Ferguson Pyrometer

25 Jun 2026

Ferguson Pyrometer is a device used to measure the linear expansion coefficient of a material. It is used to verify the principle of thermal expansion of metals, determining how different metals expand as the temperature of the metal changes. 

The device pictured comprises mahogany base; heated brass bar on turned brass pillar and bracket on wooden pillar. As temperature is applied to the sample the pointer moves on an arc scale demonstrating thermal expansion. The unit pictured is recorded in the National Inventory of Historic Scientific Instruments by Charles Mollan, entry 2765 UCP 248. The device is known to be fabricated in 1883.