After the Secretary designates the member to be Chairman, the Commission may meet as often as necessary at the call of the Chairman or of the Secretary, or upon petition of a majority of the members of the Commission. Any vacancy in the Commission shall be filled in the same manner as the original appointment was made.
Members of the Commission shall serve without compensation, as such, but the Secretary may pay, upon vouchers signed by the Chairman, the expenses reasonably incurred by the Commission and its members in carrying out their responsibilities under this section.