Dear Frank, Not the only problem in this area!
Go to 51 28 52.60 -0 00 5.51 and you will find a large sundial in Greenwich park. Not obvious on Google Earth is the fact that its incorrectly aligned by about 3.5 degrees, yet it is within sight of the observatory. Standing on the dial surface and looking uphill (south) it is obviously wrong. Details of this debacle may be found at www.thegreenwichmeridian.org/tgm/location.php?i_latitude=51.481332 Regards, Doug On 23 Aug 2014, at 16:12, Frank King wrote: > Dear All, > > Here is a cautionary tale. In summary: > NEVER believe ANYTHING without checking! > > A little while ago, Doug Bateman mentioned > that there were some lines of longitude > marked in the paving of Peninsula Square > by the O2 Arena in London. You can see > these as follows... > > Enter Google Maps and, into the search box, > key in: > > 51 30 4.75 00 00 15.91 > > Google allows this syntax for latitude and > longitude. > > You will find yourself on the Greenwich > Peninsula just south of the O2 Arena. > > Now zoom in as far as you can and you will > see a white line running roughly north-south > flanked by two black lines. Let's call this > a line-triplet. The pointer should pick out > a dark stone which punctuates the line-triplet. > > This stone carries an inscription which you > can't read but I have a photograph of it at > > www.cl.cam.ac.uk/~fhk1/Sundials/Misc/Stone.jpg > > You will see that the inscription says: > > These paving lines are > one tenth of a second > of longitude or > 18.1 m apart > 51°30'03"N 0°00'23"E > > This is intriguing because almost everything > it says is untrue, or at best, misleading!! > > Zoom out a little and you will certainly see > neighbouring line-triplets. > > To get to the neighbour on the right, key in: > > 51 30 4.75 00 00 16.85 > > We are at the same latitude but 0.94" further > to the east. How does this square with "one > tenth of a second of longitude"? > > Also, where on Earth does the 18.1m come from? > > At the latitude of Greenwich I make it that > one arc-second of longitude is about 19.4m > so one tenth of a second would be 1.94m. > > Are they lines of longitude? > > Of course that is only an implication but > it is pretty strongly implied... > > If you slide one of these line-triplets to one > of the vertical edges of your window you will > see that it fails to align by about 1 degree. > If they are lines of longitude they have been > pretty poorly surveyed. > > Where does the 51 30 03 00 00 23 on the > stone come from? > > Without knowing which coordinate system they > are using it is hard to say. If you naively > key this into the search box you will find you > land on the roof of a building. > > OK, this may simply mean they are not using > the same longitude reference as Google. > Fortunately we have the roof of the Airy > transit instrument nearby for calibration > purposes and this obligingly DOES run true > north-south!! Key in: > > 51 28 39.96 -00 00 5.3 > > Yes, a minus is allowed by the syntax too. > > The pointer indicates the rough centre of > the roof above Airy's transit instrument. > > If you are the right kind of enthusiast, > this is the "Prime Meridian of Longitude". > > The longitude quoted suggests we might try > subtracting 5.3" from the 23" on the stone. > Key in: > > 51 30 03 00 00 17.7 > > Bingo! We seem to have hit an inscription > stone. Shame it is the wrong one! I suspect > it has been moved! > > I haven't been able to find documentation > about these lines from a simple search. > > Maybe another reader knows about them? > > All this hard-landscaping must have cost > shed-loads of money. What a pity they > didn't get it right. > > Happy surfing > > Frank > > Frank H. King > Cambridge, U.K. > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
