A device consisting of two metals with different coefficients of expansion riveted together; an increase in temperature causes the strip to bend. One end of the strip is held rigidly and the movement of the other end may be used to open and close contacts, particularly in thermostats, or to move the pointer of a pointer-type thermometer. A thermal instrument that utilizes the deformation of a bimetallic element, heated directly or indirectly by an electric current, is a bimetallic instrument.