Two Methods Applicable to Computers for Evaluating Magnetic Anomalies Due to Finite Three Dimensional Bodies*

A bstract Two methods applicable to computers are described which are designed to evaluate the vertical, horizontal and total intensity magnetic anomalies due to finite three‐dimensional bodies of uniform polarisation contrast. The direction of polarisation need not be co‐linear with the Earth's field, thus allowing for a remanent component; and the calculation may be performed for a given model for several different directions of polarisation concurrently. The first programme depends on the transformation from a volume integral to a surface integral and the approximate representation of the surface by a series of plane polygonal faces. The second programme is based on an extension of Vacquier's graphical method.