THERMOMETERS
Galileo discovered the principles of the thermometer in 1592. The Grand Duke of Tuscany, Ferdinand II, is given credit for perfecting it in 1610. Athanasius Kircher is given credit for the discovery of the mercurial thermometer. This was about 1641. Ferdinand the II, in 1650 or thereabouts, filled a glass tube with colored alcohol and hermetically sealed it after graduating the tube. Fahrenheit is given credit for the discovery that water freezes always at the same temperature. With these facts he devised a scale for thermometers in 1714.