Section 4 of the joint resolution of September 2, 1958 (72 Stat. 1707; 42 U. S. C. 1958 (d)), is hereby amended to read:

The authority of the Secretary of the Interior under this joint resolution to construct, operate, and maintain demonstration plants shall terminate upon the expiration of twelve years after the date on which this joint resolution is approved. Upon the expiration of a period deemed adequate for demonstration purposes for each plant, but not to exceed such twelve year period, the Secretary shall proceed as promptly as practicable to dispose of any plants so constructed by sale to the highest bidder, or as may otherwise be directed by Act of Congress. Upon such sale, there shall be returned to any State or public agency which has contributed financial assistance under section 3 of this joint resolution a proper share of the net proceeds of the sale.

Approved September 22, 1961.

Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That the Secretary of the Interior is hereby authorized and directed to make or cause to be made a study covering --

the causes of injuries and health hazards in metal and nonmetallic mines (excluding coal and lignite mines);

the relative effectiveness of voluntary versus mandatory reporting of accident statistics;

the relative contribution to safety of inspection programs embodying --