Be it enacted by the General Assembly, that the Governor, with advice of the Council, from time to time, may hire or purchase, so many laborers to work in the lead mines, in the county of Montgomery, as may be beneficially employed therein, for the use of the public, and put them, with the others already there, under the direction of a manager. Of the lead produced from the said mines so much as may be spared, without danger of detriment to the commonwealth, shall be disposed of to the United States of America, or any of them, and what they want not may be sold to others. A reasonable annual rent shall be paid to the proprietors of the land in which the mines are opened, to be adjusted between the said proprietors and the Governor, with advice of the Council. But the said mines, if the proprietors will undertake, at their own charges, to work them, and engage to deliver one hundred tons of lead, every year, to the use of the public, at the price of by the ton, and give satisfactory assurance that the contract shall be performed, shall be resigned to the said proprietors, and shall not be resumed so long as that engagement shall be punctually observed and fulfilled. All expences incurred in the execution of this act shall be defrayed in like manner as other public debts and accounts thereof, as well as of the disposition of the lead, shall be orderly kept, and laid before the General Assembly, whenever it shall be required.