Are you interested in buying a Galileo thermometer? This instrument shaped in the form of a tube is one of the most fascinating methods of monitoring indoor climate.
Although Galileo didn’t invent the thermometer himself, his work in the field of physics served as inspiration. This device is not only accurate but also incredibly elegant.
In case you plan to buy a Galileo thermometer, this is everything you need to know about its accuracy and functionality.
How does it work?
Although not being a new invention, the Galileo thermometer is a fairly precise instrument, designed for the purpose of temperature measurement. While traditional thermometers use mercury, this thermometer has a more complex design, using several glass spheres filled with liquid in different colors. The tube in which these spheres float is filled with ethanol, not water, as the latter doesn’t show significant changes in density when the temperature rises or drops.
Moreover, the liquid inside these bubbles differs in color, each of them equipped with a metal tag, showing different degrees. The bubbles floating in the tube differ both in size and weight but slightly in density. Nevertheless, their color isn’t considered important when compared to the way they move up and down, depending on the density of the ethanol.
The ambient air is responsible for the changes happening to ethanol’s density, which expands and contracts along with the change in degrees. For instance, when the air temperature drops, ethanol experiences contraction, leading to an increase in density. In contrast, when the air temperature rises, the liquid expands, resulting in a density decrease.
In addition, the glass spheres whose density is lower in comparison to ethanol will find their way to the top. The bubbles of higher density will experience an opposite effect and sink to the bottom of the tube. Consequently, the bubbles will sink in the event of hot temperature, while rising when it’s cold.
Galileo relied on the principle of buoyancy when designing this unique thermometer. According to this principle, objects of higher density compared to their surroundings sink, while objects of lower density float. Read more about Archimedes’ principle, otherwise known as the physical law of buoyancy.
How to read this type of thermometer?
There’s nothing complicated when it comes to reading a Galileo thermometer. All you need to do is observe the way in which the glass spheres rise and fall inside the container. Usually, you’ll see a couple of bubbles floating at the top, as well as several bubbles in the bottom. In the gap, between the two groups of glass spheres, there’s usually a single bubble, indicating the current temperature. Make sure you read the metal tag attached to the bubble in order to see the degrees.
Nevertheless, sometimes, there won’t be a glass sphere in the middle of the tube to indicate the temperature. In such scenarios, you’ll have to do some calculations yourself by figuring out the average value between the bubble with the lowest temperature in the group at the top and the sphere with the highest in the group at the bottom.
In certain cases, all-glass spheres are found at the top, leaving no balls in the bottom of the thermometer. Then, you are supposed to read the metal tag of the medallion that is furthest from the top. The current temperature is lower than the one written on the metal tag. In contrast, if all balls sink, the current temperature is higher when compared to the one written on the tag of the highest medallion.
Is it accurate?
The accuracy of Galileo thermometers largely depends on their location and sphere calibration. It should be placed indoors, not exposed to sunlight or cold air. Make sure you place it away from doors, windows, and household appliances.
In terms of calibration, two-degree increments are believed to provide the best accuracy. The larger the intervals between the glass spheres, the greater the risk of making a wrong estimation. The following link, https://en.wikipedia.org/wiki/Galileo_thermometer, provides insight into the history and operation of a Galileo thermometer.
If you are a weather lover, a Galileo thermometer is the right instrument to buy!