BIMETALLIC (adj.)

This adjective describes components made by combining two metals with opposing coefficients of thermal expansion. Most often, it refers to balance wheels whose inertia remains more stable despite temperature variations. The invention of bimetallic balances is credited to John Harrison, and their use became widespread in the 20th century. However, due to advancements in alloy technology and the high precision of modern regulation, bimetallic balance wheels are no longer commonly used.

Useful link:
– Balance wheel