Travel Reference
In-Depth Information
21
THE PRIME MERIDIAN AND GREENWICH MEAN TIME
Greenwich's greatest claim to fame is as the home of the
Prime Meridian
- a meridian being
any north-south line used as a basis for astronomical observations, and therefore also for the
calculation of longitude and time. In 1884, the International Meridian Conference in
Washington DC agreed to make Greenwich the Prime Meridian of the World - in other words,
zero longitude
. As a result, the longitude of the entire world is fixed as either east or west of
Greenwich. Unfortunately for Greenwich, more and more people use
Global Positioning
System (GPS)
, which makes its calculations from the centre of the earth, not the surface, and
places the meridian approximately 336ft to the east of the observatory's red strip.
The world also used to set its clocks according to
Greenwich Mean Time (GMT
). However,
in many spheres of life and countries across the globe, GMT has been usurped by
Coordinated Universal Time (UTC)
, which is basically the same as GMT, except that it is
more accurately calculated using atomic clocks and therefore better for sub-second precision.
for the audacious, successful campaign to capture Quebec from the French in 1759, a
battle in which he and his opposite number, General Montcalm, were both mortally
wounded. Victory celebrations took place throughout England, but were forbidden in
Greenwich out of respect for Wolfe's mother, who had also lost her husband only a few
months previously.
Royal Observatory
Blackheath Ave •
Astronomy Centre
Daily 10am-5pm • Free
Flamsteed House
Daily 10am-5pm • £7
Planetarium
shows every
45min • £6.50 •
T
020 8858 4422,
W
nmm.ac.uk • Greenwich DLR/train station
Established by Charles II in 1675, the
Royal Observatory
is the longest-established
scientific institution in Britain. The chief task of John Flamsteed, the first Astronomer
Royal, was to study the night sky in order to discover an astronomical method of finding
the longitude of a ship at sea, the lack of which was causing enormous problems for the
emerging British Empire. Astronomers continued to work here at Greenwich until the
postwar smog and light pollution forced them to decamp to Herstmonceux Castle in
Sussex; the observatory, meanwhile, is now a very popular museum.
Flamsteed House
The oldest part of the observatory is
Flamsteed House
, designed by Wren (himself an
astronomer) “for the observator's habitation and a little for pompe”. The northeastern
turret sports a bright-red
Time Ball
that climbs the mast at 12.58pm and drops at 1pm
GMT precisely; it was added in 1833 to allow ships on the Thames to set their clocks.
The red strip in the observatory's main courtyard is the
Meridian Line
, and at night a
green laser beam shines northwards along the meridian. On the house's balcony
overlooking the Thames, you can take a look at a
Camera Obscura
, of the kind which
Flamsteed used to make safe observations of the sun.
Inside, beyond the
Astronomers' apartments
in which the cantankerous Flamsteed
lived, you eventually reach the impressive
Octagon Room
, built so that the king could
show off his astronomical toys to guests. The ceiling plasterwork is all that remains of
the original decor, but there are replicas of the precision clocks installed behind the
original walnut panelling in 1676.
Time galleries
he
Time and Longitude
gallery focus on the search for longitude and display the first
four marine chronometers built by
John Harrison
. Harrison eventually went on to win
the £20,000
Longitude Prize
in 1763 with his giant pocket watch, H4 - the only one
that no longer functions - after much skulduggery against his claims, most notably by
the Astronomer Royal at the time, Nevil Maskelyne (a story wonderfully told by Dava
FROM TOP
GREENWICH PARK AND THE ROYAL OBSERVATORY
P.320
; PAINTED HALL, OLD ROYAL NAVAL COLLEGE
P.316
>
