n.天文罗盘
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。
