Let me explain about the accuracy check a moment. I don't mean to compare them to another compass I think should be accurate. I mean to compare it to a known direction. Sun rises in the east and sets in the west, for my area I know which way is north, it's a fairly quick and simple thing to take each button compass and test it.
Another test is to turn the compass on its side, vertically, and then turn it about the vertical axis, and then lay it flat again so it has to find north from scratch. If it swings around quickly and confidently, then it's still strongly magnetised and pivoting OK. The slower it is, the weaker and less reliable. Do this more than once and check the result is the same each time.
You can use this to test compasses in a shop when deciding which/whether to buy, and you can use it in the field even if you don't know where north is. Obviously, if you do know where north is, you should verify that's what the compass is indicating, but in practise if it strongly indicates a direction at all, it's probably due to magnetism so it's probably north. (It might be south if the magnetism gets reversed, but that's not a likely failure mode unless someone is playing a trick on you.)
Previous Topic
Index
