IT has been suggested (I believe by Sommerfeld) that the highest possible atomic number is the constant According to Eddington's theory, this number represents the number of degrees of freedom of a system of two charges. It is natural to suppose that there is a correspondence (direct or indirect) between degrees of freedom and independent wave-functions, so that the maximum number of independent wave-functions for a nucleus and satellite electron is 137. By the exclusion principle each satellite electron must be provided with an independent wave-function, so that there cannot be more than 137 of them.