Home Transit
of Venus Sewer History in Leeds Sundials in
Leeds William Gascoigne John
Feild About
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.
ASTRONOMY
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.
TIMEBALLS
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.