How do you actually check the accuracy of a compass?
After a prolonged search I found where I had hidden my spare one, and compared the two. Yesterday they were both the same, so I reckoned they were accurate, but that might be wishful thinking. Today there was a difference of about 10 degrees, but how do I decide which one is wandering a bit?
I had put them on the kitchen windowsill, thinking I had a fair idea of the alignment of the house, where there are a few pebbles collected from various special places. Thinking one might be affected by one of the rocks I moved them both to the table, where they lined up again.
Can two compasses affect each other?
Check them against the gps on a phone? But I don't have that kind of phone, and anyway, apparently phones affect them.
I do remember the compass being way out at the top of Cross Fell. Luckily it was a sunny day and we could see where we were going. I had heard compasses were affected up there, and had really only got it out to see if it was true.