Results The difference values calculated were various with the arch form, the sequence was oval, round, parabola, catenuliform, and hyperbola from big difference to smell.

牙弓深度的差值按从大到小的顺序排列为：椭圆形、圆形、抛物线形、悬链形、双曲线形。

Besides, We indicated the main adavantages of this means and probable way of overcoming its shortage, that is, method of difference value of isoporic lines is used to process data of some stations.

另外,文中指出了该手段的主要优点及克服其缺点的可能途径,即有些台站可采用地磁等变线差值法处理。