Francois,
Several years ago I was investigating suncompasses. I asked the
British Military Attache at the UK Embassy in Canberra for
information on UK use of them. Seems that they were essentially no
longer used. The Australian Army made / makes minor use, but all
replaced by GPSs. See my earlier email re astro compasses in
Antarctica.
My guess is that GPSs have basically wiped the field of all other
forms of navigation. Aha! But what happens when your batteries go
flat? No problem, use your spares!
Personally I think that a whole lot of rubbish has been talked about
magnetic compasses in vehicles. For almost 15 y I had an ex-US Army
tank compass fitted in my Landrover. The compass was HUGE, built by
Sherrington I think. I could adjust it, and when I adjusted it for
the particular load I was carrying, it was within 5-10o. More
recently I have fitted an aircraft standby magnetic compass to my
Nissan Pathfinder (10y) and now my Toyota Prado (1.5y). Provided I
adjust it to minimise errors caused by the different amounts of steel
in different loads and trips, it is fine. Cost about $AUD35 from a
surplus store.
I also used a flux compass for a while. These are a spinoff from US
military technology. Very nice idea, but the design was pretty awful,
and obviously aimed at suburban market with no thought given to
anyone who really wanted to use on in 4WD conditions. This worked
fine, but only gave 15o cardinal points (as I recall) until the LCD
died. Pity, because it cost me about $US100.
I realise that your interest in sun compasses is almost certainly
about the instruments themselves, but their demise was inevitable.
Even during WW2 magnetic compasses could be used in vehicles MOST of
the time.
Oh yes: the flux compasses: try REI in the US (bound to have a web
site) or any of the major huntin' 'n' fishin' suppliers (e.g Cabela)
and look at their catalogues. They all take credit cards for mail
order, good to deal with.
Final point: A couple of years ago I bought a digital watch -
compass made by Seiko. Flux detector, and accurate to 15o. I have
used it all over Southern Hemisphee and it is fine within the 15o
limit. Can be "rezeroed" instrantly to account for local problems,
e.g. getting off a ship and going ashore. As I recall, it even worked
fine in McMurdo Sound in Antarctica. Pretty neat, very yuppie, but
for what I do, pure magic. Cost about $US100. Try REI, etc. Most
watch stores don't have them even though they are listed in
catalogues.
John
Dr John Pickard
Senior Lecturer, Environmental Planning
Graduate School of the Environment
Macquarie University, NSW 2109 Australia
Phone + 61 2 9850 7981 (work)
+ 61 2 9482 8647 (home)
Fax + 61 2 9850 7972 (work)
