Apparatus to demonstrate the thermal expansion of liquids, mid 19th century.
© Science Museum / Science & Society Picture Library
This apparatus consisted of five thermometers with large spherical bulbs, mounted in a row on a mahogany stand, with a lined trough in the base. The liquids in four of the thermometers are labelled mercury, spirit, oil, and water (the mercury thermometer is now broken). The fifth thermometer not named appears to contain only air. Presumably hot water was poured into the trough and the response of the thermometric fluids was noted.