Great discoverers in science must usually be satisfied with having their names attached to some one phase of scientific development, be it an instrument, a law, a unit of measurement, a process of investigation or some phenomenon which they first observed. The originality of Coulomb's genius will be better appreciated, since besides having a unit of electricity named after him, there is also a law in electro-magnetics and a torsion-balance that will always be associated with his name. Few men have been more ingenious in their ability to put complex ideas into practical shape and give them simple mechanical expression by instrumental methods. While his name is to be forever associated with the science of electrostatics, he was profoundly interested in other departments of physics, and for him to be interested always meant that he would illuminate previous knowledge by practical hints and suggestions and carry the conclusions of his predecessors a little farther into science than they had ever gone before. His was typically an experimental genius, and he must be considered one of the men of whom not more than half a dozen are born in a century, who are, in Kipling's strong term, "masterless"; who do not need to be taught, but who find for themselves a path into the domain of the unknown.Coulomb investigated the fundamental law in electricity and magnetism, that attractions and repulsions are inversely as the square of the distances, and showed that it held accurately for point-charges and point-poles. He demonstrated that these interesting phenomena were not chance manifestations of irregular forces, but that they represented a definite mode of action of force, thus setting this department of knowledge on a scientific basis. While in practical significance Ohm's Law, discovered nearly a half century later, is of much more import, Coulomb's discoveries are fundamental in character and, coming in the very beginnings of modern electrical science, did much to guide the infant science in the ways it should follow. The establishing of this law contributed very largely to the rapid development of the twin sciences of electricity and magnetism. It is experimental observation that means most for a rising science; and, in fact, that Coulomb should have been the pioneer in it stamps him as possessed not only of great originality, but also of the power of independent thinking, which is perhaps the most precious quality for the man of science.

The French investigator succeeded in demonstrating his law by two distinct methods which are still used for illustration purposes in our physical laboratories. In the first, he employed the torsion-balance devised by Michell, and re-invented by himself, an instrument of exact measurement which, in his hands, yielded as invaluable results as it did in those of Faraday half a century later. The instrument depends on the principle first established by Coulomb himself, that when a wire is twisted, the angle of torsion is directly proportional to the force of torsion. In the application of this principle, a fine wire is suspended in a glass case, on the sides of which there is a graduated scale to measure the degree of repulsion between two like poles of a magnet or between similarly electrified bodies.

In his second research on the law of the inverse square, Coulomb used what is known as the method of oscillations. A magnetic needle swinging under the influence of the earth's magnetism is known to act like a pendulum, and as such obeys the laws of pendular motion. In applying this method, Coulomb caused the magnetic needle to oscillate, first, under the influence of the earth's magnetism alone and then under the combined influence of the earth and the magnet placed at varying distances from the needle. The most interesting feature of this work is the manner in which Coulomb succeeded in eliminating the important factor of the earth's magnetism from the problem. It is so simple and ingenious that it commands the admiration of investigators, who employ it in their laboratory work even to the present day.

It is clear, then, that the International Committee which selected the term coulomb for the electromagnetic unit of electrical quantity gave honor where it was eminently due. Coulomb stands out as a man of precision and accuracy, whose methods of exact measurement revolutionized the rising science, and whose researches and discoveries in physics and mechanics furnish ample justification for giving him a place among the makers of electricity. He was one of the gifted men whose original works ushered in so gloriously the nineteenth century, and who laid the deep and firm foundations on which the last three generations have built up the magnificent temple of electrical science.

Charles Augustin de Coulomb was born at AngoulÊme, June 14th, 1736. His ancestors for several generations had been magistrates, and were looked upon as representatives of the country nobility. He made his university studies in Paris, and while still young, entered the army. From the very beginning, however, his genius for mathematics was recognized, and he was employed in the capacity of military engineer. To Americans, it will be interesting to know that his first engineering project was undertaken at Martinique, where he constructed Fort Bourbon. His sterling character and remarkable ability secured him rapid advancement in the service. In spite of the fact that the climate did not agree with him, he remained for three years on the island, because he would not employ the political influence that might have secured his recall, since he thought it his duty to serve his country in an important colonial post. Nearly all his comrades perished by fever. It is the irony of fate that after his return to France a change in the ministry deprived him of the just recompense of his devotion to country, and he did not receive the special extraordinary promotion which he had earned in this special detail.

During a short stay that he made at Paris after his return, he sought the society of men of science as far as possible, and succeeded in getting in touch with all that was most promising in scientific progress at the time. He was already known rather favorably by many of the scientific men of the capital because of the paper on The Statics of Vaults, a monograph on static problems in architecture, which he presented to the Academy of Sciences in 1779. His next military assignment was to Rochefort. Here he composed his monograph on "The Theory of Simple Machines," which carried off the double prize that had been offered by the Academy of Sciences for the solution of problems connected with this important question. This attracted the attention not only of the scientific world, but also of his military superiors. As a result, he was sent successively to Cherburg and to the Isle of Aix, to direct engineering works, and accomplished the tasks involved with success.

Two years later, when he was about forty-five years of age, he was elected member of the Academy of Sciences by a unanimous vote. He was a man of great personal magnetism, and all those who came in contact with him learned to like him for his straightforward character and for the absolute righteousness of his life. Few men have made firmer friends than Coulomb, as few have ever shown more unselfish devotion to duty and to conscience than he, though under circumstances that were neither spectacular nor theatrical. It was harder to face the deadly climate of Martinique than it would have been to take one's place at the head of a forlorn hope in an outburst of enthusiastic courage; and Coulomb was to have other trials of quite as deterrent a nature, and was to meet them with the same imperturbed sense of duty.

Graft is sometimes supposed to be temptation peculiar only to our own times, but the opportunities for it have always been present in such work as Coulomb had to oversee, and the army engineer of all ages has had to stand or fall before it. It was proposed, about this time, to build a system of government canals in Brittany. Such a canal-system would, as is easy to understand, cost an enormous sum of money and give magnificent opportunities for speculation of various kinds. No small objection had been made to the project, on the score that it would not confer all the benefits on the region that were claimed for it, and Coulomb was commissioned by the Minister of Marine to determine the question of the advisability of constructing the canals, and of the probable effect which they would have on the commerce of the country.

After careful investigation, he came to the conclusion that the advantages which were expected to accrue from the project would not compensate for the enormous expense that would be entailed. This decision aroused the angry protest of a strong political faction, who expected to reap wealth and personal advantages of many kinds from the scheme, and who protested bitterly against Coulomb's report. He was able to support his conclusions in the matter, however, with such unanswerable mathematical and engineering arguments, that his opinion prevailed and the project was given up.

As a consequence, instead of the opportunity to serve a political party with every avenue to preferment and, above all, to wealth open for him, he found himself, for the time being, deprived even of the opportunity to devote himself further to his favorite occupations in military engineering. The excuse given for this interruption in his career, for there has always been an excuse for such action, was that proper representations for permission to make the report had not been made to the Minister of Marine; and instead of commendation, Coulomb received what was practically a reprimand.

Wounded by this injustice, which was manifestly due to the fact that his honest report had displeased those who expected to reap personal benefit from the canal project, and disgusted with a service in which such things were possible, Coulomb sent in his resignation. The Minister of Marine realized that the acceptance of the proffered resignation would surely expose the ministry at least to suspicion as to the reasons why Coulomb's report was not accepted with good grace. Permission to retire from the service was refused, as this would insure his silence. He was ordered back to Brittany to continue his work there, possibly with the idea that this unfavorable experience would be sufficient of itself to make him understand what was expected of him and render him a little more complacent to the wishes of those in authority. If any such ideas were entertained, they were destined to grievous disappointment. Coulomb was not of those who, seeing duty plainly, refuse to follow it because some personal advantage or disadvantage intervenes. Selfish reasons did not appeal to his character nor obscure the issues.

He went back to Brittany, ready to express his firm opinion in the matter and with integrity of soul untouched. The consequence was that the provincial authorities, recognizing their true interests, acknowledged the error they had come near falling into, and now wished to reward the engineer handsomely for his unswerving devotion to duty. Coulomb as promptly refused a reward for doing his duty as he had ignored even the appearance of a bribe to avoid it. Only after considerable pressure was he prevailed upon to accept the best timepiece they could procure, on which the arms of the province were engraved. It had what was quite rare in those days, a second's hand, and he constantly made use of this in all his experimental work thereafter. A French biographer says that, never was a souvenir better chosen nor more suitably employed. Coulomb's merits were recognized by the government authorities not long after, and he was made superintendent of the fountains of France. A few years later, he was promoted to the position of Curator of Plans and Relief Maps of the Military Staff of France, and was chosen as one of the commission of the French Academy of Sciences who went to England in order to study hospital conditions there. At this time, he was at the acme of his career. His grade was that of Lieutenant Colonel of Engineers, a position much higher in the foreign armies at that time than would be the post with the corresponding title in our army. He had been made a Chevalier of St. Louis, and it looked as though a brilliant future were opening out before him. Each year, for a decade, had seen the publication of one or more memoirs on important subjects, nearly every one of which contained some original material of the highest value, destined not only to add to Coulomb's reputation, but to furnish basic information for the further development of science.

In 1789, however, the Revolution broke out, and there was an end to all Coulomb's opportunities for work. He was utterly out of sympathy with the movement, the worst consequences of which he foresaw from the beginning, and he at once handed in his resignation of the various positions that he occupied under the government. He went into almost absolute retirement, devoting himself to the education of his children. During this time, however, he did not cease to cultivate science, inasmuch as he gave the finishing touch to various papers which he had previously outlined. Unfortunately, however, his departure from Paris made it impossible for him to continue his investigations in electricity for want of apparatus, and so there is a ten years' interruption in his life of scientific activity and of original work. Besides, it cannot be surprising that he should not have had the heart to go on with his work under the awful social conditions that prevailed. Many of his friends lost their lives during the stormy period of the Revolution; most of the others were banished or were in hiding. His beloved country had gone into an unfortunate eclipse, as he could not help but consider it; most of the nations of the earth were indeed in league against her, and the end was not yet in sight. It would be too much to expect of human nature that it should devote itself to abstruse problems in science at moments of such disturbance as this, and so some of the possibilities of Coulomb's original genius were lost to science during that calamitous period.

Like many of the great discoveries of science, Coulomb's most important work was done in the course of other investigations, and came by what might be called a happy accident. He had been investigating the qualities of wire of various kinds, especially with regard to their elasticity, so as to be able to determine the limits of their use in various engineering projects. When he discovered that the elasticity of torsion of a wire was a constant property, he proceeded to utilize it in the calculation of such delicate phenomena as those of electric and magnetic forces. The first instrument for this purpose that he constructed consisted simply of a long magnetized needle suspended horizontally by a fine wire. Supposing this needle to be at rest, if one moves it away from the magnetic meridian by a certain number of degrees, the twisted wire will have a definite tendency to untwist and to bring back the needle to its original position by a series of oscillations whose frequency can be readily observed.

For such observations, it is possible to obtain the value of the force acting on the needle and causing it to move to and fro at a given rate. This was the underlying idea which received very simple expression in the ingenious instrument which Coulomb devised and called a torsion-balance. With it, he set about determining the law which governs the mutual action of magnets and of electrified bodies with regard to distance, and found it to be the same as that which Newton found to hold for bodies distributed throughout the universe, that is, that attraction and repulsion vary inversely as the square of the distance. He also proved, with the aid of his torsion-balance, that the forces of attraction and repulsion vary as the product of the strength of the poles in one case and as the product of the electric charges in the other. These were the important discoveries of Coulomb's life; they served to earn for him the right to have his name given to the unit of electrical quantity, the coulomb.

Coulomb did not stop here, however, but proceeded to apply his laws to various other phenomena. He proved that electricity distributes itself entirely over the surface of a body without penetrating the mass of the conductor, and he showed by calculation that this result was a necessary consequence of the law of repulsion.

A list of the papers which he published on electricity and magnetism, the titles of which, with French accuracy of expression, furnish an excellent idea of their contents, shows the thoroughly progressive and scientific spirit of the man, and how well he proceeded from the known to the less known, always widening the bounds of knowledge. Suffice it to say here that the observations of Coulomb were not only original, but that they concerned some of the most difficult questions in electricity, and that he was clearing the ground for others in such a way as to make future work and quantitative measurements in electricity reliable and comparatively easy. It is because of this pioneer work that Coulomb deserves so much praise. It was not long before Coulomb's observations were confirmed by others, and then the beginnings of the modern development of electricity became manifest, owing not a little to the researches and inventions, the genius and ingenuity of this French military engineer.

Some phases of electrical development attributed to others really belong to Coulomb. A typical example of this detraction from his merit is the attribution to Biot of the solution of the problem of the complete discharge of an electrified sphere by means of two hollow hemispheres. This experiment is fully described by Coulomb, and he even emphasizes the fact that the external discharging bodies need not necessarily be of the same shape as the charged sphere. Some of what Coulomb accepted as principles in electricity have proved in the course of time, not to be the realities that he thought them; but the progress that has led to such contradictions of his opinions has been mainly rendered possible by his own discoveries. The fable of the eagle stricken by the arrow containing some of its own feathers, is so old that one might think that, when the progress of a science due to a scientist brings men beyond the position he occupied, they would not blame him for backwardness. This is, however, one of the curious critical methods in the history of science that has most frequently to be deprecated by the historian who is tracing origins and developments.

Coulomb's papers, with the exception of his memoir on "Problems in Statics Applied to Architecture," his "Researches on the Methods of executing Works under Water without the Necessity of Pumping," his "Theory of Simple Machines," and his researches "On Windmills," which form separate monographs, were all published together in a single volume by the French Physical Society in 1884.[21]

This volume contains, besides his investigations on the best way of making magnetic needles, his theoretic and experimental investigations on the force of torsion and on the elasticity of metallic threads, which were undertaken in order to enable him to make his electric torsion-balance something more than mere guess-work. All the other papers are concerned directly with electricity or magnetism, and show how actively, nearly a hundred and twenty-five years ago, a great mind was engaged with problems in electricity which we are apt to consider as belonging more properly to our own time. The list of papers published in these memoirs, arranged in chronological order, gives a good idea of the development of electrical science in Coulomb's own mind. There is a logical as well as a chronological order to be observed in them.

In 1785, when he was just approaching his fiftieth year, there were three subjects with regard to which Coulomb's experimental observations enabled him to set down some definite principles. The first of these was the construction and use of an electric balance, founded on the property which wires have of exhibiting a torque proportional to the angle of torsion. The second was the determination of the laws, according to which the magnetic and electric "fluids," as Coulomb and investigators in electricity called them at that time, act both as regards repulsion and attraction. The third was the determination of the quantity of electricity which an insulated body loses in a given time from contact with air more or less moist.

In 1786, he published a paper in which he demonstrated what he considered the principal properties of the electric fluid. These are, that this fluid does not spread itself on a substance by any chemical affinity or any elective attraction, but that it distributes itself over various bodies that are placed in contact, entirely in accordance with their shape; and also that in electrical conductors, the charge is limited to the surface of the conductor and does not penetrate to any appreciable depth.

In 1787, his only paper was on the manner in which the electrical fluid divides itself between two conducting bodies placed in contact, and on the distribution of this fluid over the different parts of the surface of these bodies. He continued his investigations into this subject in 1788, and also succeeded in determining the density of the electricity at different points on the surface of conducting bodies.

In 1789, he began to work more particularly on magnetism. His first paper on the subject was published that year. Unfortunately, as we have said, the Revolution interrupted his scientific investigations at this point, and for the next eleven years we have nothing from his pen. As a nobleman, he was compelled to leave Paris, and this not only put him out of touch with scientific work generally, but deprived him of the opportunities of using such apparatus as was necessary to carry on his experiments. That he acted prudently in leaving Paris, the careers of other scientists amply prove. Lavoisier continued to carry on his chemical investigations during the stormy times of the Revolution, but his stay in the capital eventually cost him his life. AbbÉ HaÜy, the father of crystallography,[22] who, because of his contributions to the science of pyro-electricity, is of special interest to us, continued to work at his crystals throughout even the Reign of Terror. When thrown into prison, he asked and obtained permission to have his crystals with him. His friends saved him from Lavoisier's fate, but not without an effort, as his life was seriously endangered.

It is easy to understand, however, that a member of the nobility like Coulomb, whose life had been spent in military affairs, should not be able to devote himself seriously to scientific matters while his country was in such a turmoil.

In 1801, he resumed his investigations once more, but now they are concerned more particularly with magnetism. The first was a theoretical and practical determination of the forces which hold different magnetic needles, magnetized to saturation, in the magnetic meridian. This was followed, in the same year, by a paper which, like its predecessor, was published among the memoirs of the Institute of France, which had replaced the Royal Academy of Sciences, to which body many of Coulomb's papers of the former time had been presented, and in whose publications they originally appeared. This second paper detailed his experiments on the determination of the force of cohesion of fluids and the law of resistance in them, when the movements were very slow.

When the French Institute was organized under Napoleon in 1801, Coulomb was named among its first members. It is believed that he was even chosen to occupy a place in the first government of the state, but a man more interested in politics obtained the place, a fortunate circumstance for science. Coulomb was named, however, one of the inspectors of public instruction, then the highest place in the education department, and he did much to restore to France the educational system that had been destroyed during the Revolution. In this rather trying work he was noted for the kindliness yet firmness of his character, while his absolute fairness and sense of justice were recognized on all sides.

Unfortunately Coulomb was not long spared to continue his work. He took up his experimental and mathematical investigations, on his return to the capital, with great enthusiasm, but his health had been undermined and his work had been rudely interrupted. After 1801, no further paper by him appears to have been published until 1806. This gave the result of different methods employed in order to produce in blades and bars of steel the greatest degree of magnetism. For some time preceding this, in spite of increasing ill-health, he had continued his experiments on the influence of temperature on the magnetism of steel. His work on this subject was not destined to be completed, for not long after passing his seventieth year, in June of this year, his health gave way completely, and he died August 23d, 1806. His final observations were gathered by Biot, carefully preserved, and assigned a place in the volume of Coulomb's Memoirs, issued by the French Physical Society.

Personally, Coulomb was noted for great seriousness of character, though with this was mingled a gentleness of disposition that made for him some cordial friendships among his scientific contemporaries. He had but few friends, but those who were admitted to his intimacy made up by the depth of their affection for the smallness of their number. Even those who had occasion to meet him but once or twice, carried away from their meeting an affectionate remembrance of his kindliness and courtesy and readiness to help wherever he could be of service. He was extremely happy in his family relations, and this proved to be a great source of consolation to him during the years when the progress of the French Revolution took him away from science and made him almost despair of his country.

It is not surprising that Biot, the great French physicist, in writing of Coulomb in his MÉlanges Scientifiques et LittÉraires, Vol. III. (Paris, 1858), should have held Coulomb up as a model of the simple, earnest, helpful life and as a man of the most exemplary character. He says: "Coulomb lived among the men of his time in patience and charity. He was distinguished among them mainly by his separation from their passions and their errors, and he always maintained himself calm, firm and dignified in se totus teres atque rotundus, as Horace says, a complete, perfect and well-rounded character." Few men have deserved so noble a eulogy as this, written nearly fifty years after his death, by one who had known Coulomb himself and his contemporaries well; it has none of the exaggeration of a funeral panegyric, and is evidently founded on details of knowledge with regard to the great electrician which had become a tradition among French scientists, and which Biot has forever crystallized into the history of science by his emphatic expression.

One could scarcely wish for a better epitaph than Biot's summing up of Coulomb's personal character: "All those who knew Coulomb know how the gravity of his character was tempered by the sweetness of his disposition, and those who had the happiness to meet him at their entrance into a scientific career have kept the most tender remembrance of his gentle good-heartedness."