Former Dutch research
There hasn't been much research done on the orientation of the hunebedden.
Five studies stand out:
1878, Lukis and Dryden, unpublished [2.1]
1929, van Giffen, De hunbedden van Nederland [2.2]
1997, Reijs, www.iol.ie/~geniet.
2003, González-García en Costa-Ferrer, Possible astronomical orientation of the Duch hunebedden (SEAC 9)
2004, Langbroek, Huilen naar de maan (PIT nr. 2)
All studies aim at the orientation of the long axis of the hunebedden and have investigated trends only.
González-García and Costa-Ferrer also involve the orientation of the entrances.
Studies of the correlation between the structure and the orientation are unknown.
Langbroek has taken the mutual orientation of some hunebedden into account.
The study of Lukis and Dryden
After the hunebedden got international attention because of some unacquainted ’restorations’,
the British Lukis and Dryden came to Drenthe to make ground plans of all of the then known ’hunebedden’.
They also measured their orientation, but didn’t use a systematical determination of the axis [2.3]
The study of van Giffen
From 1925 to 1927 van Giffen has attended all hunebedden, made ground plans and measured their orientation.
This is the first systematical study. Van Giffen writes about this himself, that it was hard to have exact measurements
by the lack of a good instrument and by the fact that it's not clear how the axis should be taken [2.4]
With the second argument he appears to have the same view as Hoskin (see the page Accounts
Furthermore van Giffen applies a declination of 13½° west [2.5]
which is 2½° too much [2.6]
His data is good for a general impression, but not for depending a study upon.
The study of Reijs
Reijs bases himselfs on own measurements. Since the orientations of most of the hunebedden can be found between +/- 25° around the equinox,
initially Reijs suspects an orientation on the setting of full moon around the spring/autumn point (+/- 26°).
Next he introduces two statistical methods to check the spread of the orienations of the setting moon and the hunebedden.
In both cases the hypothesis has to be rejected.
The study of González-García and Costa-Ferrer (GG&CF)
The investigators have measured the orientations of the hunebedden by themselves.
GG&CF find a double peak around south for the orientation of the entrances.
The peaks compare to the rising and setting of celestial bodies with a declination of -35°.
The orientations of the long axis are located between the solsticies for 83% and between the extreme lunar standstills for 88%.
The study of Langbroek
Langbroek tries to interprete the data of van Giffen (via van Ginkel). First he concludes, that a determining influence
of the Hondsrug (a geological feature) is not presumable. On the indication of Rossenberg, Langbroek distinguishes between
hunebedden that are and that are not having a mutual dependend orientation. For the second type he concludes that they have
an orientation between the minor lunar standstills. 88% of the orientation find themselves between the northern and southern
minor lunar standstills. From the data one can see that the same distribution accounts for the solstitia, but this is not mentioned.
Langbroek doesn't give any information about the mutual dependend orientations:
no conclusions and no criterions on how he selected them. The orientations outside the lunar standstills aren't explained neither.
When the study of Langbroek is adjusted by the data of GG&CF, the overall picture doesn't change. Still 86% of the orientations
fall between the lunar standstills. On the other hand, the separation of mutual orientated hunebedden looses its
eloquence, because GG&CF find 88% of the orientations between the lunar standstills. None of the irregularities in the study
of Langbroek can be explained by the double peak around south found by GG&CF.