Principle 37. Thermal expansion

1. Use thermal expansion (or contraction) of materials.
   Fit a tight joint together by cooling the inner part to contract, heating the outer part to expand, putting the joint together, and returning to equilibrium.
2. If thermal expansion is being used, use multiple materials with different coefficients of thermal expansion.
   The basic leaf spring thermostat: (2 metals with different coefficients of expansion are linked so that it bends one way when warmer than nominal and the opposite way when cooler.)