Invisible Airs, Contraptions, Bristol, UK

bnr#53 => Invisible Airs, Contraptions, Bristol, UK

Bimetallic Strip

Object: 04

Bimetallic Strip

Date of origin: 1753
Author/inventor/context: John Harrison, for his first successful marine chronometers

The bimetallic strip is a thermo-mechanical component used to convert a temperature change into mechanical displacement. Affixed to the balance wheel of early marine chronometers, the bimetallic strip increased the precision of such clocks by compensating for fluctuating temperature and humidity conditions at sea. This solved the long-standing problem of how to accurately determine a ship’s longitudinal position, profoundly influencing navigation, cartography, the age of sea-borne “discovery” and increasing the predictability and frequency of trans-oceanic trading routes, with over half of the trans-Atlantic slave trade occurring in the 18th Century. Its success also prompted the insurance industry to require the bimetallic strip as a standard specification on a ship’s clock for obtaining maritime insurance coverage. It is now commonly used as a switch in thermostats.

Thomas Aston