Abstract: A tracer apparatus is disclosed which includes a template mounted on a table and arranged to be moved along two orthogonal axes, and a stylus arrangement provided with a stylus which is arranged to follow the periphery of the template as the template moves, thereby to control the movement of the table so that the stylus maintains contact with the periphery of the template. The stylus is movably mounted so as to be moved both by virtue of its abutment against the periphery of the template and by electromagnetic devices. A sensing device is provided to sense displacement of the stylus from an initial position and to control operation of the electromagnetic devices, whereby the stylus moves arcuately when displaced and then rotated until it comes into contact once more with the periphery of the template. In the preferred embodiment, the electromagnetic devices co-operate with a permanent magnet to hold the stylus under a condition of unstable equilibrium against the periphery of the template.