The horizontal coordinate of a set of rectangular coordinates. Also used in a similar sense in connection with oblique coordinates. absolu 
The horizontal coordinate of a set of rectangular coordinates. Also used in a similar sense in connection with oblique coordinates. absolu 
Related Terms 
ORDINATEThe vertical coordinate of a set of rectangular coordinates. Also used in a similar sense in connection with oblique coordinates. 
DIRECTCURRENT POWER SUPPLYA power space relative to another without reference to the distance between them; may be either threedimensional or twodimensional, the horizontal and set points. 
THREEARM PROTRACTORAn instrument consisting of a circle graduated in degrees, to which is attached one fixed arm and two arms pivoted at the center and provided with clamps so that they can be set at any angle to the fixed arm, within the limits of the instrument. It is used for finding a shipâ€™s position when the horizontal angles between three fixed and known points are measured. 
PLUNGETo set the horizontal cross hair of a theodolite in the direction of a grade when establishing a grade between two points of known level. 
RESOLUTION

ANGULATORAn instrument for converting angles measured on an oblique plane to their corresponding projections on a horizontal plane; the rectoblique plotter and the photoangulator are types. 
COORDINATE PAPERPaper ruled with lines to aid in the plotting of coordinates. In its most common form, it has two sets of parallel lines, usually at right angles to each other, when it is also called CROSS SECTION PAPER. A type ruled with two sets of mutuallyperpendicular, parallel lines spaced according to the logarithms of consec utive numbers is called logarithmic coordinate papa or semilogarithmic coordinate paper as both or only one set of lines is spaced logarithmically. A type ruled with concentric circles and radial lines from the common center is called polar coordinate paper. Also called GRAPH PAPER. 
OBLIQUE COORDINATESMagnitudes defining a point relative to two intersecting nonperpendicular lines, called AXES. The magnitudes indicate the distance from each axis, measured along a parallel to the other axis. The horizontal distance is called the abscissa and the other distance the ordinate. This is a form of CARTESIAN COORDINATES. 
UNITED STATES NATIONAL MAP ACCURACY STANDARDSA set of standards which define the accuracy with which features of U.S. maps are to be portrayed. 1. Horizontal accuracy: For maps at publication scales larger than 1:20,000, 90 percent of all welldefined features, with the exception of those unavoidably displaced by exaggerated symbolization, will be located within 0.85 mm of their geographic positions as referred to the map projection; for maps at publication scales of 1:20,000 or smaller, 0.50 mm. 2. Vertical accuracy: 90 percent of all contours will be accurate within onehalf of the basic contour interval. Discrepancies in the accuracy of contours and elevations beyond this tolerance may be decreased by assuming a horizontal displacement within 0.50 mm. Also called MAP ACCURACY STANDARDS. 
OBLIQUE RHUMB LINE

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