The Sundial and Its Development: Part 1 Mike Cowham

The Sundial and its Development: Part 1 Mike Cowham

A Sundial is a Scientific Instrument that not very accurate. They did measures time from the position of the Sun not have any date correction in the sky. It is able to do this in two differ- but told the time within per- ent ways, either from the Sun’s azimuth or haps an hour or so. On some from its altitude. churches several such dials are to be found, so they would In the earliest days, man would have no- probably have used a differ- ticed the Sun crossing the sky and, from its ent one for the various sea- position, he would have learnt to estimate sons of the year. These dials how much of the day was remaining. Later originally did not attempt to he would have been able to do similar reck- measure hours, or similar in- oning from shadows, perhaps initially those tervals, but were there mostly of trees or even rocks and hills around him. to show the times for the One of the earliest proper Sundials was various church services (Fig. Man himself, acting as the gnomon and 2). Similar dials are also found measuring his shadow by using his feet in other countries, such as in for length assessment. Time telling like this France (Fig. 3). On this dial was done by the early monks so that when the daylight is divided solely they were away from their monastery they into four equal amounts. Dials knew fairly accurately when it was the of this type were, in the past, right time to say their prayers. Fig. 1. For the known as Scratch Dials, but best results, the user should stand on some in more recent times they are flat level ground and arrange for the tip of now referred to as Mass Dials. their shadow to fall on a fixed point. Then Portable dials were fairly rare they should measure how many lengths of in early times, but the version their feet make this amount. Note that the shown in Fig. 4 was probably hours shown on the chart are reckoned made in the 5th or 6th century. from dawn to dusk, so the times given are Some Pillar Dials are known 9 am, 12 noon and 3 pm. even as far back as Roman Most early dials told the time from the times. One such is on display height of the Sun rather than its position in Fig. 1 A copy of a chart for determining the time from in the Museo Atestino at Este the sky. Therefore, such a dial would need a the shadows produced by the monk’s own bodies. The in Italy. This design of dial th scale of dates if it was to be anywhere near 6 hour is noon. was popular for many cen- accurate due to the Sun’s height variation turies since then and many of ±23·5° throughout the year. For example, examples are to be seen in the Sun’s height here in Cambridge, which church at Escomb in Northumberland. museums and collections. is approximately 52° North, varies at noon These were both made around 670AD. One such is illustrated in Fig. 5. These di- between 14·5° in the winter, 38° at the als worked solely on the Sun’s altitude. The equinoxes and 61·5° at midsummer. The earliest dials that are commonly found gnomon was set above the appropriate are incised onto the walls on the south side date and the whole dial turned until the The two earliest dials in England are to be of many of our churches. These dials had gnomon shadow was vertically down the found on the shaft of a cross in the church- horizontal gnomons sticking straight out pillar. The tip of the shadow would then yard at Bewcastle in Cumbria and on the from the holes at their centres, so were give the correct time.

Fig. 2 Mass Dial on the church at Lullington, Somerset. Fig. 3 Mass Dial at Beaumont-de-Pertuis, Vaucluse, France.

8 Bulletin of the Scientific Instrument Society No. 130 (2016) polar gnomon, in about 1400, aligned with the Earth’s axis, that proper time telling became possible. Some of the earliest known portable ver- sions of this dial were found in the wreck of the Mary Rose warship which sank in the Solent in July 1545. Nine of these dials, each being fairly similar, were found in various cabins of the wreck, so they must have belonged to different crew members (Fig. 7). They were probably sold to them at the dockyard before the ship sailed, or even on an earlier occasion. Very few other dials of this type have been found but generally Fig. 4 Portable Dial turned up by a such wooden dials of this age have been plough at Cleobury Mortimer in 1816, discarded. These dials are about 33 mm di- th th 1 probably dating from 5 or 6 Century. ameter, have a folding brass gnomon and have a compass bowl inset which is about 10 to 12 mm diameter.2 Other early portable dials were made in ivory, such as those from Nuremberg. That illustrated was made by Hans Tucher in Fig. 6 Sketch of a Portable Dial from the 1583. It is calibrated only in Italian Hours, Anglo-Saxon Period, found at Canterbury. 24 of which start at sunset (Fig. 8). Both scales operate from short pin gnomons. The portable dial became more popular Another early Altitude Dial from the Anglo- through later centuries and it was pro- Saxon period was found beneath the floor duced in various countries. In France, the of Canterbury Cathedral (Fig. 6). It is about ivory workers in Dieppe made some inter- 7cm high and is probably designed to be esting dials around 1660. These were main- suspended by a cord or chain around the ly Magnetic Azimuth Dials such as that in neck of its user. It displays only mid-morn- Fig. 9. At Nuremberg in Germany many fine ing, noon and mid-afternoon times. To do Ivory Diptych Dials were produced operat- this a pin is inserted at the correct date and ing from a string gnomon (Fig. 10). Later, time is told from the shadow tip. in France, we have the fine Butterfield Di- It was not until the development of the als, believed to have been first made by an

Fig. 5 A Portable Pillar Dial operating from the Sun’s Altitude.

Fig. 8 Ivory Dial calibrated in Italian Hours by Hans Tucher of Fig. 7 A Portable Dial found in the wreck of the Mary Rose. Nuremberg, dated 1583.

Bulletin of the Scientific Instrument Society No. 130 (2016) 9 Fig. 9 Ivory Diptych Dial by Jacques Senecal of Dieppe, ca. Fig. 10 Ivory Diptych Dial by Paulus Reinman of 1660. Nuremberg, dated 1588.

Englishman working in Paris called Michael Butterfield. This type of dial was made by a number of French instrument makers (Fig. 11). Portable dials in Britain were not very common until about 1700 when various types were being produced. An example of an Inclining Dial by Ed- mund Culpeper is shown in Fig. 12. Portable dial making was quite common until perhaps the mid-nineteenth century when the mechanical watch took over. From this time onward dials of most types became quite rare. Also, with the railways and their electrical timekeeping, the whole of Britain became locked into Green- wich Time, so local times disappeared too. Radio, and later television ensured that nearly every house in the World had access to precision timekeeping. Fig. 11 Silver ‘Butterfield’ Dial by Nicolas Bion of Paris, c. 1680. Most Portable Dials were made for use at a single latitude, so they were not universally of use to their owners. How- ever, a few designs, like the Butterfield Dial, Fig. 11., and the Inclining Dial, Fig. 12., were designed to be used over a range of latitudes. In future articles I hope to be able to give further details of these dials and their makers and will include many more types. References 1. Haigh, Daniel Henry, ‘Memoirs On Yorkshire Dials’, Yorkshire Archeological and Topographical Journal, 5 (1879), pp. 134-222. 2. Julie Gardener, ed., Before the Mast, Life and Death Aboard the Mary Rose (The Mary Rose Trust, 2005).

Author’s email address: [email protected] Fig. 12 Brass Inclining Dial by Edmund Culpeper of London, c. 1740.

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