A prototype has been produced of an instrument that automatically records on graph paper the waviness of surfaces. The instrument possesses special features of design in the marking system that provide for accurate and rapid making of traces. It is of robust construction suitable for everyday production tests on surfaces and yet is of such form that it will not harm the surfaces. Its outstanding feature is that it charts the waviness of surfaces in only 5% of the time it takes when using a simple Ames dial instrument. The consequent saving in labour costs should be large in comparison with the cost of a production instrument.