1930s Brass Rototherm Desk Thermometer In A Hexagonal Wood Surround And Plinth

This is a lovely 1930s Brass Rototherm Thermometer In A Wood Surround. It has an easy to read dial showing the ‘freezing point’ temperature of 32 ºF, and measures from -20 to 140 ºF.

Made by the British Rototherm Co. Ltd, London, England for Lister Diesel Engines, a company founded in 1867 and famous for their stationary steam and diesel industrial engines.

British Patent Number 378314 (patent dating to 1932)

Approximate Dimensions:

• Base Depth: 8.5 cm
• Base Width: 9.8cm 
• Height : 9 cm 
• Diameter of thermometer face: 6cm 

A ‘must have’ item for the man cave, she den, study or office. It measures temperature in Fahrenheit and is encased in a typical hexagonal oak surround and plinth, allowing it to display nicely on a desk. 

The bimetallic thermometer is in working order with a brass surround and black numerals. There are no cracks or restoration but there are a few surface blemishes commensurate with age and use. 

The images have been taken with/without flash and the wood is slightly darker than it appears in the photos.

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Bimetallic Thermometer

Rototherm invented the bimetallic thermometer in 1934. The thermometer has a metal pointer that moves up and down a circular scale. The pointer is mounted on a coiled piece of metal called a bimetallic strip. The hotter the temperature, the more the bimetallic strip expands, and the more it pushes the pointer up the scale.