English

The throwing overboard of objects, especially to lighten a craft in distress. Jettisoned objects that float are termed flotsam; those that sink, jetsam; and heavy articles that are buoyed for future recovery, lagan. See DERELICT.

In U.S. terminology, a structure, such as a WHARF or PIER, so located as to influence CURRENT or protect the ENTRANCE to a HARBOUR or RIVER. In British terminology, a PIER, usually of solid construction, intended as a berthing place for vessels. See DOCK, LANDING, WHARF.

The number of each day, as reckoned conse­cutively since the beginning of the present Julian period on January 1, 4713 BC. The Julian day begins at noon, 12 hours later than the corresponding civil day.

Place of meeting or joining, as that of a TRIBUTARY with a main RIVER, or of two CHANNELS in a WATERWAY. In LEVELLING, the place where two or more LINES OF LEVELS are connected toge­ther. In HYDROGRAPHIC SURVEY, the joining of two adjacent survey sheets. See OVERLAP.

A BUOY marking the inner end of a MIDDLE GROUND. Usually called a MIDDLE GROUND BUOY in British termi­nology, without regard to direction of travel.

In electronics, a mathematical-stati­sti­cal method for predicting a time-variable signal in the presence of disturbances. The method exploits the fact that certain characteristic parameters of the process vary slowly with time, so that a best estimate of the signal can be obtained as a function of time.

An offshore wind produced by cold air draining from high ground by convection. The cold air replaces the lighter warm air which is rising over the sea.

A BUOY consisting of a keg to which is attached a small pole with a flag, used by fishermen to mark the position of a trawl line. See DAN BUOY.

Thermodynamic scale of temperature (T°K) defined by assigning to the triple point of pure water, considered as a fundamental fixed point, the temperature of 273.16°K. Also called absolute temperature scale.

A long ocean wave whose amplitude decrea­ses from right to left along the wave crest when viewed in the direction of travel in the northern hemisphere and from left to right in the southern hemisphere. The component of gravity acting down the slope is exactly balanced by the deflecting force of the earth's rotation, the CORIOLIS FORCE.

A mechanical con­trivance towed beneath the surface to warn of arrival in water of a certain DEPTH. See SUBMARINE SENTRY. A contrivance for holding the inner end of an OROPESA SWEEP to the required DEPTH.