BI-METAL
A bi-metal consisted of two strips of metal with
different heat expansion coefficients, firmly pressed
against each other. This caused a straight strip of
bi-metal to bend when it was heated and to straighten
again when it cooled down. In the starter of a tube
light, the heat dissipation of the small neon glow
discharge tube was just sufficient to make the
bi-metal electrode bend and make contact with the
other electrode.
