A two-dimensional diagram that uses a parallel coordinate system in which scaled vertical axes are used to evaluate the dependence of two properties such as temperature and pressure on a third property such as the K-factor. The procedure is to draw a straight line between the left- and right-hand scales, intercepting with a third scale between them. They were once widely used for quick calculations before the advent of the calculator and computer. Nomography was invented in 1884 by French engineer Philbert Maurice d’Ocagne (1862–1938).