Each ship to be of not less than 4,000 tons burden, and the cost of each not to exceed $900,000. The Government to advance two-thirds of the cost of construction, from time to time, as the building progresses—the advance to be made in five per cent. stocks payable at the end of 30 years—such advances to be repaid by the contractors in equal annual instalments, beginning and ending with the service. The said ships to be built in accordance with plans to be submitted to and approved by the Secretary of the Navy, and under the superintendence of an officer to be appointed by the Secretary of the Navy, and to be so constructed as to be convertible, at the least possible expense, into war steamers of the first class. The ships to be kept up by alterations, repairs, or additions, to be approved by the Secretary of the Navy, so as to be at all times fully equal to the exigencies of the service, and the faithful performance of the contract. Each ship to be commanded by an officer of the Navy, who, with four passed midshipmen to serve as watch officers, shall be accommodated in a manner suitable to their rank, without charge to the Government. The Secretary of the Navy at all times to have the right to place on board of each ship two guns of heavy calibre, and the men necessary to serve them, to be accommodated and provided for by the contractors. The Secretary of the Navy to exercise at all times such control over said ships as may not be inconsistent with these terms, and to have the right to take them, or either of them, in case of war, for the exclusive use and service of the United States, on paying the value thereof; such value, not exceeding the cost, to be ascertained by appraisers mutually chosen by the Secretary and the contractors. The Secretary also to have power to direct, at the expense of the Government, such changes in the machinery and the internal arrangements of the said ships, or any of them, as he, at any time, may deem advisable. The contractors are further required to stipulate to carry, on each and every voyage they may make, so many emigrants, being free persons of color, and not exceeding 2,500 for each voyage, as the American Colonization Society may send; the said society paying in advance $10 for each emigrant over twelve years of age, and $5 for each one under that age; these sums to include the transportation of baggage, and the daily supply of sailors’ rations. The contractors also to convey, free from cost, such necessary agents as the Government or the Colonization Society may require, upon each one of said ships. Two of said ships to be finished and ready for sea within two and a half years, and the other within three years, after the execution of the contract.