The development of metal production led to the emergence of the skill - the art of some people - metallurgists to determine the "correct" or "incorrect" thermal (temperature) state by the color of the melt or product during its forging. Later, with the development of science and technology, it became necessary to determine not the qualitative, but the quantitative level of the thermal state of a product, an industrial or laboratory furnace. An instrument called a thermometer appeared. It allowed one to control the thermal state of an object - its temperature. In 1597, Galileo Galilei created the world's first device for measuring air temperature - a "thermoscope", which consisted of a glass ball filled with air. A tube, partially filled with water, extended from the bottom of the ball, ending in a tall vessel, a glass tube, also filled with water. When the air, heating up, expanded or, cooling down, contracted, the water level in the glass tube changed, which served as an indicator of the temperature, for example, of a hand heating the ball when touching it. In 1655, Huygens proposed using the boiling point of water as the reference point for a thermometer, which made it possible to compare temperatures (“observed degrees of heat”) in different places without moving the same thermometer from place to place. In 1701, I. Newton published his work “On the Scale of Degrees of Heat and Cold,” which described a 12-degree scale. He placed zero where it is now — at the freezing point of water, and 12 °C corresponded to the temperature of a healthy person.
The first modern thermometer was created by the Dutch glassblower D. Fahrenheit in 1724, whose scale is still used in the United States and Great Britain. A similar device in France began to be used in 1740 with the Reaumur scale. The modern Celsius scale was proposed in 1742. However, glass thermometers had only limited use due to the fragility of the design and the relatively small range of measured temperatures.

In 1821, the German scientist Thomas Johann Seebeck studied the Earth's magnetic field at the University of Dorpat (now Tartu). Seebeck observed the emergence of a magnetic field, which was recorded by the deflection of the magnetic needle. From this experiment, Seebeck concluded that "the temperature difference at the points of contact of the metal circuit is the source of the released magnetism, the cause of magnetic actions." Based on these experiments, the first thermoelectric battery was created. Seebeck's discovery marked the beginning of a qualitatively new stage in the development of science.

A huge number of measuring instruments (MI), energy sources and other extremely important devices have been created based on the Seebeck effect.
We will provide a description of measuring instruments whose operation is based on the Seebeck effect, by the type of controlled parameter and the method of application in metallurgy.
1. Type of controlled parameter:
1.1. temperature of the object (product) - thermoelectric thermometer (standard or non-standard calibration); natural thermocouple; Sensing element of total radiation pyrometer (battery of 10−12 thermocouples); Temperature conditions of annealing in a continuous furnace;
1.2. Heat flow — heat meter with thermoelectric sensors;
1.3. Metal and alloy composition — determination of content of one element;
determination of content of several elements; grading (separation, sorting) by grades;
1.4. Control of metal and alloy structure — determination of phase composition; control of mechanical properties, type of plastic deformation, drawing mode, nature of heat treatment (quenching, normalizing, tempering, etc.);
Definition of complex heat treatment (presence of heating to a certain temperature, quenching, cooling); Application of the thermoelectric force method to refinement of phase diagram of alloys; Study of transfer mechanism in metallurgical systems;
1.5. Oxidizing (decarburizing) potential of furnace gas atmosphere;
1.6. Surface layer and coating parameters — coating thickness and composition (elemental or phase); size of decarburized layer; carbon content in decarburized layer; depth of thermal diffusion layers; quality of bimetallic steel-copper wire.
2. State of measurement object — solid metals and alloys; metallurgical melt, furnace gas atmosphere.
3. Location of measurement process — directly in the unit;
on the working platform near the unit or in the heat shield room; in a special laboratory.
4. Nature of measurement process — static; dynamic; discrete; continuous.
5. Type of process for obtaining measurement result — direct; indirect (with calculation by mathematical model).
6. Time interval of measurement process — operational (express method); continuous measurement during operation of the unit.
As the experience of civilization development shows, the successes of modern science and technology are largely based on the use of this discovery.