Biography of coulomb

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

physics, utilitarian businesslik mechanics.

One of the major vote in the history of physics and engineering, Coulomb’s main hand-outs were in the fields rot electricity, magnetism, applied mechanics, haulage studies, and torsion.

His curate, Henry, came from Montpellier, locale the family was important play in the legal and administrative scenery of Languedoc. His mother, Wife Bajet, was related to integrity weathy de Sénac family. All along Coulomb’s youth the family struck from Angoulême to Paris, veer he attended lectures at magnanimity Collège Mazarin and the faculty de France.

An argument touch upon his mother over career plan caused Coulomb to follow emperor father to Montpellier after authority latter became penniless through cash speculations. Couloub joined the Société des Sciences de Montpellier kind an adjoint member in Walk 1757 and read several registers in astronomy and mathematics back during the next two years.

He went to Paris in loftiness autumn of 1758, seeking picture tutoring necessary for him be a result enter the École du Jinnee at Mézières.

After some months of study he passed description abbé Charles Camus’s entrance inspection and took up residence reduced Mézières in February 1760. Tempt about this time he experienced lasting friendships with Jean River Borda and with the abbé Charles Bossut, his teacher have power over mathematics at Mézières. Coulomb mark in November 1761 with nobility rank of lieutenant en premier in the Corps du Génie.

His first post was have doubts about Brest; but in February 1764 he was ordered suddenly work to rule proceed to Martinique, where forbidden remained until June 1772. Physicist was put in charge mislay constructing Fort Bourbon, at deft cost of six million livres. He directed several hundred laborers in all phases of authority construction, and this experience was important as a foundation in favour of some of his later autobiography in mechanics.

Coulomb became decidedly ill several times during coronate stay in Martinique, and these illnesses affected his health ascend the extent that he was never again a well man.

Following his return to France, Ampere-second was posted to Bouchain, at he composed an important account in mechanics that earned him the title of Bossut’s be consistent with to the Paris Academy work out Sciences (6 July 1774).

Ampere-second moved then to duty enthral Cherbourg, where he began groove on a memoir on attractive compasses that subsequently shared cap prize in the Paris Academy’s competition for 1777. The equivalent of this major physical studies: the quantitative study of desirability, torsion and the torsion advise against, friction and fluid resistance, focus on the germ of his theories of elasticity and of magnetism.

One other event during his somewhere to live at Cherbourg merits attention: climax submission in 1776 of unadorned plan for the reorganization contribution the Corps du Génie.

Description comte de St.-Germain became evangelist of war in October 1775, during the administration of Economist. Coincident with Turgot’s reform aims, St.-Germain called for memoirs adjoin the reorganization of the Génie. Coulomb’s unpublished “Mémoire sur mid service des officiers du Cadre du Génie” was organized move around two principles, the individual avoid the state.

He sought make ill define the maximum utility thesis be obtained for each near to show that the first use of the Génie bow the most to each individual.

Coulomb saw the opportunity for leak out works in time of serenity and favored the establishment director review boards to judge grandeur worth of proposed projects.

Uttermost of all, he saw greatness Corps du Génie and typical service as a whole trade in a “corps a talent,” renounce is, with appointment and enhancement based on ability and realization. He stressed not the evils of the state but magnanimity potential of the state last individual in balance.

Coulomb was sensitive to Rochefort in 1779 assume aid the notorious marquis gathering Montalembert in constructing his doubtful fort entirely of wood facts the nearby Île d’Aix.

Significant this period Coulomb found at a rate of knots to engage in a long series of experiments on rubbing in the shipyards at Rochefort. The result of these researches won the double first affection at the Academy in Town in 1781 and gained Physicist election to the Academy by the same token adjoint mécanicien.

Membership in distinction Academy finally assured Coulomb prime a Paris residence, after heptad different field posts and note years’ service in the Gang du Génie.

The year 1781 telling a decisive break in Coulomb’s life and career. Permanently stationed in Paris, he could disinter a wife and raise graceful family.

Henceforth, his engineering duties would be only as span consultant, and he was ghastly to devote the major allocation of his time to researches in physics. Coulomb the inventor became physicist and public retainer. He read twenty-five scientific recollections at the Academy (and bulldoze its successor, the Institut metier France) from 1781 to 1806.

His most famous memoirs were the series of seven diary on electricity and magnetism station the memoirs on torsion existing the applications of the tortuosity balance. In addition to dominion physics research Coulomb participated bland 310 committee reports to ethics Academy concerning machines, instruments, canals, and engineering and civic projects.

In 1787 Coulomb and Jacques Rene Tenon were sent squalid England to investigate hospital acquaintance in London. In 1801 Coulob with whom Coulomb worked greatest closely were geometers, mechanicians, vanquish astronomers (e.g., Bossut, Leroy, Borda, Prony, Laplace).

Coulomb’s most celebrated ploy consulting task was in Brittany in 1783–1784.

Here he became involved, against his will, subtract a commission to recommend canalize and harbor improvements. The assignment (which included Borda and class abbé Alexis Marie Rochon) submitted a critical report and c suffered as the scapegoat, glance confined to prison for skin texture week in November 1783.

Coulomb’s excellent reports to the Institution on canals and water assistance systems led the comte d’Angiviller to nominate him in July 1784 as intendant of high-mindedness royal waters and fountains. Probity task of intendant involved operating the management of water systems in all royal properties, together with a good part of position water supply of Paris.

Almost biographical sketches of Coulomb touch on that he was appointed ranger of the large collection pursuit secret military relief maps supporting French cities and fortresses. Archival records, however, indicate this troupe to be so.

The Revolution wheedle 1789 caused little outward make in Coulomb’s activities.

He was in the midst of diadem great series of memoirs mound electricity and magnetism, and emperor committee reports to the Institution continued as usual. By 1791, however, the National Assembly challenging overturned or reorganized many chuck out the institutions of the ancien regime, and such measures functional to the Corps du Génie led Coulomb to resign pass up the corps in April 1791.

He retired with the place of lieutenant, colonel, was proprietor of the Croix de Fierce. Louis, and had thirty-one years’ service in the corps. Noteworthy obtained an annual pension break into 2,240 livres, which was rock bottom by two-thirds after the Rotation. Coulomb continued active participation family tree the Academy until its repudiation on 8 August 1793.

Get on with the same time he was removed from his position kind intendant of waters. He lengthened work on a committee dispense standardization of weights and instruction until it was “purged” temper December 1793. At this central theme he and Borda retired give somebody no option but to La Justinière, some property Physicist owned near Blois.

He common to his research in Town in December 1795, upon circlet election as member for physique expérimentale in the new Institut de France. His elder word, Charles Augustin II, was first in Paris on 26 Feb 1790 and his younger lady, Henry Louis, was born everywhere on 30 July 1797. Physicist legitimized his marriage to Louise Françoise LeProust Desormeaux on 17 brumaire, an XI (1802).

Coulomb’s take public service was as checker general of public inspector habitual of public instrucion from 1802 until his death in 1806, in which office he influenced a significant role in directorship the establishment of the Nation system of lycées.

Coulomb’s condition, weakened long before during sovereignty duty in Martinique, declined definitely in the early summer aristocratic 1806, and he died bear in mind the morning of 23 Honourable. Since he had been dubbed in the Roman Catholic grace, his final services were taken aloof at the Abbaye de St.-Germain-des-Prés. There is little evidence, banish, to indicate the extent round his religious convictions.

Secondary investment indicate that the Revolution took most of Coulomb’s properties extremity that he died almost discredit poverty. Examination of the credentials of his estate establishes, regardless, that Coulomb left over 40,000 francs. (This at a repulse when a physics professor put down a good French university would receive perhaps 6,000 francs delay year.) Two decades of wing duty in the Corps buffer Génie must have accustomed c to a modest style signal your intention life.

The probate description characteristic his personal belongings accords familiarize yourself this. He was accomplished mass history but not a male of letters; his library restricted 307 books, 238 of which were volumes issued by rendering Academy. Coulomb is often referred to as “de Coulomb,” implying nobility. He never signed in the flesh as such, and there enquiry no evidence to indicate lose concentration any of his family were ennobled.

Applied Mechanics. Generally speaking, Coulomb’s studies in mechanics preceded crown researches in physics.

His execution included fundamental memoirs on animate mechanics, rupture of beams near masonry piers, soil mechanics, abrasion theory, and ergonomics. In these he can be considered make sure of of the great engineers smudge eighteenth-century Europe. Like Monge, good taste seemed to apply his skill to whatever was at mitt.

He took advantage of magnanimity peculiarities of each military take care and pursued his studies change into mechanics accordingly. He was imposing but not exceptionally gifted live in mathematics, although he was give someone a ring of the first to utilise the variational calculus in neat engineering problems. With the blockage of his friction studies, accumulate of Coulomb’s mechanics memoirs were little known until utilized chunk Prony, Thomas Young, and plainness in the early nineteenth century.

His most important memoir on procedure was also his first, “Sur une application des règles show off maximis et minimis à quelques problèmes de statique, relatifs à l’architecture” (1773).

(The dates delineated herein for Coulomb’s memoirs, unless otherwise indicated, are those dates when he formally presented ethics memoirs before the Paris Institution of Sciences. The actual dates of publication may be procured from the bibliography.) The point of this memoir, he supposed, was “to determine, as distant as a combination of reckoning and physics will permit, righteousness influence of friction and method cohesion in some problems gaze at statics.” Coulomb’s statics problems strength seem disconnected to the up to date reader, but they were jab the heart of eighteenth-century application mechanics.

If one examines prestige standard early eighteenth century drudgery (e.g., Bernad Forest de Bélidor’s Science ds ingénieurs, or Amédée François Frezier’s Traité de stereotomie), one finds the main orchestration topics to be the addition of masonry materials, the found of retaining walls, and birth design of arches.

These build precisely the problems that Physicist attacked.

In the beginning of grandeur 1773 essay, Coulomb introduced a handful of propositions relating to equilibrium added resolution of forces. Following that, he considered friction and community of interest, and gave virtually a hesitantly of the flexure of logs and rupture and shear show consideration for brittle materials.

Coulomb utilized Amonton’s law that frictional resistance commission proportional to the normal energy acting on the surface fairly than to the area forfeited the surface in contact. Proceed noted, however, that this edict is not strictly observed boardwalk practice and that the coefficient of friction varies with integrity materials involved.

Following this, without fear considered cohesion. Friction was disregard as resulting from tangential friend between bodies, but cohesion was supposedly due to the shouting match of close-acting central forces. Community of interest in materials was considered moisten Coulomb as a mixture admit what would today be denominated shear and tensile strengths.

According to him, cohesion is serene by the resistance that crowded bodies oppose to direct “disunion” of their parts. In unornamented homogeneous body each part resists rupture with the same position of resistance. Therefore, total coherence is proportional to the digit of parts to be unconnected, and thus to the exterior area of rupture.

Experimenting trade stone, mortar, and brick sections, Coulomb found values for latest strength under tension and shears. Although his experimentally.

determined values assorted slightly, he assumed that cut off and tensile coefficients were position same.

Having presented these basic attitude and experiments, Coulomb proceeded divulge a discussion of the flexing of a beam and accurately determined, for the first disgust, the neutral surface of nifty beam.

Considering a rectangular cantilever beam (Fig. 1) of crucifix section AD, he concluded zigzag the upper portion AC drive be under tension and position lower portion CD under concentration. Resolving the forces into even and vertical components, he showed that the sum of categorical forces along AD must require zero and the sum suffer defeat vertical forces must equal interpretation load φ.

Finally, the linger of the load φ be concerned about axis C must equal depiction sums of the internal moments of the beam. Note think about it although Coulomb took a absolutely elastic beam as an comments, he realized the distribution dead weight forces along BCe could accredit any sort of curve; nearby in Figure 1 he histrion it as some sort flawless parabola.

In addition, Coulomb stiff that shearing forces could tweak neglected in long, narrow trees. Following this, he extended government analysis to the rigid, brittle case.

In this one memoir pass judgment on 1773 there is almost fleece embarrassment of riches, for Ampere-second proceeded to discuss the premise of compressive rupture of masonry piers, the design of domed arches, and the theory show earth pressure.

In the tide he developed a generalized declining wedge theory of soil execution that remains in use any more in basic engineering practice. Practised reason, perhaps, for the interconnected neglect of this portion souk Coulomb’s work was that do something sought to demonstrate the specification of variational calculus in formulating methods of approach to radical problems in structural mechanics in or by comparison than to give numerical solutions to specific problems.

It obligatory that group of Polytechniciens, staff and students, in the at nineteenth century to appreciate distinction importance of this work hole the context of the pristine engineering mechanics. The eighteenth-century manager preferred to use empirical pattern tables, such as those compiled by Jean Rudolph Perronet tell off Antoine de Chézy.

Coulomb’s most renowned study, one that brought him immediate acclaim, was “Théorie nonsteroid machines simples,” his prize-winning chafing study of 1781.

He investigated both static and dynamic fretting of sliding surfaces and drag in bending of cords charge in rolling. From examination sustaining many physical parameters, he highly-developed a series of two-term equations, the first term a everyday and the second term different with time, normal force, hurry, or other parameters. In planning with Amontons’s work of 1699, Coulomb showed that in public there is an approximately clear up relationship between friction and average force; but he extended position investigation considerably to show set of connections effects due to difference bring in load, materials, time of inactivity, lubrication, velocity, and other considerations.

Coulomb’s work in friction remained a standard of theory stomach experiment for a century build up a half, until the arrival of molecular studies of pulling in the twentieth century. Industrial action quote Kragelsky and Schedrov’s latest monograph (p. 52) on high-mindedness history of friction: “Coulomb’s assistance to the science of pull were exceptionally great.

Without magnification, one can say that take action created this science.”

Another subject be successful much interest to Coulomb was the question of efficiency advocate output in work, and entertain this field (ergonomics) he required one of the most goodly contributions before the studies nominate F. W. Taylor, a hundred later. Coulomb began this office in Martinique and read nobleness first of several memoirs inclination the subject to the Institution in 1778.

It was eventually published in 1799 as “Résultats de plusieure expériences destinées à déterminer la quantité d’action constitution les hommes peuvent fournir level leur travail journalier, suivant discipline différent manières dont ils employent leurs forces.” Earlier studies reliable men or animals only provision very brief periods, thus in existence exaggerated results of productivity.

Amperesecond investigated various work parameters become aware of realistically and with considerable irrational insight; and he distinguished betwixt useful work and fatigue take delivery of work from living “machines,” crack to make the ratio be advantageous to effect to fatigue a utmost. In this he produced magnanimity first real study of blue blood the gentry practical aspects of labor percentage.

Among his findings were stroll frequent rest periods during confident tasks produce higher overall crop, and that maximum daily individual work results from seven discussion group eight hours’ labor for giant tasks and ten hours’ undergo for light tasks. He occupied similar isoperimetric methods to vet the theory and design behove windmills.

Physics. Coulomb’s election to nobility Paris Academy in 1781 highest his acquisition of a unchanging post in Paris allowed top research generally to turn circumvent applied mechanics to physics.

Culminate physics work, however, is integrally tied to his earlier operate in mechanics. His concern traffic friction and cohesion and reward emphasis upon the importance help shear in structural mechanics commerce continued in his studies slap torsion, in his ideas archetypal “coercive force” in electrostatics build up magnetism, and in his terminating studies in magnetism and representation properties of matter.

Coulomb’s first letters on torsion were presented fit into place his Academy prize-winning memoir sustaining 1777, “Recherches sur la meilleure maniere de fabriquer les aiguilles aimantées.” He never attacked authority general problems of elasticity (these were developed by Navier, Poisson, and Cauchy in the eminent decades of the nineteenth century), but his simple, elegant antidote to the problem of contortion in cylinders and his heavy of the torsion balance deal physical applications were important get on to numerous physicists in succeeding majority.

In chapter 3, Coulomb civilized the theory of torsion break off thin silk and hair rags. Here he was the premier to show how the crookedness suspension could provide physicists drag a method of accurately judgement extremely small forces. He showed that within certain angular purlieus, torsional oscillation consisted of genial harmonic motion.

He examined honourableness parameters relating the angle carry twist to the length, diam, and elastic properties of rank torsion thread. In the put together of simple harmonic oscillation Physicist demonstrated that the force nigh on torsion was proportional to rank angle of twist. He stirred this principle in measuring at a low level magnetic forces and also christened attention to its use comic story measuring other forces, notably those of fluids in motion.

Finally he was able to size forces of less than 9 x 10^-4 dynes.

This 1777 profile contained the design of fine torsion suspension declination compass. Congruence of this compass by authority Paris Observatory in 1780 have a word with the observatory’s subsequent request come up with a solution to seemingly unimaginable problems in magnetic measurement separately Coulomb to undertake a additional series of experiments on crookedness.

His major memoir on torque, presented 9 September 1784 (“Recherches theoriques et expérimentales sur mean force de torsion et metropolis l’élasticité des fils de métal”), emerged from this latter subject. This in turn provided him with a means to review and determine quantitatively the energy relationships in varied physical comedian. The torsion balance invented infant Coulomb (see note) and illustriousness theory of torsion aided him in constructing theories concerning primacy molecular interaction within fluids increase in intensity solids and, as is parts known, provided the instrumental leg for his work in tenseness and magnetism.

In his 1784 dissertation Coulomb sought (1) to data the laws of torsion take to determine possible applications light torsion and (2) to explore the laws of coherence don elasticity of bodies by way of torsion.

That is, although he noted, his study was in two regions of description torsion spectrum: the linear swallow nonlinear regions. Within the chief he proposed to determine nobleness linear relationship of force get closer torsion and to propose useable applications of this phenomenon pray use in measuring various petite forces.

In the nonlinear abscond he proposed to investigate say publicly mechanism of torsion itself, “in order to determine the record of coherence and elasticity match metals and of all unbreakable bodies.” Coulomb developed both perfectly and experimentally the fundamental fraction for torque in thin cylinders to be:

where M equals representation torque, μ equals a resolute rigidity coefficient, B is rendering angle of twist, and Course and L are the roster diameter and length, respectively.

Swindle doing so, he corrected disentangle error of his 1777 narrative (where he supposed the habituation on the diameter to note down D³).

Working with brass and slick wires, Coulomb found that illustriousness elasticity limit could be denaturized by work-hardening. Although the line of elasticity could be different, he found that the plasticity itself remained unchanged.

This peculiar to him the basic variation of the concepts of esprit de corps and of elasticity. Above adroit certain angle of torsion orderly thin cylinder, for example, either becomes noticeably inelastic or decency range of elastic behavior hawthorn be shifted (permanent set). Nearby Coulomb gave the theory turn this way intramolecular strains are elastically fashionable up to a certain speciality.

Beyond this limit the stresses become great enough to split the intermolecular bonds, and way the material fractures or flows along a roughly planar department. After strain beyond the flexible limit but below rupture, prestige material is rearranged but influence intramolecular elasticity remains the amount to.

As Coulomb expressed it rectitude molécules intégrantes change shape slip up stress without relative change disregard place. But when the coarsely of torsion is greater outshine the force of cohesion, ethics molecules must separate or skitter one over another. Through neat as a pin certain range the sliding increases the area of mutual technique between the molecules and, thence, the range of elasticity deterioration increased.

Coulomb posited that, at bottom limits, the molecules have cool definite shape, and thus just about is a maximum possible adjust of mutual contact between leadership sides of the molecules. At a distance this point the sliding chicago, and outright rupture occurs. Authority further experiments with regard correspond with magnetism and the various credible mechanical states of iron ascendancy seemed to confirm this idea.

Coulomb’s physical theory of torsion ambit was influenced by his hitherto theories concering soil mechanics take compressive rupture of masonry piers.

In harmony with his previously work he saw permanent backdrop as an intermolecular sliding. Remarkable, since he believed cohesion stunt be a positive force finicky between bodies, he supposed greatness molecules would tend to wave their areas of mutual appeal. J. T. Desaguliers and excess had attributed friction phenomena converge a cohesion effect proportional progress to the surface area of interpretation materials in contact.

Similarly, Ampere-second attributed the range of castiron set to this sliding have under surveillance realignment because it gave him definite points for the come out of of permanent set and familiar final rupture.

Coulomb’s torsion balance was used for many of culminate quantitative studies in electricity ray magnetism. After the French Spin he continued with his studies of elastic and cohesive bestowal of matter, particularly with love to low-velocity fluid motion.

Coulomb’s important memoirs in electricity and affinity are his 1777 memoir tyrannize magnetic compasses, the famous escort of seven electricity and affinity memoirs read at the Faculty from 1785 to 1791, mushroom several magnetism memoirs prepared aft the French Revolution.

In authority electrical studies Coulomb determined justness quantitative force law, gave honesty notion of electrical mass, snowball studied charge leakage and interpretation surface distribution of charge hire conducting bodies. In magnetism elegance determined the quantitative force knock about, created a theory of draw based on molecular polarization, instruction introduced the idea of action (basically, that combinations of hypnotic poles can “cancel” each other).

In the broadest sense Coulomb participated in the articulation and margin of the Newtonian theory thoroughgoing forces to the disciplines perceive electricity and magnetism.

With affection to electricity and magnetism loosen up said, “One must necessarily retreat to attractive and repulsive prop of the nature of those which one is obliged engender a feeling of use in order to explicate the weight of bodies talented celestial physics.” And to discharge this, it would be permissible to obtain exact quantifications clean and tidy these laws.

Particularly in wreath early writings, Coulomb stressed rank importance of destroying the Philosopher notion of vortices, which challenging again gained favor through slight Academy competition of 1746 (in which the winning entries admonishment Leonhard Euler, Daniel and Johann II Bernoulli, and François Dutour had supported the idea topple magnetic vortices).

It is blue blood the gentry attack on these ideas, started by Franz Aepinus and Bog Michell and continued by Ampere-second, that turned theories of tension and magnetism toward the solution of action at a deviate. Once the boundary conditions could be set for the corporal extent of the electric existing magnetic “fluids”; once these fluids could be assumed to recital as point sources; then in spite of of whether one employed decency one-fluid or the two-fluid arrangement, the mechanics of the Follower system of action at swell distance could be applied address electricity and magnetism.

Coulomb worked count on both electricity and magnetism during the 1780’s.

Of his digit memoirs in electricity and desirability the first six are worried with electricity, and it psychiatry to these that we at once turn. In the first narrative (1785), Coulomb presented the trivia of his torsion balance despite the fact that adapted for electrical studies allow demonstrated the inverse-square law provide forces for the case point toward two bodies of opposite potential charge.

This was established statically, using the torsion balance. Presentday were good reasons for Ampere-second to limit his early articulation to the case of abhorrent forces. The major reason stick to that the force varies monkey the inverse square of dignity distance, while torsion varies bring in the simple distance. This largesse a situation of unstable equipoise in the use of greatness torsion balance; and in principal instances the charged pith vigour under test and in nigh instances the charged pith vigour under test quickly come case and discharge, nullifying any results.

In the second memoir (1787) Physicist extended these investigations to magnanimity proof of the inverse-square construct for electricity and magnetism engage in the cases of both offensive and attractive forces.

Although explicit actually succeeded in using ethics static deflection approach to amount attractive forces, in general c utilized a dynamic oscillation course of action to demonstrate the inverse-square decree for them. A magnetic chevvy or charged pith ball was suspended from the torsion in a state at a certain distance immigrant another needle or pith brusque fixed upon a stand.

Ethics method was to deflect character torsion arm and then prior the period of the indirect oscillations, repeating this procedure embody varying distances between the hair and the oscillating bodies. That dynamic method requires the assumptions (1) that the electrical survey magnetic forces act as in case concentrated at a point person in charge (2) that the line weekend away action between the two mingy is along the axis on the verge of their centers, and that birth field lines can be putative parallel and equal (that stick to, the dimensions of the needy measured must be small compared with the distance between them).

If these assumptions hold, interpretation forces responsible for motion choice be proportional to the reciprocal square of the period, accept the period will vary tangentially as the distance between blue blood the gentry bodies.

Although Coulomb proved directly tough experiment that the electric viewpoint magnetic force laws vary reciprocally as the square of blue blood the gentry distance, he never specifically demonstrated that they are also analogical to the product of righteousness respective charges or pole subvention.

He simply stated this be be so. That is, c had demonstrated that F α (I/r2), but only implied ditch F α q₁q₂ or F α m₁m₂. He later extrinsic the proof plane device. Coronate use of this device keep from his experiments on magnetizing shackle wires show that he circumlocutorily demonstrated the effect of illustriousness product of the charges, hovel pole strengths.

Similarly, Coulomb concrete “electric mass” and “magnetic density,” but only in relative phraseology. He never defined a private house magnetic pole strength or (unlike Henry Cavendish) a unit dynamic charge.

In his third to onesixth memoirs (1787–1790), Coulomb examined sufferers due to leakage of forceful charge and investigated the division of charge on conducting penny-pinching.

He determined that charge drain is proportional to the at no cost, or:

where δ and -dδ program charge and charge loss, respectively; dt is an element pleasant time; and m is spruce constant dependent upon humidity ride other factors. Coulomb saw unbound leakage as taking place moisten direct contact on a molecular level, through charge-sharing either stomach adjacent air molecules or cincture the small idio-électrique interval flair believed to exist around command molecule in a dielectric.

Birth resistance opposed by each interlude recalls his engineering experience cede friction and strength of money, for here is a cruel or passive force that mildew be overcome.

Experiments with charge seep out and Coulomb’s conceptions of textile behavior led him to rectitude theory that in electricity forth are two classes of substance: perfect conductors and dielectrics.

Conductivity could then occur in one ways: either through perfect conductors, such as certain metals, gases, and liquids, or through insulator breakdown. Coulomb believed that row nature there is probably pollex all thumbs butte perfect dielectric; that is, repeated bodies have a limit condescending which they cannot resist righteousness passage of electricity.

In pure conductors the electricity can course freely over the surface comprehensive bodies. In dielectrics conduction level-headed resisted by the nature innumerable the dielectric; but if respecting are “conducting molecules… within rendering imperfect dielectric, or distributed stick to its surface,” then the energy may flow over the stuff, provided the electric intensity crack sufficient to overcome the dictatorial force opposed by each idio-électrique interval within the dielectric.

Further, c showed that charge distribution does not depend on chemical connection or elective attraction, but focus it depends “uniquely” on nobility mutual repulsion of charge behove like sign and on probity geometry and positioning of goodness bodies, and that static plus distribution is limited to authority surface (and not the interior) of conducting bodies, regardless shambles the material constituents or geometries of these bodies.

He accounted that charge could exist dielectrics as well as provisional their surfaces, and he nominal to examine this; but representation project never materialized. This learn about of the modes of on the surface distribution was undertaken partially in the same way a means of preparing defence a quantitative study of picture effect of body geometry set upon the distribution of charge.

That became the subject of rulership fifth (1788) and sixth (1790) memoirs, an experimental investigation lift charge distribution between conducting of differing sizes and shapes, both in contact and aft separation. These studies made bulky use of his proof face to determine the charge tightness at each point on glory charged body.

Following the measurement devotee charge distributions, Coulomb attempted, make contact with moderate success, to develop probing support for his results, screen various approximative formulations.

It was mostly from data presented dense these two memoirs that Poisson composed his beautiful theory virtuous electrostatics in 1811.

In the determined of his seven memoirs difficulty electricity and magnetism (1791), Physicist sought to determine the captivating momenta of magnetic needles jaunt the magnetic intensity at go on point as a function censure their dimensional parameters.

Also uncover this memoir he presented crown fully developed theory of charisma. In his 1777 memoir occupation magnetic compasses, Coulomb had leaned to Aepinus’ one-fluid theory outline magnetism. Although he steadfastly booked that the one-fluid and high-mindedness two-fluid systems were mathematically rendering same, experimental facts led him to question the basically megascopic view of a magnet type having an excess of liquid near one pole and simple deficiency at the other, care for as having positive fluid indulgence one pole and negative marshy at the other.

He knew that the magnetic “fluid” could not be physically transferred reject one magnet to another. Yes later discovered that bundles pass judgment on magnetized wires could produce clever more powerful magnet than swell single bar of equal explosion. The fact that a decoy could be broken into impractical number of pieces and lay to rest smaller magnets led Coulomb in all directions discard the macroscopic fluid view and hypothesize that each magnetic particle was in fact nifty polarized molécule aimantaire.

Coulomb’s molecular condition model was amenable to those of both the one-fluid coupled with the two-fluid schools, although appease personally preferred the two-fluid construct.

The molecular model received accepted approval through the textbooks loom René Just Haüy and Denim Baptiste Biot, and it was conceptually important to Biot endure Poisson. It was important as well to Ampère, although he changed the magnetic polarization idea pivotal suggested that magnetism consisted succeed molecular electric currents flowing inflexible to the axis of description molecule.

This final memoir birth Coulomb’s celebrated series of figure was presented just two life-span before the Academy was dissolved. After the Revolution, Coulomb’s studies centered on the magnetic abilities of materials as a purpose of their elastic and energy history, and on the fully of magnetic properties in compartment matter.

Coulomb’s fundamental researches in vibrations and magnetism well represent nobleness extension of Newtonian mechanics lying on new areas of physics.

Whack the same time they typify the emergence of the “empirical” areas of physics from favourable traditional natural philosophy to positions of sophisticated disciplines in physics.

It may be fitting, finally, disclose present three statements that designate Coulomb’s approach to his thought. First, both in his property value of the Corps du Génie and in public service, prohibited said men should be considered on their abilities and put off a public service body was a “corps à talent.” Erelong, in his work in functional mechanics Coulomb called for distinction use of rational analysis linked with reality in experiment; miserly the conduct of research fashionable engineering through use of nifty “combination of mathematics (calcul) take precedence physics.” Third, this use appreciate rational analysis and engineering 1 coupled in the pursuit authentication physique expérimentale, led to Coulomb’s work in physics and interpretation evaluation of Biot that “It is to Borda and permission Coulomb that one owes goodness renaissance of true physics advocate France, not a verbose queue hypothetical physics, but that penetrating and exact physics which observes and compares all with rigor.”

NOTE

Coulomb first mentioned the torsion ponder in his 1777 magnetism style (written 1776, published 1780), both for measuring magnetic declination stake in connection with the gaging of fluid resistance.

His larger memoir on torsion was review at the Academy 9 Sep 1784 (published 1787). Coulomb designated to have no knowledge cosy up any predecessors in this work.

Numerous secondary sources, however, cite Lav Michell as the inventor be required of the torsion balance. In pollex all thumbs butte known published memoir or book of Michell’s is there vulgar mention of a torsion distraught.

Henry Cavendish (“Experiments to Interesting the Density of the Earth,” in Philosophical Transactions, 88 (1798), 469–70) is usually said run into have established Michell’s claims, on the other hand Cavendish actually says nothing demur that Michell privately mentioned fillet idea of a torsion saddened before the publication of Coulomb’s experiments.

Michell, says Cavendish, exact not construct such a muddle until a short time a while ago his death (in 1793). Patently there may have been unkind fuss about the matter formerly Coulomb’s death in 1806, sue for at Coulomb’s funeral J. Itemize. Lalande, speaking of Coulomb’s absence of jealousy, said that “An Englishman seized his idea unrest the suspension of (magnetic) flappable, but Coulomb never bothered be acquainted with complain.”

For a detailed discussion possession the invention of the crookedness balance, see Gillmor, Charles Augustin Coulomb.

BIBLIOGRAPHY

I.

Original Works. Nearly every of Coulomb’s published memoirs turn up in the publications of primacy Académic des Sciences (Paris), either in the Mémoires de Berserk Académie royale des sciences (vols. published 1785–1797) and the cycle of these, the Mémoires show off l’Institut national des sciences outset arts—Sciences mathématiques et physiques (vols.

published 1799–1806), or in influence supplementary series for memoirs have a hold over nonmembers, Mémoires de mathématique obtain de physique présentés à l’Académie royale des sciences, par differing savans (vols. published 1776–1785). Extracts of his later memoirs were often published by others solution various physical journals; sometimes these bear Coulomb’s name, sometimes decency name of the reporter who wrote the extract.

One questionnaire, “Recherches sur les moyens d’exécuter sous l’eau toutes sortes prickly travaux hydrauliques sans employer aucun épuisement,” was published separately descend slightly varying title by Catchword. A. Jombert (Paris, 1779), Defence Pont (Paris, 1797), and Bachelier (Paris, 1819, 1846).

There exist collections of Coulomb’s major memoirs.

High-mindedness collection of his mechanics memories, Théorie des machines simples (Paris, 1809, 1821), is rather rarefied. The collection of his life in electricity and magnetism obey more easily located, Mémoires all the way through Coulomb, A. Potter, ed., vol. I of Collection des mémoires relatifs à la physique, publiés par la Société française phase Physique, 5 vols.

(Paris, 1884–1891). Potier’s edition of the experiences omits certain important passages captain should be checked against excellence original memoirs as published moisten the Academy. Vier Abhandlungen über die Elektricität and den Magnetismus…. Uehersetzt and herausgegeben von Director König (Leipzig, 1890), no.

13 in Ostwald’s Klassiker der Exakten Wissenschaften, is a German rendering of Coulomb’s first four diary on electricity and magnetism.

Archival stuff concerning Coulomb has been settled in numerous repositories in Writer. For a full listing friendly archival and published sources impenetrable by and concerning Coulomb, perceive Gillmor (below).

Most of rectitude extant Coulomb MS material exploits his work in the Gang du Génie and his chamber reports to the Academy. Broke exception, the location of Cede copies of his scientific journals is unknown. J. B. Itemize. Delambre and J. B. Biot had a portion of these manuscripts at one time in a little while after Coulomb’s death.

Two Manuscript notebooks compiled by Coulomb in a minute before his death are hut the Bibliothéque de l’Institut give in France, MS1581–82. His unpublished narrative on the reorganization of greatness Corps du Génie (1776) remains in Archives de l’Inspection buffer Génie, 39, rue de Bellechasse, Paris 7^e: art.

3, go through with a fine-tooth comb. 10, carton 2, no. 5a.

II. Secondary Literature. C. Stewart Gillmor, Charles Augustin Coulomb: Physics explode Engineering in Eighteenth Century France (in press), presents a filled account of Coulomb’s life most recent works; the volume also includes an extensive bibliography.

Contemporary therefore éloges of Coulomb are Record. B. J. Delambre, “Éloge historique de M. Coulomb,” in Mémoires de l’Institut national des sciences et arts—Sciences mathématiques et physiques, 7 (1806), “Histoire,” 206–223; add-on J. B. Biot, “Coulomb,” instruct in Mélanges scientifiques et littéraires accept Biot, 3 vols.(Paris, 1858), Tierce, 99–104.

For a discussion assiduousness Coulomb’s contributions to physics bare Edmond Bauer, L’electro-magnétisme—hier et aujourd’hui (Paris, 1949), pp. 213–235. Coulomb’s work in applied mechanics esoteric engineering is discussed in Heartless. B. Hamilton, “Charles Auguste [sic] de Coulomb,” in Transactions have a high regard for the Newcomen Society (London), 17 (1938), 27–49; and Stephen Proprietress.

Timoshenko, History of Strength state under oath Materials (New York, 1953), pp. 47–54, 61–62, 64–66. For Coulomb’s friction studies see. V. Kragelsky and V. S. Schedrov, Razvitia nauki o trend—Sookoi Trenia (“Development of the Science of Friction—Dry Friction”; Moscow, 1956), pp. 51–69. Hugh Q. Golder, “The Life of Earth Pressure Theory,” place in Archives internationales d’histoire des sciences, 32 (1953), 209–219, discusses Coulomb’s earth pressure theory.

C.

Stewart Gillmor