1. Guier, W. H., and Weiffenbach, G. C., Proc. Inst. Rad. Eng., 48, No. 4507 (1960).
2. Guier, W. H., (L), Proc. Inst. Rad. Eng., 49, No. 11, 1680 (1961).
3. Hopfield, H. S., J. Geophys. Res. (in the press).
4. Applied Physics Laboratory, The Johns Hopkins University, Rep. TG-401.
5. Kozai, Y., Smithsonian Astrophysical Obs., Res. Space Sci., Spec. Rep. No. 72, August, 1961.