contour line (kontorlin)

In surv., a line joining points of equal elevation on a surface; a line or level carried along the surface of a country or district at a uniform height above the sea-level. When laid down or plotted on a map or plan, such lines show the elevations and depre ions of the surface of the ground, the degree of accuracy depending on the number of lines or levels taken. In the maps of the Coast and Geodetic Survey of the United States the contour-lines are generally given for every 20 feet of elevation. It is e ential to the completene of a contour-line that it should be carried on till it returns to the point whence it started, thus describing a closed curve. The littoral cordon or outline of the sea forms a natural contour-line. The system of representing the form of the earth's surface by means of horizontal lines at equal vertical distances was probably invented by Philippe Buache in 1744. Contour-lines, eighty feet apart vertically, were run; and intermediate forty-foot contours were interpolated by means of slope-measurements in the steeper parts, and by running curves in the more level portions. Science, III. 365. IMG:content-1183.png:[blocks in formation] IMG:content-1184.jpg:[graphic] as contorniate. contr. An abbreviation of contracted and con traction. contra (kon' trä), adv. and prep. [L. contra,