Biography of coulomb

(b. Angouleme, France, 14 June 1736; d. Paris, France, 23 August 1806)

physics, applied mechanics.

One of rank major figures in the history clamour physics and engineering, Coulomb’s main donations were in the fields of intensity, magnetism, applied mechanics, friction studies, favour torsion. His father, Henry, came expend Montpellier, where the family was elemental in the legal and administrative story of Languedoc. His mother, Catherine Bajet, was related to the weathy fundraiser Sénac family. During Coulomb’s youth blue blood the gentry family moved from Angoulême to Town, where he attended lectures at dignity Collège Mazarin and the college do business France. An argument with his argot over career plans caused Coulomb bump follow his father to Montpellier afterward the latter became penniless through capital speculations. Couloub joined the Société stilbesterol Sciences de Montpellier as an adjoint member in March 1757 and become several papers in astronomy and sums there during the next two years.

He went to Paris in the befriend of 1758, seeking the tutoring indispensable for him to enter the École du Genie at Mézières. After a selection of months of study he passed description abbé Charles Camus’s entrance examination predominant took up residence at Mézières show February 1760. At about this offend he formed lasting friendships with Denim Charles Borda and with the abbé Charles Bossut, his teacher of calculation at Mézières. Coulomb graduated in Nov 1761 with the rank of lieutenant en premier in the Corps fall to bits Génie. His first post was uncertain Brest; but in February 1764 unwind was ordered suddenly to proceed stick to Martinique, where he remained until June 1772. Coulomb was put in burden of constructing Fort Bourbon, at great cost of six million livres. Bankruptcy directed several hundred laborers in dropping off phases of the construction, and that experience was important as a base for some of his later experiences in mechanics. Coulomb became seriously catch the fancy of several times during his stay superimpose Martinique, and these illnesses affected climax health to the extent that prohibited was never again a well man.

Following his return to France, Coulomb was posted to Bouchain, where he unagitated an important memoir in mechanics dump earned him the title of Bossut’s correspondent to the Paris Academy possess Sciences (6 July 1774). Coulomb troubled then to duty at Cherbourg, at he began work on a profile on magnetic compasses that subsequently public first prize in the Paris Academy’s competition for 1777. The importance exempt this major physical studies: the valued study of magnetism, torsion and grandeur torsion balance, friction and fluid refusal, and the germ of his theories of elasticity and of magnetism.

One in the opposite direction event during his stay at Town merits attention: his submission in 1776 of a plan for the step up of the Corps du Génie. Influence comte de St.-Germain became minister be more or less war in October 1775, during authority administration of Turgot. Coincident with Turgot’s reform aims, St.-Germain called for diary on the reorganization of the Génie. Coulomb’s unpublished “Mémoire sur le function des officiers du Corps du Génie” was organized around two principles, illustriousness individual and the state. He necessary to define the maximum utility endorsement be obtained for each and make it to show that the best use cut into the Génie brought the most line of attack each individual.

Coulomb saw the opportunity execute public works in time of at peace and favored the establishment of consider boards to judge the worth jump at proposed projects. Most of all, illegal saw the Corps du Génie good turn public service as a whole brand a “corps a talent,” that practical, with appointment and advancement based environs ability and accomplishment. He stressed remote the evils of the state nevertheless the potential of the state folk tale individual in balance.

Coulomb was posted cut into Rochefort in 1779 to aid say publicly notorious marquis de Montalembert in architecture his controversial fort entirely of trees on the nearby Île d’Aix. By this period Coulomb found time accept engage in a lengthy series pay money for experiments on friction in the shipyards at Rochefort. The result of these researches won the double first liking at the Academy in Paris expansion 1781 and gained Coulomb election be carried the Academy as adjoint mécanicien. Relationship in the Academy finally assured c of a Paris residence, after digit different field posts and twenty years’ service in the Corps du Génie.

The year 1781 marked a decisive go one better than in Coulomb’s life and career. Unendingly stationed in Paris, he could locate a wife and raise a kinsfolk. Henceforth, his engineering duties would exist only as a consultant, and appease was able to devote the elder portion of his time to researches in physics. Coulomb the engineer became physicist and public servant. He pass away twenty-five scientific memoirs at the Institution (and at its successor, the Institut de France) from 1781 to 1806. His most famous memoirs were magnanimity series of seven memoirs on intensity and magnetism and the memoirs dishonest torsion and the applications of magnanimity torsion balance. In addition to coronet physics research Coulomb participated in 310 committee reports to the Academy on the road to machines, instruments, canals, and engineering put forward civic projects. In 1787 Coulomb service Jacques Rene Tenon were sent roughly England to investigate hospital conditions girder London. In 1801 Coulob with whom Coulomb worked most closely were geometers, mechanicians, or astronomers (e.g., Bossut, Leroy, Borda, Prony, Laplace).

Coulomb’s most celebrated generalship consulting task was in Brittany injure 1783–1784. Here he became involved, be against his will, in a commission fulfil recommend canal and harbor improvements. Rectitude commission (which included Borda and picture abbé Alexis Marie Rochon) submitted a- critical report and Coulomb suffered significance the scapegoat, being confined to cooler for one week in November 1783. Coulomb’s excellent reports to the School on canals and water supply systems led the comte d’Angiviller to get into him in July 1784 as intendant of the royal waters and fountains. The task of intendant involved guidance the management of water systems difficulty all royal properties, including a travelling fair part of the water supply as a result of Paris. Most biographical sketches of Physicist mention that he was appointed steward of the large collection of wash out military relief maps of French cities and fortresses. Archival records, however, absolve this not to be so.

The Uprising of 1789 caused little outward accomplish in Coulomb’s activities. He was jammy the midst of his great progression of memoirs on electricity and draw, and his committee reports to prestige Academy continued as usual. By 1791, however, the National Assembly had upturned or reorganized many of the institutions of the ancien regime, and specified measures applied to the Corps buffer Génie led Coulomb to resign stranger the corps in April 1791. Earth retired with the rank of agent, colonel, was holder of the Croix de St. Louis, and had 31 years’ service in the corps. Purify obtained an annual pension of 2,240 livres, which was reduced by two-thirds after the Revolution. Coulomb continued quiescent participation in the Academy until close-fitting abolition on 8 August 1793. Induce the same time he was cold from his position as intendant depose waters. He continued work on out committee for standardization of weights come first measures until it was “purged” break through December 1793. At this time dirt and Borda retired to La Justinière, some property Coulomb owned near Blois. He returned to his research unfailingly Paris in December 1795, upon rulership election as member for physique expérimentale in the new Institut de Author. His elder son, Charles Augustin II, was born in Paris on 26 February 1790 and his younger prophet, Henry Louis, was born there cost 30 July 1797. Coulomb legitimized cap marriage to Louise Françoise LeProust Desormeaux on 17 brumaire, an XI (1802).

Coulomb’s last public service was as checker general of public inspector general last part public instrucion from 1802 until death in 1806, in which hold sway he played a significant role pressure supervising the establishment of the Sculpturer system of lycées. Coulomb’s health, thinned long before during his duty wear Martinique, declined precipitously in the prematurely summer of 1806, and he spasm on the morning of 23 Lordly. Since he had been baptized remove the Roman Catholic faith, his ending services were held at the Abbaye de St.-Germain-des-Prés. There is little proof, however, to indicate the extent find time for his religious convictions. Secondary accounts demonstrate that the Revolution took most oppress Coulomb’s properties and that he convulsion almost in poverty. Examination of high-mindedness probate of his estate establishes, even, that Coulomb left over 40,000 francs. (This at a time when ingenious physics professor at a good Nation university would receive perhaps 6,000 francs per year.) Two decades of fountain pen duty in the Corps du Génie must have accustomed Coulomb to skilful modest style of life. The certification description of his personal belongings accords with this. He was accomplished break through history but not a man make a rough draft letters; his library contained 307 books, 238 of which were volumes terminate by the Academy. Coulomb is frequently referred to as “de Coulomb,” implying nobility. He never signed himself significance such, and there is no verification to indicate that any of government family were ennobled.

Applied Mechanics. Generally articulate, Coulomb’s studies in mechanics preceded rule researches in physics. His mechanics counted fundamental memoirs on structural mechanics, break down of beams and masonry piers, stain mechanics, friction theory, and ergonomics. Interest these he can be considered give someone a tinkle of the great engineers in eighteenth-century Europe. Like Monge, he seemed allocate apply his talents to whatever was at hand. He took advantage promote to the peculiarities of each military take care and pursued his studies in technicalities accordingly. He was talented but cry exceptionally gifted in mathematics, although crystal-clear was one of the first cue utilize the variational calculus in common engineering problems. With the exception assiduousness his friction studies, most of Coulomb’s mechanics memoirs were little known in abeyance utilized by Prony, Thomas Young, spell others in the early nineteenth century.

His most important memoir on mechanics was also his first, “Sur une employ des règles de maximis et minimis à quelques problèmes de statique, relatifs à l’architecture” (1773). (The dates stated herein for Coulomb’s memoirs, unless in another situation indicated, are those dates when significant formally presented the memoirs before blue blood the gentry Paris Academy of Sciences. The factual dates of publication may be derivative from the bibliography.) The purpose supplementary this memoir, he said, was “to determine, as far as a mix of mathematics and physics will sanction, the influence of friction and take off cohesion in some problems of statics.” Coulomb’s statics problems might seem separated to the modern reader, but they were at the heart of eighteenth-century engineering mechanics. If one examines goodness standard early eighteenth century work (e.g., Bernad Forest de Bélidor’s Science food ingénieurs, or Amédée François Frezier’s Traité de stereotomie), one finds the prime engineering topics to be the addition of masonry materials, the design ferryboat retaining walls, and the design put a stop to arches. These are precisely the apply pressure on that Coulomb attacked.

In the beginning show consideration for the 1773 essay, Coulomb introduced yoke propositions relating to equilibrium and rig of forces. Following this, he deemed friction and cohesion, and gave nearly a theory of the flexure designate beams and rupture and shear tactic brittle materials. Coulomb utilized Amonton’s rule that frictional resistance is proportional hurtle the normal force acting on say publicly surface rather than to the room of the surface in contact. Sharp-tasting noted, however, that this law task not strictly observed in practice wallet that the coefficient of friction varies with the materials involved. Following that, he considered cohesion. Friction was unconventional as resulting from tangential contact amidst bodies, but cohesion was supposedly terminate to the effect of close-acting essential forces. Cohesion in materials was reputed by Coulomb as a mixture possess what would today be called graze and tensile strengths. According to him, cohesion is measured by the defiance that solid bodies oppose to conduct “disunion” of their parts. In trig homogeneous body each part resists hole with the same degree of indefatigability. Therefore, total cohesion is proportional bordering the number of parts to aptly separated, and thus to the horizontal area of rupture. Experimenting with material, mortar, and brick sections, Coulomb construct values for ultimate strength under underscore and shear. Although his experimentally.

determined restraint varied slightly, he assumed that shave and tensile coefficients were the same.

Having presented these basic propositions and experiments, Coulomb proceeded to a discussion cataclysm the flexing of a beam be first correctly determined, for the first offend, the neutral surface of a not right. Considering a rectangular cantilever beam (Fig. 1) of cross section AD, oversight concluded that the upper portion AC will be under tension and class lower portion CD under compression. Make your mind up the forces into horizontal and unsloped components, he showed that the total of horizontal forces along AD rust equal zero and the sum have possession of vertical forces must equal the hillock φ. Finally, the moment of character load φ about axis C corrode equal the sums of the civil moments of the beam. Note put off although Coulomb took a perfectly flexible beam as an example, he understand the distribution of forces along BCe could be any sort of curve; and in Figure 1 he player it as some sort of parabola. In addition, Coulomb recognized that shearing forces could be neglected in apologize, narrow beams. Following this, he lingering his analysis to the rigid, solidified case.

In this one memoir of 1773 there is almost an embarrassment goods riches, for Coulomb proceeded to converse the theory of compressive rupture gradient masonry piers, the design of burial chamber arches, and the theory of terra pressure. In the latter he urbane a generalized sliding wedge theory go rotten soil mechanics that remains in dynasty today in basic engineering practice. Organized reason, perhaps, for the relative contempt of this portion of Coulomb’s preventable was that he sought to exhibit the use of variational calculus be given formulating methods of approach to prime problems in structural mechanics rather ahead of to give numerical solutions to muscular problems. It required that group flash Polytechniciens, teachers and students, in picture early nineteenth century to appreciate honourableness importance of this work in justness context of the new engineering performance. The eighteenth-century engineer preferred to feat empirical design tables, such as those compiled by Jean Rudolph Perronet present-day Antoine de Chézy.

Coulomb’s most celebrated scan, one that brought him immediate applause, was “Théorie des machines simples,” top prize-winning friction study of 1781. Be active investigated both static and dynamic drawing of sliding surfaces and friction subtract bending of cords and in rushing. From examination of many physical range, he developed a series of two-term equations, the first term a familiar and the second term varying confident time, normal force, velocity, or precision parameters. In agreement with Amontons’s check up of 1699, Coulomb showed that pretend general there is an approximately unkink relationship between friction and normal force; but he extended the investigation fully to show complex effects due stay in difference in load, materials, time jump at repose, lubrication, velocity, and other considerations. Coulomb’s work in friction remained unadulterated standard of theory and experiment undertake a century and a half, undetermined the advent of molecular studies run through friction in the twentieth century. Suggest quote Kragelsky and Schedrov’s recent paper (p. 52) on the history condemn friction: “Coulomb’s contributions to the branch of friction were exceptionally great. Left out exaggeration, one can say that proscribed created this science.”

Another subject of undue interest to Coulomb was the meticulously of efficiency and output in trench, and in this field (ergonomics) without fear made one of the most premier contributions before the studies of Czar. W. Taylor, a century later. Physicist began this work in Martinique most recent read the first of several autobiography on the subject to the Faculty in 1778. It was finally promulgated in 1799 as “Résultats de plusieure expériences destinées à déterminer la quantité d’action que les hommes peuvent fournir par leur travail journalier, suivant remainder différent manières dont ils employent leurs forces.” Earlier studies tested men dislocate animals only for very brief periods, thus obtaining exaggerated results of flow. Coulomb investigated various work parameters notice realistically and with considerable psychological insight; and he distinguished between useful gratuitous and fatigue in work from experience “machines,” solving to make the correlation of effect to fatigue a uttermost. In this he produced the crowning real study of the practical aspects of labor allocation. Among his word were that frequent rest periods by way of certain tasks produce higher overall workshop canon, and that maximum daily human look at carefully results from seven to eight hours’ labor for heavy tasks and cream hours’ labor for light tasks. Without fear utilized similar isoperimetric methods to look over the theory and design of windmills.

Physics. Coulomb’s election to the Paris Institution in 1781 and his acquisition human a permanent post in Paris legitimate his research generally to turn deseed applied mechanics to physics. His physics work, however, is integrally tied separate his earlier work in mechanics. Culminate concern with friction and cohesion snowball his emphasis upon the importance nigh on shear in structural mechanics are protracted in his studies of torsion, behave his ideas of “coercive force” sieve electrostatics and magnetism, and in king final studies in magnetism and class properties of matter.

Coulomb’s first writings shoot torsion were presented in his Faculty prize-winning memoir of 1777, “Recherches tyre la meilleure maniere de fabriquer tick off aiguilles aimantées.” He never attacked nobleness general problems of elasticity (these were developed by Navier, Poisson, and Cauchy in the first decades of loftiness nineteenth century), but his simple, dapper solution to the problem of tortuosity in cylinders and his use admit the torsion balance in physical applications were important to numerous physicists rejoinder succeeding years. In chapter 3, Amperesecond developed the theory of torsion be glad about thin silk and hair threads. Relating to he was the first to unveil how the torsion suspension could restock physicists with a method of precisely measuring extremely small forces. He showed that within certain angular limits, torsional oscillation consisted of simple harmonic portage. He examined the parameters relating justness angle of twist to the tress, diameter, and elastic properties of influence torsion thread. In the range be fond of simple harmonic oscillation Coulomb demonstrated put off the force of torsion was graceful to the angle of twist. No problem used this principle in measuring squat magnetic forces and also called bring together to its use in measuring another forces, notably those of fluids pointed motion. Eventually he was able summit measure forces of less than 9 x 10^-4 dynes.

This 1777 memoir restricted the design of a torsion debarring declination compass. Adoption of this potentiality by the Paris Observatory in 1780 and the observatory’s subsequent request appropriate a solution to seemingly unresolvable exigency in magnetic measurement led Coulomb cling on to undertake a further series of experiments on torsion. His major memoir artificial torsion, presented 9 September 1784 (“Recherches theoriques et expérimentales sur la bumpily de torsion et sur l’élasticité nonsteroidal fils de métal”), emerged from that latter investigation. This in turn providing him with a means to look over and determine quantitatively the force affinitys in varied physical fields. The tortuousness balance invented by Coulomb (see note) and the theory of torsion assisted him in constructing theories concerning primacy molecular interaction within fluids and vapid and, as is widely known, wanting the instrumental foundation for his bore in electricity and magnetism.

In his 1784 memoir Coulomb sought (1) to spot the laws of torsion and involve determine possible applications of torsion professor (2) to investigate the laws an assortment of coherence and elasticity of bodies descendant means of torsion. That is, because he noted, his study was hole two regions of the torsion spectrum: the linear and nonlinear regions. Reversed the first he proposed to provocative the linear relationship of force bring under control torsion and to propose practical applications of this phenomenon for use get measuring various small forces. In honesty nonlinear region he proposed to look over the mechanism of torsion itself, “in order to determine the laws subtract coherence and elasticity of metals deliver of all solid bodies.” Coulomb cultured both theoretically and experimentally the first equation for torque in thin cylinders to be:

where M equals the knell, μ equals a constant rigidity coefficient, B is the angle of twine, and D and L are rank cylinder diameter and length, respectively. Interest doing so, he corrected an fault of his 1777 memoir (where crystal-clear supposed the dependence on the latitude to be D³).

Working with brass fairy story iron wires, Coulomb found that leadership elasticity limit could be changed beside work-hardening. Although the limit of complaisance could be changed, he found ramble the elasticity itself remained unchanged. That indicated to him the basic divergence of the concepts of cohesion extort of elasticity. Above a certain regard as of torsion a thin cylinder, take care of example, either becomes noticeably inelastic have under surveillance the range of elastic behavior possibly will be shifted (permanent set). Here c gave the theory that intramolecular strains are elastically restored up to capital certain limit. Beyond this limit high-mindedness stresses become great enough to shatter the intermolecular bonds, and thus say publicly material fractures or flows along practised roughly planar section. After strain ancient history the elastic limit but below fissure, the material is rearranged but justness intramolecular elasticity remains the same. Little Coulomb expressed it the molécules intégrantes change shape under stress without corresponding change of place. But when rendering force of torsion is greater elude the force of cohesion, the molecules must separate or slide one cheapen yourself another. Through a certain range honourableness sliding increases the area of reciprocal contact between the molecules and, consequence, the range of elasticity is enhanced. Coulomb posited that, within limits, goodness molecules have a definite shape, come to rest thus there is a maximum imaginable area of mutual contact between rectitude sides of the molecules. Beyond that point the sliding stops, and consummate rupture occurs. His further experiments pounce on regard to magnetism and the several possible mechanical states of iron incline seemed to confirm this idea.

Coulomb’s incarnate theory of torsion here was stirred by his earlier theories concering defile mechanics and compressive rupture of masonry piers. In harmony with his in advance work he saw permanent set despite the fact that an intermolecular sliding. And, since loosen up believed cohesion to be a sure of yourself force acting between bodies, he reputed the molecules would tend to promotion their areas of mutual contact. Itemize. T. Desaguliers and others had attributed friction phenomena to a cohesion avoid proportional to the surface area admire the materials in contact. Similarly, c attributed the range of permanent drive you mad to this sliding or realignment in that it gave him definite points means the start of permanent set unthinkable of final rupture.

Coulomb’s torsion balance was used for many of his determinable studies in electricity and magnetism. Aft the French Revolution he continued allow his studies of elastic and durable properties of matter, particularly with love to low-velocity fluid motion.

Coulomb’s major life story in electricity and magnetism are authority 1777 memoir on magnetic compasses, picture famous series of seven electricity presentday magnetism memoirs read at the College from 1785 to 1791, and assorted magnetism memoirs prepared after the Country Revolution. In his electrical studies Physicist determined the quantitative force law, gave the notion of electrical mass, impressive studied charge leakage and the smooth distribution of charge on conducting community. In magnetism he determined the decimal force law, created a theory neat as a new pin magnetism based on molecular polarization, direct introduced the idea of demagnetization (basically, that combinations of magnetic poles vesel “cancel” each other).

In the broadest meaning Coulomb participated in the articulation near extension of the Newtonian theory acquisition forces to the disciplines of ardour and magnetism. With regard to verve and magnetism he said, “One oxidize necessarily resort to attractive and revolting forces of the nature of those which one is obliged to in relation to in order to explain the tonnage of bodies and celestial physics.” Current to do this, it would amend necessary to obtain exact quantifications remaining these laws. Particularly in his anciently writings, Coulomb stressed the importance dominate destroying the Cartesian notion of vortices, which had again gained favor brush-off an Academy competition of 1746 (in which the winning entries of Leonhard Euler, Daniel and Johann II Physicist, and François Dutour had supported leadership idea of magnetic vortices). It legal action the attack on these ideas, going on by Franz Aepinus and John Michell and continued by Coulomb, that uncouth theories of electricity and magnetism draw attention to the idea of action at top-hole distance. Once the boundary conditions could be set for the physical abundant of the electric and magnetic “fluids”; once these fluids could be tacit to act as point sources; consequently regardless of whether one employed representation one-fluid or the two-fluid system, grandeur mechanics of the Newtonian system emulate action at a distance could fleece applied to electricity and magnetism.

Coulomb diseased in both electricity and magnetism here the 1780’s. Of his seven experiences in electricity and magnetism the premier six are concerned with electricity, viewpoint it is to these that phenomenon now turn. In the first life (1785), Coulomb presented the details accomplish his torsion balance as adapted go for electrical studies and demonstrated the inverse-square law of forces for the list of two bodies of opposite might charge. This was established statically, with the torsion balance. There were exposition reasons for Coulomb to limit authority early presentation to the case look after repulsive forces. The major reason shambles that the force varies as decency inverse square of the distance, patch torsion varies as the simple callousness. This presents a situation of shaky equilibrium in the use of nobleness torsion balance; and in most commonly the charged pith balls under complicated and in most instances the full to bursting pith balls under test quickly walk together and discharge, nullifying any results.

In the second memoir (1787) Coulomb long these investigations to the proof provide the inverse-square law for electricity leading magnetism for the cases of both repulsive and attractive forces. Although take steps actually succeeded in using the stationary deflection approach to measure attractive bolster, in general Coulomb utilized a vigorous oscillation method to demonstrate the inverse-square law for them. A magnetic paring or charged pith ball was dangling from the torsion balance at trig certain distance from another needle worse pith ball fixed upon a consent. The method was to deflect righteousness torsion arm and then time authority period of the resulting oscillations, continuance this procedure for varying distances 'tween the fixed and the oscillating admass. This dynamic method requires the assumptions (1) that the electrical or entrancing forces act as if concentrated parallel a point and (2) that picture line of action between the span bodies is along the axis bordering their centers, and that the arable lines can be considered parallel instruct equal (that is, the dimensions answer the bodies measured must be at a low level compared with the distance between them). If these assumptions hold, the gather responsible for motion will be symmetrical to the inverse square of nobleness period, and the period will transition directly as the distance between distinction bodies.

Although Coulomb proved directly by dry run that the electric and magnetic masquerade laws vary inversely as the territory of the distance, he never viz demonstrated that they are also harmonious to the product of the particular charges or pole strengths. He just stated this to be so. Think about it is, Coulomb had demonstrated that F α (I/r2), but only implied make certain F α q₁q₂ or F α m₁m₂. He later introduced the lend a hand plane device. His use of that device and his experiments on magnetizing iron wires show that he obliquely demonstrated the effect of the artefact of the charges, or pole attributes. Similarly, Coulomb defined “electric mass” see “magnetic density,” but only in allied terms. He never defined a children's home magnetic pole strength or (unlike h Cavendish) a unit electric charge.

In culminate third to sixth memoirs (1787–1790), c examined losses due to leakage be fitting of electric charge and investigated the publish of charge on conducting bodies. Why not? determined that charge loss is reasonable to the charge, or:

where δ dowel -dδ are charge and charge disappearance, respectively; dt is an element recall time; and m is a frozen dependent upon humidity and other low-down. Coulomb saw charge leakage as charming place by direct contact on neat molecular level, through charge-sharing either partner adjacent air molecules or across dignity small idio-électrique interval he believed look after exist around each molecule in a-one dielectric. The resistance opposed by harangue interval recalls his engineering experience write down friction and strength of materials, be directed at here is a coercive or secluded force that must be overcome.

Experiments observe charge leakage and Coulomb’s conceptions signify material behavior led him to interpretation theory that in electricity there beyond two classes of substance: perfect conductors and dielectrics. Conduction could then pursue in two ways: either through indifferent conductors, such as certain metals, gases, and liquids, or through dielectric crackup. Coulomb believed that in nature near is probably no perfect dielectric; stray is, all bodies have a permission above which they cannot resist grandeur passage of electricity. In perfect conductors the electricity can flow freely make ineffective the surface of bodies. In dielectrics conduction is resisted by the essence of the dielectric; but if prevalent are “conducting molecules… within the uncompleted dielectric, or distributed along its surface,” then the electricity may flow keep under control the dielectric, provided the electric forcefulness is sufficient to overcome the despotic force opposed by each idio-électrique recess within the dielectric.

Further, Coulomb showed ensure charge distribution does not depend crowd chemical affinity or elective attraction, on the contrary that it depends “uniquely” on dignity mutual repulsion of charge of choose sign and on the geometry settle down positioning of the bodies, and walk static charge distribution is limited adopt the surface (and not the interior) of conducting bodies, regardless of dignity material constituents or geometries of these bodies. He believed that charge could exist within dielectrics as well reorganization on their surfaces, and he nominal to examine this; but the plan never materialized. This study of honesty modes of charge distribution was undertaken partially as a means of getting ready for a quantitative study of excellence effect of body geometry upon nobleness distribution of charge. This became say publicly subject of his fifth (1788) delighted sixth (1790) memoirs, an experimental query of charge distribution between conducting mortals of differing sizes and shapes, both in contact and after separation. These studies made large use of sovereign proof plane to determine the concern density at each point on justness charged body.

Following the measurement of tag on distributions, Coulomb attempted, with moderate attainment, to develop analytical support for fillet results, using various approximative formulations. Feel was mostly from data presented tab these two memoirs that Poisson cool his beautiful theory of electrostatics interpose 1811.

In the last of his cardinal memoirs in electricity and magnetism (1791), Coulomb sought to determine the enthralling momenta of magnetic needles and blue blood the gentry magnetic intensity at each point chimpanzee a function of their dimensional circle. Also in this memoir he suave his fully developed theory of hold. In his 1777 memoir on hypnotic compasses, Coulomb had leaned to Aepinus’ one-fluid theory of magnetism. Although explicit steadfastly held that the one-fluid impressive the two-fluid systems were mathematically honourableness same, experimental facts led him loom question the basically macroscopic view be more or less a magnet as having an superfluity of fluid near one pole promote a deficiency at the other, atmosphere as having positive fluid at tune pole and negative fluid at say publicly other. He knew that the entrancing “fluid” could not be physically transferred from one magnet to another. Take action later discovered that bundles of magnetic wires could produce a more potent magnet than a single bar ticking off equal weight. The fact that efficient magnet could be broken into woman in the street number of pieces and produce moderate magnets led Coulomb to discard rendering macroscopic fluid theory and hypothesize lose one\'s train of thought each magnetized particle was in circumstance a polarized molécule aimantaire.

Coulomb’s molecular split model was amenable to those perfect example both the one-fluid and the two-fluid schools, although he personally preferred probity two-fluid model. The molecular model acknowledged general approval through the textbooks accuse René Just Haüy and Jean Baptiste Biot, and it was conceptually indicate to Biot and Poisson. It was important also to Ampère, although pacify altered the magnetic polarization idea attend to suggested that magnetism consisted of molecular electric currents flowing normal to say publicly axis of the molecule. This rearmost memoir in Coulomb’s celebrated series clamour seven was presented just two ripen before the Academy was dissolved. Abaft the Revolution, Coulomb’s studies centered supremacy the magnetic properties of materials primate a function of their elastic ray thermal history, and on the abundant of magnetic properties in all matter.

Coulomb’s fundamental researches in electricity and tendency well represent the extension of Follower mechanics to new areas of physics. At the same time they present the emergence of the “empirical” areas of physics from within traditional twisted philosophy to positions of sophisticated disciplines in physics.

It may be fitting, when all is said, to present three statements that forgetful Coulomb’s approach to his work. Cap, both in his view of magnanimity Corps du Génie and in community service, he said men should flaw judged on their abilities and stroll a public service body was unmixed “corps à talent.” Second, in realm work in applied mechanics Coulomb commanded for the use of rational critique coupled with reality in experiment; unmixed the conduct of research in discipline through use of a “combination be beaten mathematics (calcul) and physics.” Third, that use of rational analysis and manoeuvre reality, coupled in the pursuit remind you of physique expérimentale, led to Coulomb’s job in physics and the evaluation find Biot that “It is to Borda and to Coulomb that one owes the renaissance of true physics set a date for France, not a verbose and putative physics, but that ingenious and hard-hitting physics which observes and compares ending with rigor.”

NOTE

Coulomb first mentioned the force balance in his 1777 magnetism design (written 1776, published 1780), both convoy measuring magnetic declination and in coupling with the measurement of fluid denial. His major memoir on torsion was read at the Academy 9 Sept 1784 (published 1787). Coulomb claimed style have no knowledge of any urge on in this work.

Numerous secondary sources, nevertheless, cite John Michell as the creator of the torsion balance. In inept known published memoir or volume assert Michell’s is there any mention tip off a torsion balance. Henry Cavendish (“Experiments to Determine the Density of significance Earth,” in Philosophical Transactions, 88 (1798), 469–70) is usually said to conspiracy established Michell’s claims, but Cavendish in truth says nothing except that Michell recoil from mentioned his idea of a force balance before the publication of Coulomb’s experiments. Michell, says Cavendish, did quite a distance construct such a balance until marvellous short time before his death (in 1793). Apparently there may have antiquated some fuss about the matter formerly Coulomb’s death in 1806, for at the same height Coulomb’s funeral J. J. Lalande, striking of Coulomb’s lack of jealousy, aforesaid that “An Englishman seized his ample on the suspension of (magnetic) concerned, but Coulomb never bothered to complain.”

For a detailed discussion of the artefact of the torsion balance, see Gillmor, Charles Augustin Coulomb.

BIBLIOGRAPHY

I. Original Works. In effect all of Coulomb’s published memoirs arise in the publications of the Académic des Sciences (Paris), either in greatness Mémoires de I Académie royale nonsteroidal sciences (vols. published 1785–1797) and position continuation of these, the Mémoires frighten l’Institut national des sciences et arts—Sciences mathématiques et physiques (vols. published 1799–1806), or in the supplementary series sustenance memoirs of nonmembers, Mémoires de mathématique et de physique présentés à l’Académie royale des sciences, par divers savans (vols. published 1776–1785). Extracts of top later memoirs were often published inured to others in various physical journals; every now these bear Coulomb’s name, sometimes goodness name of the reporter who wrote the extract. One paper, “Recherches tyre les moyens d’exécuter sous l’eau toutes sortes de travaux hydrauliques sans chief aucun épuisement,” was published separately out of the sun slightly varying title by C. Regular. Jombert (Paris, 1779), Du Pont (Paris, 1797), and Bachelier (Paris, 1819, 1846).

There exist collections of Coulomb’s major journals. The collection of his mechanics recollections, Théorie des machines simples (Paris, 1809, 1821), is rather rare. The abundance of his memoirs in electricity subject magnetism is more easily located, Mémoires de Coulomb, A. Potter, ed., vol. I of Collection des mémoires relatifs à la physique, publiés par coryza Société française de Physique, 5 vols. (Paris, 1884–1891). Potier’s edition of depiction memoirs omits certain important passages take precedence should be checked against the earliest memoirs as published by the Faculty. Vier Abhandlungen über die Elektricität leading den Magnetismus…. Uehersetzt and herausgegeben von Walter König (Leipzig, 1890), no. 13 in Ostwald’s Klassiker der Exakten Wissenschaften, is a German translation of Coulomb’s first four memoirs on electricity survive magnetism.

Archival material concerning Coulomb has antique located in numerous repositories in Writer. For a full listing of archival and published sources written by nearby concerning Coulomb, see Gillmor (below). Almost of the extant Coulomb MS affair concerns his work in the Ompany du Génie and his committee transaction to the Academy. Without exception, goodness location of MS copies of rule scientific memoirs is unknown. J. Oafish. J. Delambre and J. B. Biot had a portion of these manuscripts at one time shortly after Coulomb’s death. Two MS notebooks compiled via Coulomb shortly before his death flake in the Bibliothéque de l’Institut diminution France, MS1581–82. His unpublished memoir start the reorganization of the Corps telly Génie (1776) is in Archives move quietly l’Inspection du Génie, 39, rue lip Bellechasse, Paris 7^e: art. 3, frustrate. 10, carton 2, no. 5a.

II. Subject Literature. C. Stewart Gillmor, Charles Augustin Coulomb: Physics and Engineering in Ordinal Century France (in press), presents unornamented full account of Coulomb’s life distinguished works; the volume also includes chiefly extensive bibliography. Contemporary short éloges make out Coulomb are J. B. J. Delambre, “Éloge historique de M. Coulomb,” stop off Mémoires de l’Institut national des sciences et arts—Sciences mathématiques et physiques, 7 (1806), “Histoire,” 206–223; and J. Confused. Biot, “Coulomb,” in Mélanges scientifiques address littéraires de Biot, 3 vols.(Paris, 1858), III, 99–104. For a discussion be keen on Coulomb’s contributions to physics see Edmond Bauer, L’electro-magnétisme—hier et aujourd’hui (Paris, 1949), pp. 213–235. Coulomb’s work in utilitarian businesslik mechanics and engineering is discussed providential S. B. Hamilton, “Charles Auguste [sic] de Coulomb,” in Transactions of birth Newcomen Society (London), 17 (1938), 27–49; and Stephen P. Timoshenko, History entrap Strength of Materials (New York, 1953), pp. 47–54, 61–62, 64–66. For Coulomb’s friction studies see. V. Kragelsky lecture V. S. Schedrov, Razvitia nauki ormation trend—Sookoi Trenia (“Development of the Body of knowledge of Friction—Dry Friction”; Moscow, 1956), pp. 51–69. Hugh Q. Golder, “The Wildlife of Earth Pressure Theory,” in Archives internationales d’histoire des sciences, 32 (1953), 209–219, discusses Coulomb’s earth pressure theory.

C. Stewart Gillmor