2. Pilotage is a lien on the ship, when the contract has been made by the master or quasi master of the ship, or some other person lawfully authorized to make it; 1 Mason, R. 508; and the admiralty court has jurisdiction, when services have been performed at sea. Id.; 10 Wheat. 428; 6 Pet. 682; 10 Pet. 108; and see 1 Pet. Adm. Dec. 227.