azimuth lines
Greetings, fellow dialists, Attached is a picture of the dial on a lighthouse in North Shields, England (55N 1.5W). It is probably from the eighteenth century and is badly eroded. As well as its hour marks it has a series of vertical azimuth lines labelled with the points of the compass. These may lie between the solstice curves. I am at a loss as to how the lines would have worked. There is no sign of a nodus on the gnomon (which looks old). Possibly, if there was a date scale associated with the azimuth lines, now eroded away, then it would be possible to get the sun's bearing from where the time line crosses the azimuth line but that looks pretty cumbersome. Any suggestions? Frank 55N 1W <>--- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: azimuth lines
Hi Frank et al, Dials with azimuth lines are rare but not unknown in the UK. Writing from memory, there is a rather nice one on Grundisburgh church near me and I believe the famous Queens' College, Cambridge, dial also has them amongst all the other furniture. There are a few others, I'm sure: didn't Ian Butson restore a wooden one? The key requirement, of course, is that there has to be a nodus so the gnomon on your lighthouse dial can't be original. The dial is in obvious need of restoration, or at least conservation. Perhaps a nodus could be added. Once the spacings of the azimuth lines have been measured, the trig to calculate the nodus position is straigntforwrad. Regards, John D -- Dr J Davis Flowton Dials From: Frank Evans To: Sundial Sent: Thursday, 1 August 2013, 14:03 Subject: azimuth lines Greetings, fellow dialists, Attached is a picture of the dial on a lighthouse in North Shields, England (55N 1.5W). It is probably from the eighteenth century and is badly eroded. As well as its hour marks it has a series of vertical azimuth lines labelled with the points of the compass. These may lie between the solstice curves. I am at a loss as to how the lines would have worked. There is no sign of a nodus on the gnomon (which looks old). Possibly, if there was a date scale associated with the azimuth lines, now eroded away, then it would be possible to get the sun's bearing from where the time line crosses the azimuth line but that looks pretty cumbersome. Any suggestions? Frank 55N 1W --- https://lists.uni-koeln.de/mailman/listinfo/sundial--- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: azimuth lines
The Queens' College dial certainly has azimuth lines as John wrote. Frank, is it possible that some feature of the rather nice ornamental and unusual gnomon support provides the nodus? Working from the azimuth line spacing you should be able to estimate the required height of the nodus and see whether this is at all plausible. The "8" support looks too low down the dial really, but it may be worth a calculation if only to rule it out! Regards Andrew James Secure Meters (UK) Ltd. is a registered company in England: 2199653 Secure House, Moorside Road, Winchester, SO23 7RX This correspondence is confidential and solely for the intended recipient(s). If you are not the intended recipient, you must not use, disclose, copy, distribute or retain this message or any part of it. If you are not the intended recipient please delete this correspondence from your system and notify the sender immediately. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
