Mike, Unfortunately, the azimuth of the Sun does not generally change at a constant rate throughout the day. Thus any drive system would have to incorporate a mechanism to compensate for both the vehicle's latitude and the declination of the sun. As I understand this sun-compass it works on the same principle as an analemmatic dial which can be oriented with the meridian once the time is known. I guess that it would not have been too tiresome to reset the compass every 15 minutes and this would have avoided the problem of how to keep sand out of the clockwork.
Geoff Thurston 51.31N 00.91W -----Original Message----- From: The Shaws [SMTP:[EMAIL PROTECTED] Sent: Sunday, November 12, 2000 11:12 AM To: Geoff & Suzanne Thurston; [email protected] Subject: Re: suncompass If I remember correctly, the Long Range Desert Group used a sun compass for driving in a known direction, by mounting one on the bonnet of their vehicle. But, they kept having to make adjustments throughout the day as the sun progressed. Couldn't they have mounted it on a (clockwork in those days) table which rotated once in 24 hours anticlockwise - then once set, they could drive all day to the same setting? Or am I missing something. Mike Shaw Wirral, UK 53' 22" N 03' 02" W
