Laszlo Tisza and Irwin Manning."March 15, 1957." "Reprinted from The Physical Review, Vol. 105, No. 6, 1695-1705, March 15, 1957." "This paper is a development of the Ph.D. thesis submitted by Irwin Manning to the Dept. of Physics, Massachusetts Institute of Technology."Army Signal Corps Contract No. W-36-039 sc-32037 Project No. 102B. Dept. of the Army Project No. 3-99-10-022 and DA 3-99-10-000.