Part 1 - Why Look at Sundials in Leeds?
Sadly, not many public sundials remain in the city. In days gone by, nearly every church had a dial. Some were bold vertical dials, given pride of place above the entrance: others were mostly horizontal dials on a pedestal in the church grounds. Many church dials - especially the pedestal type - have now fallen victim to vandalism or theft.
Some of the dials which still exist are well worth a visit. Excellent examples of vertical dials, still keeping good time, are to be seen at St.Ricarius' Church in Aberford and St.John's Church in the city centre (pictured). Of more recent origin, a superb example of a large polar sundial is to be seen on the riverside at Otley.
Nowadays sundials tend to be regarded merely as attractive garden ornaments. Our ancestors however relied on sundials whenever they needed an accurate measure of the time of day. Many people today find sundials very confusing and dismiss them as unreliable. Hence the verse by Hilaire Belloc:
"I am a sundial
and I make a botch
of what is done far
better by a watch!"
This attitude is only possible because we have forgotten the nature of time and how it is measured. To our forebears, seeing the shadow cast on the sundial at St.John's Church, nothing could have been more natural than to rely on the Sun for time-keeping. Each day, when the Sun was exactly due South, it was noon: by definition. Every day, at noon the shadow would be cast in precisely the same place on the sundial.
The trouble started when clocks became commonplace. Twelve o'clock, midday, usually doesn't coincide with the 'noon' shown by the sundial. Sometimes the clock can be as much as quarter of an hour out from the time shown by a sundial. This doesn't mean that there is anything inaccurate about the clock or something unreliable about the sundial. They are measuring different things. The clock measures the flow of time, but the sundial marks the passing of the days.
The surprising inconstancy of the sundial reflects some fundamental astronomical facts: the length of the day changes as the Earth progresses in its majestic orbit around the Sun! The average length of a day may be 24 hours, but the actual length of the day varies throughout the year. Clocks had to be set to show the mean time indicated by the Sun.
Even if sundials cannot be made to coincide with clocks, it might be thought that at least they will coincide with other sundials. A moment's reflection however will enable us to see that this is not the case. Because the Earth is spinning eastward about its axis, at the rate of one degree every four minutes, then the London noon, as measured with a sundial, occurs several minutes before the Leeds noon.
With the advent of rapid communications - such as the railways - this time difference between towns became a source of difficulty. Train timetable organisers, in particular, had a hard time of it.
Pressure mounted for the introduction of standard time, so that clocks throughout the country were synchronised. By 1855, 98% of all public clocks in Britain were set to show the mean time of Greenwich (GMT). Why Greenwich? Traditionally, astronomers have been the custodians of time-keeping and the Royal Observatory at Greenwich was home to some of the most accurate clocks in the country. Unfortunately, Greenwich, being to the east of London, had a mean time which was significantly ahead of the most westerly parts of the country. At 10pm in Greenwich it was only 9-40pm local mean time in the north-west. Therefore, standardising on GMT caused resentment in some areas and was characterised as "railway agression". Nevertheless, in August 1880 GMT became British Standard Time by law.
In the late nineteenth century clocks and watches were becoming widespread, but of course there was no radio time-signal or telephone 'speaking clock' to enable synchronisation of time-pieces with the new 'standard time'. Instead, people sometimes relied upon the visual signal given by time-balls outside buildings which housed particularly accurate clocks. The old time-ball outside Dysons in Lower Briggate is an example which can still be seen.
WASTE OF DAYLIGHT
So what about British Summer Time and the practice of putting our clocks forward by an hour in summer? Where did that come in? Although 'daylight saving time' was mentioned by Benjamin Franklin in a humorous essay, the real credit for it has to be given to a little-remembered London builder, William Willett (1865-1915). As he was taking an early morning a ride through Petts Wood, near Orpington, Willett was struck by the fact that the blinds of nearby houses were closed, even though the Sun was fully risen. In his pamphlet "The Waste of Daylight" he wrote "Everyone appreciates the long, light evenings. Everyone laments their shortage as Autumn approaches; and everyone has given utterance to regret that the clear, bright light of an early morning during Spring and Summer months is so seldom seen or used". His campaign led to the introduction of British Summer Time in an Act of Parliament in 1916. Clocks were put one hour ahead of GMT during the Summer months. The energy saving benefits of this were recognised during World War II, when clocks were put two hours ahead of GMT during the Summer. This became known as Double Summer Time. During the war, clocks remained one hour ahead of GMT throught the winter.
Nowadays many of us have extremely accurate clocks and watches and, whether we be on GMT or BST, synchronisation is a doddle. We certainly don't require sundials to tell the time. What is more, the pace of life is now so hectic that we need to keep track of the minutes and seconds, not just the sundial's hours. Even so, it is a great pity that so few sundials have survived in Leeds. The humble sundial can remind us that we are citizens of the Solar System. It can illustrate the eccentricity of our orbit. The changing length of it's noon shadow during the course of the year can demonstrate the tilt of the Earth's axis, relative to the orbit - the same tilt which is the very cause of the Seasons. The markings on a sophisticated sundial can allow us to determine the equinoxes and to understand their significance.