This attractive glass pillar is a simple, fairly accurate indoor thermometer, based on scientific concepts and a thermoscope invented by Galileo Galilei in the early 1600s.
Don't confuse this model with cheap imitations made in China-- this one is hand-blown in Germany and is a top quality scientific and gift item.
THE ARTISTIC REASON TO BUY ONE: "It's Magic!"
THE PRACTICAL REASON TO BUY ONE: "It's beautiful and it's actually very accurate for indoor temperatures from 64-80 degrees Fahrenheit"
THE LONG SCIENTIFIC EXPLANATION OF HOW IT ACTUALLY WORKS, AS FAR AS WE CAN UNDERSTAND IT-- PHYSICS TEACHERS PLEASE FEEL FREE TO EMAIL US WITH CORRECTIONS:
SUMMARY- It has to do with the density of the liquid in the tube compared to the density of the glass bubbles, and gravity.
Galileo Galilei was an Italian physicist, mathematician, astronomer and philosopher who played a major role in the Scientific Revolution. Galileo has been called the "father of modern observational astronomy," the "father of modern physics," and "the father of science." Stephen Hawking says, "Galileo, perhaps more than any other single person, was responsible for the birth of modern science."
Galileo discovered that the density of a liquid is a function of its temperature. Also, in 1592-1593, Galileo built a device showing variation of hotness, known as the thermoscope, using the contraction of air to draw water up a tube. This was one of the earliest thermometers in western science.
The modern "Galileo Thermometer" consists of a sealed glass tube that is filled with liquid and several floating bubbles. The bubbles are glass spheres filled with a colored liquid mixture.
Since the bubbles are all hand-blown glass, they aren't exactly the same size and shape. Once the hand-blown bubbles have been filled with liquid and sealed, their effective densities are then calibrated, and little metal tags are attached to the bottom of each bubble. Each little metal tag is stamped with a number indicating temperature in degrees Fahrenheit.
If an object immersed in fluid weighs less than the mass of water it displaces, it floats. If the object weighs more than the mass of the water it displaces, it sinks. Very small changes in the density of the liquid can easily cause an almost-floating object to sink.
The basic idea is that as the temperature of the air in the room changes, so does the temperature of the liquid in the glass tube, surrounding the bubbles. As the temperature of the liquid changes, it either expands or contracts, thereby changing its density. At any given density, the less-dense bubbles will float and the more-dense bubbles will sink. The lowest floating bubble is closest to the density of the surrounding liquid. The surrounding liquid is the same temperature as the air of the room. Therefore, the lowest floating bubble indicates the current temperature of the room.
Want to keep reading? OK !
There are five bubbles in the smallest 11 inch thermometer:
The yellow bubble (64 degrees) is the heaviest (densest) bubble, and each bubble thereafter is slightly less dense, with the black bubble being the least dense. Now, let's say the temperature in the room is 72 degrees. The liquid inside the thermometer would also be about 72 degrees. The yellow and blue bubbles (64 and 68 degrees, respectively) have higher densities than the liquid does at 72 degrees, so they sink in 72 degree liquid. They end up at the bottom of the tube. The green and black bubbles (marked 76 and 80 degrees) each have a density that is lower than the surrounding 72 degree liquid, so they float at the very top of the thermometer. Since the red bubble has the same density as an equal amount of 72 degree liquid, it floats neutrally in the tube below the green and black bubbles -- thereby indicating the room's temperature!
If the room temperature is lower than 64 degrees, all the bubbles will be floating at the top. If the room temperature is higher than 80 degrees, all the bubbles will sink to the bottom.
(some information adapted from Wikipedia: The Free Encyclopedia)
Trust us, it works, it's an interesting reference to the history of science and Galileo, and it's beautiful.