There is hereby authorized to be appropriated, to be expended under the direction of the Secretary of State, in paying the annual share of the United States as an adhering member of the International Council of Scientific Unions and Associated Unions, including the International Astronomical Union, International Union of Chemistry, International Union of Geodesy and Geophysics, International Union of Mathematics, International Scientific Radio Union, International Union of Physics, and International Geographical Union, and such other international scientific unions as the Secretary of State may designate, such sum as may be necessary for the payment of such annual share, not to exceed $100,000 in any one year.