When was the thermometer invented? The history of the creation of the thermometer: how was the first thermometer invented? What is heat? Degrees and temperature
Today there is not a single person who does not use such a device as a thermometer. At the moment it is a common occurrence. However, this was not always the case. Few people know what a long and difficult journey the thermometer had. The history of its appearance goes deep into the past.
The first thermometer, or rather thermoscope, was invented during the Renaissance at the end of the 16th century. Its creator was none other than Galileo Galilei. The thermoscope was a glass ball to which a tube was soldered. Heating the ball with his hands and turning it, the Italian physicist lowered the free end of the glass tube into a bowl with colored water or wine. After the ball cooled, the volume of air it contained decreased significantly, and water rose through the tube. The difference between a thermoscope and a modern thermometer was that in Galileo's invention, instead of mercury, air expanded.
Almost simultaneously with Galileo, still not knowing about his discovery, Professor S. Santorio from the University of Padua created his own device with which it was possible to measure the temperature of the human body.
The device was quite bulky and also had the shape of a ball and an oblong winding tube on which divisions were drawn. The free end of the tube was filled with colored liquid. In order to measure the temperature, a person had to take this ball into his mouth or warm it with his hands. Since Santorio’s device was quite large, it was installed in the courtyard of the house.
In Europe at the beginning of the 15th century, a very large number of unique thermometers were manufactured. For example, in the Netherlands, the so-called “Dutch” type of thermometer, which had two balls and a winding tube, was widespread. The lower ball was filled with liquid, and the upper ball was filled with air.
The invention of the first thermometer, the data of which was not determined by changes in atmospheric pressure, occurred in 1641. Such a thermometer was created under the Holy Roman Emperor, Ferdinand II, who was not only a patron of the arts, but also the author of many instruments. Physicist Toricelli's experiments with barometers filled with mercury gave impetus to the improvement of the thermoscope, which was invented by Galileo. This device was simply turned over, colored alcohol was added to the ball and the upper end of the tube was sealed.
German physicist Otto von Guericke, while studying atmospheric air, invented a number of unique thermometers, including the largest one, whose height was seven meters. This original thermometer was attached to the wall of the house. A large copper ball, covered with blue paint and decorated with gold stars, was filled with air. One elbow of the tube, welded from below, was partially filled with liquid, while the other remained open. In hot weather, the hot air in the glass ball pushed the liquid out of the tube, the float began to rise, and the angel fell down, thereby pointing to the corresponding division of the scale. The lowest division showed “great heat”, and the highest, seventh division showed “great cold”.
At that time, the single scale that we use today did not exist. Scientists for a long time could not find the starting points, the distance between which would need to be divided evenly. They suggested taking into account, for example, the melting points of ice and melted butter. After some time, more precisely in 1714, a more or less usable thermometer appeared. The creator of such a thermometer was the German physicist Gabriel Fahrenheit.
Initially, Fahrenheit created two alcohol thermometers, but thanks to them, only conditionally accurate measurements could be made. Then the physicist decided to use mercury in the thermometer. This invention turned out to be more successful. In thermometers he used several types of scales, the last of which was based on three established points. The first point was the temperature of the composition of water, ice and ammonia, which was marked 0 degrees, the second was the temperature of the mixture of water and ice, designated 32 degrees, and the third was the boiling point of water, which was 212 degrees. This scale was later named after its creator. The Fahrenheit scale is still used in the USA and England.
After 30 years, astronomer Anders Celsius began conducting experiments with a mercury thermometer to study the correlation between the melting point of snow and the boiling point from atmospheric pressure. Celsius came to the conclusion that it would be rational to divide the distance between points into 100 intervals. The number 100 marked the melting point of ice, and 0 the boiling point of water.
However, in 1860, the English scientist William Kelvin proposed a new model of the temperature scale. A temperature of -273 degrees Celsius corresponded to zero kinetic energy of the molecules. Since no substance could be cooled further, a temperature of -273 degrees is considered “absolute zero.” In William Kelvin's scale, zero was taken as the beginning, and each subsequent division was equal to an ordinary degree. This scale turned out to be very convenient, because with its help it was possible to fairly fully display all the phenomena that occur on Earth.
In medicine, thermometry began to be used much later than in technology. As early as 1861, Karl Gerhard believed that temperature measurement was a very difficult procedure to introduce into practice and regular use. After some time, these simple but very necessary devices came to our homes from laboratories and clinics - medical thermometers, which worthily serve science and guard human health.
Probably the first device that could, if not measure, then at least estimate temperature was Galileo thermoscope : a flask the size of a chicken egg, the neck of which was thin like a wheat stalk, was filled halfway with water and immersed in a cup. Despite this simplicity, the device was very sensitive, although it responded, in addition to temperature, to air pressure.
In 1636 the word first appears "thermometer" . That's what it was called device of the Dutchman K. Drebbel — "Drebbel tool" for measuring temperature, having as many as 8 divisions.
Thermos to op Galileo. Drawing from about the 17th century.
I. Newto n in work 1701 “On the scale of degrees of heat and cold” described 12 degree scale , 0 0 which corresponded to the freezing temperature of water, and 12° to the body temperature of a healthy person. All these and many other thermometers were gas thermometers: when heated, the air expanded.
The first liquid thermometer, similar to a modern thermometer, was made by the German physicist G. Fahrenheit in 1724. Having been constructing alcohol and mercury thermometers for more than fifteen years, he figured out how to make them identical and more accurate readings: you need to take several points with a known temperature, plot their values on the scales and divide the distances between them.
Fahrenheit took the lowest temperature of the extremely harsh winter of 1709 as 0° and subsequently imitated it in a mixture of table salt and ammonia with ice. As a second reference point, he took the temperature of melting ice and divided this segment by 32 degrees. The third point - the temperature of the human body - turned out to be almost 98, and the boiling point of water was 212.
In A. Gaidar’s film script “The Commandant of the Snow Fortress” there is the following episode:
“The nanny points to Sasha:
- Look, father, he has a fever.
— Every person has a temperature.
“He has a temperature of one hundred degrees,” says Zhenya.
“Not everyone has this,” the doctor agrees.”
The dialogue invariably causes cheerful excitement among young readers, but children in the USA and England, where it is still accepted Fahrenheit , his comedy may not be appreciated: the patient’s temperature is 100° - just a slight fever, which just about anyone can have - 37.8° C.
Used in France and Russia Reaumur scale , created in 1730.
Com A natural thermometer from the early 20th century with Celsius and Reaumur scales.
.
R. Reaumur. Thermometers of this type were in use in our country until the 30s of the 20th century.
French naturalist, broad-minded scientist, “Pliny of the 18th century,” as his contemporaries called him, R. Reaumur built it in accordance with the thermal expansion of the liquid. Having discovered that when heated, a mixture of water and alcohol expands by 80 thousandths of its volume between the freezing and boiling temperatures of water (the modern value is 0.084), Reaumur divided this interval into 80 degrees.
A little earlier, at the beginning of the 18th century, thermometers of the St. Petersburg academician J. Delisle with a 150-degree scale on the same temperature range were widespread in Russia, but did not last long. Those who drove them out Réaumur thermometers were in use for almost two centuries and only some 50-60 years ago finally gave way to Celsius thermometers with a modern 100-degree scale .
By the end of the 18th century, the number of different temperature scales approached two dozen, which was both inconvenient and unnecessary. In addition, it soon became clear that even carefully calibrated instruments with different liquids show different temperatures. At 50°C, the mercury thermometer showed 43°C with alcohol, the thermometer with olive oil -49°C, with clean water - 25.6°C, and with salt water - 45.4°C.
Found a way out famous English physicist W. Thomson (Lord Kelvin) . In 1848, he proposed to measure not temperature, but the amount of heat that in a certain process called Carnot cycle , is transmitted from a hot body to a cold one: it is determined only by their temperatures and is completely independent of the heated substance. In the thermodynamic, or absolute, temperature scale built on this principle, The unit of temperature is called kelvin .
The thermodynamic scale was good for everyone, me one: in everyday practice, thermal measurements with subsequent calculations are extremely inconvenient, and Carnot cycle, perfectly studied theoretically, is difficult to reproduce outside of a specialized metrological laboratory. Therefore, on its basis in 1968 it was finally established International Practical Temperature Scale (MPTS-68) , which is based on 11 reproducible reference points between triple point in hydrogen (13.81 K) and solidification temperature of gold (1337.58 K ) and diverges from the thermodynamic scale in the boiling region of water by only 0.005 K. This scale is still used today.
Sometimes found in English and American scientific literature absolute scale of the Scotsman W. Rankin (mid-nineteenth century), one of the creators of technical thermodynamics. Its zero point coincides with 0 K, and degree Rankine equal in magnitude to a degree Fahrenheit.
Of all the many temperature scales, only four have reached our time, although this is clearly too much. In science, temperature is expressed in Kelvin, but in life we use Celsius and occasionally see the Reaumur and Fahrenheit scales.
It can be done using special relationships (formulas) or automatically on the pages of our website (follow the link on the left).
What is heat? Degrees and temperature
Everyone knows what heat is. It is known that particles in gases, liquids and solids are in continuous motion and this movement is perceived as heat. The energy of movement of particles, averaged over their huge number, determines the temperature.
The theory of heat did not arise immediately. For a very long time they could not understand what heat is, nor what the difference is between temperature and heat. Many physicists associated heat with the movement of molecules. So, in particular, Lomonosov thought. But turning general reasoning into a rigorous science was not easy.
The story of how they learned to measure temperature is interesting and unusual. Thermometers were invented many years before people understood what they measured.
Temperature is associated with very vague concepts of warmth and cold, which were located in the creation of man somewhere next to smell and taste. Since time immemorial, man has known that when two bodies come into close contact, thermal equilibrium is established between them. A hand placed in water becomes heated (or cooled) to the same degree as the water. Heat flows exist everywhere in nature. Natural scientists have long seen this as a manifestation of the great laws of nature.
Ancient scientists and medieval scholastics compared the properties of attraction and repulsion with heat and cold. Ancient doctors were the first to need a comparative and, moreover, fairly accurate scale of body heat. They noticed a long time ago that a person’s health is somehow related to the warmth of his body and that drugs can change this quality. Medicines were credited with a cooling or warming effect, and the degree of this effect was determined in degrees. Medicines were mixed with each other, and the mixtures had different degrees. “Mixture” in Latin means “temperature”.
History of the creation and development of the thermometer
Galileo
None of Galileo's contemporaries could compare with him in the ability to see great laws in simple phenomena. He was one of the first to write about the mechanical nature of heat.
Galileo published a book he called "EL saggiatore" (scales for weighing gold), in which he sets out in great detail his views on the nature of physical phenomena. In it, he talks, in particular, about the heating of solids by friction and provides other evidence of the mechanical nature of heat. However, he did not know that mechanically it is possible to heat not only solids, but also liquids or even gases. Galileo was also hampered by the lack of numerical data on heat.
Galileo approached the study of thermal phenomena from the same positions; First of all, he studied how to measure body temperature. Thermometers made by Galileo (circa 1597) consisted of a glass ball filled with air; From the bottom of the ball came a tube partially filled with water, which ended in a vessel also filled with water. The height of the column depended on both temperature and atmospheric pressure, and it was impossible to measure it with any accuracy with such a thermometer. Under Galileo, the very idea that air could press on the earth seemed quite wild. Therefore, Galileo's thermometer measured a rather uncertain value, but even such a thermometer made it possible to compare the temperature of different bodies at the same time and in the same place.
Even then, with the help of a still imperfect thermometer, the physician and anatomist Sanctorius from the University of Padua began to measure the temperature of the human body. To do this, he himself, not knowing about Galileo, built a similar thermometer.
Otto von Guerick
The history of the thermometer owes a lot to one of the most amazing people of the 18th century - Otto von Guericke. He made the first barometer. Similar to Galileo's device. But with a very long tube. Unlike Galileo's device, the air was pumped out of Garicke's barometer, so that water filled not only the long tube, but also part of the ball. The barometer was attached to the outside wall of the house, and the air pressure was noted on a scale pointed at by a wooden man floating in a glass ball. Guericke was the first to systematically measure atmospheric pressure and tried to discover the connection between changes in pressure and weather.
Garike also built a relatively good thermometer. It consisted of a brass ball filled with air and a U-shaped tube containing alcohol. On his thermometer in the middle of the scale there was a point near which the pointer stopped at the first frost - Garike chose this point as the beginning of the scale. It is clear that such a choice was naive, but still Garike took the first step.
Newton
Let us also mention Newton’s work “On the Scale of Degrees of Heat and Cold,” published in 1701, which describes a 12-degree scale. He placed zero in the same place where we place it now - at the freezing point of water, and 12 degrees corresponded to the temperature of a healthy person.
Amontan built a completely sealed thermometer, finally making it completely independent of atmospheric pressure.
The first modern thermometer was described in 1724 by Daniel Fahrenheit, a glassblower from Holland. Different Fahrenheit thermometers could be checked against each other by comparing their readings at different “reference” points on the scale. Therefore, they became famous for their accuracy. This scale is still in use in England and the USA.
Modern scale Celsius was proposed in 1742. The Swedish physicist did not like negative temperatures, and he considered it necessary to invert the old scale and place zero at the boiling point of water, and 100 degrees at its freezing point. But the “inverted scale” did not gain popularity and was very soon “inverted” back.
Before the revolution, the Reaumur scale was adopted in Russia (the water point was 0 and the boiling point was 80) - Reaumur thermometers hung on the streets and in all houses. Only in the thirties were they supplanted by Celsius thermometers.
What is heat? Thermal equilibrium
By the beginning of the 19th century, the thermometer had become a completely common device. But for a long time there was no consensus on what the thermometer measures.
Having learned to measure temperature, physicists have made little progress in understanding what heat is. The concepts of “heat” and “temperature” were even more difficult to separate. When a body is heated, its temperature rises. When heat flows from one body to another, the temperature of one body drops and the temperature of the other rises.
Concept "thermal equilibrium" very often found in the theory of heat. It is easiest to understand what thermal equilibrium is in the case of a monatomic gas. If the gas in a vessel behaves in such a way that the temperature at all points of the vessel is the same - naturally, the temperature of the walls of the vessel is also always the same - then the gas is in thermal equilibrium. This means that in such a gas heat does not flow from one part of the vessel to another, neither the pressure nor the chemical composition changes in it and, in general, from the point of view of classical thermal phenomena in a gas, “nothing happens.”
Heat always flows so that the temperature is equalized, so that the system goes into a state of thermal equilibrium. The transition to a state of thermal equilibrium can be a complex and rather lengthy process.
Temperature scale. Absolute temperature scale
Temperature scale
In all instruments that were invented in the 18th century, temperature measurement was reduced to measuring the length of a column of water, alcohol or mercury. Thermometers worked only in a limited temperature range. The substances filling them froze and boiled, and these thermometers could not measure very low or very high temperatures.
The Celsius scale accurately established the position of two points - 0 and 100 degrees, the distance between which on the scale was divided into equal parts. But the role of each division remained uncertain. It was also necessary to understand what happens in the body when the mercury in the thermometer rises by one degree. The easiest way would be to assume that in this case the energy of the body increases by the same amount. This value, per unit body mass, is called specific heat capacity.
Absolute temperature scale
The unit of temperature arose by chance - they set the number 100 at the boiling point of water. This act had important consequences: a new gas constant R = 8.3157 joule/degree appeared in the Clapeyron-Clausius law. This number arose only because the degree value was introduced a very long time ago and all changes occurring in gases were attributed, out of habit, to a rather randomly chosen temperature scale. It would be more convenient now to change the definition of a degree and “link” it to the ideal gas equation. To do this, you just need to reduce the degree value by 8.3157 times and assume that the temperature is on such an “ideal gas” scale:
Lord Kelvin's discovery
The question of the meaning of temperature became interested in Thomson (later Lord Kelvin), who in 1848 discovered that a simple but very important conclusion could be drawn from Carnot’s theorem. Kelvin noted that if the operation of the Carnot cycle depends only on the temperatures of the heater and refrigerator, then this makes it possible to establish a new temperature scale that does not depend on the properties of the working fluid.
The Carnot cycle, if it can be carried out between two bodies, allows one to determine the temperature ratio of these two bodies. The temperature scale defined in this way is called absolute temperature scale. In order for the absolute temperature itself to have a certain value, it is necessary to select some number for one point of the new absolute scale: one numerical value of the temperature must be set arbitrarily. After this, all other values are determined in principle using a Carnot cycle.
Unfortunately, despite all the beauty of the theoretical construction of the Kelvin scale, it is very difficult to practically implement the Carnot cycle. It is difficult to implement a reversible cycle, it is difficult to get rid of losses.
Real temperature scale
For many years, two points were chosen for the temperature scale - the melting point of ice and the boiling point of water - and the distance between them was divided into 100 parts, each of which was considered a degree. This scale with two reference points has been adopted throughout the world.
But this scale, however, had a big drawback in terms of measurement accuracy. For it, it was necessary to be able to accurately reproduce both the conditions for melting ice and the conditions for boiling water. It was easier to get by with one reference point, for example the melting point of ice, and measure the temperature in relation to the pressure ratio associated with the temperature ratio by the equation of state.
The so-called triple point of water is now selected as a reference reference point - the temperature at which all three of its phases are in equilibrium: steam - water - ice. The transition to such a scale went almost unnoticed. Such a reform was carried out in 1954, and now the question of what temperature ice melts at normal pressure must be answered “at approximately 0.”
International temperature scale
A scale with one reference point is not difficult to reconcile with the Kelvin-Mendeleev scale, based on Carnot's theorem. The thermodynamic scale does not change if all temperature values are multiplied by the same number. Selecting a reference point eliminates this ambiguity.
The thermodynamic scale can only be used in special, well-equipped laboratories. In ordinary laboratories they use a scale called MPTS68 (International Practical Temperature Scale, adopted in 1968). In this scale, the boiling point of water is exactly 100 degrees, in addition, there are other reference points that are also assigned a certain temperature value.
Low temperatures
Interest in obtaining low temperatures arose not only from practical considerations. Physicists have long been interested in the question of whether it is possible to turn gases such as air, oxygen, and hydrogen into liquid. The beginning of this story dates back to 1877.
In 1877, mining engineer Cayete dropped drops of liquid acetylene in a laboratory vessel, which suddenly developed a leak. The sharp drop in pressure caused fog to form. Almost on the same days, Pictet from Geneva reported a successive, cascading reduction of various gases, culminating in the production of liquid oxygen at a temperature of -140 degrees Celsius and a pressure of 320 atmospheres.
We must also mention Dewart. Which in 1898 produced liquid hydrogen, reducing the temperature to approximately 129 K. Finally, in 1908, Kamerlingh Onnes in Holland also obtained liquid helium. The temperature that he achieved was only 1 degree different from absolute zero.
In 1939, P.L. Kapitsa proved the great efficiency of liquefaction machines in which gas does work using a turbine. Turboexpanders have since become widespread. He also proposed the design of an effective installation for liquefying helium.
Bibliography
Edelman V.S. “Near absolute zero.” 1-M., 1987.
Detlaf A.A., Yavorsky B.N., “Physics course”. -M., 1989.
Trofimova T.I. "Physics course". 1-M., 1990.
Smorodinsky Ya.A. "Temperature". - M., 1987.
Text taken from the site: www.xreferat.ru
Megalov A.
Temperature is one of the most important indicators that is used in various branches of natural science and technology. In physics and chemistry it is used as one of the main characteristics of the equilibrium state of an isolated system, in meteorology - as the main characteristic of climate and weather, in biology and medicine - as the most important quantity that determines vital functions.
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Presentation on the topic: “History of the invention of thermometers” The presentation was made by a student of the Municipal Educational Institution “Gymnasium No. 2” 10 “A” class Megalov Artem
Galileo Galilei's thermoscope In 1592, Galileo Galilei created the thermoscope. The thermoscope was a small glass ball with a soldered glass tube. The ball was heated and the end of the tube was dipped into water. When the ball cooled, the pressure in it decreased, and the water in the tube, under the influence of atmospheric pressure, rose to a certain height. As the weather warmed, the water level in the tubes dropped. The disadvantage of the device was that it could only be used to judge the relative degree of heating or cooling of the body, since it did not yet have a scale.
Florentine thermometers Later, Florentine scientists improved Galileo's thermoscope by adding a scale of beads and pumping out the air from the balloon. In the 17th century, the air thermoscope was converted into an alcohol thermoscope by the Florentine scientist Torricelli. The device was turned upside down, the vessel with water was removed, and alcohol was poured into the tube. The operation of the device was based on the expansion of alcohol when heated - now the readings did not depend on atmospheric pressure. This was one of the first liquid thermometers. Florence thermometer
Two extreme points At that time, the instrument readings were not yet consistent with each other, since no specific system was taken into account when calibrating the scales. In 1694, Carlo Renaldini proposed taking the melting point of ice and the boiling point of water as two extreme points.
Fahrenheit's mercury thermometer In 1714, D. G. Fahrenheit made a mercury thermometer. He marked three fixed points on the scale: 32°F is the freezing point of saline solution, 96°F is the human body temperature, and 212°F is the boiling point of water. The Fahrenheit thermometer was used in English-speaking countries until the 70s of the 20th century, and is still used in the USA.
The Frenchman Reaumur scale Another scale was proposed by the French scientist Reaumur in 1730. He experimented with an alcohol thermometer and came to the conclusion that a scale could be constructed in accordance with the thermal expansion of alcohol. Having established that the alcohol he used, mixed with water in a ratio of 5:1, expands in a ratio of 1000:1080, the scientist proposed using a scale from 0 to 80 degrees. Taking the melting temperature of ice as 0°, and the boiling temperature of water at normal atmospheric pressure as 80°.
Anders Celsius scale In 1742, Anders Celsius proposed a scale for a mercury thermometer in which the interval between extreme points was divided into 100 degrees. At the same time, at first the boiling point of water was designated as 0 °, and the melting temperature of ice as 100 °. However, in this form the scale turned out to be inconvenient, and later astronomer M. Stremer and botanist K. Linnaeus decided to swap the extreme points.
Various thermometers and scales M. V. Lomonosov proposed a liquid thermometer with a scale of 150. I. G. Lambert was responsible for the creation of an air thermometer with a scale of 375 °, where one thousandth of the expansion of air volume was taken as one degree. There were also attempts to create a thermometer based on the expansion of solids. So in 1747, the Dutchman P. Muschenbrug used the expansion of an iron bar to measure the melting point of a number of metals.
Absolute Kelvin scale In the temperature scales discussed above, the reference point was arbitrary. At the beginning of the 19th century, the English scientist Lord Kelvin proposed an absolute thermodynamic scale. At the same time, Kelvin substantiated the concept of absolute zero, denoting the temperature at which the thermal movement of molecules ceases. In Celsius it is -273.15 °C.
How it was then This is the basic history of the emergence of the thermometer and thermometric scales. Today, thermometers with the Celsius, Fahrenheit (in the USA), and Kelvin scales are used in scientific research
As it is now Currently, temperature is measured using instruments whose action is based on the various thermometric properties of liquids, gases and solids. Today, there are many devices used in industry, in everyday life, and in scientific research - expansion thermometers and laboratory equipment, thermoelectric and resistance thermometers, as well as pyrometric thermometers that allow you to measure temperature in a non-contact way.
Before the invention of such an ordinary and simple measuring device for our everyday life as a thermometer, people could judge their thermal state only by their immediate sensations: warm or cool, hot or cold.
History of invention
The history of thermodynamics began when Galileo Galilei created the first instrument for observing changes in temperature in 1592, calling it a thermoscope. The thermoscope was a small glass ball with a soldered glass tube. The ball was heated and the end of the tube was dipped into water. When the ball cooled, the pressure in it decreased, and the water in the tube, under the influence of atmospheric pressure, rose to a certain height. As the weather warmed, the water level in the tubes dropped. The disadvantage of the device was that it could only be used to judge the relative degree of heating or cooling of the body, since it did not yet have a scale.
Later, Florentine scientists improved Galileo's thermoscope by adding a scale of beads and pumping out the air from the balloon.
In the 17th century, the air thermoscope was converted into an alcohol thermoscope by the Florentine scientist Torricelli. The device was turned upside down, the vessel with water was removed, and alcohol was poured into the tube. The operation of the device was based on the expansion of alcohol when heated - now the readings did not depend on atmospheric pressure. This was one of the first liquid thermometers.
At that time, the readings of the instruments were not yet consistent with each other, since no specific system was taken into account when calibrating the scales. In 1694, Carlo Renaldini proposed taking the melting point of ice and the boiling point of water as two extreme points.
In 1714, D. G. Fahrenheit made a mercury thermometer. He marked three fixed points on the scale: the bottom, 32°F, is the freezing point of the saline solution, 96°, the human body temperature, and the top, 212°F, the boiling point of water. The Fahrenheit thermometer was used in English-speaking countries until the 70s of the 20th century, and is still used in the USA.
Another scale was proposed by the French scientist Reaumur in 1730. He experimented with an alcohol thermometer and came to the conclusion that a scale could be constructed in accordance with the thermal expansion of alcohol. Having established that the alcohol he used, mixed with water in a ratio of 5:1, expands in a ratio of 1000:1080 when the temperature changes from the freezing point to the boiling point of water, the scientist proposed using a scale from 0 to 80 degrees. Taking the melting temperature of ice as 0°, and the boiling temperature of water at normal atmospheric pressure as 80°.
In 1742, the Swedish scientist Andres Celsius proposed a scale for a mercury thermometer in which the interval between extreme points was divided into 100 degrees. At the same time, at first the boiling point of water was designated as 0°, and the melting temperature of ice as 100°. However, in this form the scale turned out to be not very convenient, and later astronomer M. Stremer and botanist K. Linnaeus decided to swap the extreme points.
M.V. Lomonosov proposed a liquid thermometer with a scale with 150 divisions from the melting point of ice to the boiling point of water. I. G. Lambert is responsible for the creation of an air thermometer with a scale of 375°, where one thousandth of the expansion of air volume was taken as one degree. There were also attempts to create a thermometer based on the expansion of solids. So in 1747, the Dutchman P. Muschenbrug used the expansion of an iron bar to measure the melting point of a number of metals.
By the end of the 18th century, the number of different temperature scales had increased significantly. According to Lambert's Pylometrics, there were 19 of them at that time.
The temperature scales discussed above are distinguished by the fact that the starting point for them was chosen arbitrarily. At the beginning of the 19th century, the English scientist Lord Kelvin proposed an absolute thermodynamic scale. At the same time, Kelvin substantiated the concept of absolute zero, denoting the temperature at which the thermal movement of molecules ceases. In Celsius it is -273.15°C.
Types of thermometers
This is the basic history of the emergence of the thermometer and thermometric scales. Today, thermometers with the Celsius, Fahrenheit (in the USA), and Kelvin scales are used in scientific research. Currently, temperature is measured using instruments whose action is based on the various thermometric properties of liquids, gases and solids. And if in the 18th century there was a real “boom” of discoveries in the field of temperature measurement systems, then in the last century a new era of discoveries began in the field of methods for measuring temperature. Today there are many devices used in industry, in everyday life, and in scientific research - expansion thermometers and manometric thermometers, thermoelectric and resistance thermometers, as well as pyrometric thermometers that allow you to measure temperature in a non-contact way.
