Hi Fred Many thanks for your reply. I just rushed outside into the wonderful Tasmanian spring sunshine with the paper model and it all now makes sense.
Regards john -- John D Hall School of Architecture - University of Tasmania Launceston TAS 7250 - AUSTRALIA Tel (+61) 0363 24 3502 Latitude 41d 26m 1s South Fax (+61) 0363 24 3557 Longitude 147d 7m 49.5s East ---------- > azimuth - since it's the direction of the shadow that matters for this > dial. You then notice where the line for the current date crosses the > shadow. At that point, you read from altitude lines (or the alidade, as > mentioned in the article) what the sun's altitude is. Similarly, you note > where that point falls among the hour curves, and you can tell what time it > is. The sun's altitude is always 1) an output item or 2) an input item > from another knowledge source independent of the dial (e.g. an observation > with a quadrant) - so you never need to know exactly how tall the gnomon is > or how long its shadow is.
