Engine ndicator planimeter in a box with a weight and a board. The shorter arm is supported by a small cylindrical pointer. The weight is placed on the top of this pointer. There is a disc integrator mounted between two offset clips at the apex of the tracing and supporting arms. The longer arm has a sharp needle for tracing. The board consists of a fixed and a sliding track. The fixed track has a groove running horizontally along it, in which the cylindrical pointer of the planimeter is placed. The sliding track can be adjusted to accommodate the indicator card which is slipped under the two metal clamps, one attached to the board and the other attached to the sliding track.

This is a planimeter designed to measure the irregular-shaped graph given by the engine indicator device. It is done by tracing accurately once around the shape and reading the difference in the figures on the vernier scale (the circular disc). It can give the power in the cylinder. These would be used regularly aboard steam ships and early motor ships in the merchant navy.