The History of Thermometers

Ⅰ. The invention of the thermometer—Start with Galileo's "Gas"

Galileo Galilei, an Italian scientist, and mathematician was giving a lecture at the University of Padua in Venice in 1592 while doing experiments on heating water.

"Why does the water level rise when the temperature of the water in the tank rises?" Galileo enquired of his disciples.

"Because as the water temperature rises, the volume rises and the water surface rises," the student explained, "and when the water temperature falls, the volume decreases and the water surface falls."

Galileo came into a difficulty he had previously experienced while listening to the pupils' responses.

It was later discovered that some doctors contacted Galileo and pleaded with him: "When people are unwell, their body temperature tends to rise. Is there a way to correctly measure body temperature to aid in disease diagnosis?"

Galileo employed the idea of heat expansion and cold contraction to solve this question, and after many years of research and development, he produced the bubble-shaped glass tube thermometer in 1593, inspired by his pupils' responses. This thermometer has a glass bulb on top, and a glass tube connecting to it is filled with colored liquid that is inverted in a cup of water to measure the temperature. When the substance of the measured temperature (here, air) comes into contact with the glass bubble, the air above the glass tube changes in volume due to thermal expansion and contraction, causing the colored liquid column to drop or rise accordingly; the glass tubes were marked with some standard "hotness" - what is now called the temperature. This is the first scaled thermometer in the world - a gas thermometer.

Changes in atmospheric pressure also raise the liquid column, therefore gas thermometers aren't perfect. The concept of measuring temperature using the thermal expansion and contraction properties of gases existed long before Galileo. Philon and Alexander Shiron, for example, were ancient Greek scientists who developed thermometers based on the idea of air expansion.

Ⅱ. The evolution of thermometers -From gas to liquid and solid

Galileo's friend and colleague, Professor Sanctorio Sanctorius, a physiologist and doctor at the University of Padua, refined Galileo's gas thermometer and built a serpentine glass tube in 1612. thermometer for gas It contains a red liquid. The liquid is pressed down as the air expands, and the temperature change can be observed on the 110 scales engraved on the glass tube. It can be used to determine the temperature of a person's body. It is the world's earliest thermometer.

Because Sanctorius' thermometer was inaccurate, Jean Rey, a French physician, chemist, and physicist, inverted Galileo's glass tube and utilized the volume change of water instead of air to measure how hot or cold an object was in 1632. However, because the nozzle of this thermometer is not sealed, water evaporation will create mistakes. This is the first thermometer that uses water to measure temperature.

In 1641, Ferdinand II, Grand Duke of Tuscany, Italy, introduced the first thermometer that used red-stained alcohol as a temperature measurement material. From 1644 until 1650, he worked on perfecting it into a contemporary thermometer: a glass tube filled with red alcohol was sealed with wax, and a scale was written on the glass tube. As a result, some people credit the Archduke with inventing the thermometer. This thermometer became famous in Florence in 1654.

Another way of putting it is that in 1629, another of Galileo's University of Padua colleagues, Joseph Demitigo, an Italian physicist and Jewish instructor, produced a book called "In the Garden" fountain. The first thermometer is depicted in the novel as a glass bubble thermometer filled with brandy with the words "oleb" (to rise) next to it. The originator of this thermometer, however, is unknown; it is most likely Galileo or Demetrio.

The freezing and boiling temperatures of water were suggested as the two fixed points of a graduated thermometer by the Italian physicist Reinaldini in 1646. Unfortunately, the boiling point of alcohol (78.5°C) was lower than that of water (100°C) in the common alcohol thermometer at the time. As a result, if the boiling point of water was the second fixed point, it was evident that this recommendation would be impractical for alcohol thermometers at the time. It's worth noting that the International Committee of Weights and Measures announced in 1989 that the boiling point of water would be set at 99.975 °C beginning January 1, 1990.

Ismail Borio, a French astronomer, mathematician, and Catholic priest who has been called "the most fascinating individual in the history of science," invented the first thermometer in 1658. One of his stories is that the formula for calculating universal gravitation was discovered long before British physicist and mathematician Isaac Newton, among others, but Borio later denied the accurate formula.

Huygens, a Dutch physicist, astronomer, and mathematician, proposed in 1665 that thermometers be standardized by using the freezing and boiling points of water as two fixed points. Based on Boyle's law, which he established in 1662, British scientist and chemist Boyle pointed out the reasons behind the inaccuracy of gas thermometers and other flaws in the same year. Since then, the development of thermometers that use various media as temperature-measuring substances has dominated. Hubin, a French inventor, produced the first air thermometer in Paris in 1672 that was not impacted by atmospheric pressure.

There were 19 different types of temperature scales with precise historical records in 1779. There were more than 30 types by the end of the nineteenth century, and there were innumerable types of thermometers.

Amonton, a French physicist, was the first to notice that the temperature-measuring liquid expands in a regular pattern and that the temperature "exists at absolute zero." He created a more practical air thermometer in 1703.

Ⅲ. "On-demand improvement" temperature scale

A temperature scale is a standard scale (such as fixed point, scale, and scale interval) used to measure temperature in order to assure that temperature results are uniform and accurate. Following Galileo's invention of the gas thermometer, scientists have continued to explore the thermometer's temperature measurement material and temperature scale, making it more precise, convenient, and practical and expanding the thermometer's research content. The following is a brief overview of five commonly used temperature scales.

A kind of "empirical temperature scale" - "Fahrenheit temperature scale"

Warren Heights, a physicist, inventor, instrument maker, and glassworker, set the equilibrium temperature of a mixture of ice, water, and ammonium chloride at 0°F, and the temperature of the human body at 96°F (based on today's average standard body temperature of 37°C, it should be 98.6°F), which is divided into 96 grids, each of which is 1°F, between 1709 and 1714. He put the boiling point of water at 212°F again in 1724; regrettably, he did not place the melting point of ice at 0°F, but rather at 32°F. This is the well-known "Fahrenheit temperature scale," which is still commonly used in various European and American countries, as well as Hong Kong, Macau, and other Chinese territories. It's an "empirical temperature scale" based on empirical formulas or experimental methodologies. Warren Heights is also credited with inventing the alcohol thermometer in 1709. In addition, he created the world's first practical mercury thermometer in 1714 and established the purification procedure for filling the working substance mercury.

Why did Warren Heights set the freezing point at a "weird" 32°F and the boiling point at 212°F?

The benefit of this setup, according to him, was to divide the water into 180 equal parts from freezing to boiling, and then to get one's body temperature as close to 100°F as feasible (actually 98.6°F). . In reality, the true reason for his setup has yet to be revealed.

Two temperature scales with water as the "standard" - "Lee's temperature scale" and "Celsius temperature scale"

Leo Muir, a French biologist, scientist, entomologist, and inventor, invented an alcohol thermometer in 1730 that set the freezing point of water to 0°R and the boiling point to 80°R. Each grid is 1°R and there are 80 of them. The famous "Lee's temperature scale" is seen here.

In France and Germany, the Leigh temperature scale is only utilized on rare occasions. In 1742, the Swedish physicist and astronomer Celsius devised a mercury thermometer that put the boiling point of water at 0°C and the melting point of ice at 100°C, respectively, and split it into 100 grids, each grid being 1°C. The renowned "Celsius temperature scale" is shown here.

Chrissen noted in 1743 that the temperature scale's fixed point did not follow the usual pattern of hotter items being warmer. Celsius's colleague Carl von Linnaeus reversed the degrees of freezing and boiling in 1745, a year after his death (the boiling point of water and the melting point of ice were placed at 100°C and 0°C, respectively). This is the Celsius scale, after all, which is still in use today. Others, however, claim that this "inverted" work was completed in 1750 by another of Celsius's colleagues, Martin Strawmore, his successor.

The three temperature scales listed above are the original fundamental temperature scales. They have three drawbacks: the temperature value is only correct at two fixed places, and the remaining points are erroneous; the definition range is limited - for example, a mercury thermometer's measurement range is -38.87°C+356.9°C; thermometer (such as water or mercury). Is it possible to come up with a temperature scale that doesn't require the use of a thermometer? The fourth temperature scale below, Can, compensates for these flaws.

Throwing off the temperature scale of the thermometer containing the temperature-measuring substance - "thermodynamic temperature scale"

The "thermodynamic temperature scale" was proposed by British physicist William Thomson, Lord Kelvin, in 1848. In 1854, he also noted that such a temperature scale can be totally established by selecting a value at a fixed point, which is "absolute zero." However, he had to utilize the interval of 0-100°C of Celsius as 100 temperature intervals, that is, each interval was 1 Kelvin degree (1°K), when he actually formed the thermodynamic temperature unit, taking into consideration historical tradition and technical constraints at the time. This is the "Kelvin temperature scale," also known as "ideal gas temperature scale," "thermodynamic absolute temperature scale," and so on, which is still widely used in scientific research. The Kelvin temperature scale is unique in that it has nothing to do with the object's qualities, and the thermodynamic temperature is exclusively related to heat. The Kelvin temperature scale has the advantage of being unaffected by the temperature-measuring substance, and it removes the temperature-measuring material's limitations due to solidification and vaporization.

Because of its accuracy and simplicity, the Seventh International Conference on Weights and Measures (CGPM) chose to use the Kelvin temperature scale as the most basic temperature scale in 1927. While studying at the Massachusetts Institute of Technology in 1934, Huang Ziqing, a well-known Chinese chemist and chemical educator, estimated the triple point of water to be 0.009810.00005°C (about 0.01°C) (MIT). The 10th CGPM resolved to utilize this temperature as a single fixed point of the thermodynamic temperature scale in 1954, and it was given the numerical value of 273.16°K.

Another fixed point exists on the thermodynamic temperature scale that cannot be characterized by known physical properties of materials. Absolute zero, or 0 Kelvin, is the lowest temperature that can be calculated mathematically. The 13th CGPM, in 1967, altered the thermodynamic temperature unit from Kelvin (the above °K) to Kelvin (K - short for Kelvins); Temperature Scale" (abbreviated as "International Practical Temperature Scale" or "International Temperature Scale") and "Thermodynamic Temperature." The International Committee on Weights and Measures followed suit in 1968. On January 1, 1973, it was also adopted by China.

Thermodynamic temperature (K) and Celsius (°C) are the only two legal temperature measurement units in China - and the only two legal temperature measurement units in the International System of Units. Thermodynamic temperature (K) has been abandoned and can only be used in exceptional circumstances. 1K=1°C=1.8°F is the conversion formula for thermodynamic temperature (K), Celsius (°C), and Fahrenheit (°F).

Until now, a temperature scale is known as "Lan's temperature scale" has been "illegally employed" in the country.

The fifth temperature scale, known as the "Rankine temperature scale," was established by "the genius of his day," British inventor and civil engineer Rankin, and is currently utilized by the American engineering community. The Rankine temperature unit is °R. The Rankine temperature scale is also a "absolute temperature scale" because it starts at the triple point of water (273.16K).

Ⅳ. "On-demand improvement" thermometer

People have improved and invented various thermometers to measure different temperatures of various objects in response to the establishment of the Celsius temperature scale and the thermodynamic temperature scale, the maturity of thermometer manufacturing technology, and the needs of actual measurement.

Consider the telemetry resistance thermometer developed by German inventor Karl Wilhelm Siemens in 1860. Another example is the modern mercury thermometer, which was designed by British doctor Thomas Clifford Albert between 1865 and 1867 and is still in use today to measure the temperature of the human body - it reads the same after leaving the human body and is accurate to 0.1 °C. When it leaks, though, the mercury can be dangerous. The electronic thermometer was designed in 1984 by a Finnish medical equipment designer (more convenient, no leakage of harmful substances).

The successful development of the "inverted thermometer" in 1874 can be used to determine the temperature of various strata beneath the surface of rivers and lakes. This thermometer has become exceedingly dependable and accurate (up to 0.02°C) after more than a century of continual refinement, and it is still commonly used in oceanographic surveys.

The Belgian astronomer and scientist Nan Huairen, who first introduced the thermometer to China during the reign of Emperor Kangxi of the Qing Dynasty, depicted the gas thermometer he produced in the "Lingtai Yixiang Tu," which was completed in 1664.

Lingtai is an observatory—an old observatory in what is now Beijing, located southwest of Jianguomen. A U-shaped glass tube is placed on a wooden frame in Nan Huairen's thermometer. The U-shaped tube's upper left end is attached to a glass ball, while the upper right end is open. The liquid (water or wine) is pumped into the U-shaped tube when it reaches the horizontal line. The liquid will rise in the right or left arm of the U-shaped tube as the gas in the glass ball expands or contracts owing to the impact of the external temperature, and there are scales beside the left and right arms to display the temperature.

Different media materials, measuring objects, purposes, temperature display technologies, temperature measurement ranges, and different means of showing temperature (typically linear scales and pointers) are all available in today's thermometers. Many new types of thermometers are available in the interior, including semiconductor thermometers, thermocouple thermometers, bimetal thermometers, liquid crystal thermometers, digital thermometers, optical pyrometers, double-standard thermometers with easy conversion between °C and °F, and dry-type thermometers that can measure both air temperature and air humidity. For fast body temperature measurement, use a wet bubble thermometer or a forehead thermometer.