Image Credit Flickr User Tadek
Galileo Galilei was an Italian jack of all arts and science trades who played a major role in the Scientific Revolution of the seventeenth century. His discoveries about the effect of temperature on the density of liquids led to a thermometer being named after him.The instrument consists of a sealed glass cylinder containing a clear liquid and a series of bulbs with weights attached. As the temperature changes, the bulbs rise and fall depending of a number of mathematical principles first conceived by Galileo. It is not only functional; it is also very beautiful.Link
@Ron R : There is no gas inside the bulbs. I think the bulbs just have water in them and the clear liquid is similar to oil. I read about it but it's sort of difficult to understand for non-chemists like me. There is something to do with the weight of the metal tabs on the bulbs too.