PANTOGRAPH (from Gk. eras, pas, all rypdcpecv, graphein, to write). An instrument used to make an outline copy of a map, design, draw ing, or other picture either at the same scale or larger or smaller. It consists of four so joined as to form a parallelogram. (Inc of the rods is pivoted about a fixed axis, while the ap paratus is supplied with a tracer or point which is moved over the original drawing and a pencil which makes the line of the copy. A form of the pantograph \villah is extensively used is shown in the illustration. The rod, are jointed at a, 1,, c, and d, so that db is equal to cd and ac to bd. thus making the figure andr a parallelogram. At d and f are the tracing point and pencil respectively, .while at c the rod is pivoted so as to move freely. The points e, d, and f are in a straight line which is maintained no matter how the framework is moved about c. The triangles bed and fief are
similar and the distance by the point f with respect to that traversed by d depend on the ratio of ur to of. It is of course possible to interchange f (tnd d, and in that case there will he a reduced drawing made. By of screws or pins at b and c the ratio of tie sides of the parallelogram and the scale of re duction may be altered to suit the artist, the appropriate scale being marked on the arms. There are several forms of pantographs and in struments in which numerous refinements in the way of rollers, pivots. suspenders, ete., are in troduced, hut all operate on the principle just described. The invention of the pantograph is ascribed to Christopher Seheiner, a prie,t, in 1603. and a description of the instrument was published at Rome in 1631.