Dear All, In anticipation of this thread, I took up the matter of the location of the sundial with its designer/maker, Quinten Hollick. He lives not far from the site.
As you can see from his reply below, we had this discussion over 13 years ago! The tree wasn't so big then! It sounds as though he was attempting to set the stone at the U.K. Ordinance Survey version of the Greenwich Meridian. This runs through the Bradley Transit Instrument at Greenwich which is 5.79m to the west of the Airy Transit Instrument which was used to define longitude zero in 1884. The GPS meridian is to the east of the Airy Instrument. See: http://en.wikipedia.org/wiki/Royal_Observatory,_Greenwich Using the GPS kit of the 2001, you could choose different reference systems. I didn't get to the bottom of how he set the stone up in the first place but he went out and did some checks. You can see from his report that there are still some outstanding questions. I didn't press him further. Frank King Cambridge, U.K. [A few arc-minutes east of this stone] == MESSAGE FROM QUINTEN HOLLICK OF COMBERTON == Subject: Re:Meridian Stone From: Quin Hollick Date: Tue, 11 Sep 2001 10:53:34 +0100 To: Frank King Dear Frank This is what I did:- GPS Map Datum setting --- Ord Survey GB Satellite Visibility Atmospheric conditions etc --- Accuracy 22 feet Stood opposite W end of bridge by painted bike on path GPS Position 52° 11' 6.5" N O° 0' 6.1" W Walked West to Meridian Marker Stone GPS Position 52° 11' 0.71" N 0° 0' 0.1" W Walked 8 Paces East to GPS 0° Walked back to bridge GPS Position 52° 11' 6.5" N O° 0' 5.4" W Returned to Meridian Stone GPS Position 52° 11' 0.71" N 0° 0' 0.3 " or 0.2" W Walked 8 Paces back to GPS Position 0° Re Set MAP DATUM WGS 84 GPS Now reads 0° 0' 6.1" W (World Geographical Survey 1984 I think) Walked 154 paces East GPS Position 0° (WGS 84) Re Set Map Datum back to Ord Survey GB GPS position 0° 0' 6.4" E (Ord Survey GB) Conclusion: According to the GPS with accuracy of 22 feet in Ord Survey GB Map Datum the stone is approx. 24 feet West of GPS 0° According to the GPS with accuracy of 22 feet in WGS 84 Map Datum the stone is approx. 154 Paces West of GPS 0° Quin --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
