In carrying out the provisions of the national irrigation law approved , and in constructing works thereunder, the Secretary of the Interior is authorized to use and to permit the use by those engaged in the construction of works under said law, under rules and regulations to be prescribed by him, such earth, stone, and timber from the public lands of the United States as may be required in the construction of such works, and the Secretary of Agriculture is authorized to permit the use of earth, stone, and timber from the national forests of the United States for the same purpose, under rules and regulations to be prescribed by him.June 17, 19021902-06-17