A magnetic plotting compass is an instrument used to measure and map the strength and direction of magnetic fields. It consists of a small, lightweight compass needle mounted on a pivot and enclosed in a plastic case. The compass is designed to be placed on a flat surface and can be rotated to any desired angle. By measuring the deflection of the needle, the strength and direction of the magnetic field can be determined. Magnetic plotting compasses are commonly used in geology, mining, and other fields where the study of magnetic fields is important.