This beautiful sealed glass container contains 10 colourful, carefully weighted balls of hand-blown glass.
In liquid, each globe with the same weight and size is compelled to go down as the temperature rises. The globe will rise if the temperature falls. The lowest suspended globe in the upper part of the cylinder equals the right temperature.
This property was first observed by Galileo, and our thermometers have been named in his honour. By observing which bauble is floating in the middle of the column, or by averaging the ones bracketing the gap (if there is no ball in the middle), the temperature can be read. This large model is accurate between 16°C and 34°C, and sits at a proud 44cm tall.