Accession No

6029

Brief Description

prototype thermocouple, pyrometer and resistance thermometer, by Cambridge Scientific Instrument Company Ltd., English, mid-20th century

Origin

England

Maker

Cambridge Scientific Instrument Company Ltd.

Class

thermometry; physics

Earliest Date

1950

Latest Date

1980

Inscription Date

Material

metal (steel, platinum, brass); plastic; mica

Dimensions

length 390mm; depth 100mm; depth 95mm

Special Collection

Provenance

Donated by a former employee of Cambridge Scientific Instruments Company on or before 29/11/2004.

Inscription

[inscription runs around the head of instrument and is only partial due to the cut away section]

“[...]GE [part of the word Cambridge, the rest of which has been cut away]
[Cambridge Scientific Instrument Company logo]
PYROMETER
[arrowhead]
CLAMP”

[on paper label attached to instrument]
“RESISTACE [mis-spelling of resistance]
THERMOMETER
WITH PLAT COIL
FITTED IN SHEATH”

Description Notes

Prototype thermocouple by Cambridge Scientific Instrument Company, with section cut away to provide ‘exploded’ view of inside the instrument. Mid-20th century. Approximately one quarter of the instrument is cut away to allow instrument makers to see how the thermocouple is assembled.

Instrument is composed of a bulbous head attached to a long metal sheath containing a metal element. Short brass chain attached to head. The cut away section exposes the inside of the head and the element. An attached label describes the element as a ‘plat coil’. (According to CSI catalogue this is the ‘platinum’ element, which consists of platinum and 13% rhodium-platinum.) Instrument has a thin mica layer running along the length of the metal sheath.

Condition good-fair. Mica layer is broken into three pieces and appears to have been detached from top metal strip. Mica layer bears some sticky tape residue. Element shows some corrosion.

References

Events

Description
Thermocouples measure the temperature of ovens and furnaces, particularly in laboratories. They work by taking advantage of a physical effect that turns heat into electricity. Two lengths of different metals are connected together along their lengths. The type of metals used in the thermocouple depends on the maximum temperature that the thermocouple should be able to withstand.

One end of the connection is put into the oven and the other end remains outside. When one end of the connection is at a different temperature to the other, it causes electricity to flow along the connection. This electricity can be measured and gives a reading of the temperature inside the oven.

Created by: Ruth Horry

FM:46495