One of the first pieces of home decor I bought (long before I had a house) was a Galileo thermometer. It’s a pretty glass decoration that tells the temperature quite accurately.

Here’s how it works: “The object known as the Galileo Thermometer is a vertical glass tube filled with a liquid in which are suspended a number of weighted glass balls. As the temperature of the liquid changes, so does the density. Since each glass ball is set to float at equilibrium in a sightly different density of the liquid, as the temperature increases, each glass ball sinks to the bottom.” (source)

Today I learned that the Galileo thermometer was not invented by Galileo Galilei (1564-1642).

It was in fact invented by a group of scientists and technicians who had formed a society called the Accademia del Cimento, which operated in Florence between 1657 and 1667. Details about the device were published in 1666. It was also known as the termometro lento (slow thermometer).

The Galileo thermometer is named after Galileo because he discovered the principle that the density of a liquid changes in proportion to its temperature. That explains the name. (What I can’t explain is why my husband calls our Galileo thermometer “Archimedes”!)

Sources

• “Galileo thermometer” via Wikipedia
• “The Galileo Thermometer was not invented by Galileo” via ScienceBlogs