First for Surveyors and a first for World Heritage
On 15 July 2005 the UNESCO World Heritage Committee inscribed a new name
on its list of important sites – the Struve Geodetic Arc. This is a
triangulation network observed between 1816 and 1855 which stretched from
near North Cape in Norway to the Black Sea. In today’s geography it passes
through ten countries, namely Norway, Sweden, Finland, Russian Federation,
Estonia, Latvia, Lithuania, Belarus, the Republic of Moldova and Ukraine.
The Struve Geodetic Arc is the first survey scheme and also the first
such scientific and technological landmark to be entered on the World
Heritage List and it joins a select list of less than 900 such listed sites
around the world. Whereas one is used to seeing ancient buildings, stunning
scenery and famous archaeological sites as Heritage monuments the Struve Arc
is but a series on marks in the ground barely covering a square metre or so
each. However taken as a whole the Arc was, for its time, a major scientific
achievement using state-of-the-art instrumentation to achieve amazing
accuracies straddling such a vast distant and several countries. Much
smaller similar schemes preceded it and longer and more accurate ones
succeeded it but it was a veritable milestone in the quest to determine
accurate values for the parameters of the earth.
Arc measurement is the determination of the linear length of a section of
meridian (line of longitude) on the earth together with the astronomical
determination of the positions of the two end points. Whilst it should
theoretically follow exactly along such a line of longitude in practice this
is not essential, and indeed would be impractical, and appropriate
corrections can be made. The terminal points of the Struve Arc are at
Fuglenaes, latitude 70º 40’ 12” N and longitude 23º 39’ 48” E, and
Staro-Nekrassowka, latitude 45º 19’ 54” N and longitude 28º 55’ 41” E. Hence
it is said to run more or less along the 26º E line of longitude for a
distance of 2820 km.
The use of such a scheme was particularly designed to assist in the
accurate determination of the size and shape of the earth. It was an
extraordinary example of scientific collaboration among scientists from
different countries and of collaboration between monarchs for a scientific
cause. Additionally it formed the basis upon which long required accurate
mapping of the areas concerned could be based.
The historic monument is defined by the initial preservation of 34 of the
265 main survey stations involved. The ten countries involved, with
encouragement and help from the International Institution for the History of
Surveying & Measurement (IIHSM), a Permanent Group within the International
Federation of Surveyors (FIG), cooperated since 1954 in the recovery,
verification, monumentation and documentation of the selected points. These
were chosen (a) to give a spread of preserved points along the whole arc,
(b) to be representative of all countries, (c) that could be verified as
original points (d) were reasonably accessible to the public (e) were in
such positions that if restored, they would not by liable to imminent
destruction by building developments and (f) were generally in areas where
the local population were keen to take such a monument under their wing for
its up-keep.
Where possible the most prominent sites have been selected including the
obelisks at each terminal, the Tartu Observatory in Estonia (known at the
time as Dorpat) which served as the origin of the scheme and the point in
the tower of Alatornio church. The church itself has remained unchanged
since the time of the measurements. Other points take a variety of forms
such as drill holes in rock, cairns and crosses chiselled rock.
F G W Struve (1793-1864), after whom the arc gets its name, was born in
Altona, Holstein and died in Pulkova, Russia. He married twice and had 18
children. By age 20 he became Professor of Mathematics and Astronomy at
Dorpat. His involvement in the survey of Livonia was the start of almost 40
years work on the meridian arc. He founded Pulkova astronomical observatory,
then the best in the world, and of the Russian Geographical Society. The
other principal name associated with the arc was that of the Russian
military officer Carl F Tenner (1783-1859). In 1816 he became Head of the
vast Russian triangulation work in western provinces of the Empire. He had
started in 1817, on his own initiative, a triangulation scheme to the south
of Livonia. After Struve and Tenner became acquainted with each others
activities they joined forces. Some of the route in the northern parts
covered similar territory to that surveyed in 1735 by Maupertuis when
observing his much shorter scheme that was is particularly remembered, with
a similar expedition to Peru, 1735-1745, for solving once and for all the
controversy between Newton in England and the Cassinis in France, regarding
the shape of the earth i.e. was it a prolate (flattened at the Equator) or
oblate (flattened at the Poles) spheroid. The latter version was proven to
be correct.
With the achievement of World Heritage Monument status for this arc what
enhancements are possible? Monuments can be extended at any later date and a
“monument” such as the Struve arc can be extended southwards as far as South
Africa.
This is feasible because (a) in the 1930s a join was made from the Struve
Arc in Belarus to Crete and (b) the Arc of the 30th Meridian through East
Africa stretches from near Port Elizabeth to near Cairo but in the 1950s a
connection was made across the Mediterranean Sea to Crete. Hence there
exists a connection that would extend the whole arc to one of 105º. Such an
extension would though involve a further 20 or so countries and would be no
small task.
Other related activities are also envisaged:
- the restoration of the Old Tartu Observatory (now owned by Tartu
University) to become a Struve Museum,
- for the Struve archival material, presently in several locations, to
be properly indexed – a task already well under way with the assistance of
Vitali Kaptjug and the IIHSM,
- for there to be scientific experiments across the 34 points that could
in the future be archive material for tectonic and other investigations.
- the translation of Struve’s volumes into English.
Further information can be obtained from:
J R Smith Professor Jan de Graeve,
24 Woodbury Ave, Petersfield, 5 Ave de Meysse,
Hants GU32 2EE, UK 1020 Brussel, Belgium
e-mail jimsmith1780@gmail.com
National Land Survey of Finland
e-mail kirjaamo@nls.fi
Further information:
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