Chinese English

A PROJECTION of the cylindrical type, being in principle equivalent to the regular MERCATOR PROJEC­TION turned (transversed) 90° in AZIMUTH. In this PROJEC­TION, the CENTRAL MERIDIAN is represented by a straight line, corresponding to the line which represents the EQUATOR on the regular MERCA­TOR PROJECTION. Neither the GEOGRAPHICAL MERIDI­ANS, except the CENTRAL MERIDIAN, nor the GEODETIC PARAL­LELS, except the EQUATOR (if shown), are repre­sented by straight lines. It is a CONFORMAL PROJEC­TION. Also called transverse cylindrical orthomorphic projection.

An optical instrument which throws the IMAGE of a NEGATIVE or PRINT upon a SCREEN or other viewing surface, usually at a larger scale. An underwater acoustic TRANSMITTER. See UNDERWATER SOUND PROJECTOR.

In PHOTOGRAMMETRY, an instrument by means of which the IMAGE of an AERIAL PHOTOGRAPH can be projected onto a MAP. By varying the position of the projector lens, the scale of the projected IMAGE can be varied, and, by tilting the table top, compensation can be made for any tilt in the PHOTO­GRAPH.

In CARTOGRAPHY, an advanced copy of a MAP produ­ced to check the design, register and/or to enable ERRORS to be detected and corrected before final prin­ting.

An advanced copy of a map or chart produced by a PLOTTER to check the design and registration, and to detect and correct errors before final printing.

An instrument consisting in its simple form of two legs pointed at both ends and provi­ded with an adjustable PIVOT, so that for any given pivot setting, the distance between one set of pointed ends always bears the same ratio to the di­stance bet­ween the other set. A change in the PIVOT changes the ratio. The dividers are used in transfer­ring measure­ments between CHARTS or other drawings which are not at the same SCALE.

An instrument for measuring angles on a surface; an angular SCALE. In its most usual form it consists of a circle or part of one (usually a semi­circle) graduated in DEGREES. See PROTRACTOR: THREE ARM and COMPASS ROSE.

Square or rectangular sheet of trans­parent xylonite engraved with a circle graduated in DEGREES and half DEGREES. Observed angles are drawn, in general, on the under side. See PROTRACTOR: THREE ARM.

An instrument consisting essentially of a PROTRACTOR and one or more arms attached to a parallel motion device, so that the movement of the arms is everywhere parallel. The protractor can be rotated and set at any position so that it can be oriented to a CHART. Also called univer­sal drafting machine.