The following brief biographies includes astronomers, mathematicians, architects, craftsmen and authors worldwide who have contributed to gnomonics. Some of the subjects are better known in other fields, but their contributions to dialling are stressed here. This is by no means a comprehensive list, but does include the most important figures. For a much more comprehensive listing of British dial makers, see:
J. Wilson: ‘Biographical Index of British Sundial Makers from the Seventh Century to 1920’, British Sundial Society (2003).
c. (circa) approximate date.
fl. (flourished) period known to have been working.
Individuals names in the period before 1700 showed much variation, even by their owners. Those used here are the ones most commonly found. although some alternatives are shown where known.
Airy, George Biddell 1801-1892: was an English astronomer and Astronomer Royal from 1835 until 1881. Amongst many scientific achievements, he introduced an improved system of meridian observation and introduced many new instruments to the Greenwich Observatory, including the Airy transit circle which re-defined the Greenwich Meridian which, largely through his efforts, was accepted as the Prime Meridian in 1884. He introduced the electrical timing of transists in 1854, and the daily recording of sunspots using the Kew heliograph in 1873. He determined the exact longitudes of Paris, Edinburgh, Brussels and Cambridge, helped with the mapping of the Canadian/American border, and assisted in the construction of the clock chimes for the Westminster Tower.
Allen, Elias fl.1606-1654: was the most famous mathematical instrument maker of his day, and is sometimes regarded as the father of the English instrument making industry. He was born in Kent and may have undertaken estate surveys when young. He was first established with a shop in Blackhorse Alley, near Fleet St., London, in 1606-11 but later moved to the Sign of the Horse Shoe, Strand. He specialised in instruments of brass and silver, giving instructions in their use. Allen was the second in a long line of master-apprentice relationships, training under Charles Whitwell and with his most notable apprentice being the renowned Ralph Greatorex, leading through Henry Wynne to Thomas Tuttell. He was a friend of William Oughtred, for whom he made double horizontal dials and who described him as ‘a man well knowne and esteemed by all men of art for his skilfullness in making instruments of metal’. The high quality of his engraving can be seen in his instruments in the British Museum, the Science Museum, London, the Museum of the History of Science in Oxford, the Whipple Museum, Cambridge, and St. Andrews University, Edinburgh.
Abbo of Fleury c.C11: a French Benedictine monk who produced an horologium in the late C11 which gave shadow lengths for his location at each hour and for each month.
Adams, George senior fl.1760-1772: was a Fleet St., London, instrument maker. He served his apprenticeship under Thomas Heath, and went on to become instrument maker to King George III. He made, for example, a number of large horizontal dials. He was succeeded by his sons George jnr. (1750-95) and Dudley (1760-1826).
Albategnius (or Abu-'Abdullah Muhammad ibn Jabir Al-Battani) 858-929: was an Arab astronomer (born Haran, Turkey, died Samarra, Iraq) who refined Ptolemy's work with careful measurements, particularly of the length of the year and the precession of the equinoxes. He was also a brilliant mathematician who extended plane trigonometry to the surface of a sphere (spherical trigonometry). His work, including the invaluable cosine rule, became known in Europe during the Renaissance.
Alhazen (or Abu Ali al-Hassan ibn al-Haytham) c.965-1038: was born in Basra (now in Iraq) and was the greatest scientist of the Middle Ages, particularly in the field of optics. He wrote a treatise on Arabic astronomical instruments, including many forms of sundial, and which noted the innovation of a polar style to produce equal hours. He contested the views of Hero and Ptolemy that vision involves rays emerging from the eye, postulating that light originates from the sun or a flame. He made and described lenses and spherical/parabolic mirrors, and measured the refraction of light. He also postulated that rainbows are formed in the atmosphere. His chief work was published in 1572 as ‘Opticae Theasurus’ from a 13th century Latin translation.
Anaxagoras c.500-428 BC: a Greek astronomer who gave the correct explanation of solar and lunar eclipses, hypothesised that the moon is observed by reflected light, and maintained that all heavenly bodies are composed of rocky material.
Anaximander the Elder c.611-547 BC: an Ionian natural philosopher, he helped bring the knowledge of the ancient Egyptians, and others, to Greece. He also introduced the sundial there. This dial with a vertical gnomon enabled him to ascertain the lengths and angles of shadows, thereby allowing him to measure the lengths of the years and seasons, and set the times of the equinoxes and solstices. He envisaged the Earth as a cylinder (sic) with its axis running E-W, floating in space.
Apian, Peter (or Apianus or Bennewitz) 1495-1552: discussed quadrants in his ‘Instrument Buch’ of 1533, and also developed the Apian dial (a universal card dial). Some of his famous dials still exist in Austria.
Apollonius of Perga c.245-c.190 BC: was the last of the great Greek mathematicians. His great work was on the conic sections. His work on epicycles and ellipses formed the basis for Ptolemy's cosmology. A sundial named the arachne is attributed to him by Vitruvius.
Aristarchos of Samos c.320-250 BC: was probably the first astronomer to propose a heliocentric theory of the solar system. This had the Earth and the planets circling the sun, with the stars infinitely distant. He was able to make some (inaccurate) estimates of the sizes and distances of the sun and the moon by noting that the moon must lie at the right angle of a triangle with the sun and Earth when it is half illuminated. The document that describes this, ‘On the Magnitude and Distances of the Sun and the Moon’, still exists.
Arsenius, Gualterus Regnerus c.1525-c.1580: was a master instrument maker in the Low Countries, who graduated from the university of Louvain in 1546. He often signed himself on instruments as the ‘nephew’ of the mathematician Gemma Frisius and, although it is uncertain if they were actually related, Arsenius certainly succeded Mercator as Gemma's instrument maker. His main output was astrolabes, but he also made, for example, a magnificent bowl scaphe dial with an astrolabe lid.
Bacon, Roger 1214-1294: was an English philosopher and scientist. He was Franciscan friar educated in Paris and Oxford. At the Pope's request, he wrote a three-volume encyclopaedia on all the known sciences. Although he suffered religious persecution, he developed magnifying glasses, made proposals for a telescope, and promoted the use of latitude and longitude. He also wrote to the Pope suggesting calendar reform as the equinox date was in error by 9 days.
Bede St. (known as the Venerable Bede) c.673-735 AD: an English monk, theologian and historian who lived in a monastery at Jarrow, Northumbria. He wrote ‘the Ecclesiastical History of the English People’ (731 AD), a primary source for English history. His work ‘Horologia’ contained tables of shadow lengths for different times of the year, and also compared the day-lengths in Jarrow with those in Italy (though he never travelled far from Jarrow). His ‘De temporum ratione’ of 725 gave a table of the paschal cycle. He wrote in Old English vernacular, and also in Latin, and his work survives through manuscripts copied by his pupils. His Feast Day is 27 May.
Bion, Nicholas fl.1652-1723: a well-known Parisian instrument maker who made many Butterfield dials – indeed, he may have originated the style. He also wrote an influential treatise ‘The Construction and Principal Uses of Mathematical Instruments’ in 1709 (translated into English by Edmund Stone in 1723).
Blagave, John c.1558-1611: a mathematical practitioner from Reading, educated at St. John's College Oxford. He is best known for his ‘Mathematical Jewel’, which was a uranical astrolabe, (using a stereographic projection) and was described in a book called ‘The Mathematical Jewel’ published in English in 1585. It contained much material on dialling and in 1609 he published ‘The Art of Dyalling’ dedicated to the subject. Being a strong Protestant in this Elizabethan period, he was able to adopt and promote the Copernican system. He also designed a map of the world in 1596 (now in the British Museum). His monument, in St. Laurence's church, Reading, features five cherubs each holding a Platonic solid.
Bradley, James 1693-1762: was the third Astronomer Royal. He was educated at Balliol College, Oxford, where he studied theology and he was a vicar in Bridstow. He resigned a position as chaplain to the Bishop of Hertford in 1721 to become Savilian Professor of Astronomy at Oxford. Bradley is famous for discovering the aberration of light (and hence correctly determining the speed of light), and for accurately describing the nutation of the earth.
Brahe, Tycho 1546-1601: often known by his first name only, he was the last of the great naked-eye astronomers. Born of aristocratic parents, he was educated in Copenhagen in law and philosophy, but took up astronomy after observing the 1560 solar eclipse. After working in Basle, King Frederick II of Denmark offered him the island of Hven in 1576 for what is regarded as the first observatory of its kind in the world. Brahe was the last great astronomer to reject the heliocentric theory of Copernicus, although he did suggest that the planets other than the Earth revolved around the sun. His carefully prepared tables of the motion of the sun allowed him to determine the length of the year to within a second, making calendar reform inevitable. Tycho moved to Germany in 1597 and took as his assistant Johannes Kepler. Kepler made great use of Tycho's data. Brahe was also an instrument builder, producing advances in a number of instruments, including an improved transversal scale for quadrants.
Butterfield, Michael b.1635, fl.1674-1724: was born in England but moved to Paris at an early age. He had a workshop ‘Aux Armes d’Angleterre’, and was, uniquely, granted his own coat of arms. He has given his name to the portable Butterfield dial, although he was not the only maker and probably was not the originator. As his workmanship was of the highest quality, many other makers signed their dials ‘Butterfield à Paris’.
Briggs, Henry (1561-1630): was the Savilian Professor of Geometry at St. John's College, Cambridge, and the first holder of the chair of geometry at Gresham College. He was a colleague of Gunter and worked with Napier, producing tables of logarithms to base 10 in 1617. He made the famous sundials on the east buttresses of the Merton College, Cambridge, chapel, which still exist.
Cassini, Giovanni Domenico (or Jean Dominique) 1625-1712: was a brilliant Italian-born astronomer who moved to France in 1669 to set up the new Paris Observatory. Before moving, he had been Professor of Astronomy at Bologna University, and had set up the great meridian line of San Petronio in 1653, allowing him to publish accurate tables of the sun in 1662. Although a well-regarded observational astronomer who had influence with the Pope and the French King, he was slow to adopt the Copernican system and insisted (wrongly) that the earth was flattened at the Equator, despite arguments from Newton and Huygens. He was the head of a dynasty of four generations of astronomers at the Paris Observatory.
Chaucer, Geoffrey c.1342-1400: was an English poet and author. His most famous work, ‘Canterbury Tales’, includes at least one reference to a sundial – the chilindrum. It is also cited as the first occurrence of the phrase ‘of the clokke’ (o'clock), showing that equal hours were already becoming known. The prologue to the Parson's Tale relates shadows and time in a manner consistent with equal hours. Additionally, he wrote a treatise on the astrolabe.
Clavius, Christopher c.1580: an Italian astronomer working in Rome. He published ‘Gnomonices Libri Octo’, a complete synthesis of the theory and practice of gnomonics. He did much of the work that led to the Gregorian calendar reform.
Cole, Humphrey (or Humfray Colle or a bewildering number of variants on his instruments) c.1525-1591: is the best-known of the Elizabethan instrument makers, with examples of high quality workmanship being found in many museums. Born in the north of England, he moved to London and was probably a member of the Goldsmiths’ Company. He was an assistant at the Mint in 1564 and set up his own workshop ‘near the North door of St.Paul’s’. It is possible that he was a student of Nicholas Kratzer. He made principally quadrants and rules, often incorporating dials. There are also existing examples of horizontal, ring and equinoctial dials. His masterpieces include the two-foot astrolabe dated 1571 at the University of St. Andrews and the misnamed ‘Drake’s astrolabe’ (compendium) at the National Maritime Museum..
Copernicus, Nicholaus (Mikolaj Kopernigk) (1473-1543): was a Polish astronomer and cleric who was responsible for finally overturning the geocentric theory of the cosmos. He was educated at Krakow and Bolgna, and spent most of his working life as the Canon of Frombork. He only made a small number of astronomical observations, relying on other people's data. His model of the planets orbiting the Sun, with the axis of the Earth tilted by 23.5º, was largely correct, although he retained the system of epicycles. His ideas were first formulated and circulated in 1513 and 1530, but publication of his master-work ‘De Revolutionibus Orbium Coelestrium’ was delayed until he was on his deathbed. It remained on the Roman Catholic Church's index of forbidden books from 1616 until 1835.
Culpeper, Edmund 1660-1738: There were actually two Edmund Culpepers (father and son) together with a grandson Edward. They were all accomplished instrument makers; a signed horary quadrant with a sundial on the reverse is in the Whipple Museum, Cambridge.
Daniel, Christopher St. J.H. 1933- : was one of the founders of the BSS, and is its current chairman. After a career at sea and as a curator at the National Maritime Museum, Greenwich, he is now a freelance sundial designer. His most notable dials include the famous ‘Dolphin dial’ at the National Maritime Museum, and the four vertical dials on St. Margaret's Church, Westminster. He is also author of the Shire book ‘Sundials’ which has helped to re-popularise the subject in the UK.
Democritus c.460-c.370 BC: was a Greek philosopher (born in Thrace) who travelled to Egypt and the East. He is mainly remembered for introducing the term ‘atom’ for tiny indivisible particles which make up the whole universe. He also drew the first maps with rectangular grids i.e. an early form of latitude and longitude and wrote a treatise ‘Polographié’ on the polos.
Drecker, Joseph c.1925: A German historian, author and scholar, he wrote the influential and rather mathematical ‘Die Theorie der Sonnenuhren’ including the definition of planetary hours used here.
Dyson, Frank Watson 1868-1939: was an English astronomer educated at Trinity College, Cambridge. He was Astronomer Royal for Scotland (1906-1910) and for England (1910-1933). His main area of research was stellar motion but he was also deeply interested in solar phenomena, being actively involved in two solar eclipse expeditions, including Arthur Eddington's famous one which confirmed the General Theory of Relativity. Dyson was also passionately interested in time measurement and initiated the first public broadcasting of time signals by the BBC over radio – the familiar six-pip signal.
Emerson, William 1701-1782: was an English mathematician and teacher who lived at Hurworth, County Durham, where at least one of his dials can still be seen. His tomb is in the churchyard and the village pub, the Emerson Arms, is named after him. His ‘Dialling, or the Art of Drawing Dials…’ was published in 1770 and gave a good description of geometrical dialling.
Emilianus, Palladius c.C5: wrote ‘De Re Rustica’ in about 450 AD. This horologium gave the shadow lengths in Sicily for every hour of the day for each month, and was much used by scholars such as Bede and Abbo of Fleury in future centuries.
Eratosthenes c.276-c.194 BC: a Greek scholar and polymath, born in Cyrene (now part of Libya). He was appointed as the librarian of the famous museum of Alexandria in 235 BC. He is best known for measuring the circumference of the Earth by means of the difference in noon shadow lengths from a vertical gnomon in a hemispherical bowl between Alexandria and Syene. His value of 46,500 km compares quite well with the modern figure of 40,075 km at the Equator. Eratosthenes also managed to measure the obliquity of the ecliptic, obtaining a value of 23º 51', and introduced the concept of the tropics, temperate zones, and polar regions.
Evans, Lewis: a collector of portable dials and astrolabes in the early 20th century. One of his forebears had been an assistant at the Greenwich Observatory. In 1924 he donated his collection to be the foundation of the Oxford Museum of the History of Science.
Fale, Thomas c.1555-c.1610: a Caius College, Cambridge, mathematician, credited with publishing the first work in English devoted to dialling. It is ‘Horologiographia: the Art of Dialling’, completed 1586 and first published 1593. This was substantially a translation from the Latin of Wittekind's treatise of 1576.
Ferguson, James 1710-76: was sent to Edinburgh University by patrons. He became a prolific writer and lecturer in natural philosophy, able to make his own apparatus and instruments. He wrote specifically for the non-mathematical public. His main contribution to dialling was the publication in 1770 of ‘Lectures on select subjects: with the use of Globes, the art of dialling, etc.’ A signed instrument engraved ‘The Universal Dialling Machine and Solar Time-Finder’ is at The National Maritime Museum.
Finé, Oronce (or Orontius Finaeus) 1494-1555: was the diallist to Francis I of France. He published a number of books of solar horology (e.g. ‘Protomathesis’, 1532). He was an approximate contemporary of Nicholaus Kratzer, and performed a similar rôle as Kratzer's for the English king. He was an astrologer as well as an astronomer and mathematician, and was jailed in 1518 for an unpopular horoscope. An ivory navicula signed by him still exists. He produced a world map which coined the named ‘Terra Australia’, and wrote on the use of lunar eclipses to determine longitude.
Flamsteed, John 1646-1719: the first Astronomer Royal of England. In 1665, at the age of 19, he made the first accurate tables of the Equation of Time in England – ‘De Aequatione Dierum’ (published in 1669). He was educated at Jesus College, Cambridge, and was also a clergyman with the living of Burstow, Surrey. He became King Charles II's ‘Astronomical Observator’ at the newly established Greenwich Observatory in 1675. He was a fastidious observer who invested heavily in the best instruments available. His book ‘Doctrine of the Sphere’ in 1680 gave a new determination of the solar eccentricity at almost its true value of 0.01675. He made a precise determination of the latitude of Greenwich, the obliquity of the ecliptic, and the position of the equinoxes. He also produced tables of atmospheric refraction, tidal tables, and supervised the compilation of the first table describing the inequality of the lunar ecliptic following Kepler's second law . Flamsteed's main body of work, including star maps and detailed observations, was only published posthumously (‘Historia Coelestis Britannica’ in 1725, and ‘Atlas Coelestis’ in 1729), despite the fact that they were needed by his contemporaries Isaac Newton and Edmond Halley. He probably never made a sundial, although his papers show that he had dial construction in mind and he certainly corresponded with dial makers, particularly in his early years.
Foster, Samuel c.1600-1652: was an English mathematician and astronomer, and was amongst the first-rank of 17th century diallists. He was born (probably) in Coventry and educated at Emmanuel College, Cambridge. After a period teaching in Coventry, he became the Professor of Astronomy at Gresham College, London, in 1636. As a Puritan, he suffered persecution, forcing him to return to Coventry between 1637 and 1641. He published ‘The Art of Dialling’ in 1638, providing the first printed account of the use of Latitude and Hour scales for dial design. At this stage the scales were drawn out on a quadrant, rather than the ruler-like layout adopted by George Serle. The book also introduced the prosthaphaeretical arc for solving the spherical triangle when constructing inclining/declining dials. Foster constructed a geographical dial of great complexity on the internal wall of the astronomy professor's chambers at Gresham College. Following his death, several books were published from Foster's manuscripts. These included ‘Elliptical or Azimuthal Horologiography’ (1654) which had three important sections. One of these developed the mathematics of the analemmatic dial for the first time in English. The second considered dials on arbitrary planes with movable styles, now known as Foster-Lambert dials. The third deals with rectilinear or the diametral designs not covered elsewhere.
Fourier, Jean Baptiste Joseph 1768-1830: was a French mathematical physicist who was principally interested in heat. His mathematical methods for harmonic analysis, called Fourier analysis (and f. series, integrals, transforms etc.) are now widely used to describe mathematical functions, e.g. the EoT.
Franklin, Benjamin 1706-1790: the famous American President and scientist, he showed a great interest in dialling. In a humorous essay, he proposed a form of noon gun with an different number of canon on each hour line. He also strongly championed the use of Daylight Saving Time.
Galileo (properly, Galileo Galilei) 1564-1642: one of the greatest scientists ever, he was born in Pisa (where he famously demonstrated the acceleration due to gravity) but he also worked in Florence and Padua. He discovered the isochronal properties of the pendulum, invented the thermometer and was one of the earliest users of the refracting telescope. This he improved and developed to study the surface of the moon and to discover the satellites of Jupiter, which he suggested could be used to measure longitude. His ‘Siderius Nuceus’ (Starry Messenger) of 1610 showed the ‘imperfections’ of the heavens, and brought him into conflict with the Church. The imperfections included sunspots, which moved with time. After the new Pope Urban VIII was elected, Galileo published his ‘Dialogue Concerning the Two Chief World Systems’ in 1632, clearly favouring the Copernican system. The book was banned and Galileo convicted of heresy, dying later under house arrest and reportedly muttering ‘Yet it does move’.
Gatty, Margaret (Mrs Alfred Gatty) 1809-1873: a Victorian author on a wide variety of subjects, famous amongst diallists for her book ‘The Book of Sun-Dials’, first published in 1872. The first edition consisted mainly of dial mottoes, but later editions (by her daughter H.K.F. Eden and Eleanor Lloyd, but still referred to as ‘Gatty’) carried much more material.
Gemini, Thomas (T.G. or TC on dials) c.1515-62: a map engraver (trained with Mercator) and instrument maker from Flanders who migrated to London around 1540. A superb calligrapher and engraver, he made extant astrolabes and quadrants: one of the earliest known English horizontal dials (in the Science Museum) is dated 1551 and attributed to him.
Gemma Frisius, Regnier (or Regner, Reiner) 1508-1555: was born in Friesland in the Low Countries (hence his nickname) and became a professor of medicine and mathematics at the University of Louvain. He cooperated with his student Mercator in the construction of maps, globes and astronomical instruments. These included the form of astrolabe named after him and which he described in ‘De Astrolabio’ in 1556, a new cross-staff, and both terrestrial and celestial globes. In his 1530 book ‘De Principiis Astronomiae Cosmographicae’ he showed theoretically, for the first time, how longitude could be found with an accurate clock and also described the method of trigonometric surveying.
Gibbs, George c.1880-1947: was a consulting engineer and astronomer from Yorkshire. He was at one time the Director of the Jeremiah Horrocks Observatory, Preston. He is best known as the designer of the high-quality Pilkington & Gibbs heliochronometer, marketed from around 1906 until the First World War. He later fell out with his financial partner William Pilkington. A Foucault pendulum which he set up is in the Preston Museum.
Gibbs, Sharon L: a modern historian whose 1976 treatise ‘Greek and Roman Sundials’ is the standard text on the subject.
Gilbert, Sir William 1544-1603: the physician to Elizabeth I and an early physicist, admired by Galileo. Born in Colchester, Essex (where his house Timperlys is now a clock museum and features a horizontal dial outside). He described the newly-discovered magnetic variation and described making metal magnets in his 1600 treatise ‘On the magnet’. He was also the first Englishman to accept the astronomical system of Copernicus.
Greatorex, Ralph (or Gratrix) fl.1654-1712: was a London mathematical instrument maker and surveyor. He served his apprenticeship under Elias Allen and later took over his business. He was a friend of both William Oughtred and Samuel Pepys, for whom he made several instruments. He made portable dials amongst many other instruments. There is a horizontal string-gnomon dial by Greatorex in the Horniman Museum (London).
Gregory, James 1638-75: a professor at St Andrews and Edinburgh, he was a famous mathematician (discovering an infinite series that sums to pi) and astronomer. He is best known for inventing the Gregorian (reflecting) telescope in 1661. He employed men such as John Knibb and Henry Wynne to furnish the Observatory at St Andrews, and the meridian line in the Long Gallery of the university library at St Andrews is attributed to him.
Gunter, Edmund 1581-1626: was born in Hertfordshire and educated at Christ Church, Oxford. He taught mathematics for some years before becoming the third Professor of Astronomy at Gresham College 1619-26; he was also a Rector in Southwark (1615-26). He designed a large and complicated sundial for the King's Privy Garden at Whitehall; the dial was demolished in 1697, though Gunter's descriptive book of 1624 survives. In orientating the dial with John Marr by use of a magnetic compass, magnetic variation was discovered. He also developed the Gunter quadrant and a precursor to the slide-rule. He published seven-figure tables of logarithms, sines and tangents in ‘Canon Triangulorum’ (1620) which also coined the terms cosine and cotangent and the contractions sin and tan.
Halley, Edmond (or Edmund) 1656-1742: an English astronomer, best known for describing the orbit of the comet named after him. He studied at Oxford and although he did not obtain a degree he published a book on Kepler's Laws. He made an expedition to St. Helena to study the southern skies, and was appointed as the second Astronomer Royal in 1720. He was a friend of Newton, being partly instrumental in getting him to publish the ‘Principia’. He had wide scientific interests, publishing papers on the rainbow, tides, magnetism etc. He made a study of Ptolemy's writings and hypothesised that the apparent position of the stars had altered over the 15 centuries since the original observations had been made. Although he is not known to have had a direct input to dialling, his work at that period had a great influence on the underlying principles.
Hawney, William fl.1710-50: was a mathematics teacher from Lydd in Kent. He undertook land-survey, supplied sundials and quadrants for house and garden as well as teaching the whole range of simple practical mathematics and the use of mathematical instruments. According to custom he made his teaching notes into books. ‘The Doctrine of Plain and Spherical Trigonometry’ (1725) contains 87 pages devoted to ‘Dialling, Arithmetical and Instrumental, on all sorts of Planes’.
Heath, Thomas fl.1714-1765, d.1773: a celebrated London mathematical instrument maker who was born in Luton and apprenticed to Benjamin Scott. He later went into partnership (‘Heath and Wing’) with his son-in-law, the mathematical practitioner, surveyor and almanac maker Tycho Wing (Jnr). Amongst his other apprentices were George Adams senior and John Troughton. A famous Heath dial is at Penshurst Place, Kent. He is particularly well known for his large universal equinoctial ring dials.
Herschel, Frederick William 1738-1822: was originally a German musician but emigrated to Britain in 1757 and became a celebrated astronomer and the foremost telescope maker of his time. In 1800 he examined the solar spectrum using prisms and thermometers, discovering the existence of the infrared solar energy. By using Maskelyne's data, he established for the first time that the sun was not fixed in the universe, and he was also able to measure the sun's velocity relative to seven bright stars. His house in Bath is now a museum, and has an armillary sphere in the garden.
Hevelius, Johannes (or Hewel or Hewelcke) 1611-1687: a German astronomer, mostly famous for his careful charting of the moon. Between 1642 and 1645 he produced a fairly accurate value for the period of the solar rotation, and gave a good description of the structure of sunspots, coining the term ‘faculae’. His observations of the sun over this period are detailed in an appendix to his ‘Selenographia’.
Hipparchus c.190 BC- after c.126 BC: a great Greek astronomer and mathematician, born in Nicaea (now in Turkey). His star maps (using a system of celestial latitude and longitude) were of great accuracy for their time, were extensively copied by Ptolemy, and were used much later by Halley. From the movements of the star Spica over 150 years, he deduced a value of around 45 arc-seconds for the annual precession of the equinoxes (cf. the modern value of about 50.26"). He measured the length of the tropical year as 365¼ days and obtained a value of the lunar period which was only 1 second too short. Despite these accuracies, Hipparchus accepted the notion of a geocentric universe, with the Earth not quite at the centre of the sun's orbit. He also contributed in the field of mathematics with one of the earliest formulations of trigonometry.
Horne, Dom. Ethelbert 18xx-19xx: was an English priest who lived and worked at Downside Abbey, Somerset, for most of his life. He published extensive reviews of mass dials – ‘Primitive sundials or scratch dials’ in 1917 and ‘Scratch dials – their description and history’ in 1929.
Huygens, Christiaan 1629-1695: the most famous Dutch astronomer, mathematician and physicist. He invented the accurate pendulum clock and produced the first accurate table of the Equation of Time in 1665. He republished this table in his ‘Horologium Oscillatorium’ in 1673.
John of Holywood: see Sacrobosco.
Jackson, Joseph fl.1735-1760: was an important mathematical instrument maker who was a member of the Guild of Grocers and served his apprenticeship under Thomas Heath. One of his horizontal dials can be seen at Wandlebury, Cambs.
Kepler, Johannes 1571-1630: was a German astronomer who is famous for Kepler's laws of planetary motion. His interest in astronomy was sparked by the Great Comet of 1577. As a Lutheran, he suffered with religious persecution throughout his life and went to Prague as Tycho Brahe's assistant in 1600. Kepler completed Tycho's observations after his death (the celebrated Rudolphine Tables of 1627) and made use of them to formulate his laws of planetary motion. His first two laws were published in his ‘Astronomia Nova’ of 1609. By postulating elliptical orbits, he finally broke the Ptolemaic cosmos and provided a firm footing for the Copernican one. His ‘Mysterium Cosmographium’ had earlier (1596) shown that the five Platonic solids (regular polyhedrons) could be fitted inside a series of spheres to match the distances of the planets from the Sun (within 5%). Kepler also wrote the first science fiction book, ‘Solemnium’, in which a man travelled to the moon.
Kircher, Althanasius fl.1636-1646: was a polyglot Jesuit priest who lived with his students in the Collegio Romano, Rome. His magnus opus ‘Ars Magna Lucis et Umbrae’ (The great art of light and shadows) shows designs for many complex dials, some of which were not previously known and some of which (e.g. magnetic gnomons, light projection with sound and fire) are fanciful. He is credited by some authors with the introduction of the signs of the zodiac on declination lines. Some of his dials were made as the ‘Sciatheric Tables’; four table-tops made of slate.
Kratzer, Nicholaus (or Nicholas) c.1487-1550: born in Munich, Bavaria, he studied at the University of Cologne and at the Carthusian Monastry of Maurbach, near Vienna, where he learned his dialling skills. He came to the court of King Henry VIII in 1517/8 as an astronomer and ‘deviser of the king's horologies’, and as tutor in Sir Thomas More's household. He also entered Cardinal Wolsey's service, lecturing at Oxford at Corpus Christi College (1521-24). Only four dials can definitely be attributed to Kratzer. One is a small gilt brass octagonal dial now in the Oxford Museum of the History of Science. A stone dial, made in 1520 but rejected as incorrectly made, was found as part of a wall and is now in the City of Bristol Museums and Art gallery. The two others, now lost, were a pillar dial at St. Mary's Church, Oxford – the source of inspiration for the famous Turnbull or ‘Pelican dial’, and a multiple cube dial at Christ Church College. This latter dial has recently been used as the basis for David Brown's prize-winning dial, also at Christ Church. Kratzer is famously depicted, together with numerous dialling instruments and partially completed dials, in the 1528 portrait by Hans Holbein (the Younger), currently in the Louvre, Paris. A 1520 portrait by Albrecht Dürer has been lost.
Lambert, Jean Henri (or Johann Heinrich)1728-1777: was born in poverty in the Alsace and was a self-taught mathematical prodigy. He worked in Switzerland and Germany (for the Emperor of Prussia) as a private tutor. He was a multi-talented scholar, publishing on mathematics, physics, astronomy and philosophy. He is remembered amongst diallists for devising a form of analemmatic dial with a circular scale (the Foster-Lambert dial) and for Lambert's circles. He also developed (1772) several map projections still used today, including a conic projection and the Universal Transverse Mercator projection.
Leybourn(e), William 1626-1716: principally a London-based publisher, he was also an author and mathematical practitioner. His first work dedicated to dialling, in 1669, was ‘The Art of Dialling: performed geometrically by scale and compasses; arithmetically by the canons of sines and tangents; instrumentally by a trigonal instrument……’. It became a standard work, and the third edition in 1721 was called ‘Dialling Improv'd’. His great work on dialling was ‘Dialling: plain, concave, Convex, projective, reflective, refractive…..’. He was a contemporary of John Flamsteed and Henry Wynne.
Mach, Ernst 1838-1916: was an Austrian physicist, now remembered for the Mach number, describing supersonic velocities. Amongst his many interests, he investigated the stimulation of the retinal field with spatial patterns and discovered the strange visual effect now called Mach bands. This was subsequently forgotten and rediscovered in the 1950s.
Maskelyne, Rev. Nevil 1732-1811: an English astronomer and the fifth Astronomer Royal. He studied divinity at Trinity College, Cambridge, but went to the Greenwich Observatory instead of taking up a living. Although recently portrayed as the villain in the battle with John Harrison to win the Longitude prize (he was both a competitor and, later, a member of the Longitude Board), he was a talented astronomer who made strong contributions to the study of transits. His most enduring legacy for diallists is the Nautical Almanac which he founded in 1767, comprising a compendium of astronomical tables and navigational aids, including many of his observations of the sun, moon, planets and stars. He also observed the proper motion of several stars, and made measurements at a mountain in Perthshire to determine the gravitational constant.
Melville, Richard (sometimes Melvin) fl.1840-1871: a well known and prolific maker of quality decorative dials, he originally worked from Belfast and Edinburgh, but came to England at a later date. He is particularly known for his multi-gnomoned horizontal dials, usually in slate.
Mercator, Gerardus 1512-1594: was a Flemish engraver, cartographer, astronomer, instrument maker etc. He studied mathematics and philosophy at the University of Louvain, and made a living from making and selling quadrants, astrolabes, armillary spheres and sundials. He is now most remembered for devising the Mercator projection, introduced in his masterpiece map of the world in 1569 and still much used in map making. Several sundials were built in Ruplemonde, Belgium, to celebrate the quatercentenary of his death.
Meton 5th century BC: was a famous Greek astronomer who worked in Athens. Together with Euctemon, he made a series of observations of the solstices and, in 432 BC, derived a calendar with a 19-year cycle – the modern metonic cycle. This may have been based on earlier developments in Mesopotamia. He also built a water clock at Colonus, and developed the parapegma.
Molyneux, William (1656-1698): was an FRS and a gifted amateur astronomer, working from Trinity College, Dublin. He corresponded with Flamsteed and published his ‘Sciothericum Telescopicum: a new contrivance…’ in 1686 describing a combination of dial and telescope. It also included his own version of the EoT.
Müller, Johannes: see Regiomontanus.
Napier, John 1550-1617: was an aristocratic Scottish mathematician and amateur scientist, famous for the invention of logarithms, a term which he derived from the Greek words ‘logos’ and ‘arithmos’ (expression, number). He devised these because of the difficulty in performing astronomical calculations involving sines, which were well tabulated. The first logarithm tables were published in his ‘Mirifici Logarithmorum Canonis Descriptio’ in 1614, although it was only with collaboration from Henry Brigg's that the standard base-ten form was published in 1617. ‘Napier's Bones’ were a primitive mechanical computer and comprised numbered rods, usually of boxwood or ivory, which allowed multiplication to be easily performed and square roots to be found. Napier is also credited with the introduction and popularisation of the decimal point.
Newton, (Sir) Isaac 1642-1727: was the foremost British scientist of all time and is often credited with inventing the ‘scientific method’. His birthplace, where he performed his most inspired work in the annus mirabilis of 1665, was Woolsthorpe Manor, Lincolnshire which is now owned by the National Trust. He was educated at Trinity College, Cambridge, where he was made Lucasian Professor of Mathematics at the age of 26. He invented a reflecting telescope in 1673, and gave a good explanation of the causes of the rainbow, later published in his opus ‘Opticks’ in 1704. His major work is generally called the Principia (‘Philosophae Naturalis Principia Mathematica’) and was published in 1687 after much prompting and financial support from Edmund Halley. In it, Newton described the inverse square law of gravitation, his laws of motion, and set the foundation for the mathematics of calculus. He made two scratched dials as a boy at Woolsthorpe Manor; one is now in the library of The Royal Society, London, and the other is inside Colsterworth church (Lincolnshire). Various other dials, notably the celebrated one at Queens' College, Cambridge, have been ascribed to him, almost certainly erroneously.
Nicholson, Peter 1765-1844: was an English mathematician, born at Prestonkirk in Haddingtonshire. He was largely self-taught. He was one of the leading intellects behind 19th century building technology. In 1833 he wrote ‘A Treatise on Dialling: one showing the geometrical and the other the arithmetical construction….’. He drew many dials for the Newcastle and Morpeth area in it.
Nonius (Filde Nunez Salaciense) 1502-78: was a Portuguese mathematician and astronomer who, around 1540, devised the idea of engraving an astrolabe with a series of concentric circular scales (a ‘nonius’) to allow accurate determination of an angle. He also discovered that the loxodrome on the current maps described a spiral and not a circle.
Oughtred, Rev. William 1573 (or 1575) – 1660: (pron. Owt-red) was an English mathematician, educated at King's College, Cambridge. He taught at Albury near Guildford for most of his life. His ‘Clavis Mathematica’ (the key to mathematics) became the standard mathematics textbook. He showed an interest in dialling early in his career, inventing an easy method of geometrical dialling as an undergraduate. He is most famous for his Double Horizontal dial, often referred to as an Oughtred dial, incorporating a projection of the celestial sphere and a vertical style to function as an astrolabe. He designed a popular form of universal equinoctial ring dial, and also produced a circular slide rule. He collaborated closely with Elias Allen and was also a friend of Ralph Greatorex.
Ozanam, Jacques 1640-1717: was a French mathematician and member of the Royal Academy of France. His four-volume ‘Récréations mathématiques et physiques’ (1694) gives comprehensive instructions for dial designs and, in improved form and translated into English, was reprinted as late as 1840.
Plato (real name Aristocles) c.427-c.347 BC: was a highly influential Greek mathematician and philosopher who founded a school of learning which rejected practical experimentation in favour of mathematical and intellectual harmony. His insistence in the perfection of the heavens, with the planets moving in circles around the earth, held back astronomy for centuries.
Pliny, Gaius Plinius Secundus AD 23-79: known as Pliny the Elder to distinguish him from his nephew, the biographer. Pliny was a Roman military officer who retired to become an author and scientist. All the important assumptions from classical astronomy are described in Book II of his ‘Historia Naturalis’. This contains his own views together with, for example, the theories of Hipparchus and Eratosthenes. He expounded a geocentric universe, with the Earth as the pivot for the heavens and the seven planets (Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn). The sun was seen as the ruler of the heavens and had a zodiacal orbit around the Earth, divided into 12 equal parts. The sun was allowed 360 days to complete its circuit, with a surplus 5¼ added to bring it back to the ‘same’ position in the heavens. Although he had no idea of celestial distances, Pliny judged that the sun was much larger than the Earth, and lay at a great distance, by the fact that the shadows of rows of trees are parallel, and that during the equinoxes the sun reaches the vertical simultaneously ‘for all the inhabitants of the southern region’.
Ptolemy, Claudius Ptolemaeus c.90-c.170 AD: was an astronomer, astrologer, geographer and philosopher, probably of Egyptian extraction. He worked at Alexandria (then under Roman domination), with access to the famous library there with its works by Plato, Hipparchus, Aristarchos etc. His master-work was the famous ‘Almagest’, which influenced astronomical and religious conceptions for at least 13 centuries, despite the serious errors which it propagated. Ptolemy's cosmos was geocentric with all the orbits being perfect circles, although not always centred on the Earth. He made much use of epicycles, where the planet rotates around a small circle, which itself rotates around a larger one. Ptolemy also drew maps of Asia and Africa in his collection ‘Geography’, which included notes on latitude and longitude which much later influenced Christopher Columbus. His astrological treatise ‘Tetrabiblios’ has had a deplorable long-term effect. The Ptolemaic co-ordinates are named after him.
Regiomontanus 1436-1476: was a great German astronomer and mathematician who made observations, compiled astronomical tables, assisted in the reform of the Julian calendar and was also an active diallist. He was born Johannes Müller in Königsberg, (the king's mountain) which he latinized for his name. He studied in Vienna, where he translated Ptolemy's ‘Almagest’ from Greek into Latin for his posthumous ‘Epitome’, which also included criticisms of Ptolemy's theories which later influenced Copernicus. In 1467 he started compiling astronomical and trigonometrical tables, giving celestial co-ordinates which were useful for latitudes up to 60º N and calculating sine tables (which were not published until 50 years after his death). In 1471 he moved to Nuremberg, where he installed a printing press in his house allowing him to publish his own ‘Ephemerides’ – giving the positions of the heavenly bodies for every day between 1475 and 1506 – as well as scientific works from other authors. Regiomontanus had a strong influence on the Nuremberg group of diallists and dial makers, and described a universal form of card dial in his publication ‘Quadratum horarium generale’ of 1474. He travelled to Rome in 1475 to assist in amending the notoriously incorrect Julian calendar, but died there (probably of the plague) the following year.
Richard of Wallingford c.1292-1336: was an Oxford mathematician and astronomer. He made scientific instruments, probably including an astrolabe and the famous astronomical clock at the abbey of St. Albans, where he became Abbot. He is thought to have suffered from a form of leprosy, as extant paintings show him with a spotted face.
Rohr, René R-J 1905-1999: was born in Strasbourg and had a long naval career, becoming a captain. He was Honorary Vice-President of the BSS, and wrote many articles on gnomonics. His book on dialling, ‘Les Cadrans Solaires’ has been translated into English, German and Italian, is still in print and is valuable to modern diallists.
Rowley, John fl.1698 d.1728: was a London instrument maker who turned to large engineering projects after about 1715. He built the first orrery for the Earl of Orrery, for whom he also made a Butterfield dial (in the National Maritime Museum, together with another for the first Duke of Marlborough). He made two large (29 inch) horizontal dials in 1710 for St. Paul's Cathedral and a set of four for Blenheim Palace, the latter comprising a double horizontal, a geographical, an equation and a moon dial. The dial at Cranbury Park, Otterbourne, which is sometimes attributed to Newton, is by Rowley. A characteristic of many of his dials is the use of transversals, which he may have introduced to dialling.
Sacrobosco, Johannes (also known as John of Holywood) c.1195, d. between 1244 and 1256: was an astronomer and mathematician who was born in Yorkshire (probably Halifax) and studied at Oxford. He became a professor and taught in Paris. He was one of the first Europeans to use the astronomical writings of the Arabs, and translated Ptolemy's ‘Almagest’. His ‘Tractatus de Sphaera’ (commonly known as the Sphere) dealt with the spherical Earth and the heavens, defined the celestial equator, the ecliptic and zodiac, the length of the day and night at different seasons and ‘climates’ and also gave a (poor) description of the motion of the sun and moon. The Sphere was published in 1220 and remained the basic astronomy textbook until the 17th century, despite numerous errors. Sacrobosco wrote ‘De Anni Ratione’ in 1232, describing many forms of time and declaring that the Julian calendar was 10 days in error (which he proposed correcting by omitting one day in 288 years). He also wrote on the quadrant in ‘Tractatus de Quadrante’.
Sawyer, Frederick W III 1950-: is a co-founder of the NASS and its current President and Editor. He is a graduate of Yale and Pittburgh universities, where he obtained B.A. and M.A degrees in Mathematics, Philosophy, and History and Philosophy of Science. He has authored more than 65 articles on dialling and is the inventor of the Equant dial and the Ptolemaic co-ordinate category of dials. He is an expert on the work of Samual Foster and has done much original work on dialling theory.
Scaliger, Joseph Justus 1540-1609: was a French scholar and Calvinist who found many supposed errors in Pope Gregory XIII's calendar. In 1583 he devised his own calendar of 7980 astronomical years, counting a day at a time, which is now the basis of the Julian Day count.
Scott, Benjamin fl.1712- d.1751: was a London mathematical instrument maker who moved to the St. Petersburg Academy of Sciences (Russia) in around 1747. He served his apprenticeship under James Anderton and John Rowley, and worked in the partnership of Scott & Price 1714-18. He wrote ‘The Description and Use of an Universal and Perpetual Mathematical Instrument’ in 1733. He made ring, inclining and garden dials and also globes. He also made a magnificent French double horizontal dial, now in the Paris museum of science.
Seller, John Snr. fl.1658-1698: a compass, instrument and dial maker, who was also a surveyor and notable mathematical practitioner. He is one of the few makers of double horizontal dials. He taught and wrote on the arts of navigation and gunnery, published ‘Praxis Navigation’ in 1669, was appointed Hydrographer to His Majesty the King, and made measurements of magnetic variation at Wapping.
Serle, George: a C17 mathematical practitioner who produced the first set of dialling scales on a ruler and described them in a 1657 instruction booklet ‘Dialling Universal’.
Singh, Maharaja Jai 1688-1743: an Indian Maharaja and astronomer, he is best known for the series of five monumental naked-eye observatories that he built at various sites in India. The first was at Delhi (1724) but the most famous is at Jaipur, where the ‘Brihat Samrat Yantra’ was until modern times the largest sundial in the world. Singh also wrote a two-volume treatise on the astrolabe entitled ‘Yantra Raj Karika’.
Sosigenes 1st century BC: was an Alexandrian astronomer to the Egyptian court who wrote several books about the stars (now lost). He strongly influenced the Roman Julius Caesar to reform the calendar (see Julian calendar) in 46 BC.
Tompion, Thomas 1638-1713: the leading clockmaker of his day, working from London. He made the two ‘Great Clocks’ or astronomical regulators for John Flamsteed at the Royal Observatory. Amongst his sundials are a famous pair dated c.1690 at Hampton Court, one of them a double horizontal. The other dial was copied in 1959, and is at Kew (where the original was from 1832 to 1959). Two portable dials by him, in silver and gold, are in the British Museum. He was one of the earliest adopters of the EoT for his clocks and dials.
Tuttell, Thomas fl.1695-1702: was instrument maker to the king. He trained under Henry Wynne and made and sold Serle's dialling scales in 1700. He popularised a combination of portable horizontal and analemmatic dials which is self-orientating.
Tycho: see Brahe.
Ulugh Beg 1394-1449: a Mongol prince and Muslim of Tartar descent and the grandson of Tamerlane. He built a monumental observatory at Samarkand (now Uzbekistan). It included a huge stone sextant with a radius of 48m with which he could measure to 10 arcminutes and determine the length of the solar year to a minute of time. The remains of the instrument are still extant and his results were used by Flamsteed.
Vernier, Pierre 1584-1638: was a French engineer and instrument maker who devised the precision vernier scale. He worked as a military engineer for the Spanish Hapsburgs and the rulers of Franche-Comté, and devised his scale after studying the work of Nonius.
Vitruvius Pollio, Marcus fl. 46-30 BC: a Roman soldier (served with Julius Caesar in Africa) and architect. In his retirement, he wrote ‘De architectura’ which was much translated and very influential in Renaissance Europe. It included two chapters of information on the 13 kinds of sundial, and sundial construction methods, then known.
Biogs: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Waugh, Albert E 1903-1985: the Provost and Vice President of the University of Connecticut (USA), he is best known to diallists as the author of the 1973 classic ‘Sundials: their theory and construction’ which is still in print. Waugh had a library of early dialling books (including Fale and Ozanam), which he bequeathed to the Homer Babbidge Library of his university, where he is commemorated by a pillar dial. He also designed many dials, including two at Connecticut's Mystic Seaport.
Wheatstone, Sir Charles 1802-1875: a British physicist whose name is best remembered for the Wheatstone bridge, an electrical circuit which he did not invent himself. He was a Professor of Experimental Physics at King's College, London, working initially in acoustics but also in optics and electricity. His contributions to dialling were the invention of the polarised light sundial (1848), and a precision heliochronometer: examples of both are in the Science Museum, London. He also contributed considerably to the demise of the sundial through his pioneering work with William Cooke to develop a commercial electric telegraph, which was used to distribute railway time.
Whipple, Robert: a great collector of early scientific instruments – particularly portable dials and microscopes – in the early 20th century. He was the managing director of the Cambridge Scientific Instrument Company and donated his instrument collection as the foundation of the Whipple Museum of the History of Science, Cambridge in 1944.
Whitwell, Charles c. 1568-1611: was originally trained as an engraver of maps etc. but went on to become the founder of a long line of instrument makers at the Grocers’ Guild. He had Elias Allen as an apprentice and worked ‘without Temple Barre against St. Clement’s Church’, London. Numerous instruments, including sundials and compendia, are in major museums (including the British Museum and Science Museum).
Wing, Tycho fl.1751 – d.1776: was a mathematical instrument maker who served his apprenticeship under Thomas Heath and later went into partnership with him. Several high-quality horizontal dials signed “Heath and Wing” are recorded.
Wren, Sir Christopher 1632-1723: is best known as the English architect responsible for St. Paul's Cathedral, London, and the Greenwich Observatory (1675). He also had numerous mathematical and astronomical interests, having invented an astronomical instrument at the age of twelve. In his second year as student at Wadham College, Oxford, he had translated into Latin a treatise on dialling by William Oughtred. Additionally, he had devised a mirror sundial for the ceiling of his college rooms. Wren's best-known dial is the magnificent 1658 vertical decliner, now found on the south wall of the Codrington Library at All Souls' College, Oxford. It was originally positioned centrally on the south wall of the chapel in the Front Quadrangle, having been removed during 1869. In its original position, the dial with its diagonal scale could be read to one minute.
Wright, Thomas fl.1718- d.1767: held the appointment of Mathematical Instrument Maker to His Majesty the Prince of Wales, later George III, and was the leading maker of his day. He served his apprenticeship under John Rowley. One of his horizontal dials can be seen at Lacock Abbey, Wilts.
Wynne, Henry (or Wynn) 1640-1709, fl.1654-1709: a London instrument maker who served his apprenticeship to Ralph Greatorex and later numbered Thomas Tuttell and Richard Glynne amongst his apprentices. He is noted for his magnificent double horizontal dials, such as the one at Drumlanrig Castle. He is also known for his ring dials, and the small book he produced explaining them as well as moon dials. In 1677 Wynne made the magnetic dip needles with which Henry Bond's longitude solution was tested. Wynne is also attributed with introducing the domestic barometer.