Greetings fellow dialists, Here is a cautionary tale. I recently provided the dimensions for an analemmatic dial for the newly-restored municipal winter garden in Sunderland, England. When I visited the site the dial had been laid out in chalk. I asked the surveyor in charge how he had obtained north. He told me it was by means of a prismatic compass. There was no sun at the time of my visit but I persuaded him to mark out some shadows later and telephone me with their times and I would provide the azimuths. In due course he got three sun readings which produced a north line lying within an arc of less than half a degree. And the compass line? I asked over the phone. Forget it, was his answer. On a site carrying much building machinery and protective steel fencing it proved to be more than five degrees out. The restorers were pressing to finish and my visit was just in time. Frank, 55N 1W -- Frank Evans
