I wouldn't be surprised if Kintyre other than NR71 & NR72 (Campbeltown) is derived from much earlier mapping. Those two octads are the only ones published for Kintyre in the 25k provisional/first series. Certainly for other parts of highland Scotland serious errors existed until the 50k 2nd series (one reason why this appeared for the Highlands first). If I'm right there may also be errors on Arran, which also only had 2 10km squares published. On the other hand, Arran may have been much better surveyed in the 19th century because of its geological interest.
Jerry Clough SK53 ________________________________ From: TimSC <mapp...@sheerman-chase.org.uk> To: talk-gb@openstreetmap.org Sent: Sunday, 18 October, 2009 16:11:08 Subject: [Talk-GB] OS 7th series, accuracy update, request for calibration help Hi all, I have updated the 7th series layer with improved accuracy. It seems as if the Helmert approximation of the OS grid reference to WGS84 was not accurate enough; I was getting transform errors of approximately 20m. Also, to my surprise the next biggest error seems to be surveying errors. For example, see around the Mull of Kintyre where the survey errors are around 40m (near NR730100). http://www.openstreetmap.org/?lat=55.3339&lon=-5.5737&zoom=14&layers=B000FTF ..snip Tim _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb Send instant messages to your online friends http://uk.messenger.yahoo.com
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