Santorio Santorio (1561-1636) made a similar instrument in Venice in 1612. A precursor of the modern thermometer, the thermoscope consists of a glass vessel with a long neck. The vessel was heated with the hands and partially immersed, in an upright position, in a container full of water. When the heat of the hands was taken away, the water was observed to rise in the thermoscope neck. The experiment showed the changes in air density produced by variations in temperature.