1930s Parkinson Rototherm Chrome Square Folding Desk Thermometer

A Vintage 1930s Parkinson Rototherm Chrome Square Folding Desk Thermometer. Small in size with a lovely face and an easy to read dial measuring from -20 to 140 ºF.

British Patent Number 378314: patent dating to 1932. Marked 'Parkinson' (the manufacturer) and 'Rototherm' on the face.

A ‘must have’ item for the man cave, she den, study or office. It measures temperature in Fahrenheit, and is encased in a Chromed Brass case with a fold out stand on the rear allowing it to display nicely on an office desk or mantelpiece. It is pretty portable since it is foldable and fairly light.

The bimetallic thermometer is in working order but I can't attest as to its accuracy. There is pitting /loss of chrome and some blemishes on the face. The brass has discoloured with age.

Approximate Dimensions:
Folded Depth: 2.3cm
Width: 6.6cm
Height: 6.6cm

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NB: The photos have been taken with and without flash hence the differences in colour.

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.