actuation cam pin 48 is affixed to element end 47 and extends transversely out therefrom the use thereof which will be later described the gear mechanism 17 consists of an axially extending shaft 51 rotatably supported at one end to housing back surface 21 with its front end portion extending through the central aperture of support bar 42 and thence through aligned apertures 34 to have the indicator pointer element 18 affixed to the front end thereof and movable therewith a circular gear 52 is permanently affixed concentrically to shaft 51 rearwardly of bar 42 and in compartment 23 a second circular gear 53 is mounted parallel to gear 52 and in intermeshing engagement therewith the gear 53 being supported for rotation on a shaft 54 which has its opposite ends journaled for rotation in housing back surface 21 and support bar 42 respectively a cylindrical collar member 55 is disposed concentric with shaft 54 and has one end affixed to gear 53 with the collar extending rearwardly therefrom the collar having cylindrical side walls 56 with the portion of the side wall nearest the end 47 of bimetallic element 16 having formed integrally therein a diagonal slot 57 defining a cam follower slot adapted to receive therein the projecting free end of actuation cam pin 48 the gear 53 is of a much larger diameter than the gear 52 such that it only requires between one quarter and one third of rotation of gear 53 to effect almost complete rotation of.