There is hereby authorized to be appropriated from time to time, out of any moneys in the Treasury not otherwise appropriated, such sums as may be necessary to carry out the provisions of the convention and of this subchapter, including (1) contributions to the Commission for the United States share of any joint expenses of the Commission agreed by the United States and any of the other contracting governments, and (2) the expenses of the United States Commissioner and his staff, including (a) personal services in the District of Columbia and elsewhere, without regard to the civil-service laws and chapter 51 and subchapter III of chapter 53 of title 5; (b) travel expenses without regard to subchapter I of chapter 57 of title 5 and