The Civil Service Commission shall consist of three (3) electors of the Municipality, not holding other Municipal office or employment, to be appointed by the Mayor, with the concurrence of a majority of the members of Council for terms of six (6) years each, except that of the three members of the Commission appointed for the term beginning January 1, 1954, one shall be appointed for a term of two (2) years, one for a term of four (4) years and one for a term of six (6) years. A vacancy occurring during the term of any member of the Civil Service Commission shall be filled for the unexpired term in the manner authorized for an original appointment.