International Institution for
the History of Surveying and Measurement
A Permanent Institution within the International
Federation of Surveyors (FIG)
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Figure
of the Earth
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From Geometrei. J Kobel, 1556. Courtesy
Jan de Graeve. |
By the figure of the earth is meant the
set of parameters that define the size and shape of the earth. In its
simplest form if considered as a true sphere that would be the radius. As
the accepted figure is more complicated than that so there are more
parameters. Included in this is also the range of methods and equipment that
over the years have been used to determine the parameters.
Among these methods are arc
measurements and the use of baselines
in triangulation schemes. In addition particular personalities
have played important roles in the gradual refining of the results.
A listing and details of the methods used
is being accumulated. From the earliest measures such as that attributed to Eratosthenes
c230 BC to the numerous ones made since the introduction of triangulation by
Snellius and others in the early 17th century up to the introduction
of electromagnetic methods from the early 1950s.
Among the useful references are:
Erdgestalt,
Kosmologie und Weltanschauung. V Bialas. 1982. Konrad Wittwer,
Stuttgart. ISBN 3-87919-135-2
Ellipsoidischeparameter
der Erdfigur (1800-1950). G Strasser. 1957. Deutsche Geodätische
Kommission. München.
From
Plane to Spheroid. Determining the figure of the Earth from 3000 BC to the
18th century Lapland and Peruvian survey expeditions. J R Smith. 1986.
Landmark Enterprises, California. ISBN 0-910845-29-8
The
History of the theories of attraction and the Figure of the Earth. 2
vol. I Todhunter. 1873. Macmillan and Co.
Practical
geodesy. M Hooijberg. 1997.
Springer-Verlag, Berlin. ISBN 3-540-61826-0
Figure
of the Earth. G B Airy. 1845. Encyclopaedia
Metropolitana. Vol. 5 pp 165-240
Introduction
to geodesy. The history and
concepts of modern geodesy. J R Smith 1996. John Wiley & Sons. ISBN
0-471-16660-X
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