Last updated  

10.01.12

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SUNDIALS

On the left a sundial in Leicester, on the right a wooden version from Klosters, Switzerland

Imagine a world without wrist watches or, for that matter, mobile phones or any other device that tells you the time. Whilst urban dwellers might have had a town clock or even a town crier calling out the time, in rural locations you would have been dependent on the position of the sun in the sky for a rough indication of what the hour was. A more accurate measurement could have been achieved by looking at a sundial and you will still see these as you wander around the lanes and footpaths in the countryside.

This sundial, dated 1720, is on the church of St Teilo's, Merthyr Mawr. It is all that remains of the previous church.

In ancient Mesopotamia it was found that the simple division of time into day and night needed further refinement and the time between sunrise and sunset (and later, sunset and sunrise) was split into 12 seasonal hours. Adding on the hours at night gave us the 24 hour clock. Attempts to measure time used water clocks, clepsydra, with water dripping from a large urn. Models from ancient Egypt around 3,500 years ago have calibration markings showing elapsed time. A Greek version ran for a fixed period, say 20 minutes, and was used to limit the amount of time a case could be argued in court – hence the saying ‘your time has run out’. Other methods used flowing sand and you can still buy an hourglass or sandglass or used burning candles with elapsed time marked on the side. The mechanical clock first appeared in the 13^th century in Europe.

Left, a Roman sundial on display in Leicester. Right, sundial on church at Naunton in the Cotswolds

However the other method for telling the time which once positioned accurately could give a good indication of the time of day as long as there was light enough for a shadow was the sundial. Both the time of day and time of year can be gauged by the position of the sun in the sky. Rather than look directly at the sun, the shadow from a tree, stick or even oneself can be used with the shadow shortest at mid-day. The first accurate sundials whose working we understand came with the ancient Greeks who used a hollowed-out block of stone to show the time of day and time of year. This is called a Hemicyclium. The Romans copied the idea and would often have them in the courtyards of their villas.

The apparent simplicity of a sundial belies its actual complexity. Some sundials use a line of light, others the shadow from a stick or similar object, the Gnomon. This used to be pointed towards the Pole Star but some gnomons can be moved according to the month or other variable. Most of the sundials you are likely to see when out and about are mounted vertically and often on the sides of churches, although horizontally-mounted ones may be seen in gardens and parks.

Stick sundial in the porch of St Mary's Church, Rhossili.

A very basic version, a 'scratch' sundial can be see in St Mary's church in Rhossilii just inside the entrance porch. At first this might seem puzzling as the dial is under cover. However it is believed that this doorway came from the old church in the Warren and faced south in the open. A stick would be inserted in the hole and the time read from the scratched lines. As St Mary's dates from the 12th century this would have to be very old.

Portable sundial on display in Leicester's Jewry Wall museum.

If you think sundials are always fixed, think again. Try Googling Portable or Pocket Sundials to see what a range is available to buy today. They have been in use for hundreds of years, some incorporating a compass to help with alignment. The City of Leicester has a time trail which takes you round the inner city looking at all sorts of sundials.

Multi-faceted sundial in Cambridge

Another city to promote its sundials is Cambridge - the example above having several faces, each with a different design.

Corpus Christie clock

With its amazing blend of old and new technology, the Corpus Christie clock, shown above, is on public display near Kings Parade in Cambridge. Costing over £1 million and five years in the making you can find plenty more on the internet about it.