Geoscience Reference
In-Depth Information
approach; the British were driven by practical applications and executed their various
programs independently through the application of instrument technology.
Places
Dunkerque
The link between the Paris and Greenwich meridians is commemorated at Dunkerque by a
monument in the urban park of Fort de Petite-Synthe (off Rue de Nancy running south from
the N1), moved here from its original location in the center of the city to a new location on
the Paris Meridian. Standing beside a lake, the monument is an obelisk surrounded by four
smaller ones. At one time a globe symbolizing the Earth surmounted the obelisk at a height
of about 4 meters. The meridian itself runs into the sea in the sand dunes to the north. The
fort was originally built in 1878 and re-fortified prior to the First World War; it saw action
in the Battle of Flanders in 1940.
JUST AS THE MERIDIANS were linked by astronomy and geodesy, the astronomers
who mapped the Greenwich and the Paris Meridians were linked as scientific
colleagues, but they were also to become political rivals. The simultaneous exist-
ence of scientific cooperation and competition is today dubbed “coopertition.”
Coopertition over the Paris and Greenwich Meridians came to a head at the
Washington Conference in 1884 which was a significant event in the development
of the Paris Meridian. In the sixteenth to the nineteenth centuries the Meridian was
a living scientific location but today is historic. The change in 1884 rendered it, not
obsolete, but certainly less vibrant.
The reason for the Conference was because as trade and global communication
became more common in the nineteenth century, it also became necessary to
rationalize the systems of longitude and time based on numerous different national
observatories. In the second half of the nineteenth century there were nautical
maps circulating based on meridians at London (Greenwich), Paris, Cadiz (San
Fernando), Naples, Christiania, Hierro (in the Canary Islands), Pulkowa, Stockholm,
Lisbon, Copenhagen, and Rio de Janeiro. Land maps were based on these merid-
ians and others at Madrid, Munich, Brussels, Amsterdam, Washington, and Warsaw;
it was confusing for everyone. Even as recently as the late 1970's, one of the first
telescope buildings erected on the island of La Palma in the Canary Islands at the
Observatorio del Roque de los Muchachos was erected at an angle to the cardinal
points because of this confusion. The foundations of the building, which now no
longer exists, had been laid out by observing the shadows cast by the Sun at local
noon and local noon was calculated from a watch reading GMT, applying the
correction for longitude of the place. The longitude was read from a Mapa Militár
or the Spanish equivalent of the British Ordnance Survey, but not many of these
topographical maps were distributed in the Canaries (even in the late 1980's a new
printing disappeared from the shops in days) and the one used to orient the tele-
scope building was well-loved and somewhat aged. Unnoticed, its longitude system
was based on Madrid. (Spain used the port of Cadiz, more specifically the observa-
tory at San Fernando, for the meridian of the origin of longitude for its navy's
maps, but Madrid for its land maps). The longitude of Madrid, 3° 41′W, is not so
different from that of Greenwich that the discrepancy in the longitude of La Palma
(14° 12′ instead of 17° 53′) was obvious on the ground, so the building was laid
out nearly 4° skew.
