English

A HYDRO­GRAPHIC SURVEY made utilizing a WIRE DRAG. In areas of rocky BOTTOM or where submer­ged obstacles such as WRECKS are present, a wire-drag survey represents the most practical way of making sure that all OBSTRUCTIONS or dangers have been found and least DEPTHS over them obtained. Also called wire drag sweep.

Specifically, the science or art of making such measure­ments as are necessary to determine the RELATIVE POSITION of points above, on, or beneath the surface of the EARTH, or to establish such points. Generally, the art of making a SURVEY.

A branch of the art of SURVEYING in which the surface of the EARTH is considered a plane surface. In plane surveying, curvature of the EARTH is neglected, and computations are made using the formu­lae of plane geometry and plane trigonome­try.

An object placed at the site of a station to identify the surveyed location of that station. In particular, an object whose coordinates are used for control in a geodetic network. Also called MARKER, geodetic marker, and MONUMENT.

A tubular BUOY, usually made of alumi­nium, that can be adjusted to remain at a selected density level to drift with the motion of that water mass. The FLOAT is tracked by shipboard listen­ing devices and current velocities can be determined.

An area of spongy land saturated with water. It may have a shallow covering of water, usually with a considerable amount of vegetation appearing above the surface.

A narrow CHANNEL or SOUND within a sand bank, or between a sand bank and the SHORE. Also calledswash­way. A BAR over which the SEA washes. The rush of water up onto a BEACH following the brea­king of a WAVE.