Although old and a navigator, I never had the pleasure of
using a time ball to obtain the error of the ship's chronometer. I do remember
the daily ritual of winding the chronometer every day as a part of my
navigational duties and recording the error in the chronometer book by checking
it against a radio time signal.
Positions were obtained by calculations using the
chronometer time, corrected for any error, and the altitude of any celestial
bodies. In my early days, and for exams, we used to use two methods: longitude
by chronometer method or Marc St Hilaire method. Later, sight reduction tables
were introduced that made the calculations easier.
At 'noon' the chronometer was not needed as the celestial
body was watched rising, through the sextant, to the point where it 'stopped'
and then started to fall. Using the declination of the body the latitude could
be calculated.
The Royal
Museums Greenwich website [
visit link
]
tells us:
"The bright red Time Ball on top of
Flamsteed House is one of the world's earliest public time signals, distributing
time to ships on the Thames and many Londoners. It was first used in 1833 and
still operates today.
What does
the Time Ball do?
Each day, at
12.55, the time ball rises half way up its mast. At 12.58 it rises all the way
to the top. At 13.00 exactly, the ball falls, and so provides a signal to anyone
who happens to be looking. Of course, if you were looking the wrong way, you had
to wait until the next day before it happened again.
The
Time Ball drops at 13.00 GMT during the winter months and 13.00 BST during the
summer. Please note: the time ball will not be run if the weather is too
windy.
What did people do before there
was a time ball?
Only the richest
people could afford to buy clocks and watches of their own. Most people relied
public sundials to tell the time. This led to different local times across the
country, with clocks on the eastern side of the country about 30 minutes ahead
of those in the west.
The difficulties
created by everyone using their own local time eventually led to the creation of
Standard Time based on the Prime Meridian at Greenwich."
The Greenwich
Phantom website/blog [
visit link
]
additionally tells us:
"It’s one of those wonderful oddities of London
which makes our city so vibrant. In the same way that we don’t actually need
beefeaters marching around a dead royal palace with a bunch of keys every night,
an annual dinner for two warring livery companies to settle medieval differences
or a bloke in black to open parliament every session, there is no real necessity
for us to squint up at the Greenwich skyline at 1.00pm to set our watches, but
if we ever catch the Greenwich Time Ball at that microsecond when it drops, we
feel a little shiver of excitement; a little link with our maritime
past.
It all goes
back to that old chestnut of longitude, which I promise I’m not going into
today. The problem had been more or less solved by the end of the 18th Century,
but none of John Harrison’s splendid clocks was going to stand a cat’s chance in
hell if they weren’t set correctly to start with. Trouble was, that they didn’t
have radio-controlled digital timepieces in those days. A few people, such as
ships’ captains had clocks and watches, and the ships themselves, by the 19th
Century, had chronometers, but they were useless if they couldn’t be set.
They’d been
experimenting with the idea of time balls in Portsmouth and in 1833, it was
suggested by one Captain Robert Wauchope that Greenwich would be an ideal place
for one for the Thames. John Pond, who was Astronomer Royal at the time, thought
it was a great idea and the Admiralty agreed – Greenwich Observatory was
well-placed, up a hill, and with the right instruments to gauge the time
accurately. I doubt that Pond was quite as pleased when he realised that it
would be the job of the astronomers working there to toil up the stairs of the
little tower, haul the ball to the top of the weather vane then drop it at one
o’clock every day, rain or shine, when they could be doing a million other, more
exciting things.
Nevertheless,
the world’s first public time signal was duly manufactured by Maudslay, Son
& Field. A giant red ball, with a winch, was installed. The ball was
originally made of leather, which must have become like lead when sodden with
winter rain.
I’m not going
to go into the concept of standard time and GMT today – do try to contain your
excitement, I’ll come to it. Suffice to say that the Observatory was
central to anything that went on throughout the 19th Century to do with Railway
Time, Local Time or any other time. But all through that time the Greenwich Time
Ball was hoisted to the top of its little pole at two minutes to, then dropped
precisely at one o’clock. As the years passed, telegraphic communication helped
to let people across the globe know what the time was, but Greenwich remained at
the centre.
Today the ball
is automated – there are no more astronomers left to winch it up and let it
drop. But it continues to do so by machine, every day like – well, like
clockwork, I guess. It’s aluminium these days, but still a big bugger. I heard
they had to take it down for a spruce-up recently and it proved exceeding
unwieldy.
Why 1.00pm
rather than midday? At first I was told that it was because the astronomers were
always doing important experiments at midday when the sun is at its apex, but
more recently I’ve heard that it’s because in order to know the exact time you
have to know noon. Since you’re actually waiting for noon, it’s difficult to be
really accurate, so once the astronomers saw noon, they could actually count
more accurately to 1.00pm.
I am terribly
fond of our time ball. Not least because it’s discreet. If you don’t know to
look for it you might miss it completely. If you need the time it’s there (set
your watch precisely “1.00pm” the moment the ball drops) if you don’t need to
know, you don’t get bothered. As a local resident, I guess I’m quite glad I’m
not in Edinburgh where 1.00 is signalled with a
cannon…"
The Archive website [visit link] tells us:
Time-balls
As the name implies, a marine timekeeper
is designed to keep time at sea. But for navigational purposes it is necessary
to know the time in the first place, and the going of the timekeeper - the
chronometer - must be checked period- ically thereafter. In the early days of
chronometers this could be done by lunar observations ashore or afloat (not very
accurate), by stellar observations ashore with a sextant and artificial horizon,
or by comparison with an observatory clock ashore. Whatever method was used, it
was most un- wise actually to move the chronometer (this might disturb its
going), so a pocket watch had to be used as an inter- mediary, or a signal made
from ashore which could be seen or heard on board. In the 1820s there are
several reports of these signals being made from shore for the benefit of ships
in harbour - a flag dipped, a gun fired, a searchlight eclipsed, a rocket fired.
But these all seem to have been ad hoc arrangements; there were no regular time
signals.
Captain Robert Wauchope, RN, seems to have been the
first person to propose that time-balls should be erected,in a letter to the
British Admiralty in December 1824, 63 though no immediate steps were taken to
implement his sugges- tions. However, in 1833 the following Notice to Mariners
was issued.
80 GREENWICH TIME
Admiralty, 28 October 1833.
The Lords Commissioners
of the Admiralty hereby give notice, that a ball will henceforward be dropped,
every day, from the top of a pole on the Eastern Turret of the Royal Observatory
at Greenwich, at the moment of one o'clock P.M. mean solar time. By observing
the first instant of its downward movement, all vessels in the adjacent reaches
of the river as well as in most of the docks, will thereby have an opportunity
of regulating and rating their 21 chronometers.
The ball will be hoisted
half-way up the pole, at five minutes before One o'clock, as a preparatory
signal, and close up at two minutes before One.
By command of their
Lordships
John Barrow"'
One o'clock was chosen for dropping the ball
because, at noon, the astronomers might be busy finding the time.
The
apparatus, constructed in 1833 by Messrs. Maudslay & Field at a cost of
about £180, remains substantially unchanged today except that, since 1852, the
actual moment of drop has been controlled by an electric current from a master
clock (see next chapter) and, since i960, the raising of the ball has also been
made automatic. 65 A time-ball had been erected by the East India Company on the
island of St. Helena by December 1834. Other time-balls followed.
Not only did the Greenwich
time-ball - said to be the world's first public time signal - give Greenwich
time to ships in London's river and docks, but, for the first time, it made
Greenwich time regularly available to those ashore who could see it, including
much of London.