"Pendant Charles Augustin"
Charles Augustin Pendant ( 1736- 1806)
French military engineer and physicist, researcher of electromagnetic and mechanical phenomena; Member of the Paris Academy of Sciences. A unit is named after him electric charge and the law of interaction of electric charges.
Charles Coulon was born on June 14, 1736 in Angouleme, in the family of a government official. He studied at the College of Four Nations. After graduating from this institution, he passed the exams and in February 1760 entered the Military Engineering School in Mézières, one of the best higher technical educational institutions of the 18th century. He graduated from the School in 1761, received the rank of lieutenant and was sent to Brest, where he was engaged in cartographic work. Then, for several years, Coulon served in the engineering forces on the French island of Martinique at Fort Bourbon. I was seriously ill many times. Due to health reasons, he was forced to return to France and served in La Rochelle and Cherbourg. In 1781 he settled in Paris. After the outbreak of the revolution in 1789, he resigned and lived in Blois.
Scientific activity
In the early 1770s, Coulomb became actively involved in scientific research. Published works on technical mechanics (statics of structures, theory of windmills, mechanical aspects of torsion of threads, etc.) Coulomb formulated the laws of torsion; invented torsion balances, which he himself used to measure electric and magnetic interaction forces. In 1781 he described experiments on sliding and rolling friction? and formulated the laws of dry friction. From 1785 to 1789 he published seven memoirs, where he formulated the law of interaction of electric charges and magnetic poles(Coulomb's law), as well as the pattern of distribution of electrical charges on the surface of a conductor. Introduced the concepts of magnetic moment and charge polarization. In 1789 he published a work on the theory of sliding friction.
After the revolution, the Academy of Sciences repeatedly summoned the scientist to Paris to participate in the determination of weights and measures. Coulomb became one of the first members of the National Institute, which replaced the academy. Coulomb died on August 23, 1806 in Paris.
Charles Augustin Coulomb (1736-1806)- an outstanding French engineer and physicist, one of the founders of electrostatics. He studied the torsional deformation of threads and established its laws. He invented (1784) the torsion balance and discovered (1785) the law named after him. Established the laws of dry friction. Coulomb's experimental studies were fundamental to the formation of the doctrine of electricity and magnetism. Member of the Paris Academy of Sciences.
C. Coulon achieved brilliant scientific results. The laws of external friction, the law of torsion of elastic threads, the basic law of electrostatics, the law of interaction of magnetic poles - all this is included in the golden fund of science. “Coulomb field”, “Coulomb potential”, and finally, the name of the unit of electric charge “coulomb” is firmly established in physical terminology.
Years of study
Charles's father, Henri Coulon, a government official, soon after the birth of his son moved with his family to Paris, where for some time he held a lucrative position collecting taxes, but, having embarked on speculation that ruined him, he returned to his homeland, to the south of France, to Montpellier. Charles and his mother remained in Paris.
In the late 1740s, Charles was placed in one of the best schools of that time for young people of noble origin - the “College of the Four Nations”, also known as the Mazarin College. The level of teaching there was quite high, in particular, much attention was paid to mathematics. In any case, young Charles Coulomb was so carried away by science that he resolutely opposed his mother’s intentions to choose for him the profession of a doctor, or, in extreme cases, a lawyer. The conflict became so serious that Charles left Paris and moved to his father in Montpellier.
Military engineer
In this city, back in 1706, a scientific society was founded, second only to the capital's academy. In February 1757, 21-year-old Coulomb read his first scientific work there, “Geometrical Essay on Mean Proportional Curves,” and was soon elected an adjunct in the mathematics class.
But this brought only moral satisfaction; it was necessary to choose a further path. After consulting with his father, Charles chose a career as a military engineer. The Montpellier Scientific Society supplied Coulomb necessary recommendations, and after passing the exams (quite difficult, so preparing for them required nine months of classes with a teacher), Charles Coulon in February 1760 went to Mézières, to the Military Engineering School, one of the best higher technical educational institutions of that time.
Education at school was conducted with a clearly expressed practical bias: in addition to mathematics, physics and other “theoretical subjects”, many purely applied disciplines were studied - from construction and what would now be called “materials science”, to issues of labor organization (students were entrusted with leadership brigades of peasants mobilized for public works). Charles Coulon graduated from the School in 1761.
Although the review of him by the head of the School looks in some places not at all enthusiastic (“His work on the siege is worse than average, the drawings are made very poorly, with erasures and marks... Coulomb believes, like others with a similar way of thinking, that wood for gun carriages and carts can be easy to find in the forest..."), he was probably among the best graduates (rewarded with a cash prize).
First 10 years of service
Having received the rank of lieutenant, Charles Coulon was sent to Brest, one of the major ports on the west coast of France. In Brest, Kulon was entrusted with cartographic work related to the construction and reconstruction of fortifications on the coast. But this activity was rather short-lived.
Less than two years later, Coulon had to urgently get involved in the construction of a fortress on the island of Martinique in the West Indies to protect it from the British. The announced competition for the fortification project was won by the experienced military engineer de Rochemore, but this project caused a great controversy, in which Charles Coulomb was also involved. Although the project as a whole was successfully defended, significant changes had to be made to it; in particular, appropriations were reduced by more than half. Coulon, who remained the de facto manager of the construction, under whose supervision almost one and a half thousand people worked, found himself faced with many very complex, and not only technical, problems. The working conditions were difficult, the climate was very difficult, there were not enough people, and those who remained were seriously ill. During his eight years of work on the island, Coulon himself was seriously ill eight times and subsequently returned to France with severely compromised health. The extensive experience he acquired came at a high cost to his own health.
After returning home
Returning to France, Charles Coulon in 1772 received an appointment to Bouchaine. The working conditions here were incomparably easier, and the opportunity arose to actively continue scientific activities again. The problems he solved belong to the area that would now be called structural mechanics and strength of materials. Already at that time, this area attracted great attention from many physicists and mathematicians. After returning to his homeland, Coulomb, having carried out quite a large number of new studies, sent his memoir to the Paris Academy of Sciences, and then read it at two meetings in March and April 1773. Two academicians who were entrusted with its review spoke highly of this work (one of them, Borda, was subsequently saved by Charles Coulon during the Jacobin dictatorship, hiding him on his estate). This was a great support for the author.
But soon Coulomb became interested in new problems. In 1775, the Paris Academy of Sciences announced a competitive task: “Research the best way making magnetic needles, hanging them and checking whether their direction coincides with the direction of the magnetic meridian and, finally, explaining their regular daily variations." As for the last part of the problem, its solution was clearly inaccessible at that time (even about the very reason for the existence magnetic field Not everything is known about the Earth not only then, but even now!), but here is the problem of the best device the compass and, in particular, the suspension of the magnetic needle was relevant. She captivated Coulon.
About how difficult this task was, what high accuracy required to be ensured, one can judge at least from the following fact: the arrow suspended on a thin silk thread reacted so sensitively to all influences that it was necessary to protect it not only from the weakest air currents, but even from the approach of the observer’s eye (on the arrow and on the human body there is always there may be electric charges, and their interaction can affect the forces).
To eliminate this, Coulomb decided to replace the silk threads with metal wire that conducts electricity. This was a step that played a very important role later when Coulomb invented and began to use torsion balances. But so far this work was still far away.
In 1777, Charles Coulomb won a competition to develop an instrument for studying the Earth's magnetic field, and immediately plunged into another major work: the study of friction. In 1779 (and then again in 1781), the Academy announced another competition dedicated specifically to friction. Already in 1780, Coulomb submitted a competition work to the academy, “The Theory of Simple Machines,” which a year later was also awarded a prize. The results of this work were based on numerous experiments by Coulomb, which examined how friction between solids, and friction in liquids and gases. Coulomb carried out this work already in Lille, where he was transferred at the beginning of 1780. About a year later, his long-standing wish was fulfilled: he was transferred to Paris, where on December 12, 1781 he was elected to academician in the class of mechanics.
In Paris
In the capital, Charles Coulon was almost immediately faced with many cases, including administrative ones. Some of them also had political overtones, and one of them even ended for Coulon with a week's imprisonment in the prison of the Abbey of Saint-Germain des Pres. Meetings in numerous commissions, in particular the Canal Commission in Brittany, left little time for science, and, nevertheless, Coulomb presented his work to the academy in 1784, which can be considered very important: a memoir about the torsion of thin metal threads, and 1785-89 - a series of memoirs on electricity and magnetism.
The study of thread torsion may seem to have only an auxiliary “technical” value, but without it further quantitative measurements of the force of interaction between electric charges and magnetic poles would be impossible. As always, Charles Coulomb's work was distinguished by its depth and ingenuity. Thus, the diameter of very thin threads was determined by Coulomb by weighing and measuring their length. Much of what was included in the classical studies of Coulomb can now be seen in the works of some of his predecessors. Thus, torsion balances were used by the outstanding English scientist Henry Cavendish back in 1773, but he did not publish his works; they were published only a century later.
An important point for solving the whole problem was that Coulomb understood: it is necessary to study the interaction of “point” charged bodies, i.e. such, the distances between which significantly exceed their sizes. But even here Coulomb was not the first. The Englishman Robison (1739-1805) came to the same idea, who, as a result of careful experiments, came to the conclusion that the force electrical interaction between bodies is inversely proportional to the square of the distance between them, but he reported his results only in 1801, much later than Coulomb.
However, the law inverse squares“has long seemed almost obvious to many. And it's not just the hypnotizing example of the law universal gravity the great Newton. Another law would not explain many observable facts (for example, why inside a box with conducting walls, no matter what charge is placed on it, no electric field not felt).
Coulomb's law is now probably known to every schoolchild. But it’s unlikely that many people know what skill and observation the researcher had to show.
Charles Coulomb noticed in passing, that charges “drain” from bodies quite quickly, and he correctly explained this by the fact that air has some conductivity. This circumstance complicated the experiment, but it itself became important discovery. Many people know that the law of interaction of magnetic poles, also carefully studied by Coulomb, is outwardly very similar to the law of interaction of electric charges. Because of this, electrostatics and magnetostatics have long seemed similar to each other in everything, except that amazing fact that “magnetic charges” of opposite signs for some reason always occur in pairs and never separately. Only after Ampere's work did it become clear that magnetic fields permanent magnets are due not to the fact that they consist of a huge number of small magnets (as, we note, Coulomb believed), but electric currents, i.e. movement of electric charges.
The modern classical (i.e., non-quantum) theory of electrical and magnetic phenomena is often called the electrodynamics of Faraday and Maxwell. Of course, many other remarkable scientists also took pride of place in the writing of this most important chapter of physics, and the name of Charles Coulomb should rightfully be mentioned here among the first.
More about Charles Coulomb:
Charles Augustin Coulon was born in Angoulême, which is located in southwest France. His father, Henri Coulon, who had once tried to make a military career, had become a government official by the time his son was born. Angoulême was not permanent place residence of the Coulon family, some time after the birth of Charles, she moved to Paris.
Charles's mother, née Catherine Bage, who came from the noble de Senac family, wanted her son to become a doctor. Based on the overall plan, she chose educational institution, which Charles Augustin initially attended - the College of the Four Nations, also known as the Mazarin College.
The further fate of Pendant was determined by the events that occurred in the life of his family. Henri Coulon, who apparently did not have serious abilities in the financial field, went bankrupt, embarking on speculation, as a result of which he was forced to leave Paris for his homeland, Montpellier, in the south of France. Many influential relatives lived there who could help the unlucky financier. His wife did not want to follow her husband and remained in Paris with Charles and his younger sisters. However, young Coulon did not live long with his mother.
His interest in mathematics grew so much that he announced his decision to become a scientist. The conflict between mother and son led to Charles Coulon leaving the capital and moving to his father in Montpellier.
His father's cousin Louis, who occupied a prominent position in Montpellier, knew many members of the Royal Scientific Society of the city. Soon he introduced his nephew Charles to the society.
In February 1757, at a meeting of the Royal Scientific Society, a young mathematics enthusiast read his first scientific work, “A Geometrical Essay on Mean Proportional Curves.” Since the work earned the approval of members of the society, the aspiring researcher was soon elected an adjunct in the mathematics class. Subsequently, Charles Coulomb took an active part in the work of the society and presented five more memoirs - two on mathematics and three on astronomy. His interest in astronomy was sparked by observations he made with another member of the Montpellier Society, de Ratt. Charles participated in observations of the comet and lunar eclipse, the results of which he presented in the form of memoirs. Coulomb was also interested in theoretical issues of astronomy: one of his works was devoted to determining the meridian line.
In February 1760, Charles entered the Mézières school military engineers. Luckily for him, a mathematics teacher, Abbot Charles Bossu, who later became a famous scientist, worked at the school. Having become close to Bossu during his studies at Mézières due to his interest in mathematics, Coulomb maintained friendly relations with him for many years
Another important source of knowledge that was later useful to Charles Coulomb in scientific work, there were lectures on experimental physics, which in the summer of 1760 began to be given at school by the famous French naturalist Abbot Nollet.
In November 1761, Charles graduated from the School and was assigned to a major port on the western coast of France - Brest. Then he came to Martinique. During the eight years he spent there, he was seriously ill several times, but each time he returned to perform his official duties. These illnesses did not pass without a trace; after returning to France, Coulomb could no longer feel like a completely healthy person.
Despite all these difficulties, Coulomb performed his duties very well. His success in building the fort on Montgarnier was marked by a promotion - in March 1770 he received the rank of captain - at that time this could be considered a very rapid promotion. Soon, Coulon became seriously ill again and finally submitted a report requesting a transfer to France.
After returning home, Charles Coulon was appointed to Bushey. Here he completes research begun while serving in the West Indies. Although Coulomb, with his characteristic modesty, considered himself to be among the “rest of the workers,” in fact, many of the ideas he formulated in his first scientific work are still considered fundamental by specialists in the strength of materials.
According to the tradition of that time, in the spring of 1773, Coulomb presented his memoir to the Paris Academy of Sciences. He read the memoir at two meetings of the Academy in March and April 1773. The work was received with approval. Academician Bossu, in particular, wrote:
“Under this modest title, Monsieur Coulomb embraced the whole of architectural statics... Throughout his research we note a deep knowledge of infinitesimal analysis and wisdom in the choice of physical hypotheses, as well as in their application. Therefore, we believe that this work fully deserves the approval of the Academy and is worthy of publication in the Collection of Works of Foreign Scientists.”
In 1774, Coulon was transferred to the large port of Cherbourg. Coulomb was happy about this appointment - he believed that it was in the port city that a military engineer could find best use your knowledge and abilities. In Cherbourg, where Charles Coulon served until 1777, he was involved in the repair of a number of fortifications. This work left enough free time, and the young scientist continued his Scientific research. The main topic that Coulomb was interested in at this time was the development of an optimal method for manufacturing magnetic needles for accurate measurements of the Earth's magnetic field. This topic was asked in a competition announced by the Paris Academy of Sciences.
Two winners of the 1777 competition were announced at once - the Swedish scientist van Schwinden, who had already nominated his work for the competition, and Coulomb. However, for the history of science, the greatest interest is not the chapter of Coulomb’s memoirs devoted to magnetic arrows, but the next chapter, which analyzes mechanical properties threads on which the arrows are suspended. The scientist conducted a series of experiments and established general order dependence of the moment of torsional deformation force on the angle of twist of the thread and on its parameters: length and diameter.
The low elasticity of silk threads and hair with respect to torsion made it possible to neglect the arising moment of elastic forces and assume that the magnetic needle exactly follows variations in declination. This circumstance served as the impetus for Charles Coulomb to study the torsion of cylindrical metal threads. The results of his experiments were summarized in the work “Theoretical and experimental studies Torsional Force and Elasticity of Metal Wires,” completed in 1784.
The picture of deformations drawn by Coulomb, of course, differs in many of its features from the modern one. However, the general reason for the occurrence of inelastic deformations - the complex dependence of the forces of intermolecular interaction on the distance between molecules - was correctly indicated by Coulomb. The depth of his ideas about the nature of deformations was noted by many scientists of the 19th century, including such famous ones as Jung.
Gradually Charles Coulomb became increasingly involved in scientific work, although it cannot be said that he was indifferent to his duties as a military engineer. In 1777, Coulon was transferred again, now to the east of France to the small town of Salins. At the beginning of 1780, he was already in Lille, and everywhere Coulon found opportunities for scientific research.
Charles Coulon did not serve long in Lille. His dream came true - in the first half of September 1781, the Minister of War announced the transfer of Coulomb to Paris, where he was supposed to deal with engineering issues related to the notorious Bastille prison fortress. On September 30 he was awarded the Cross of Saint Louis. His hopes associated with the Paris Academy of Sciences were also justified. On December 12, 1781, Coulomb was elected to the academy in the class of mechanics. Moving to the capital meant not only a change in duty station and responsibilities. This event led to a qualitative change in the topics of Coulomb’s scientific research.
Charles Coulomb conducted a series of experiments in which he studied the most important features friction phenomena. First of all, he studied the dependence of the static friction force on the duration of contact of the bodies. He found that for bodies of the same name, for example tree - tree, the duration of contact has an insignificant effect. When unlike bodies come into contact, the coefficient of static friction increases within several days. Coulomb also noted the so-called phenomenon of stagnation: the force required to transfer bodies in contact from a state of rest to a state of relative motion significantly exceeds the force of sliding friction.
With his experiments, Charles Coulomb laid the foundations for studying the dependence of the sliding friction force on the relative speed of contacting bodies. The particular significance of Coulomb's work for practice is that when conducting experiments he used large loads close to those found in real life: their mass reached 1000 kg. This feature of Coulomb’s research determined the long life of his results - the measurement data contained in the memoir “The Theory of Simple Machines” was used by engineers for almost a century. In the field of theory, Coulomb's merit lies in the creation of a fairly complete mechanical picture friction.
He returned to research on this topic ten years later. In 1790, Coulomb presented a memoir to the academy, “On Friction at the Point of a Support.” In it, the scientist studied the friction that occurs during spinning and rolling. And in 1784, Coulomb took up the issue of internal friction in liquids. The scientist was able to give a more complete solution to it many years later, in a work of 1800, which was called “Experiments devoted to the determination of the adhesion of liquids and the law of their resistance during very slow movements.” Coulomb especially carefully examines the dependence of the resistance force on the speed of movement of the body. In his experiments, the speed of body movement varies from fractions of a millimeter to several centimeters per second - as a result, Charles Coulomb comes to the conclusion that at very low speeds the resistance force is proportional to the speed, at high speeds it becomes proportional to the square of the speed.
Coulomb's study of the torsion of thin metal threads for the 1777 competition had an important practical consequence - the creation of torsion balances. This device could be used to measure small forces of different nature, and he provided a sensitivity unprecedented in the 18th century.
Having developed a very precise physical device, Coulomb began to look for a worthy use for it. The scientist begins work on the problems of electricity and magnetism. His seven memoirs represent the implementation of a research program that was rare in the breadth of the 18th century.
The most important result obtained by Coulomb in the field of electricity was the establishment of the fundamental law of electrostatics - the law of interaction of motionless point charges. The experimental substantiation of the famous “Coulomb’s law” forms the content of the first and second memoirs. There the scientist formulates the fundamental law of electricity:
“The force of repulsion between two small balls, electrified by electricity of the same nature, is inversely proportional to the square of the distance between the centers of the balls.”
In his third memoir, Coulomb drew attention to the phenomenon of electric charge leakage. The main result was the establishment of an exponential law of charge decrease over time. In the next, one of the shortest memoirs in the series, Coulomb examined the question of the nature of the distribution of electricity between bodies. He proved that "the electric fluid is distributed in all bodies according to their form."
The fifth and sixth memoirs are dedicated to quantitative analysis charge distribution between contacting conducting bodies and determining the charge density on different parts of the surface of these bodies.
In relation to magnetism, Charles Coulomb tried to solve the same problems as for electricity. The description of experiments with permanent magnets makes up a significant part of the second memoir and almost the entire seventh memoir in the series. The scientist managed to capture some peculiar features of magnetism. In general, however, the generality of the results obtained by Coulomb in the field of magnetism is much less than the generality of the laws established for electricity.
Thus, Coulomb laid the foundations of electrostatics and magnetostatics. He obtained experimental results that have both fundamental and applied significance. For the history of physics, his experiments with torsion balances were also of great importance because they gave physicists a method for determining the unit of electric charge through quantities used in mechanics: force and distance, which made it possible to conduct quantitative studies of electrical phenomena.
Coulomb's last memoir in the series on electricity and magnetism was presented to the Paris Academy of Sciences in 1789. In December 1790, Coulomb submitted his resignation. In April of the following year, his request was granted, and he began to receive a pension of 2240 livres per year, which, however, was significantly reduced after a few years.
By the end of 1793, the political situation in Paris became even more tense. Therefore, Charles Coulomb decided to move away from Paris. He and his family move to his estate near Blois. Here the scientist spends almost a year and a half, escaping political storms.
Coulon lived in the village until December 1795 The return to Paris occurred after Coulomb was elected as a permanent member of the experimental physics department of the Institute of France - the new national academy.
Exactly when Coulomb became a family man is unclear. It is only known that the scientist’s wife Louise Françoise, née Desormeaux, was much younger than him. Their marriage was officially registered only in 1802, although Coulomb's first son, named Charles Aupostin after his father, was born in 1790. The second son, Henri Louis, was born in 1797.
He devotes the last years of his life to the organization new system education in France. Traveling around the country completely undermined the scientist’s health. In the summer of 1806, he fell ill with a fever that his body could no longer cope with. Pendant died in Paris August 23, 1806.
Charles Coulon left a fairly significant inheritance to his wife and sons. As a sign of respect for the memory of Coulomb, both of his sons were enrolled at state expense in privileged educational institutions.
Javascript is disabled in your browser.Charles Augustin de Coulon(fr. Charles-Augustin de Coulomb, June 14 - August 23) - French military engineer and physicist, researcher of electromagnetic and mechanical phenomena; Member of the Paris Academy of Sciences. The unit of electric charge and the law of interaction of electric charges are named after him.
After the revolution, the Academy of Sciences repeatedly summoned the scientist to Paris to participate in the determination of weights and measures (an initiative of the revolutionary government). Coulomb became one of the first members of the National Institute, which replaced the academy. In 1802, he was appointed inspector of public buildings, but his health, undermined in the service, did not allow the scientist to significantly prove himself in this position.
Back in the early 1770s, having returned from Martinique, Coulon was actively engaged in scientific research. Published works on technical mechanics (statics of structures, theory of windmills, mechanical aspects of torsion of threads, etc.). Coulomb formulated the laws of torsion; invented torsion balances, which he himself used to measure electric and magnetic interaction forces.
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Charles Augustin Coulomb (1736-1806)- an outstanding French engineer and physicist, one of the founders of electrostatics. He studied the torsional deformation of threads and established its laws. He invented (1784) the torsion balance and discovered (1785) the law named after him. Established the laws of dry friction. Coulomb's experimental studies were fundamental to the formation of the doctrine of electricity and magnetism. Member of the Paris Academy of Sciences.
C. Coulon achieved brilliant scientific results. The laws of external friction, the law of torsion of elastic threads, the basic law of electrostatics, the law of interaction of magnetic poles - all this is included in the golden fund of science. “Coulomb field”, “Coulomb potential”, and finally, the name of the unit of electric charge “coulomb” is firmly established in physical terminology.
Years of study
Charles's father, Henri Coulon, a government official, soon after the birth of his son moved with his family to Paris, where for some time he held a lucrative position collecting taxes, but, having embarked on speculation that ruined him, he returned to his homeland, to the south of France, to Montpellier. Charles and his mother remained in Paris.
In the late 1740s, Charles was placed in one of the best schools of the time for young people of noble origin - the College of the Four Nations, also known as the Mazarin College. The level of teaching there was quite high, in particular, much attention was paid to mathematics. In any case, young Charles Coulomb was so carried away by science that he resolutely opposed his mother’s intentions to choose for him the profession of a doctor, or, in extreme cases, a lawyer. The conflict became so serious that Charles left Paris and moved to his father in Montpellier.
Military engineer
In this city, back in 1706, a scientific society was founded, second only to the capital's academy. In February 1757, 21-year-old Coulomb read his first scientific work there, “Geometrical Essay on Mean Proportional Curves,” and was soon elected an adjunct in the mathematics class.
But this brought only moral satisfaction; it was necessary to choose a further path. After consulting with his father, Charles chose a career as a military engineer. The Montpellier Scientific Society provided Coulon with the necessary recommendations, and after passing the exams (quite difficult, so preparing for them required nine months of study with a teacher), Charles Coulon in February 1760 went to Mézières, to the Military Engineering School, one of the best higher technical educational institutions of that time.
Education at school was conducted with a clearly expressed practical bias: in addition to mathematics, physics and other “theoretical subjects”, many purely applied disciplines were studied - from construction and what would now be called “materials science”, to issues of labor organization (students were entrusted with leadership brigades of peasants mobilized for public works). Charles Coulon graduated from the School in 1761.
Although the review of him by the head of the School looks in some places not at all enthusiastic (“His work on the siege is worse than average, the drawings are made very poorly, with erasures and marks... Coulomb believes, like others with a similar way of thinking, that wood for gun carriages and carts can be easy to find in the forest..."), he was probably among the best graduates (rewarded with a cash prize).
First 10 years of service
Having received the rank of lieutenant, Charles Coulon was sent to Brest, one of the major ports on the west coast of France. In Brest, Kulon was entrusted with cartographic work related to the construction and reconstruction of fortifications on the coast. But this activity was rather short-lived.
Less than two years later, Coulon had to urgently get involved in the construction of a fortress on the island of Martinique in the West Indies to protect it from the British. The announced competition for the fortification project was won by the experienced military engineer de Rochemore, but this project caused a great controversy, in which Charles Coulomb was also involved. Although the project as a whole was successfully defended, significant changes had to be made to it; in particular, appropriations were reduced by more than half. Coulon, who remained the de facto manager of the construction, under whose supervision almost one and a half thousand people worked, found himself faced with many very complex, and not only technical, problems. The working conditions were difficult, the climate was very difficult, there were not enough people, and those who remained were seriously ill. During his eight years of work on the island, Coulon himself was seriously ill eight times and subsequently returned to France with severely compromised health. The extensive experience he acquired came at a high cost to his own health.
After returning home
Returning to France, Charles Coulon in 1772 received an appointment to Bouchaine. The working conditions here were incomparably easier, and the opportunity arose to actively continue scientific activities again. The problems he solved belong to the area that would now be called structural mechanics and strength of materials. Already at that time, this area attracted great attention from many physicists and mathematicians. After returning to his homeland, Coulomb, having carried out quite a large number of new studies, sent his memoir to the Paris Academy of Sciences, and then read it at two meetings in March and April 1773. Two academicians who were entrusted with its review spoke highly of this work (one of them, Borda, was subsequently saved by Charles Coulon during the Jacobin dictatorship, hiding him on his estate). This was a great support for the author.
But soon Coulomb became interested in new problems. In 1775, the Paris Academy of Sciences announced a competitive problem: “To find the best method for making magnetic needles, hanging them and checking whether their direction coincides with the direction of the magnetic meridian and, finally, explaining their regular daily variations.” As for the last part of the problem, its solution at that time was clearly inaccessible (not even everything is known about the very reason for the existence of the Earth’s magnetic field not only then, but even now!), but the problem of the best design of a compass and, in particular, the suspension of a magnetic needle was relevant. She captivated Coulon.
How difficult this task was, what high accuracy was required to ensure, can be judged by the following fact: the arrow suspended on a thin silk thread reacted so sensitively to all influences that it had to be protected not only from the weakest air currents, but even from the approach of the observer's eye (there can always be electrical charges on the arrow and on the human body, and their interaction can affect the forces).
To eliminate this, Coulomb decided to replace the silk threads with metal wire that conducts electricity. This was a step that played a very important role later when Coulomb invented and began to use torsion balances. But so far this work was still far away.
In 1777, Charles Coulomb won a competition to develop an instrument for studying the Earth's magnetic field, and immediately plunged into another major work: the study of friction. In 1779 (and then again in 1781), the Academy announced another competition dedicated specifically to friction. Already in 1780, Coulomb submitted a competition work to the academy, “The Theory of Simple Machines,” which a year later was also awarded a prize. The results of this work were based on numerous experiments by Coulomb, which investigated both friction between solids and friction in liquids and gases. Coulomb carried out this work already in Lille, where he was transferred at the beginning of 1780. About a year later, his long-standing wish was fulfilled: he was transferred to Paris, where on December 12, 1781 he was elected to academician in the class of mechanics.
In Paris
In the capital, Charles Coulon was almost immediately faced with many cases, including administrative ones. Some of them also had political overtones, and one of them even ended for Coulon with a week's imprisonment in the prison of the Abbey of Saint-Germain des Pres. Meetings in numerous commissions, in particular the Canal Commission in Brittany, left little time for science, and, nevertheless, Coulomb presented his work to the academy in 1784, which can be considered very important: a memoir about the torsion of thin metal threads, and 1785-89 - a series of memoirs on electricity and magnetism.
The study of thread torsion may seem to have only an auxiliary “technical” value, but without it further quantitative measurements of the force of interaction between electric charges and magnetic poles would be impossible. As always, Charles Coulomb's work was distinguished by its depth and ingenuity. Thus, the diameter of very thin threads was determined by Coulomb by weighing and measuring their length. Much of what was included in the classical studies of Coulomb can now be seen in the works of some of his predecessors. Thus, torsion balances were used by the outstanding English scientist Henry Cavendish back in 1773, but he did not publish his works; they were published only a century later.
An important point for solving the whole problem was that Coulomb understood: it is necessary to study the interaction of “point” charged bodies, i.e. such, the distances between which significantly exceed their sizes. But even here Coulomb was not the first. The Englishman Robison (1739-1805) came to the same idea, who, as a result of careful experiments, came to the conclusion that the force of electrical interaction between bodies is inversely proportional to the square of the distance between them, but he reported his results only in 1801, much later than Coulomb.
However, the “inverse square law” has long seemed almost obvious to many. And the point here is not only in the hypnotizing example of the great Newton’s law of universal gravitation. Another law would not explain many observed facts (for example, why no electric field is felt inside a box with conducting walls, no matter what charge is placed on it).
Coulomb's law is now probably known to every schoolchild. But it’s unlikely that many people know what skill and observation the researcher had to show.
Charles Coulomb noticed in passing, that charges “drain” from bodies quite quickly, and he correctly explained this by the fact that air has some conductivity. This circumstance complicated the experiment, but it itself became an important discovery. Many people know that the law of interaction of magnetic poles, also carefully studied by Coulomb, is outwardly very similar to the law of interaction of electric charges. Because of this, electrostatics and magnetostatics have long seemed similar to each other in everything, except for the amazing fact that “magnetic charges” of opposite signs for some reason always occur in pairs and never separately. Only after Ampere’s work did it become clear that the magnetic fields of permanent magnets are caused not by the fact that they consist of a huge number of small magnets (as, we note, Coulomb also believed), but by electric currents, i.e. movement of electric charges.
The modern classical (i.e., non-quantum) theory of electrical and magnetic phenomena is often called the electrodynamics of Faraday and Maxwell. Of course, many other remarkable scientists also took pride of place in the writing of this most important chapter of physics, and the name of Charles Coulomb should rightfully be mentioned here among the first.
More about Charles Coulomb:
Charles Augustin Coulon was born in Angoulême, which is located in southwest France. His father, Henri Coulon, who had once tried to make a military career, had become a government official by the time his son was born. Angoulême was not the permanent residence of the Coulon family; some time after the birth of Charles, they moved to Paris.
Charles's mother, née Catherine Bage, who came from the noble de Senac family, wanted her son to become a doctor. Based on the overall plan, she chose the educational institution that Charles Augustin initially attended - the College of the Four Nations, also known as the Mazarin College.
The further fate of Pendant was determined by the events that occurred in the life of his family. Henri Coulon, who apparently did not have serious abilities in the financial field, went bankrupt, embarking on speculation, as a result of which he was forced to leave Paris for his homeland, Montpellier, in the south of France. Many influential relatives lived there who could help the unlucky financier. His wife did not want to follow her husband and remained in Paris with Charles and his younger sisters. However, young Coulon did not live long with his mother.
His interest in mathematics grew so much that he announced his decision to become a scientist. The conflict between mother and son led to Charles Coulon leaving the capital and moving to his father in Montpellier.
His father's cousin Louis, who occupied a prominent position in Montpellier, knew many members of the Royal Scientific Society of the city. Soon he introduced his nephew Charles to the society.
In February 1757, at a meeting of the Royal Scientific Society, a young mathematics enthusiast read his first scientific work, “A Geometrical Essay on Mean Proportional Curves.” Since the work earned the approval of members of the society, the aspiring researcher was soon elected an adjunct in the mathematics class. Subsequently, Charles Coulomb took an active part in the work of the society and presented five more memoirs - two on mathematics and three on astronomy. His interest in astronomy was sparked by observations he made with another member of the Montpellier Society, de Ratt. Charles participated in observations of a comet and a lunar eclipse, the results of which he presented in the form of memoirs. Coulomb was also interested in theoretical issues of astronomy: one of his works was devoted to determining the meridian line.
In February 1760, Charles entered the Mézières school military engineers. Luckily for him, a mathematics teacher, Abbot Charles Bossu, who later became a famous scientist, worked at the school. Having become close to Bossu during his studies at Mézières due to his interest in mathematics, Coulomb maintained friendly relations with him for many years
Another important source of knowledge that was later useful to Charles Coulomb in his scientific work were lectures on experimental physics, which the famous French naturalist Abbot Nollet began reading at school in the summer of 1760.
In November 1761, Charles graduated from the School and was assigned to a major port on the western coast of France - Brest. Then he came to Martinique. During the eight years he spent there, he was seriously ill several times, but each time he returned to perform his official duties. These illnesses did not pass without a trace; after returning to France, Coulomb could no longer feel like a completely healthy person.
Despite all these difficulties, Coulomb performed his duties very well. His success in building the fort on Montgarnier was marked by a promotion - in March 1770 he received the rank of captain - at that time this could be considered a very rapid promotion. Soon, Coulon became seriously ill again and finally submitted a report requesting a transfer to France.
After returning home, Charles Coulon was appointed to Bushey. Here he completes research begun while serving in the West Indies. Although Coulomb, with his characteristic modesty, considered himself to be among the “rest of the workers,” in fact, many of the ideas he formulated in his first scientific work are still considered fundamental by specialists in the strength of materials.
According to the tradition of that time, in the spring of 1773, Coulomb presented his memoir to the Paris Academy of Sciences. He read the memoir at two meetings of the Academy in March and April 1773. The work was received with approval. Academician Bossu, in particular, wrote:
“Under this modest title, Monsieur Coulomb embraced the whole of architectural statics... Throughout his research we note a deep knowledge of infinitesimal analysis and wisdom in the choice of physical hypotheses, as well as in their application. Therefore, we believe that this work fully deserves the approval of the Academy and is worthy of publication in the Collection of Works of Foreign Scientists.”
In 1774, Coulon was transferred to the large port of Cherbourg. Coulomb was pleased with this appointment - he believed that it was in the port city that a military engineer could find the best use of his knowledge and abilities. In Cherbourg, where Charles Coulon served until 1777, he was involved in the repair of a number of fortifications. This work left enough free time, and the young scientist continued his scientific research. The main topic that Coulomb was interested in at this time was the development of an optimal method for manufacturing magnetic needles for accurate measurements of the Earth's magnetic field. This topic was asked in a competition announced by the Paris Academy of Sciences.
Two winners of the 1777 competition were announced at once - the Swedish scientist van Schwinden, who had already nominated his work for the competition, and Coulomb. However, for the history of science, the greatest interest is not the chapter of Coulomb’s memoirs devoted to magnetic arrows, but the next chapter, which analyzes the mechanical properties of the threads on which the arrows are suspended. The scientist conducted a series of experiments and established the general order of dependence of the moment of torsional deformation force on the angle of twist of the thread and on its parameters: length and diameter.
The low elasticity of silk threads and hair with respect to torsion made it possible to neglect the arising moment of elastic forces and assume that the magnetic needle exactly follows variations in declination. This circumstance served as the impetus for Charles Coulomb to study the torsion of cylindrical metal threads. The results of his experiments were summarized in the work “Theoretical and Experimental Studies of Torsional Force and Elasticity of Metal Wires,” completed in 1784.
The picture of deformations drawn by Coulomb, of course, differs in many of its features from the modern one. However, the general reason for the occurrence of inelastic deformations - the complex dependence of the forces of intermolecular interaction on the distance between molecules - was correctly indicated by Coulomb. The depth of his ideas about the nature of deformations was noted by many scientists of the 19th century, including such famous ones as Jung.
Gradually Charles Coulomb became increasingly involved in scientific work, although it cannot be said that he was indifferent to his duties as a military engineer. In 1777, Coulon was transferred again, now to the east of France to the small town of Salins. At the beginning of 1780, he was already in Lille, and everywhere Coulon found opportunities for scientific research.
Charles Coulon did not serve long in Lille. His dream came true - in the first half of September 1781, the Minister of War announced the transfer of Coulomb to Paris, where he was supposed to deal with engineering issues related to the notorious Bastille prison fortress. On September 30 he was awarded the Cross of Saint Louis. His hopes associated with the Paris Academy of Sciences were also justified. On December 12, 1781, Coulomb was elected to the academy in the class of mechanics. Moving to the capital meant not only a change in duty station and responsibilities. This event led to a qualitative change in the topics of Coulomb’s scientific research.
Charles Coulomb conducted a series of experiments in which he studied the most important features of the phenomenon of friction. First of all, he studied the dependence of the static friction force on the duration of contact of the bodies. He found that for bodies of the same name, for example tree - tree, the duration of contact has an insignificant effect. When unlike bodies come into contact, the coefficient of static friction increases within several days. Coulomb also noted the so-called phenomenon of stagnation: the force required to transfer bodies in contact from a state of rest to a state of relative motion significantly exceeds the force of sliding friction.
With his experiments, Charles Coulomb laid the foundations for studying the dependence of the sliding friction force on the relative speed of contacting bodies. The particular significance of Coulomb's work for practice is that when conducting experiments he used large loads, close to those encountered in real life: their mass reached 1000 kg. This feature of Coulomb’s research determined the long life of his results - the measurement data contained in the memoir “The Theory of Simple Machines” was used by engineers for almost a century. In the field of theory, Coulomb's merit lies in the creation of a fairly complete mechanical picture of friction.
He returned to research on this topic ten years later. In 1790, Coulomb presented a memoir to the academy, “On Friction at the Point of a Support.” In it, the scientist studied the friction that occurs during spinning and rolling. And in 1784, Coulomb took up the issue of internal friction in liquids. The scientist was able to give a more complete solution to it many years later, in a work of 1800, which was called “Experiments devoted to the determination of the adhesion of liquids and the law of their resistance during very slow movements.” Coulomb especially carefully examines the dependence of the resistance force on the speed of movement of the body. In his experiments, the speed of body movement varies from fractions of a millimeter to several centimeters per second - as a result, Charles Coulomb comes to the conclusion that at very low speeds the resistance force is proportional to the speed, at high speeds it becomes proportional to the square of the speed.
Coulomb's study of the torsion of thin metal threads for the 1777 competition had an important practical consequence - the creation of torsion balances. This device could be used to measure small forces of various natures, and it provided sensitivity unprecedented in the 18th century.
Having developed a very precise physical device, Coulomb began to look for a worthy use for it. The scientist begins work on the problems of electricity and magnetism. His seven memoirs represent the implementation of a research program that was rare in the breadth of the 18th century.
The most important result obtained by Coulomb in the field of electricity was the establishment of the fundamental law of electrostatics - the law of interaction of stationary point charges. The experimental substantiation of the famous “Coulomb’s law” forms the content of the first and second memoirs. There the scientist formulates the fundamental law of electricity:
“The force of repulsion between two small balls, electrified by electricity of the same nature, is inversely proportional to the square of the distance between the centers of the balls.”
In his third memoir, Coulomb drew attention to the phenomenon of electric charge leakage. The main result was the establishment of an exponential law of charge decrease over time. In the next, one of the shortest memoirs in the series, Coulomb examined the question of the nature of the distribution of electricity between bodies. He proved that "the electric fluid is distributed in all bodies according to their form."
The fifth and sixth memoirs are devoted to a quantitative analysis of the charge distribution between contacting conducting bodies and determining the charge density on various parts of the surface of these bodies.
In relation to magnetism, Charles Coulomb tried to solve the same problems as for electricity. The description of experiments with permanent magnets makes up a significant part of the second memoir and almost the entire seventh memoir in the series. The scientist managed to capture some peculiar features of magnetism. In general, however, the generality of the results obtained by Coulomb in the field of magnetism is much less than the generality of the laws established for electricity.
Thus, Coulomb laid the foundations of electrostatics and magnetostatics. He obtained experimental results that have both fundamental and applied significance. For the history of physics, his experiments with torsion balances were also of great importance because they gave physicists a method for determining the unit of electric charge through quantities used in mechanics: force and distance, which made it possible to conduct quantitative studies of electrical phenomena.
Coulomb's last memoir in the series on electricity and magnetism was presented to the Paris Academy of Sciences in 1789. In December 1790, Coulomb submitted his resignation. In April of the following year, his request was granted, and he began to receive a pension of 2240 livres per year, which, however, was significantly reduced after a few years.
By the end of 1793, the political situation in Paris became even more tense. Therefore, Charles Coulomb decided to move away from Paris. He and his family move to his estate near Blois. Here the scientist spends almost a year and a half, escaping political storms.
Coulon lived in the village until December 1795 The return to Paris occurred after Coulomb was elected as a permanent member of the experimental physics department of the Institute of France - the new national academy.
Exactly when Coulomb became a family man is unclear. It is only known that the scientist’s wife Louise Françoise, née Desormeaux, was much younger than him. Their marriage was officially registered only in 1802, although Coulomb's first son, named Charles Aupostin after his father, was born in 1790. The second son, Henri Louis, was born in 1797.
He devoted the last years of his life to organizing a new education system in France. Traveling around the country completely undermined the scientist’s health. In the summer of 1806, he fell ill with a fever that his body could no longer cope with. Pendant died in Paris August 23, 1806.
Charles Coulon left a fairly significant inheritance to his wife and sons. As a sign of respect for the memory of Coulomb, both of his sons were enrolled at state expense in privileged educational institutions.
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