Standard base "Loenermark"
Report on the results of the measurements performed by T.J.
Kukkamäki and T. Honkasalo of the Finnish Geodetic Institute
G.J. Bruins (Editor)
Nederlandse Commissie voor Geodesie 13,
Delft, 1964. 44 pagina's.
ISBN-13: 978 90 6132 020 3. ISBN-10: 90 6132 020 8. € 6,50
Introduction
In 1913 the primary triangulation network of the Netherlands was
augmented with a base line. This base line was measured near Stroe and
the results of the measurements were published by Prof. Ir. Hk.J.
Heuvelink in 1931.*)
The object of this base line measurement was to check the unit of length
derived in 1900 from the German base line near Bonn. When the length of
the latter proved to be in good agreement with the results of the
measurements at Stroe (with an accuracy of 1:2.5 x 106) the primary
triangulation of the Netherlands – including the unit of length
determination - was considered to be completed.
Apart from the base line measurement at Stroe the only work done in the
field of primary length measurements in those years was an occasional
comparison in length between the invarwires No. 89, 90 and 91 of the
Netherlands Geodetic Commission and the wires No. 285, 286 and 287
belonging to the Topographic Service of the former Netherlands East
Indies during the period 1915 - 1922. This occurred when the latter were
sent via Delft to the Bureau International des Poids et Mesures for
calibration.
It was not until 1957 that primary length measurements in the
Netherlands drew attention again. In that year in the Loenermark (near
the town of Apeldoorn) a standard base with a length of about 576 m and
an accuracy of about 1:107 was measured by the Finnish geodesists Prof.
Dr. T.J. Kukkamäki and Prof. Dr. T. Honkasalo using the interference
method of Väisälä. The results of this measurements are laid down in the
following chapters:
Chapter 1, by the editor, contains the history of the base and a
detailed description of the preparations and construction of it.
Chapter 2, by Prof. Dr. T.J. Kukkamäki and Prof. Dr. T. Honkasalo, is
the most important part of this publication and deals with the
measurements itself and the results. The authors preferred to omit from
this publication the more technical description of the interference
method and the instruments used. For details of the method etc. the
reader is referred to the references at the end of this chapter.
Chapter 3 gives a short description of an auxiliary base constructed in
1960 for the calibration of invar wires of which the length was derived
from the interference base.
This base makes it possible to calibrate in the Netherlands invar wires
belonging to several institutes and survey departments which until 1957
had to be done in other countries. The Loenermark base has in particular
proved its usefulness when in 1960 in German-Dutch collaboration the
base of the German primary triangulation near Meppen was remeasured. Use
has also been made of the base for the calibration of the rapidly
increasing number of instruments for electronic distance measurements.
Prospective users of the standard base are kindly invited to contact the
Netherlands Geodetic Commission, Kanaalweg 4, Delft who will gladly give
the necessary information.
This is also the place to thank all who contributed to the realization
of this base and the publication of its result. First of all sincere
gratitude may be expressed to Prof. Dr. T.J. Kukkamäki and to Prof. Dr.
T. Honkasalo and through them to the Finnish Geodetic Institute for the
measurements and computations. The generous offer of contributing their
time and instruments to this work is gratefully acknowledged. The
cooperation of the municipality of Apeldoorn who permitted the
construction of the base on her territory is greatly appreciated.
Sincere thanks are also due to the engineering firm Grabowski and Poort
and to the contractor Mr. Reusken who were always willing to comply with
the sometimes unusual requests in the design and construction of the
base and the sudden wishes of the geodesists in charge.
Many thanks are due to Ir. G. Bakker and Ir. G.L. Strang van Hees for
reading the manuscript and suggesting several improvements.
Last but not least thanks are due to Mr. N. van der Schraaf and Mr. H.C.
van der Hoek for correcting the manuscript and preparing the lay-out and
to the printer W.D. Meinema N.V., who all contributed to give this
edition its present form.
G.J. Bruins,
Member of the Netherlands Geodetic Commission
--------
*) Hk.J. Heuvelink, Basis bij Stroe 1913. Netherlands Geodetic
Commission, Delft, 1931.
Contents
Chapter 1. History and construction of the standard base "Loenermark" 11
1. Introduction 11
2. Preparations 13
3. Description of the standard base "Loenermark" 19
Chapter 2. The interference and the projection measurements 23
1. Programme of measurements and its accomplishment 23
2. Refraction correction 23
3. Interference measurements 26
4. Projection measurements 33
5. Length of the base line 36
6. Accuracy of the measurements 39
7. Final results 40
Chapter 3. Summary of the data of the standard base line and the invar wire base
line 42
1. Underground bolts of the interference base line 43
2. Invar wire base line 43
3. Projection measurements 44
4. Heights of the bench marks in the concrete pillars 44