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Questions about Francis Barker M73 liquid prismatic compass
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01-28-2018 07:06 AM
# ADS
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First, the tilted card. The axis hole in the card is slightly larger than the actual axis and this allows for the card to be moved slightly so that it will balance exactly square on the brass axis before it is clamped up. I wouldn't worry about it too much unless it becomes impossible to read the car through the prism when taking a bearing. There is a facility to focus the card readings but if you can't get it in focus..... Never noticed one where the line doesn't accurately align with the small holes you show. Will the error you show make a vast distance? I'd say no, not unless you are driving a great distance across the desert using compass stops as guidance. The notch on the thumb ring is used for aligning the compass with the grid lines on the map. That glue does look a bit scrappy but it won't make any difference to the operation of the compass. If you go along the Ayer Rajah Road where our big REME Base Workshop was, you'll find zillions of these radium dials buried where we just dumped them. No such thing as health and safety radium regimes in the 60's!!!!!
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Contributing Member
Radium
I guess you'd be easy to find in a dark room then Peter!
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You're right! We used to use it without thought. In fact, in the 50's my dad bought me a small jar of luminous paint that was probably radium based, to paint the headlights of my dinky toys headlights. And I'd be nodding off to sleep with hundreds of these lights twinkling in the dark bedroom. We also used to put a dob of similar paint onto wrist watch dials, open anti-tank gun sights and compass dials. That and the fact that we had open tanks of boiling trichlorthylene vapour big and deep enough to put a complete Centurion tank engine and gearbox into. Alas, one of my uni professors (and the best mentor anyone could ever wish to meet) was one of those who flew Canberra bombers through the Christmas Island atomic bomb cloud to collect samples. He wasn't so lucky..... but I blame Australia!
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Thank You to Peter Laidler For This Useful Post:
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I was only being flippant about blaming Australia Cinders. I blame Prof H's death on old age!!!!! We won't hear from the thread author again. I don't know why they even ask the Q.
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Peter, thank you very much for your insights. I did bring the compass for a spin in the mountains and it was really at home there.