1. The notation N', S' for the main dip-poles, N, S for the geographical poles, and B, A for the axis-poles, is that used in Geomagnetism, , by S., Chapman, , and J., Bartels, , , Oxford, ( 1940, ); see pp. 104, 105, 659.
2. Sect. Mag. Electr. Terr., Bull, No.;Fisk,1931
3. Batavia, , , Obsns. 22, , Appendix I, Fig. 1 ( 1900, ).