Italian astronomer and physicist, Galileo Galilei s (1564-1642) discovery that the density of liquid expands or contracts with temperature changes led to the creation of the world"s oldest thermometer a method of searching for actual room temperature. The thermometer is made up of a glass cylinder. Inside the cylinder are hand blown, calibrated, glass spheres each with imprinted designated temperature reading medallions. As temperatures fall, spheres will rise, as temperatures rise, spheres will sink. The lowest floating sphere in the upper group will indicate actual room temperature. A functional work of art!