2. No person shall be a senator [of the national senate] who shall not have attained the age of thirty years, and been nine years a citizen of the United States and who shall not when elected, be an inhabitant of that state for which he shall be chosen. Const. U. S. art. 1, s. 3, cl. 5. Vide 1 Kent, Com. 224 Story on the Const. 726 to 730.