Dial at Staunton Harold

An analysis of one of the most sophisticated 17th-century dials made by Henry Wynne. The article describes the history, features (including its use as a moondial, star dial, and geographical dial), and modern restoration efforts of this large bronze dial.
Dials: Double Horizontal, Historical Dials, Restoration projects

June 2001 page 47
Michael Lowne

The Design and Characteristics of the Double-Horizontal Sundial

This comprehensive article details the double-horizontal sundial, distinguishing it from William Oughtred's earlier portable instrument. It explains its design, historical prevalence from 1630-1713, and methods for reading its complex graduations. The author also discusses modern examples and the use of stereographic projection in its delineation, providing a list of existing historical and contemporary dials.
Dials: Double Horizontal, Historical Dials, Mathematics of Dialling, Sundial Design & Layout

December 2001 page 138
Michael Lowne

The Design and Characteristics of the Double-Horizontal Sundial

This article examines the double-horizontal sundial, a 17th-century invention by William Oughtred. It features two sets of graduations: one for an inclined polar gnomon and another for a central vertical gnomon, operating from altitude and azimuth. The article details its design, use for time, date, and solar altitude, and discusses its self-setting property and limitations due to orientation error.
Dials: Double Horizontal, Historical Dials, Mathematics of Dialling, Sundial Design & Layout

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

June 2000 page 88
Michael Lowne

Book Review: 'The Sun in the Church'

Review of John Heilbron's book detailing cathedral meridian lines and the Catholic Church's role in astronomy.
Book Reviews, Historical Dials

October 2000 page 120
Michael Lowne

The Conference at Cirencester, March 31–April 2, 2000

Report on the 11th BSS Annual Conference, with summaries of lectures, site visits, exhibitions, and society updates.
The BSS and Members

February 1998 page 30
Michael Lowne

Reflecting Sundials

Describes novel non-shadow dials using reflectors. Parabolic and cylindrical forms generate bright caustic lines on a screen; hour indication follows motion of the cusp or inner edge. Includes formulae, constructional notes and an aperture version using a sundial curve.
DIY Sundial Projects, Dials: Reflected, How Sundials Work, Mathematics of Dialling

April 1997 page 11
Michael Lowne

An Analysis of Some Mass Dials of Sussex and Kent

A systematic study of seventy medieval mass dials, analysing their patterns, calibrations, and probable uses, with observations on design variations, dating, and functional purpose.
Historical Dials, Mathematics of Dialling

July 1997 page 15
R. A. Nicholls
Michael Lowne

Window Dial at Apuldram, West Sussex

This article investigates a window dial in a church at Apuldram, using a vertical gnomon, thus being accurate on only two days in the year, one of which is the patronal saints day. It discusses the history of the church and the dial, and that the architectural changes to the church mean that the dial is now shaded for half the time.
Dials: Unusual, Historical Dials

October 1997 page 49
Michael Lowne

The 1997 Essex Sundial Meeting

Summarises the second Essex Sundial Meeting at Moulsham Mill. Presentations included a history of calendars, the sun's nuclear reactions, and a detailed look at the massive astronomical instruments and sundials at Jaipur, India, built in the early 18th century to determine celestial positions. The meeting concluded with slides of the German sundial safari.
The BSS and Members

February 1996 page 12
R. A. Nicholls
Michael Lowne

Two Unusual Mass Dials in Dorset

A technical analysis of two rare mass dials found on a Dorset church, discussing their design, orientation, and potential liturgical functions.
Dials: Mass Dials, Historical Dials

October 1996 page 25
Michael Lowne

Shepherds' Sundial

An article about simple portable sundials used by shepherds, exploring their historical use, practicality, and variations in design.
Dials: Portable

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