Galileo thermometer
Galileo thermometer- a sealed glass cylinder filled with liquid in which glass buoy vessels float. Each such spherical float has a gold or silver tag attached to the bottom with the temperature value stamped on it. Depending on the size of the thermometer, the number of floats inside varies from 3 to 11. Currently, the thermometer has aesthetic value as a spectacular piece of furniture.
History of invention[ | ]
Galileo's thermometer close up
The name comes from the Italian physicist Galileo Galilei, who in 1592 invented the thermoscope, which became the ancestor of all thermometers. According to some sources, Galileo himself had a very indirect relationship with the creation of this device, which is often used as a souvenir; according to other sources, the world owes this invention of the late 16th century to Galileo.
Operating principle[ | ]
The floats are filled with liquid in different ways in such a way that their average density is different: the lowest density is at the top, the highest at the bottom, but for all of them it is close to the density of water, differing from it only slightly. As the air temperature in the room decreases, the temperature of the water in the vessel decreases accordingly, the water contracts, and its density becomes greater. It is known that bodies whose density less density the liquid surrounding them float up in it. When the temperature in the room decreases, the density of the liquid in the cylinder increases, and the balls rise up one after another, and when it rises, they drop. This effect is achieved due to the very high precision of thermometer manufacturing. All balls are calibrated by ascent temperature in the range of 0.4 °C. The temperature range measured by the thermometer is around room temperature: 16-28°, step: 1 °C. The current temperature value is determined by the lower of the floating balls.
Galileo thermometer
Galileo thermometer
Galileo thermometer It is a sealed glass cylinder filled with liquid in which glass spherical buoy vessels float. Each such spherical float has a gold or silver tag attached to the bottom with the temperature value stamped on it. Depending on the size of the thermometer, the number of floats inside varies from 3 to 11. Currently, the thermometer has aesthetic value as a spectacular piece of furniture.
History of invention
Galileo's thermometer close up
The name comes from the Italian physicist Galileo Galilei, who in 1592 invented the thermoscope, which became the progenitor of all thermometers. According to some sources, Galileo himself had a very indirect relationship with the creation of this device, which is often used as a souvenir; according to other sources, the world owes this invention of the late 16th century to Galileo.
Operating principle
The floats are filled with liquid in different ways in such a way that their average density is different: the smallest density is at the top, the highest at the bottom, but for all of them it is close to the density of water, differing from it only slightly. As the air temperature in the room decreases, the temperature of the water in the vessel decreases accordingly, the water contracts, and its density becomes greater. It is known that bodies whose density is less than the density of the surrounding liquid float in it. As the temperature in the room decreases, the density of the liquid in the cylinder increases and the balls rise up one after another, and as the temperature rises, they drop. This effect is achieved due to the very high precision of thermometer manufacturing. All balls are calibrated by ascent temperature in the range of 0.4 °C. The temperature range measured by the thermometer is around room temperature: 16-28°, step: 1 °C. The current temperature value is determined by the lower of the floating balls.
see also
Notes
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See what "Galileo's thermometer" is in other dictionaries:
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Before the first thermometer was invented, temperature was measured by touch. There was no talk of any measurement accuracy. And this went on for quite a long time, until in 1597 Galileo Galilei invented the first instrument for measuring temperature.
Galileo thermoscope
Galileo's device was very simple. It consisted of a glass tube, to the end of which a glass ball was soldered. Having slightly heated the ball, Galileo lowered the free end of the tube into a vessel with water. When the air in the ball cooled, the air pressure in it became less, and the water was influenced atmospheric pressure went up the tube. And depending on the height to which the water rose, it was possible to determine the temperature. This device was called thermoscope. Of course, it also showed very approximate temperature values. In addition, its readings depended on the value of atmospheric pressure.
IN 1657 Galileo's thermoscope was improved by Florentine scientists. They pumped out the air from a glass ball and made a scale out of beads. The readings from Galileo's thermoscope were approximate: high temperature, low temperature. Now the temperature values were measured more accurately: one bead, two beads, etc.
A little later, in 1700, the Florentine scientist Torricelli turned the thermoscope upside down and filled the tube with the ball with tinted alcohol. In addition, he removed the vessel containing water. The new device no longer depended on atmospheric pressure. This was the prototype of the modern thermometer.
Types of reference scale
But there was one problem. No one knew which point to take as the starting point and how to calibrate the scale. The first step in this direction was taken by the German physicist Daniel Gabriel Fahrenheit. In 1714 he came up with temperature scale. Instead of tinted alcohol, Fahrenheit poured mercury into a tube with a ball, pumped out the air from the tube and sealed it. The coldest, but still in a liquid state, was the mixture table salt and ice. Fahrenheit placed a tube with a ball into this mixture. And the height of the mercury column on the scale was marked as 0 degrees. The next point on the Fahrenheit scale was 32 degrees. It corresponded to the temperature at which ordinary ice without salt melted. Then the 96 degree point was marked. This was the temperature of the human body. Water boiled at 212 degrees on the Fahrenheit scale.
Different scientists have proposed different calibrations of thermometers. Thus, the French physicist Rene Antoine Reaumur studied the thermal expansion of alcohol. If alcohol is mixed with water in a ratio of 5:1, then when heated from the freezing point to the boiling point of water, the alcohol expands in proportion 1000:1080. Reaumur proposed a scale on an alcohol thermometer, where the zero reference point 0 o R was taken to be the temperature at which the ice melted. And the temperature at which water boiled was 80 o R.
But for the first time, taking the melting point of ice and the boiling point of water as the main reference points on a thermometer scale was proposed in 1665 by the Dutch physicist Christian Huygens and the English physicist Robert Hooke.
Swedish astronomer Anders Celsius in 1742 came up with his scale on the Fahrenheit mercury thermometer. Unlike the modern thermometer, zero degrees Celsius corresponded to the boiling point of water. And Celsius took the melting temperature of ice to be 100 degrees.
This is how the Celsius thermometer has reached our days. The only difference is that the scale of a modern thermometer is inverted relative to the Celsius scale. The melting point of ice is taken to be 0°, and the boiling point of water is 100° Celsius. And the astronomer Morten Stremer and the botanist Carl Linnaeus “turned over” the Celsius scale.
In all the described cases, the starting point of the thermometer scale was set arbitrarily. In 1848, the English scientist Lord Kelvin proposed the concept of “absolute zero”. He considered absolute zero to be the temperature at which molecular motion ceased. Absolute zero corresponds to -273.15 o on the Celsius scale.
Today, in most countries it is common to use thermometers with the Celsius scale. In some English-speaking countries, until recently, the Fahrenheit scale was used. It is still used in the USA today. And in scientific research The Kelvin scale is used.
He was a famous Italian physicist, mathematician, astronomer and philosopher who played a key role in the development of science in the 16th century. It was he who first discovered that the density of a liquid changes depending on the decrease or increase in temperature.
Photo: Flickr, Tadek 
Photo: Flickr, Gingko
The thermometer, named after the great scientist, is made of a sealed glass cylinder. The container is filled with liquid in which several buoys float. Each buoy has a tag attached to it. Depending on the temperature of the water, these floats either sink to the bottom or rise to the ceiling of the vessel. However, from an aesthetic point of view, the Galileo thermometer is much more attractive than its functionality - it is beautiful in itself!
Photo: Flickr, Tuchodi 
Photo: Flickr, Kansas City Royalty
And although this device was not invented by Galileo himself, it was named after the outstanding Italian scientist because the design would not have existed without Galileo's discoveries. These thermometers began to be made in the 17th century precisely on the basis scientific works Galileo.
Photo: Flickr, Steve 2.0
Let us remind you that all buoys have labels. Each of these tags is engraved with a number and a degree symbol. The weight of each float is precisely adjusted and calibrated. The colored liquid in the buoys plays its own role in equalizing the weight of the floats, but for the common man this is, first of all, a very beautiful sight.
Photo: Flickr, Steve 2.0
The mathematical principle used in the Galileo thermometer operates according to the rule directly proportional dependence. You can find out the temperature using this thermometer due to the fact that each float is filled with liquid to a different extent, which affects the average density of each float. An object floating highest has a lower density than an object hovering above the very bottom. But the specific gravity of these buoys does not differ much from that of the liquid in which they reside.
Photo: Flickr, jhritz 
Photo: Flickr, anujraj
When the temperature in the room drops, the water in the thermometer also cools. The liquid in the container is compressed and its density increases. And, as you know, bodies whose density is less than the density of their environment tend upward. Therefore, when the water heats up, the buoys sink, and when the room gets cooler, the floats float to the ceiling of the flask. As a result, the air temperature is determined by the lowest buoy with the corresponding tag.
Photo: Flickr, daisee 
Photo: Flickr, Rachel D 
Photo: Flickr, Anna Ghislaine
In this video you can watch what is happening in this device in slow motion:
The Galileo thermometer is a true example of the embodiment of beauty in scientific world. And although the relevance of such a device is modern world has long been lost, this thermometer can still be found in some apartments of connoisseurs of original interior design.
Photo: Flickr, Matthew Boyle
