Silas is, of course, trying to get the client, who does not understand these things, to measure the declination of his own (the client's) wall, to avoid having to visit (expensive and time consuming)
I use two methods, both of which I have found to be very accurate, and which I think should be suitable for use by the uninitiated client:- 1) Hang a string with plumb-bob about 20 cm from the wall - let the plumb-bob be immersed in water to stop the wind blowing it about if necessary. Stick or hold a small, flat mirror on the wall. Note the time when the string, the shadow of the string, and the reflection of the string are all in line. If you then know the date of the reading and the longitude, you can calculate the declination. or 2) Note the time at which the sun first (or last, or preferably both) shines on the wall. Again, knowing the date and longitude, the declination of the wall can be calculated. As with all declination measurements, the usual problem is that the wall is not perfectly constructed. You should really mount a temporary dial plate in the place where the "real" dial plate will eventually go - but I have found both methods to be pretty good. The calculation becomes simplicity itself if you have a copy of Fred Sawyer and Bob Terwiliger's excellent "Diallists companion" programme. Mike [EMAIL PROTECTED] 53.37N 3.02W "The meak shall inherit the earth - if that's OK with everyone else"
