((a)) Except as otherwise provided by law, the business of the executive part of the Department of the Navy shall be distributed among the bureaus as the Secretary of the Navy considers expedient and proper.

((b)) Each bureau shall perform its duties under the authority of the Secretary, and its orders are considered as coming from the Secretary.

((c)) Under the Secretary, each bureau has custody and charge of its records and accounts.

((d)) Each bureau shall furnish to the Secretary estimates for its specific, general, and contingent expenses.