Planimeter

— An. instrument used for measuring areas, as in indicator diagrams. It consists of two hinged levers, with points at the ends; one of which is secured | Plast to the paper, while the other, having at attached to it a graduated wheel, is traced around the outline of the figure; the circuit being completed, the area is read from a graduated wheel, a vernier being provided so the area may be read to three decimal places. For a diagram, the area is divided by the length, which gives the average height or mean pre ure.