等磁偏线图 isogonic map ; isogonic chart

等磁差曲线图 curves of equal magnetic variation ; magnetic variation charts ; Chart of Equal Variation

等磁力曲线图 curves of total magnetic intensity ; curves of total magnetic force

地磁等年变线图 isoporic chart

等磁力线图 isomagnetic chart

等磁倾角曲线图 curves of magnetic dip ; curves of equal magnetic dip

等磁倾线图 isoclinal chart

等垂直磁力曲线图 curves of equal vertical magnetic force

等水平磁力曲线图 curves of equal horizontal magnetic force ; curve of equal horizontal magnetic force