This beautiful sealed glass container contains colourful, carefully weighted balls of hand-blown glass. As the ambient temperature changes, the paraffin within the thermometer changes density, affecting which baubles float and which sink. This property was first observed by Galileo, and these 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 model is accurate between 18°C and 28°C and is 28cm tall.