Galileo Galilei, the infinitely talented scientist and astronomer (and all round rebel of the 15th century), discovered the principle that offered us the first accurate reading of ambient temperature. Galileo’s Thermometer, while not technically created by himself (it was created by scientists in his honour), demonstrates his discovery of the principle on which this thermometer is based - that the density of a liquid changes as temperature changes.
This beautiful glass sealed cylinder contains a paraffin liquid that suspends colourful hand-blown glass baubles which are carefully weighted to different volumes. Attached to each of the baubles is a metal tag with the correlating temperature.
The theory behind the weather gauge suggests that as ambient temperature changes so does the temperature of the paraffin liquid within the cylinder. This temperature has an effect on the density of the liquid contained within the carefully weighted glass baubles, as each bauble is weighted differently they sink or float at different ranges. Observing the bauble nearest to the centre of the cylinder provides the accurate ambient temperature. If there are no baubles in the centre, an average reading of both the top and bottom closest bauble will provide the temperature.
