Hi Mac et al,
You are, of course, completely right - you can turn a polar dial around its gnomon to make allowance for the EoT - my humble apologies. It isn't intuitive (to me, at least) that this should work and I foolishly made my comment without experimenting or doing the maths. I have now done so and it is quickly clear that the distance of the shadow edge from the noon line is the height of the gnomon multiplied by the tan of (hour angle plus rotation angle of the dialplate). Question: does it become a declining polar dial once the dialplate is rotated?! The mechanics of making such a dial will be interesting if it is to be robust enough to survive the elements. Does anyone know of a real dial in a public place? Happy Hogmanay to all diallists, John Davis --------- Dr J R Davis Flowton Dials N52d 08m: E1d 05m -
