After an introductory discussion of the two-tilt problem and of similar problems in the new art of magnetic core orientation, four fundamental equations for solving these problems in terms of two new parameters are derived. The use of these equations in constructing nets for the solution of the problems under discussion is described, and it is shown that these new equations are the basis of the stereographic-net solution recently described in this Bulletin by D. Jerome Fisher. After a discussion of the use of Fisher's stereographic-net method in cases of overturn of the beds, a new method of employing the stereographic net is described which, while generally applicable, is particularly useful in cases of overturn.

When cores are magnetically oriented by the method of Lynton, an orientation correction and a strike-and-dip correction are necessary when the cores are from non-vertical holes. These corrections are briefly described, and their solution by the methods of the first part of this paper is illustrated.