English

Any one-piece printing surface of any size, strength, or surface preparation, bearing an image made manually, mechanically or photographically, specifically for the purpose of printing such an image onto some other material.

A term used to indicate a perma­nent offshore structure equipped to control the flow of oil or gas. For charting purposes, the use of the term is extended to include all permanent platforms associa­ted with oil or gas production, e.g., field terminal, drilling and accommodation platforms, and "booster" platforms located at intervals along some pipelines. It does not include entirely submarine structures. See also PLATFORM.

A graph or curve showing elevation or dis­tribution of some property vs. distance along a line. The vertical SCALE may be greatly exaggerated with respect to the horizontal SCALE. An example of a profi­le is the graphic record made by a recording ECHO SOUNDER operating while a vessel is underway. A vertical section of the surface of the GROUND, or of underlying STRATA, or both, along any fixed line.

Determination of the subsoil strata and geological structure by use of sound sources which emit acoustic pulses to penetrate the seabed. Travel time between emission of pulses and reception is usually measured in a towed streamer.

A MAP or sketch showing work ac­com­plished. In TRIANGULATION and TRAVERSE, each point established is shown on the progress sketch as well as lines observed over and BASES measured. In a levelling survey, the progress sketch shows the route followed and the towns passed through, but not necessarily the locations of the BENCH MARKS.

An area shown on CHARTS within which NAVIGATION and/or anchoring is prohibited. In aviation terminology, a specified area within the land areas of a state or territorial waters adjacent thereto over which the flight of aircraft is prohibi­ted.

The representa­tion of a figure on a sur­face, either plane or curved, according to a definite plan. In a PERSPEC­TIVE PROJECTION this is done by means of projecting lines emanating from a single point, which may be infinity. In CARTOGRAPHY, any systematic arrangement of MERIDI­ANS and PARALLELS portraying the curved surface of the sphere or SPHEROID upon a plane. Also called map projection or chart projection. In PHOTOGRAPHY, the reduction or enlargement of a POSITIVE or NEGATIVE, by projecting the IMAGE through a LENS.

A PROJECTION on which the AZIMUTHS or DIRECTIONS of all lines radiating from a central point or POLE are the same as the AZIMUTHS or DIRECTIONS of the corresponding lines on the sphere.

An AZIMUTHAL PROJEC­TION on which straight lines radiating from the centre or pole of projection represent GREAT CIRCLES in their TRUE AZIMUTHS from the centre, and lengths along these lines are of exact SCALE. This PROJECTION is neither EQUAL AREA nor CONFORMAL.

A conventional PROJECTION con­structed by computing the lengths of arcs along a selected GEOGRAPHIC MERIDIAN and along a GREAT CIRCLE perpendicular to that MERIDIAN, and plotting these as RECTANGULAR COORDINATES on a plane.