Charles coulomb biography summary

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

physics, pragmatic mechanics.

One of the major returns in the history of physics and engineering, Coulomb’s main endowment were in the fields assiduousness electricity, magnetism, applied mechanics, fretting studies, and torsion.

His cleric, Henry, came from Montpellier, vicinity the family was important uncover the legal and administrative world of Languedoc. His mother, Empress Bajet, was related to influence weathy de Sénac family. Mid Coulomb’s youth the family mincing from Angoulême to Paris, whirl location he attended lectures at birth Collège Mazarin and the institution de France.

An argument deal with his mother over career structure caused Coulomb to follow sovereign father to Montpellier after rank latter became penniless through 1 speculations. Couloub joined the Société des Sciences de Montpellier significance an adjoint member in Amble 1757 and read several records in astronomy and mathematics in the matter of during the next two years.

He went to Paris in decency autumn of 1758, seeking primacy tutoring necessary for him achieve enter the École du Spirit at Mézières.

After some months of study he passed probity abbé Charles Camus’s entrance study and took up residence rot Mézières in February 1760. Send up about this time he erudite lasting friendships with Jean River Borda and with the abbé Charles Bossut, his teacher build up mathematics at Mézières. Coulomb gentle in November 1761 with authority rank of lieutenant en premier in the Corps du Génie.

His first post was wrap up Brest; but in February 1764 he was ordered suddenly detain proceed to Martinique, where blooper remained until June 1772. Physicist was put in charge loom constructing Fort Bourbon, at first-class cost of six million livres. He directed several hundred laborers in all phases of blue blood the gentry construction, and this experience was important as a foundation lease some of his later recollections in mechanics.

Coulomb became critically ill several times during cap stay in Martinique, and these illnesses affected his health be in breach of the extent that he was never again a well man.

Following his return to France, Ampere-second was posted to Bouchain, site he composed an important biography in mechanics that earned him the title of Bossut’s well to the Paris Academy time off Sciences (6 July 1774).

Physicist moved then to duty be neck and neck Cherbourg, where he began bore on a memoir on alluring compasses that subsequently shared principal prize in the Paris Academy’s competition for 1777. The desirability of this major physical studies: the quantitative study of benefit, torsion and the torsion superfluity, friction and fluid resistance, spreadsheet the germ of his theories of elasticity and of magnetism.

One other event during his pause at Cherbourg merits attention: potentate submission in 1776 of regular plan for the reorganization chide the Corps du Génie.

Description comte de St.-Germain became track of war in October 1775, during the administration of Economist. Coincident with Turgot’s reform aims, St.-Germain called for memoirs intensification the reorganization of the Génie. Coulomb’s unpublished “Mémoire sur accidental service des officiers du Team du Génie” was organized about two principles, the individual increase in intensity the state.

He sought calculate define the maximum utility impediment be obtained for each coupled with to show that the unqualified use of the Génie paralysed the most to each individual.

Coulomb saw the opportunity for let slip works in time of calm and favored the establishment love review boards to judge integrity worth of proposed projects. Apogee of all, he saw leadership Corps du Génie and the upper crust service as a whole by the same token a “corps a talent,” defer is, with appointment and stage based on ability and completion.

He stressed not the evils of the state but say publicly potential of the state stand for individual in balance.

Coulomb was official statement to Rochefort in 1779 control aid the notorious marquis secondary Montalembert in constructing his debatable fort entirely of wood delicate the nearby Île d’Aix.

Not later than this period Coulomb found offend to engage in a prolonged series of experiments on pulling in the shipyards at Rochefort. The result of these researches won the double first award at the Academy in Town in 1781 and gained Amperesecond election to the Academy monkey adjoint mécanicien.

Membership in high-mindedness Academy finally assured Coulomb disagree with a Paris residence, after heptad different field posts and note years’ service in the Detachment du Génie.

The year 1781 conspicuous a decisive break in Coulomb’s life and career. Permanently stationed in Paris, he could surprise a wife and raise pure family. Henceforth, his engineering duties would be only as shipshape and bristol fashion consultant, and he was silhouette to devote the major quantity of his time to researches in physics.

Coulomb the contriver became physicist and public help. He read twenty-five scientific recollections at the Academy (and calm its successor, the Institut sell France) from 1781 to 1806. His most famous memoirs were the series of seven reminiscences annals on electricity and magnetism cranium the memoirs on torsion boss the applications of the contortion balance.

In addition to consummate physics research Coulomb participated dependably 310 committee reports to goodness Academy concerning machines, instruments, canals, and engineering and civic projects. In 1787 Coulomb and Jacques Rene Tenon were sent reverse England to investigate hospital situation in London. In 1801 Coulob with whom Coulomb worked lid closely were geometers, mechanicians, restricted astronomers (e.g., Bossut, Leroy, Borda, Prony, Laplace).

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

Here he became involved, against his will, increase twofold a commission to recommend messenger and harbor improvements. The sleep (which included Borda and righteousness abbé Alexis Marie Rochon) submitted a critical report and Ampere-second suffered as the scapegoat, personality confined to prison for prepare week in November 1783. Coulomb’s excellent reports to the School on canals and water mammon systems led the comte d’Angiviller to nominate him in July 1784 as intendant of interpretation royal waters and fountains.

Honourableness task of intendant involved directorate the management of water systems in all royal properties, counting a good part of righteousness water supply of Paris. Almost biographical sketches of Coulomb pass comment that he was appointed janitor of the large collection scope secret military relief maps be unable to find French cities and fortresses.

Archival records, however, indicate this gather together to be so.

The Revolution take away 1789 caused little outward throw out in Coulomb’s activities. He was in the midst of her majesty great series of memoirs focused electricity and magnetism, and sovereignty committee reports to the Institution continued as usual. By 1791, however, the National Assembly difficult overturned or reorganized many company the institutions of the ancien regime, and such measures optimistic to the Corps du Génie led Coulomb to resign unapproachable the corps in April 1791.

He retired with the person of lieutenant, colonel, was bearer of the Croix de Sitin. Louis, and had thirty-one years’ service in the corps. Recognized obtained an annual pension confiscate 2,240 livres, which was brief by two-thirds after the Turn. Coulomb continued active participation jacket the Academy until its extirpation on 8 August 1793. Undervalue the same time he was removed from his position makeover intendant of waters.

He drawn-out work on a committee in line for standardization of weights and distrait until it was “purged” bother December 1793. At this intention he and Borda retired familiar with La Justinière, some property c owned near Blois. He joint to his research in Town in December 1795, upon sovereign election as member for physique expérimentale in the new Institut de France.

His elder difference, Charles Augustin II, was basic in Paris on 26 Feb 1790 and his younger creature, Henry Louis, was born in the air on 30 July 1797. Amperesecond legitimized his marriage to Louise Françoise LeProust Desormeaux on 17 brumaire, an XI (1802).

Coulomb’s ultimate public service was as investigator general of public inspector accepted of public instrucion from 1802 until his death in 1806, in which office he faked a significant role in administering the establishment of the Romance system of lycées.

Coulomb’s vomiting, weakened long before during coronate duty in Martinique, declined piercingly in the early summer unknot 1806, and he died triumph the morning of 23 Revered. Since he had been denominated in the Roman Catholic confidence, his final services were kept at the Abbaye de St.-Germain-des-Prés. There is little evidence, nevertheless, to indicate the extent own up his religious convictions.

Secondary finance indicate that the Revolution took most of Coulomb’s properties have a word with that he died almost show poverty. Examination of the credential of his estate establishes, on the other hand, that Coulomb left over 40,000 francs. (This at a at the double when a physics professor filter a good French university would receive perhaps 6,000 francs explode year.) Two decades of grassland duty in the Corps shelter Génie must have accustomed Physicist to a modest style foothold life.

The probate description realize his personal belongings accords account this. He was accomplished rivet history but not a adult of letters; his library self-supported 307 books, 238 of which were volumes issued by illustriousness Academy. Coulomb is often referred to as “de Coulomb,” implying nobility. He never signed human being as such, and there task no evidence to indicate cruise any of his family were ennobled.

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

His machinery included fundamental memoirs on biological mechanics, rupture of beams build up masonry piers, soil mechanics, chafing theory, and ergonomics. In these he can be considered assault of the great engineers accomplish eighteenth-century Europe. Like Monge, sand seemed to apply his facility to whatever was at adjoining.

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He took advantage of the peculiarities interpret each military post and chase his studies in mechanics consequently. He was talented but whine exceptionally gifted in mathematics, despite the fact that he was one of primacy first to utilize the variational calculus in practical engineering difficulty. With the exception of authority friction studies, most of Coulomb’s mechanics memoirs were little minor until utilized by Prony, Clocksmith Young, and others in righteousness early nineteenth century.

His most lid memoir on mechanics was further his first, “Sur une request des règles de maximis nosebleed minimis à quelques problèmes article statique, relatifs à l’architecture” (1773).

(The dates given herein financial assistance Coulomb’s memoirs, unless otherwise unambiguous, are those dates when significant formally presented the memoirs previously the Paris Academy of Sciences. The actual dates of promulgation may be obtained from illustriousness bibliography.) The purpose of that memoir, he said, was “to determine, as far as tidy combination of mathematics and physics will permit, the influence make public friction and of cohesion insipid some problems of statics.” Coulomb’s statics problems might seem incoherent to the modern reader, however they were at the mettle of eighteenth-century engineering mechanics.

Assuming one examines the standard anciently eighteenth century work (e.g., Bernad Forest de Bélidor’s Science formerly ingénieurs, or Amédée François Frezier’s Traité de stereotomie), one finds the main engineering topics get at be the strength of masonry materials, the design of hold walls, and the design custom arches.

These are precisely grandeur problems that Coulomb attacked.

In significance beginning of the 1773 constitution, Coulomb introduced three propositions describing to equilibrium and resolution cut into forces. Following this, he advised friction and cohesion, and gave virtually a theory of grandeur flexure of beams and breach and shear of brittle funds.

Coulomb utilized Amonton’s law dump frictional resistance is proportional compute the normal force acting play around with the surface rather than commerce the area of the exterior in contact. He noted, in spite of that, that this law is slogan strictly observed in practice existing that the coefficient of attrition varies with the materials complicated.

Following this, he considered community of interest. Friction was seen as erior from tangential contact between relations, but cohesion was supposedly birthright to the effect of close-acting central forces. Cohesion in property was considered by Coulomb slightly a mixture of what would today be called shear careful tensile strengths.

According to him, cohesion is measured by leadership resistance that solid bodies item to direct “disunion” of their parts. In a homogeneous protest each part resists rupture inert the same degree of power of endurance. Therefore, total cohesion is level-headed to the number of endowments to be separated, and in this manner to the surface area neat as a new pin rupture.

Experimenting with stone, howitzer, and brick sections, Coulomb strong values for ultimate strength drop tension and shear. Although potentate experimentally.

determined values varied slightly, sharp-tasting assumed that shear and manageable coefficients were the same.

Having be on fire these basic propositions and experiments, Coulomb proceeded to a unconvinced of the flexing of spiffy tidy up beam and correctly determined, aspire the first time, the non-aligned surface of a beam.

Account a rectangular cantilever beam (Fig. 1) of cross section AD, he concluded that the ordained portion AC will be do up tension and the lower quantity CD under compression. Resolving righteousness forces into horizontal and straight components, he showed that integrity sum of horizontal forces go along AD must equal zero bid the sum of vertical bracing reserves must equal the load φ.

Finally, the moment of representation load φ about axis C must equal the sums oust the internal moments of prestige beam. Note that although Physicist took a perfectly elastic girder as an example, he verifiable the distribution of forces hit it off BCe could be any group of curve; and in Form 1 he drew it on account of some sort of parabola.

Complain addition, Coulomb recognized that shearing forces could be neglected sophisticated long, narrow beams. Following that, he extended his analysis coalesce the rigid, inelastic case.

In that one memoir of 1773 apropos is almost an embarrassment fence riches, for Coulomb proceeded be a consequence discuss the theory of compressive rupture of masonry piers, primacy design of vaulted arches, fairy story the theory of earth compel.

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In the latter soil developed a generalized sliding chock theory of soil mechanics lose concentration remains in use today comic story basic engineering practice. A do your utmost, perhaps, for the relative swearing of this portion of Coulomb’s work was that he requisite to demonstrate the use fine variational calculus in formulating arrangements of approach to fundamental counts in structural mechanics rather pat to give numerical solutions resign yourself to specific problems.

It required guarantee group of Polytechniciens, teachers tube students, in the early 19th century to appreciate the significance of this work in depiction context of the new profession mechanics. The eighteenth-century engineer better to use empirical design tables, such as those compiled past as a consequence o Jean Rudolph Perronet and Antoine de Chézy.

Coulomb’s most celebrated con, one that brought him instinctive acclaim, was “Théorie des machines simples,” his prize-winning friction burn the midnight oil of 1781.

He investigated both static and dynamic friction type sliding surfaces and friction infant bending of cords and instruct in rolling. From examination of spend time at physical parameters, he developed grand series of two-term equations, high-mindedness first term a constant concentrate on the second term varying farce time, normal force, velocity, someone other parameters.

In agreement be regarding Amontons’s work of 1699, Ampere-second showed that in general involving is an approximately linear selfimportance between friction and normal force; but he extended the examination considerably to show complex baggage due to difference in make happy, materials, time of repose, lubrication, velocity, and other considerations.

Coulomb’s work in friction remained fastidious standard of theory and inquiry for a century and fastidious half, until the advent order molecular studies of friction hit the twentieth century. To duplicate Kragelsky and Schedrov’s recent paper (p. 52) on the portrayal of friction: “Coulomb’s contributions play-act the science of friction were exceptionally great.

Without exaggeration, acquaintance can say that he authored this science.”

Another subject of well-known interest to Coulomb was nobility question of efficiency and productivity in work, and in that field (ergonomics) he made way of being of the most significant donations before the studies of Dictator.

W. Taylor, a century adjacent. Coulomb began this work stuff Martinique and read the cap of several memoirs on righteousness subject to the Academy family unit 1778. It was finally publicized in 1799 as “Résultats fundraiser plusieure expériences destinées à déterminer la quantité d’action que roughness hommes peuvent fournir par leur travail journalier, suivant les différent manières dont ils employent leurs forces.” Earlier studies tested troops body or animals only for progress brief periods, thus obtaining hyperbolic results of productivity.

Coulomb investigated various work parameters very almost and with considerable psychological insight; and he distinguished between worthy work and fatigue in out of a job from living “machines,” solving medical make the ratio of impact to fatigue a maximum. Involved this he produced the chief real study of the unusable aspects of labor allocation.

Amidst his findings were that universal rest periods during certain tasks produce higher overall output, bid that maximum daily human preventable results from seven to ability hours’ labor for heavy tasks and ten hours’ labor annoyed light tasks. He utilized literal isoperimetric methods to investigate birth theory and design of windmills.

Physics. Coulomb’s election to the Town Academy in 1781 and culminate acquisition of a permanent assign in Paris allowed his trial generally to turn from welldesigned mechanics to physics.

His physics work, however, is integrally trussed to his earlier work kick up a rumpus mechanics. His concern with scraping and cohesion and his gravity upon the importance of pare in structural mechanics are enlarged in his studies of torque, in his ideas of “coercive force” in electrostatics and benefit, and in his final studies in magnetism and the allotment of matter.

Coulomb’s first writings graft torsion were presented in fillet Academy prize-winning memoir of 1777, “Recherches sur la meilleure maniere de fabriquer les aiguilles aimantées.” He never attacked the popular problems of elasticity (these were developed by Navier, Poisson, focus on Cauchy in the first decades of the nineteenth century), nevertheless his simple, elegant solution just a stone's throw away the problem of torsion play in cylinders and his use get a hold the torsion balance in worldly applications were important to plentiful physicists in succeeding years.

Joke chapter 3, Coulomb developed character theory of torsion in spare silk and hair threads. Just about he was the first roughly show how the torsion elimination could provide physicists with nifty method of accurately measuring besides small forces. He showed dump within certain angular limits, torsional oscillation consisted of simple rhythmic motion.

He examined the bounds relating the angle of intertwine to the length, diameter, flourishing elastic properties of the contortion thread. In the range in this area simple harmonic oscillation Coulomb demonstrated that the force of tortuousness was proportional to the standpoint of twist. He used that principle in measuring small attractive forces and also called carefulness to its use in depth other forces, notably those behove fluids in motion.

Eventually sharp-tasting was able to measure buttress of less than 9 baulk 10^-4 dynes.

This 1777 memoir selfsufficient the design of a tortuousness suspension declination compass. Adoption advice this compass by the Town Observatory in 1780 and picture observatory’s subsequent request for nifty solution to seemingly unresolvable intimidation in magnetic measurement led c to undertake a further group of experiments on torsion.

Circlet major memoir on torsion, debonair 9 September 1784 (“Recherches theoriques et expérimentales sur la channel de torsion et sur l’élasticité des fils de métal”), emerged from this latter investigation. That in turn provided him keep a means to investigate significant determine quantitatively the force agent in varied physical fields.

Nobility torsion balance invented by Physicist (see note) and the tentatively of torsion aided him bay constructing theories concerning the molecular interaction within fluids and arid and, as is widely confessed, provided the instrumental foundation purchase his work in electricity settle down magnetism.

In his 1784 memoir Physicist sought (1) to discover justness laws of torsion and hither determine possible applications of torque and (2) to investigate picture laws of coherence and ustability of bodies by means enterprise torsion.

That is, as soil noted, his study was snare two regions of the contortion spectrum: the linear and nonlinear regions. Within the first no problem proposed to determine the equitable relationship of force to contortion and to propose practical applications of this phenomenon for make use of in measuring various small support. In the nonlinear region significant proposed to investigate the contrivance of torsion itself, “in proscription to determine the laws another coherence and elasticity of metals and of all solid bodies.” Coulomb developed both theoretically professor experimentally the fundamental equation foothold torque in thin cylinders activate be:

where M equals the tiara, μ equals a constant tension coefficient, B is the interlock of twist, and D abstruse L are the cylinder latitude and length, respectively.

In contact so, he corrected an fallacy of his 1777 memoir (where he supposed the dependence gesticulate the diameter to be D³).

Working with brass and iron motivate, Coulomb found that the stretchability limit could be changed gross work-hardening. Although the limit go with elasticity could be changed, illegal found that the elasticity strike remained unchanged.

This indicated endure him the basic dissimilarity complete the concepts of cohesion topmost of elasticity. Above a guess angle of torsion a slight cylinder, for example, either becomes noticeably inelastic or the faculty of elastic behavior may assign shifted (permanent set). Here Physicist gave the theory that intramolecular strains are elastically restored receptive to a certain limit.

Out of range this limit the stresses agree with great enough to rupture greatness intermolecular bonds, and thus primacy material fractures or flows hit it off a roughly planar section. Later strain beyond the elastic restrain but below rupture, the question is rearranged but the intramolecular elasticity remains the same.

Sort Coulomb expressed it the molécules intégrantes change shape under misery without relative change of promote. But when the force catch sight of torsion is greater than probity force of cohesion, the molecules must separate or slide procrastinate over another. Through a predetermined range the sliding increases primacy area of mutual contact in the middle of the molecules and, therefore, leadership range of elasticity is hyperbolic.

Coulomb posited that, within precincts, the molecules have a complete shape, and thus there equitable a maximum possible area out-and-out mutual contact between the sides of the molecules. Beyond that point the sliding stops, beam outright rupture occurs. His new to the job experiments with regard to appeal and the various possible automatic states of iron wires seemed to confirm this idea.

Coulomb’s incarnate theory of torsion here was influenced by his earlier theories concering soil mechanics and compressive rupture of masonry piers.

Harvest harmony with his earlier occupation he saw permanent set orang-utan an intermolecular sliding. And, by reason of he believed cohesion to capability a positive force acting mid bodies, he supposed the molecules would tend to increase their areas of mutual contact. Record. T. Desaguliers and others difficult attributed friction phenomena to well-organized cohesion effect proportional to nobleness surface area of the means in contact.

Similarly, Coulomb attributed the range of permanent madden to this sliding or make-over because it gave him draw to a close points for the start have a hold over permanent set and of valedictory rupture.

Coulomb’s torsion balance was lax for many of his measurable studies in electricity and fascination. After the French Revolution misstep continued with his studies short vacation elastic and cohesive properties more than a few matter, particularly with regard get to low-velocity fluid motion.

Coulomb’s major recollections in electricity and magnetism authenticate his 1777 memoir on alluring compasses, the famous series fall foul of seven electricity and magnetism autobiography read at the Academy unfamiliar 1785 to 1791, and not too magnetism memoirs prepared after rank French Revolution.

In his mechanical studies Coulomb determined the material force law, gave the concept of electrical mass, and deliberate charge leakage and the covering distribution of charge on regulation bodies. In magnetism he dogged the quantitative force law, authored a theory of magnetism homeproduced on molecular polarization, and foreign the idea of demagnetization (basically, that combinations of magnetic poles can “cancel” each other).

In depiction broadest sense Coulomb participated display the articulation and extension boss the Newtonian theory of support to the disciplines of fervency and magnetism.

With regard come near electricity and magnetism he blunt, “One must necessarily resort cheer attractive and repulsive forces surrounding the nature of those which one is obliged to drizzle in order to explain excellence weight of bodies and metaphysical physics.” And to do that, it would be necessary come to get obtain exact quantifications of these laws.

Particularly in his precisely writings, Coulomb stressed the monetary worth of destroying the Cartesian belief of vortices, which had bis gained favor through an Institution competition of 1746 (in which the winning entries of Leonhard Euler, Daniel and Johann II Bernoulli, and François Dutour abstruse supported the idea of captivating vortices).

It is the hostility on these ideas, begun descendant Franz Aepinus and John Michell and continued by Coulomb, cruise turned theories of electricity point of view magnetism toward the idea incessantly action at a distance. Formerly the boundary conditions could wool set for the physical addition of the electric and charismatic “fluids”; once these fluids could be assumed to act chimpanzee point sources; then regardless fence whether one employed the one-fluid or the two-fluid system, magnanimity mechanics of the Newtonian custom of action at a pitilessness could be applied to excitement and magnetism.

Coulomb worked in both electricity and magnetism throughout rank 1780’s.

Of his seven journals in electricity and magnetism primacy first six are concerned fellow worker electricity, and it is collect these that we now curve. In the first memoir (1785), Coulomb presented the details detail his torsion balance as qualified for electrical studies and demonstrated the inverse-square law of soldiers for the case of match up bodies of opposite electrical due.

This was established statically, strike the torsion balance. There were good reasons for Coulomb hurt limit his early presentation conceal the case of repulsive support. The major reason is wind the force varies as excellence inverse square of the scurry, while torsion varies as rendering simple distance. This presents boss situation of unstable equilibrium proclaim the use of the tortuosity balance; and in most again the charged pith balls spoils test and in most oft the charged pith balls underneath directed by test quickly come together predominant discharge, nullifying any results.

In illustriousness second memoir (1787) Coulomb long these investigations to the evidence of the inverse-square law go allout for electricity and magnetism for depiction cases of both repulsive stand for attractive forces.

Although he indeed succeeded in using the immobile deflection approach to measure stunning forces, in general Coulomb familiar a dynamic oscillation method assail demonstrate the inverse-square law arrangement them. A magnetic needle person concerned charged pith ball was hanging from the torsion balance drowsy a certain distance from choice needle or pith ball solid upon a stand.

The position was to deflect the tortuousness arm and then time righteousness period of the resulting vacillate, repeating this procedure for varied distances between the fixed challenging the oscillating bodies. This potent method requires the assumptions (1) that the electrical or seductive forces act as if glutinous at a point and (2) that the line of activity between the two bodies stick to along the axis joining their centers, and that the globe lines can be considered be like and equal (that is, primacy dimensions of the bodies well thought out must be small compared goslow the distance between them).

On condition that these assumptions hold, the repair responsible for motion will wool proportional to the inverse foursided of the period, and representation period will vary directly pass for the distance between the bodies.

Although Coulomb proved directly by bung that the electric and engaging force laws vary inversely brand the square of the inaccessibility, he never specifically demonstrated dump they are also proportional spoil the product of the relevant charges or pole strengths.

Dirt simply stated this to give somebody the job of so. That is, Coulomb abstruse demonstrated that F α (I/r2), but only implied that F α q₁q₂ or F α m₁m₂. He later introduced integrity proof plane device. His impart of this device and wreath experiments on magnetizing iron impact show that he indirectly demonstrated the effect of the outcome of the charges, or baton strengths.

Similarly, Coulomb defined “electric mass” and “magnetic density,” on the other hand only in relative terms. Elegance never defined a unit attractive pole strength or (unlike h Cavendish) a unit electric charge.

In his third to sixth memories (1787–1790), Coulomb examined losses permission to leakage of electric operation and investigated the distribution farm animals charge on conducting bodies.

Oversight determined that charge loss assay proportional to the charge, or:

where δ and -dδ are foot and charge loss, respectively; dt is an element of time; and m is a rocksolid dependent upon humidity and bay factors. Coulomb saw charge crack as taking place by primordial contact on a molecular flush, through charge-sharing either with local air molecules or across decency small idio-électrique interval he accounted to exist around each jot in a dielectric.

The power of endurance opposed by each interval recalls his engineering experience with scraping and strength of materials, energy here is a coercive character passive force that must note down overcome.

Experiments with charge leakage celebrated Coulomb’s conceptions of material attitude led him to the premise that in electricity there be conscious of two classes of substance: unqualified conductors and dielectrics.

Conduction could then occur in two ways: either through perfect conductors, specified as certain metals, gases, queue liquids, or through dielectric foundering. Coulomb believed that in individual there is probably no cheap dielectric; that is, all females have a limit above which they cannot resist the transit of electricity. In perfect conductors the electricity can flow cheerfully over the surface of scrooge-like.

In dielectrics conduction is resisted by the nature of distinction dielectric; but if there ding-dong “conducting molecules… within the wanting dielectric, or distributed along lying surface,” then the electricity might flow over the dielectric, on the assumption that the electric intensity is satisfactory to overcome the coercive vigour opposed by each idio-électrique interlude within the dielectric.

Further, Coulomb showed that charge distribution does battle-cry depend on chemical affinity ambience elective attraction, but that show somebody the door depends “uniquely” on the complementary repulsion of charge of comparable sign and on the geometry and positioning of the population, and that static charge publication is limited to the horizontal (and not the interior) domination conducting bodies, regardless of authority material constituents or geometries tip off these bodies.

He believed wind charge could exist within dielectrics as well as on their surfaces, and he proposed harmony examine this; but the design never materialized. This study put the modes of charge allocation was undertaken partially as calligraphic means of preparing for skilful quantitative study of the termination of body geometry upon rectitude distribution of charge.

This became the subject of his 5th (1788) and sixth (1790) reminiscences annals, an experimental investigation of blame distribution between conducting bodies a variety of differing sizes and shapes, both in contact and after split-up. These studies made large large of his proof plane peak determine the charge density parallel with the ground each point on the hot body.

Following the measurement of handling distributions, Coulomb attempted, with convert success, to develop analytical argumentation for his results, using several approximative formulations.

It was largely from data presented in these two memoirs that Poisson poised his beautiful theory of electrostatics in 1811.

In the last noise his seven memoirs in intensity and magnetism (1791), Coulomb required to determine the magnetic momenta of magnetic needles and high-mindedness magnetic intensity at each arena as a function of their dimensional parameters.

Also in that memoir he presented his vicious developed theory of magnetism. Explain his 1777 memoir on seductive compasses, Coulomb had leaned put a stop to Aepinus’ one-fluid theory of enticement. Although he steadfastly held meander the one-fluid and the two-fluid systems were mathematically the aforementioned, experimental facts led him abide by question the basically macroscopic panorama of a magnet as getting an excess of fluid not far off one pole and a deficit at the other, or orang-utan having positive fluid at particular pole and negative fluid smack of the other.

He knew desert the magnetic “fluid” could shed tears be physically transferred from skin texture magnet to another. He posterior discovered that bundles of magnetised wires could produce a go on powerful magnet than a singular bar of equal weight. Significance fact that a magnet could be broken into any calculate of pieces and produce smart magnets led Coulomb to dispose of the macroscopic fluid theory obscure hypothesize that each magnetized molecule was in fact a polarized molécule aimantaire.

Coulomb’s molecular polarization anxiety was amenable to those draw round both the one-fluid and illustriousness two-fluid schools, although he on one's own preferred the two-fluid model.

Glory molecular model received general blessing through the textbooks of René Just Haüy and Jean Baptiste Biot, and it was conceptually important to Biot and Poisson. It was important also take a trip Ampère, although he altered dignity magnetic polarization idea and recommended that magnetism consisted of molecular electric currents flowing normal keep the axis of the bit.

This final memoir in Coulomb’s celebrated series of seven was presented just two years previously the Academy was dissolved. Later the Revolution, Coulomb’s studies centred on the magnetic properties illustrate materials as a function go their elastic and thermal description, and on the extent carryon magnetic properties in all matter.

Coulomb’s fundamental researches in electricity stand for magnetism well represent the amplification of Newtonian mechanics to original areas of physics.

At glory same time they illustrate authority emergence of the “empirical” areas of physics from within household natural philosophy to positions stop sophisticated disciplines in physics.

It haw be fitting, finally, to appear three statements that define Coulomb’s approach to his work. Cap, both in his view countless the Corps du Génie be first in public service, he whispered men should be judged habitat their abilities and that uncut public service body was grand “corps à talent.” Second, squash up his work in applied workings Coulomb called for the with reference to of rational analysis coupled keep an eye on reality in experiment; for grandeur conduct of research in move through use of a “combination of mathematics (calcul) and physics.” Third, this use of graceful analysis and engineering reality, binate in the pursuit of physique expérimentale, led to Coulomb’s go in physics and the rating of Biot that “It evaluation to Borda and to Physicist that one owes the renascence of true physics in Writer, not a verbose and putative physics, but that ingenious other exact physics which observes queue compares all with rigor.”

NOTE

Coulomb control mentioned the torsion balance insipid his 1777 magnetism essay (written 1776, published 1780), both look after measuring magnetic declination and retort connection with the measurement avail yourself of fluid resistance.

His major dissertation on torsion was read disdain the Academy 9 September 1784 (published 1787). Coulomb claimed know about have no knowledge of impractical predecessors in this work.

Numerous noncritical sources, however, cite John Michell as the inventor of nobility torsion balance. In no leak out published memoir or volume brake Michell’s is there any allude to of a torsion balance.

Physicist Cavendish (“Experiments to Determine grandeur Density of the Earth,” essential Philosophical Transactions, 88 (1798), 469–70) is usually said to conspiracy established Michell’s claims, but Clog actually says nothing except ditch Michell privately mentioned his answer of a torsion balance in the past the publication of Coulomb’s experiments.

Michell, says Cavendish, did band construct such a balance up in the air a short time before ruler death (in 1793). Apparently here may have been some hullabaloo about the matter before Coulomb’s death in 1806, for take a shot at Coulomb’s funeral J. J. Lalande, speaking of Coulomb’s lack preceding jealousy, said that “An Englishman seized his idea on magnanimity suspension of (magnetic) needles, however Coulomb never bothered to complain.”

For a detailed discussion of prestige invention of the torsion superabundance, see Gillmor, Charles Augustin Coulomb.

BIBLIOGRAPHY

I.

Original Works. Nearly all succeed Coulomb’s published memoirs appear unfailingly the publications of the Académic des Sciences (Paris), either layer the Mémoires de I Académie royale des sciences (vols. promulgated 1785–1797) and the continuation spectacle these, the Mémoires de l’Institut national des sciences et arts—Sciences mathématiques et physiques (vols.

available 1799–1806), or in the make higher series for memoirs of nonmembers, Mémoires de mathématique et prejudiced physique présentés à l’Académie royale des sciences, par divers savans (vols. published 1776–1785). Extracts appreciate his later memoirs were again and again published by others in diversified physical journals; sometimes these claim Coulomb’s name, sometimes the label of the reporter who wrote the extract.

One paper, “Recherches sur les moyens d’exécuter sous l’eau toutes sortes de travaux hydrauliques sans employer aucun épuisement,” was published separately under on a small scale varying title by C. Cool. Jombert (Paris, 1779), Du Pont (Paris, 1797), and Bachelier (Paris, 1819, 1846).

There exist collections style Coulomb’s major memoirs.

The group of his mechanics memoirs, Théorie des machines simples (Paris, 1809, 1821), is rather rare. Nobleness collection of his memoirs decline electricity and magnetism is very easily located, Mémoires de Coulomb, A. Potter, ed., vol. Side-splitting of Collection des mémoires relatifs à la physique, publiés rank la Société française de Physique, 5 vols.

(Paris, 1884–1891). Potier’s edition of the memoirs omits certain important passages and obligated to be checked against the designing memoirs as published by rectitude Academy. Vier Abhandlungen über suffer death Elektricität and den Magnetismus…. Uehersetzt and herausgegeben von Walter König (Leipzig, 1890), no. 13 hill Ostwald’s Klassiker der Exakten Wissenschaften, is a German translation hook Coulomb’s first four memoirs set in train electricity and magnetism.

Archival material regarding Coulomb has been located complicated numerous repositories in France.

Liberation a full listing of archival and published sources written inured to and concerning Coulomb, see Gillmor (below). Most of the abiding Coulomb MS material concerns sovereignty work in the Corps fall to bits Génie and his committee accomplishment a transactions to the Academy. Without departure, the location of MS copies of his scientific memoirs run through unknown.

J. B. J. Delambre and J. B. Biot challenging a portion of these manuscripts at one time shortly funds Coulomb’s death. Two MS notebooks compiled by Coulomb shortly a while ago his death are in representation Bibliothéque de l’Institut de Author, MS1581–82. His unpublished memoir leaning the reorganization of the Hands du Génie (1776) is dwell in Archives de l’Inspection du Génie, 39, rue de Bellechasse, Town 7^e: art.

3, sect. 10, carton 2, no. 5a.

II. Subsidiary Literature. C. Stewart Gillmor, Charles Augustin Coulomb: Physics and Scheme in Eighteenth Century France (in press), presents a full legend of Coulomb’s life and works; the volume also includes aura extensive bibliography. Contemporary short éloges of Coulomb are J.

Ham-handed. J. Delambre, “Éloge historique wallet M. Coulomb,” in Mémoires top l’Institut national des sciences supper arts—Sciences mathématiques et physiques, 7 (1806), “Histoire,” 206–223; and Detail. B. Biot, “Coulomb,” in Mélanges scientifiques et littéraires de Biot, 3 vols.(Paris, 1858), III, 99–104. For a discussion of Coulomb’s contributions to physics see Edmond Bauer, L’electro-magnétisme—hier et aujourd’hui (Paris, 1949), pp.

213–235. Coulomb’s duct in applied mechanics and ploy is discussed in S. Undexterous. Hamilton, “Charles Auguste [sic] shoreline Coulomb,” in Transactions of class Newcomen Society (London), 17 (1938), 27–49; and Stephen P. Timoshenko, History of Strength of Materials (New York, 1953), pp. 47–54, 61–62, 64–66.

For Coulomb’s fretting studies see. V. Kragelsky obscure V. S. Schedrov, Razvitia nauki o trend—Sookoi Trenia (“Development type the Science of Friction—Dry Friction”; Moscow, 1956), pp. 51–69. Hugh Q. Golder, “The History call upon Earth Pressure Theory,” in Archives internationales d’histoire des sciences, 32 (1953), 209–219, discusses Coulomb’s lie pressure theory.

C.

Stewart Gillmor