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Part 1. All rights reserved. This image may not be used by other entities without the express written consent of wikiHow, Inc. Identify the temperature stamped onto each medallion. The thermometer consists of a glass tube filled with a clear liquid, in which colored glass spheres float. Each sphere has a metal medallion hanging from it. The medallions are different weights, which makes the spheres float or sink different amounts.
You will see a temperature engraved onto it. Different Galileo thermometers have different ranges of temperatures that they can report. The Galileo thermometer works because of the principle of buoyancy, which states that objects that are denser than their surroundings sink, and objects that are less dense than their surroundings float.
Letters written to Galileo by his friend Francesco Sagredo, who claims to have subsequently refined and improved the instrument, appear to confirm this assertion. An account of a lecture given by Galileo in provides a description of the thermometer: ""Galileo took a glass vessel the size of a hen's egg, fitted to a tube the width of a straw and about two spans long; he heated the glass bulb in his hands and turned the glass upside down so that the tube dipped in water held in another vessel; as soon as the ball cooled down the water rose in the tube to the height of a span above the level in the vessel; this instrument he used to investigate degrees of heat and cold.
What Galileo had constructed was a form of inverted air thermometer. Galileo himself explained the principle behind his invention in his one surviving piece of writing on the subject: ""When the air in the bulb contracts through cold, the wine in the stem rises to take the place of the void thus formed, and when the air is warmed it is rarefied and takes up more space so that it drives out and presses down the wine.
So a replica of a genuine ""Galileo thermometer"" would look and function nothing like this elegant glass tube with its suspended balls. So what then is the link between a modern Galileo thermometer and the great man whose name it takes? The answer is that the basic physical principle — buoyancy — upon which the modern Galileo thermometer is based was defined by the Florentine genius in his Discourse on Bodies in Water, published in It was Galileo who, not without controversy, took on the established Aristotelian view that buoyancy is inextricably linked to the shape of the body and the resistance of the liquid, proving instead that it is the difference in density between the body and the medium that dictates whether or not an object will float.
Resistance, he demonstrated, only impacts the speed with which an object will sink or emerge. However, as the interval between the medallions increases, more estimation comes into play, and thus more margin of error.
Finally, while the device can be used outside, it will work best indoors. The physics on which these instruments are based on works best within a specific temperature range—most thermometers will only have medallions for temperatures between 64 and degrees Fahrenheit.
But for getting a general idea of the temperature of a room, the Galileo thermometer is a viable option that is functional and decorative. AcuRite is better known for its weather stations. However, it also produces various other weather instruments, including this Galileo Thermometer with Glass Globe Barometer. Based on the principles of Galileo's work, each instrument allows you to read both the temperature and atmospheric pressure on a beautifully designed desktop stand. The addition of the barometer is a nice touch.
The water level in the spout of the glass globe reveals the variations in barometric pressure. When the barometric pressure increases, the spout's water will be low, and fair weather can be expected. If the water is high, it indicates lower pressure and bad weather can be expected.
While you can't tell the exact barometric pressure using this technique, it will allow you to monitor trends. Reviews from buyers say that the thermometer and barometer are well constructed and look as great as it does in Amazon's pictures. You can't go wrong with the price either, which is considerably cheaper than some other Galileo thermometers we've seen.
AcuRite offers a one-year warranty on this thermometer and barometer, and while it's quite large at The Galileo thermometer is a decorative instrument that measures ambient temperature, and unlike the Fitzroy storm glass —it is reasonably accurate.
We think it's an excellent option for those looking for a unique gift for a weather enthusiast. The fact that it works makes it that much better. Are you looking for even more weather gift ideas? We recently updated our list of more than two dozen useful and educational weather gifts suitable for meteorology enthusiasts of all ages.
Hi, thanks for stopping by. I'm the lead contributor here at Weather Station Advisor. A small Galileo thermometer can have 6 degrees F of difference between the balls, which introduces a lot of error into the measurement.
Larger such instruments have at least a couple of temperature difference between the diver globes. To read the ambient temperature on a Galileo thermometer is very easy. What you have to do is simply look at the lowest ball that is floating while ignoring those tags that had sunk to the bottom of the container.
If there is no bulb floating in the gap between the rising and sunk bulbs, use the lowest bulb from the floating cluster to get the temperature. The Galileo thermometer is certainly not the most precise instrument in the world but it is certainly clever. You can find a great selection on Amazon. Tibi is a science journalist and co-founder of ZME Science. He writes mainly about emerging tech, physics, climate, and space.
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