Click to run thermometer animation The first thermometer was invented by Galileo Galilei, who like Madonna and Cher, is often just called by his first name. Galileo was born in Italy in 1564. Just 32 years later, in 1596, Galileo invented the thermometer. After a number of experiments, Galileo devised a simple contraption. He inverted a flask with a narrow neck over a shallow bowl containing liquid (apparently he usually used wine, although if was because of the red color or just because it was what he happened to have lying around the house is unclear). The liquid would go part way up the flask's neck; changes in surrounding temperature would either raise or lower the liquid. Click on the Shockwave animation to the left to see what happens when the temperature increased. There were problems with this thermometer. It had no way to tell what the temperature actually was, just that the temperature had changed. Even after Galileo's friend Sanctorius Sanctorius added a scale in 1611, it was still just measuring relative changes in the temperature, not the actual temperature itself. The next great advance in thermometers came in 1632 when Jean Rey used liquid instead of air to measure temperature changes; that is, the thermometer had fluid at the bottom and air at the top, more closely resembling modern-day thermometers. In 1672, the first sealed thermometer was created by the Frenchman Hubin. It was Daniel Ganbriel Fahrenheit who invented the calibration scale for his version of the thermometer that is still used in some parts of the world today. Mercury was one of the many fluids used in early thermometers, but Fahrenheit's mercury thermometers were so accurate in reading tempertures that they became the thermometers of choice for many years. There is a commerical version of what some people call the "Galileo thermometer" available from stores like The Nature Company. It is only loosely based on Galileo's theory, and is not what Galileo actually built. It's still pretty clever, though. It is based on the knowledge that as the temperature of a liquid increases, its buoyancy decreases. In liquid, a solid body with a fixed density tends to go down as the temperature rises. The inverse is also true; the solid body goes up in the liquid if the temperature falls. This occurs because the liquid containing the solid body expands very slightly at higher temperatures and contracts very slightly at lower temperatures. By precisely calibrating the density (weight) of glass balls filled with different substances, the makers of this "Galileo thermometer" can make the balls rise or fall at precise temperature points. Return to Adrienne's and Jeanne's Fun Facts About Science page! Hi! Welcome to our homepage!
After a number of experiments, Galileo devised a simple contraption. He inverted a flask with a narrow neck over a shallow bowl containing liquid (apparently he usually used wine, although if was because of the red color or just because it was what he happened to have lying around the house is unclear). The liquid would go part way up the flask's neck; changes in surrounding temperature would either raise or lower the liquid. Click on the Shockwave animation to the left to see what happens when the temperature increased.
There were problems with this thermometer. It had no way to tell what the temperature actually was, just that the temperature had changed. Even after Galileo's friend Sanctorius Sanctorius added a scale in 1611, it was still just measuring relative changes in the temperature, not the actual temperature itself.
The next great advance in thermometers came in 1632 when Jean Rey used liquid instead of air to measure temperature changes; that is, the thermometer had fluid at the bottom and air at the top, more closely resembling modern-day thermometers. In 1672, the first sealed thermometer was created by the Frenchman Hubin. It was Daniel Ganbriel Fahrenheit who invented the calibration scale for his version of the thermometer that is still used in some parts of the world today. Mercury was one of the many fluids used in early thermometers, but Fahrenheit's mercury thermometers were so accurate in reading tempertures that they became the thermometers of choice for many years.
