French silver boatswain's call with a spherical buoy with a large rosette at each side and a scalloped ridge running around it. There is a wide gun, and the keel is shaped as a stylised crocodile or sea serpent, with two integral loops below to which a short chain is attached (see also PLT0450 for a larger call of similar design).

The boatswain's call has a long history both as a symbol of office and as a practical instrument for conveying orders at sea. The call's shrill whistle can be varied in pitch to convey a variety of information, and can be heard above the sound of wind and sea. Such instruments were private possessions rather than official equipment and silver calls like this one made suitable gifts and presentation pieces.