Following on from Rolf Menzl's message, can anyone tell me if there is a way of determining the declination of a wall RAPIDLY with a single reading AT ANY TIME OF THE DAY ? The method to find true north using a horizontal board with a vertical gnomon, whereby measurements are made either side of noon and the positions of shadows marked at the intersections of graduated circles, and then measuring the angle between north and the wall, works fine, but requires a whole day to perform. In Great Britain, which does not qualify as the sunniest place on Earth, it is important to be able to make a single reading at the moment the sun shines, which almost certainly will NOT be conveniently at noon ! It is also quite likely that the sun will shine in the morning and then, annoyingly, not in the afternoon, so a single measurement would be most useful.
Many thanks Peter Tandy Peter Tandy Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD Tel: +44 (0)171-938-8778 INTERNET: [EMAIL PROTECTED]
