Abstract: A signalling gauge may utilize a non-captivating, magnetically actuated switch element which is mounted in an influence zone of a path of a magnet carried by an indicating pointer of the gauge. The gauge may operate despite the presence of dust, dirt or other pollutants for an extended period of time without inducing sparks or arcing often associated with electromechanical contacts. Hall effect switch elements such as latches or digital switches may be utilized as a switch element for signalling to drive an audio or visual alarm or a digital signal.