全部

1·A gyrocompass or astrocompass can be used to find true north, while being unaffected by stray magnetic fields, nearby electrical power circuits or nearby masses of ferrous metals.

旋转罗盘或星象罗盘能够用来发现真北极，在飘移磁场区域也不受影响，接近于电路或接近于铁元素块。