Fellow dialists Thank you for the many interesting responses to my request. On reading Fernendo's list of possible errors I have decided to have nothing further to do with the use of a compass for a wall declination and will stick to sun readings only.
Thank you for your solution Mike, ( I liked your idea of the plumb bob in water) but I think a simple reading from a vertical stick should be of sufficient accuracy. I shall continue to read these pages with interest. Silas
