This one may be too easy, but I had forgotten how beautiful it can be. So, what is it? Stylized ornaments? Blowing glass? Maybe even earrings? No, the answer is much more functional than that.
It's called Galileo's Thermometer and yep, named after Galileo Galilei, the man pretty much responsible for the birth of modern science. How does it work? Well, in a nutshell, the thermometer is a sealed glass cylinder containing clear liquid and a series of objects who rise and fall depending on mathematical principle. Basically, they rise and fall as the temperature changes. Here's what it looks like:
The mathematical principles applied to the Galileo thermometer are straightforward. Each bulb in the thermometer has the same volume and therefore exactly the same density. This means that each bulb has the same magnitude of both gravitational and buoyant forces. Gravity pushes down, buoyancy upwards.
The temperature would be the "lowest" floating bulb. Surprisingly, Galileo didn't invent the Galileo Thermometer. Instead, it was named in his honour since without his discoveries, it wouldn't have been possible to invent. [Kuriositas via Neatorama]
Image Credit: taddek