The Secretary of the Navy is authorized, in his discretion, at the request of the Secretary of Health and Human Services, to place gratuitously, at the disposal of the proper quarantine authorities, at any of the ports of the United States, to be used temporarily for quarantine purposes, such vessels or hulks belonging to the United States as are not required for other uses of the national government, subject to such restrictions and regulations as the Secretary of the Navy may deem necessary to impose for the preservation thereof.