FROM THE HISTORY OF PHYSICS

THOMAS YOUNG

F. Arago1

A biography read at a public meeting of the Academy of Sciences
on November 26, 1832.

Gentlemen, death, which so tirelessly strikes our ranks, directs its blows with cruel persistence against our all too few foreign members. In a short space of time the following have been struck from the rolls of the Academy: Herschel, whose bold ideas on the structure of the universe become more plausible with every year; Piazzi, who on the very first day of our century enriched the solar system with a new planet; Watt, who, if he was not the inventor of the steam engine—for a Frenchman invented it—was at least the creator of a multitude of remarkable combinations by means of which Papin’s little apparatus became the most ingenious, the most useful, the most powerful means of motion in industry; Volta, to whom his electric pile will bring immortality; Davy, no less celebrated for the decomposition of the alkalis and for his invaluable miner’s lamp; Wollaston, whom the English called the Pope, since he never once erred either in his numerous experiments or in his most subtle theoretical reasonings; and, finally, Jenner, whose invention needs no recommendation to fathers of families. To pay to such illustrious names the lawful tribute of regret, admiration, and gratitude on behalf of all who have devoted themselves to science is one of the most important duties entrusted by the Academy to those to whom it grants the perilous honor of speaking in its name at these solemn assemblies. This duty seems to me no less inescapable: I must not delay in rendering this sacred debt. Indeed, gentlemen, a native academician will always leave behind him, among his colleagues, several persons initiated into all his secret thoughts, acquainted with the history of the emergence of all his discoveries and with all the vicissitudes of his fate. By contrast, a foreign member of our Academy lives far from us and rarely sits in our circle. Only from travelers’ accounts do we learn of his life, his habits, and his character. After several years have passed over these fleeting notes, if any trace of them remains, they cease—

...beware of trusting their accuracy. Literary novelties, until the press takes them up, are like small change, which in circulation at the same time changes both its weight and its value.

This reasoning makes it possible to understand why at our meetings we had to recall the names of Herschel, Davy, and Volta before honoring the memory of several famous academicians who ended their lives in our midst. Moreover, I believe that in a little while no one will be able to deny a certain preference with regard to a universal scholar, whose life I am about to describe and whose works I am about to analyze.

The Birth of Young.—Childhood.—The Beginning of Scientific Activity

Thomas Young was born at Milverton, in the county of Somerset, on June 13, 1773, to parents who belonged to the Quaker sect. The first years of his life he spent with his maternal grandfather, Mr. Robert Davis, in Minehead, who was a rare example of a man of business preserving a taste for the culture of the classical authors. At the age of two Young was already reading fluently. His memory was truly astonishing. In the intervals between long lessons with the village schoolmistress, in a village situated near Minehead, he had, at the age of four, learned by heart a large number of works by English authors and even various Latin verses, from beginning to end, although at that time he did not yet understand that language. Thus Young’s name, along with the multitude of other celebrated names already noted by biographers, will nourish the hopes and fears of good fathers of families, who see in the faultless or poor assimilation of this or that lesson either sure signs of incorrigible mediocrity or an unquestionable pledge of a brilliant career. We should stray from our purpose if these historical notes served to strengthen such prejudices. Therefore, while being far from wishing to weaken the lively and pure agitation aroused by the annual distribution of prizes, we shall nevertheless remind some, so that they do not surrender excessively to dreams which in the future may not come true, and others, so that they do not sink into hopelessness, that Pico della Mirandola, that phoenix of schoolboys of all countries and all times, was in mature age only a minor author; that Newton, that mighty mind of whom Voltaire could say without incurring the charge of exaggeration:

Confidents du Très-Haut, substances éternelles
Qui parez de vos feux, qui couvrez de vos ailes
Le trône où votre maître est assis parmi vous,
Parlez, du grand Newton n’étiez-vous point jaloux?¹

¹ Confidants of the Most High, eternal substances, adorning with your fires, overshadowing with your wings the throne on which the Lord sits among you—answer, did you not envy the great Newton?

that the great Newton by no means distinguished himself in college by his successes; that at first learning did not attract him at all; that he first had to show diligence in order to get the place of a mischievous pupil who sat above him in rank and kicked him with his feet; that at the age of twenty-two he took part in a competition for admission to Cambridge (fellowship of Cambridge) and was defeated by a certain Robert Uvedale, whose name, were it not for this circumstance, would have been completely forgotten; that, finally, Fontenelle was more witty than accurate when he said of Newton in Lucian’s words: “It was not granted to humanity to see the Nile weak and in its infancy.”

When Young was six years old, he began studies with a Bristol professor—fortunately for the pupil, a very mediocre one. This is by no means a paradox: being unable to submit to the sluggish and excessive restraint of measured guidance, the pupil became his own teacher, and it was precisely here that those brilliant qualities developed which, under excessive pressure, might have remained unmanifested.

Young was eight years old when chance—whose role in the events of life is more significant than vanity permits us to admit—tore him away from purely literary pursuits and revealed his vocation. A land surveyor living nearby, a very worthy man, became very fond of him. Sometimes on holidays he took him with him to a plot of land and allowed him to play with geodetic and physical instruments. The operations by means of which the distances and heights of inaccessible objects were determined struck the imagination of the little schoolboy, but several chapters from a mathematical dictionary soon dispelled all mystery. From that day onward, on Sunday walks, geodetic instruments took the place of a kite. In the evenings, during hours of leisure, the pupil-engineer calculated the heights measured in the morning.

From the age of nine to fourteen Young lived at Compton, in the county of Dorset, with Professor Thomson, of whom he always retained a bright memory. During these five years all the pupils of the boarding school, following the custom of English schools, were occupied exclusively with a detailed study of the principal writers of Greece and Rome. Young all this time held first place in his class and nevertheless at the same time managed to study French, Italian, ancient Hebrew, Persian, and Arabic; French and Italian—accidentally, striving to satisfy the curiosity of a comrade who possessed several books published in Paris and whose contents he wished to know; ancient Hebrew—in order to be able to read the Bible in the original; Persian and Arabic—in order to resolve a question that had arisen in conversation at the school dinner table: do there exist among the Eastern languages differences as sharp as among the European ones?

I wish to point out that I am writing on the basis of authentic documents before adding that, simultaneously with such

with astonishing success in the study of languages, Young, while taking walks in the environs of Compton, became passionately interested in botany; having no means of obtaining the magnification used by naturalists in examining the finest parts of a plant, he resolved to construct a microscope on his own, with as his only guide a description of this instrument compiled by Benjamin Martin. Since in order to carry out this difficult task he had to acquire great skill in turning, and since, having stumbled in the algebraic formulae of optics upon symbols incomprehensible to him (the symbols of fluxions), he fell into great confusion, yet, unwilling to abandon the idea of magnifying his petals and stamens, he decided that it would be easier to study differential calculus in order to understand the ill-fated formula than to go to the neighboring town to buy a microscope.

The seething activity of the young Young forced him to exceed the measure of human strength. At the age of fourteen his health was greatly shaken.

Certain symptoms gave cause to fear a pulmonary disease; however, medical prescriptions and the ardent care of his family overcame these ominous signs.

Among our overseas neighbors it is a rare occurrence for a wealthy man, entrusting his son to a special tutor, not to try to find him a companion in studies among youths of the same age who have already distinguished themselves by their successes. On this basis Young in 1787 became the study companion of the grandson of Mr. David Barclay of Youngsbury, in the county of Hertford. On the very day of his arrival Mr. Barclay, evidently not considering himself entitled to be too demanding with respect to a fourteen-year-old schoolboy, gave him several phrases to copy, in order to see whether his handwriting was good. Young, apparently offended by such a test, asked permission to withdraw to the adjoining room to perform this task. His absence continued longer than the copying could have required, and Mr. Barclay had already begun to jest about the slowness of the little Quaker when he finally returned. The copy had been executed with extraordinary beauty: a writing master could not have done it better. As for the delay, it was no longer mentioned, for the little Quaker, as Mr. Barclay called him, not content with copying the proposed English phrases, had translated them into nine different languages.

The tutor, or tutor, as they say on that side of the English Channel, to whom the education of both schoolboys from Youngsbury had been entrusted, was a young man of very refined upbringing, at that period wholly devoted to perfecting himself in his knowledge of the ancient languages; he was the future author of Calligraphia graeca. However, he soon perceived the enormous superiority of one of his two pupils and, with very praiseworthy modesty, admitted that in their ordinary studies the true mentor was not always the one to whom that title belonged.

During this period Young, constantly resorting to original sources, compiled a detailed analysis of the numerous philosophical systems of the various schools of Greece. His friends speak of this work with sincere admiration. I do not know whether it was ever destined to become public property. In any case, it played a role in its author’s life, since, in devoting himself to the attentive and precise study of the oddities (I use a polite expression) with which the conceptions of the Greek philosophers abound, Young felt how his former attachment to the principles of the sect to which he belonged by birth was weakening in him. True, he wholly broke with them only several years later, during his stay in Edinburgh.

The little industrious colony from Youngsbury would leave the county of Hertford for several winter months and move to London. During one of these trips Young met a professor worthy of him. He was introduced to chemistry by Dr. Higgins, whose name it is all the harder for me to pass over here in silence because, despite his sharp and repeated statements, the share that rightfully belongs to him in the discovery of the law of definite proportions—one of the most valuable acquisitions of modern chemistry—has still not been recognized.

Dr. Brocklesby, Young’s uncle on his mother’s side and one of the most eminent physicians of London, rightly proud of the youth’s brilliant successes, would sometimes show his works to scholars, men of letters, and people of the world, whose approval could most flatter his self-esteem. Thus, already very early, Young entered into personal relations with the famous Burke and Windham of the House of Commons, and with the Duke of Richmond. The latter, being at that time Master-General of the Ordnance (grand maître de l’artillerie), offered him the post of adjutant secretary (secrétaire assistant). Two other statesmen, while also wishing to draw him into an administrative career, advised him first to enter Cambridge, into the faculty of law. Having such powerful patrons, Young could count on one of those lucrative positions upon which the powerful of this world never stint in respect to those who relieve them of all work upon themselves, of every mental effort, and, never offending their ambition by immodesty, hourly help them to shine at court, in the council, or on the rostrum. Fortunately, Young knew his own strength; he felt within himself the germ of brilliant discoveries that would later glorify his name; he preferred the laborious but independent career of a scholar to the glitter of the golden fetters with which they tried to tempt him. Let us give him his due for this. May his example serve as a lesson to all young people whom the striving for power diverts from their noble calling and turns into bureaucrats; may they, like Young, seeing into the future, not sacrifice to the empty and equally fleeting pleasure of seeing around themselves seekers and petitioners that gratitude and esteem with which almost always high-intellectual—

THOMAS YOUNG

...toilsome labor. And if, trusting the illusions inherent in inexperience, they found that too heavy a sacrifice was being demanded of them, we would suggest that they take a lesson in ambition from the lips of the great commander, whose ambition knew no bounds. We would suggest that they reflect on the following words, addressed by the First Consul, the victor at Marengo, to one of our most respected colleagues (Mr. Lemercier) on the day when the latter, without hesitation, refused an office—at that time a very high one—that of councillor of state:

“I understand, sir. You love science and wish to belong to it wholly. I can make no objection to this decision. Yes, I myself—do you think that if I had not become commander-in-chief and the instrument of the destinies of a great people, I would have run about salons and chancelleries in order to become dependent on someone or other, whether as minister or ambassador? No and no! I would have immersed myself in the study of the exact sciences. I would have followed the path of the Galileos and Newtons. And since success has constantly accompanied me in all my great undertakings, I would have distinguished myself highly by my scientific labors as well. I would have left behind the memory of magnificent discoveries. No other glory would have enticed my ambition!”

Young chose a medical career, hoping that it would provide him with means and independence. He began his medical studies in London, under the direction of Baillie and Cruikshank; he continued them in Edinburgh, where at that time the physicians Black, Monro, and Gregory were celebrated, but only in Göttingen, a year later (1759), did he receive the degree of doctor. Before undergoing this rather empty, and yet so insistently required, formality, Young, while still almost a youth, had already shown himself in the scientific world by an article on the resin Ladanum; by a dispute with Dr. Beddoes on Crawford’s theory of heat; by an essay in which the peculiarities of the behavior of spiders and Fabricius’s system were considered—all this being supported by scientific investigations—and, finally, by a work on which I shall dwell further because of its high merits, the unusual success that accompanied its appearance, and the oblivion to which it was afterward consigned.

The Royal Society of London enjoys, in all three kingdoms, enormous and deserved respect. The desire to see one’s name in the list of fellows of this truly national assembly, beside the names of Newton, Bradley, Priestley, and Cavendish, has always been the liveliest and most legitimate stimulus to emulation among the scholars of the famous universities of Cambridge, Oxford, Edinburgh, and Dublin. This is the highest rung of the ambitious aspirations of a scholar. He attains it only by presenting some capital work, while the first attempts of his youth reach readers more in keeping with their significance by means of one of those numerous “Reviews” which have contributed so much among our neighbors to the spread of human knowledge. Such is the usual course of things. Young’s path was to be, accordingly—

...naturally, turn out to be different. At the age of twenty he presents his work to the Royal Society. A council, composed of all the outstanding scholars of that time, honors this work with an approving review, and it soon appears in the Transactions. In it the author speaks about vision.

Theory of Vision

The problem was by no means new. Plato and his disciples had dealt with it four centuries before our era; however, at the present time their conceptions could be quoted only in justification of that famous and very unflattering maxim of Cicero: “It is impossible to imagine anything so absurd that one could not find a philosopher capable of asserting it!” Whoever wishes to find phenomena of vision worthy of the attention of a historian of ideas will have to travel across a span of two thousand years to Greece, to Italy. It was there—never solemnly forbidding, like the philosopher from Aegina, access to his school to all who were not geometers—that cautious experimenters set milestones on the only path that unfailingly leads man to the conquest of unknown regions. It was there that Maurolycus and Porta cried out to their contemporaries that the task of discovering what is is difficult enough that the striving toward the world of knowledge in search of what ought to be should appear, at the very least, presumptuous.

It was there that these famous compatriots of Archimedes began to discover the purpose of the various parts of the eye and, like Galileo and Newton in later times, resolved not to go beyond the limits of knowledge that can be acquired or verified with the aid of our senses, and that beneath the porticoes of the Academy had been branded with the contemptuous name—mere opinion. Such, however, is human weakness that, having traced with rare success the principal deviations of light in passing through the cornea and the crystalline lens, almost at the very goal Maurolycus and Porta suddenly stopped, as if before an insurmountable obstacle, as soon as their theory was met with the objection that, since an inverted image is formed in the eye, objects must appear to us in the same position. Kepler’s bold mind, on the contrary, remains unshaken. The attack is made from the side of psychology and with the aid of that same psychology—clear, precise, mathematical—he overturns the objection. Under the powerful influence of this great man the eye finally becomes a simple optical instrument known by the name of camera obscura: the retina serves as the screen, the crystalline lens replaces the glass lens.

This comparison, which after Kepler received universal recognition, encountered only one obstacle. The camera obscura, like an ordinary telescope, must be aimed...

THOMAS YOUNG

...is shifted into focus depending on the distance of the objects. When objects approach, the screen must be moved away from the lens; when objects are removed, the reverse displacement is required. Thus it is in no way possible to preserve the necessary sharpness of the image without changing the position of the reflecting surface, unless one changes the convexity of the lens, increasing it for viewing near objects and decreasing it when objects are distant. There is no doubt that nature chose one of these methods for obtaining a sharp image, since man is capable of seeing with great clarity at the most varied distances. Such a formulation of the question served physicists as the subject of numerous investigations and discussions. Great names figure in this dispute.

Kepler, Descartes, and others maintain that the entire eyeball is capable of elongating and flattening.

Porterfield, Zinn, and others suppose that the crystalline lens, which replaces the lens, is movable; that when necessary it can shift relative to the retina.

Jurin, Musschenbroek... consider that the curvature of the cornea changes.

Sauvages, Bourdelot... also introduce a change of curvature, but only in the crystalline lens. Such too is Young’s system. This system is set forth in full in two papers successively presented by our confrere to the Royal Society of London.

In the first of the papers the question is considered only from the anatomical point of view. Young proves, by means of direct and very subtle observations, that the crystalline lens possesses a fibrous or muscular structure, magnificently adapted to various changes of form. This discovery destroyed the only serious objection that had until then been raised against the hypothesis of Sauvages, Bourdelot, and others. Scarcely had it been published when Hunter asserted his rights to it. The famous anatomist thereby merely emphasized the success of the young debutant, since his own work, having remained unpublished, was known to no one. Moreover, this subject of discussion soon lost its importance: some erudite scholar proved that, with the aid of his powerful microscopes, Leeuwenhoek had already observed and sketched the muscular fibers of the crystalline lens of a fish with all their ramifications. In order to revive public attention, wearied by numerous debates, the high reputation of two more members of the Royal Society who took part in the dispute was needed. An enlightened anatomist and the most celebrated artist of whom England could be proud presented to the Royal Society a work that was the result of their joint efforts, and that was destined definitively to establish the absolute invariability of the form of the crystalline lens. In the scholarly world people could hardly suppose that Mr. Everard Home and Ramsden, having joined forces, might produce inaccurate experiments, or that they had erred in micrometric measurements. Young himself could in no way believe this, and therefore without hesitation publicly renounced his...

theory. This readiness to admit himself defeated, so rare in a man of twenty-five, especially rare since it concerned his first publication, was in this case an act of boundless modesty. For in fact Young had nothing to renounce. Having subsequently withdrawn his renunciation, our colleague in 1800 again developed the theory of deformation of the crystalline lens in vision, to which no serious objections have since been opposed.

Nothing can be simpler than his argumentation, nothing more ingenious than his experiments. First of all Young refutes the hypothesis of a change in the curvature of the cornea by means of microscopic observations, in which the slightest changes would have proved distinguishable. Next, he places the eye under special conditions in which changes of curvature could not play the slightest role: he immerses it in water and proves that in this case, too, the ability to see at different distances is fully preserved.

After this, by a whole series of convincing considerations and experiments, the following of the three possible assumptions is eliminated—the notion of a change in the dimensions of the entire organ.

It would seem that the problem was finally solved. Indeed, it is clear to everyone that if, of the three possible solutions, two are excluded, then the third becomes inevitable; that if the radius of curvature of the cornea and the longitudinal diameter of the eye remain unchanged, then one must conclude that the shape of the crystalline lens changes. Young, however, does not stop there; by delicate observations on the deformation of images he proves directly that the curvature of the crystalline lens does indeed change; he invents, or at least improves, an instrument that can be used by the least sophisticated people, those least accustomed to conducting delicate experiments, and, armed with this new means of investigation, he verifies that all individuals deprived of the crystalline lens as a result of cataract removal lose the ability to see distinctly at different distances.

It is truly astonishing that this remarkable theory of vision, this most artful weaving in which reasoning and the most ingenious experiment continually support one another, has not yet occupied in science the honorable place that rightly belongs to it; and yet, is it really necessary to resort to a kind of fatalism to explain this strange fact? Was Young really, as he himself often said with bitterness, a new Cassandra, tirelessly proclaiming important truths rejected by ungrateful contemporaries? It seems to me that it would be more correct, though less poetic, to conclude that Young’s discoveries were not known to the greater part of those who might have appreciated them: physiologists did not read his excellent work, since it requires greater mathematical knowledge than is usually imparted in the faculties. Physicists, for their part, neglected it, since in oral lectures and in printed works the public in our time seeks to acquire only superficial information, which an ordinary mind easily grasps. All this, whatever opinion one may hold,

our famous confrère, is nothing supernatural. Like all those who investigate the innermost depths of science, he remained unknown to the crowd, but the approval of a few chosen men must have served him as a reward. In questions of this kind one should not count votes; it is far more reasonable to compare them by weight.

INTERFERENCES

The most precious discovery of Dr. Young, destined forever to immortalize his name, was suggested to him by an object seemingly quite insignificant: those brightest and lightest bubbles of soap foam which, scarcely escaping from a schoolboy’s pipe, become the plaything of the most imperceptible movements of the air. I believe that, before so enlightened an audience, it would be superfluous to explain that the difficulty with which a given phenomenon is obtained, its unusualness, or its practical utility, are by no means necessary indicators of its importance in science. Therefore I connect the discovery which I am about to analyze with an ordinary children’s game, confident that such an origin will not damage it in anyone’s eyes. In any case, I might have resorted to recalling the apple which, having broken from a branch and unexpectedly fallen at Newton’s feet, awakened in the great scientist the thought of the simple laws governing the motions of the heavens; the same is true of the frog and the blow with a surgeon’s knife, which only quite recently bestowed upon physics the remarkable voltaic pile. Let us suppose, indeed, without mentioning the name of soap bubbles, that a certain physicist chose as the subject of his investigations distilled water, i.e. a liquid which, in its pure state, acquires light, barely perceptible shades of green and blue only in very thick layers. Could one have doubted the truth of his words if he suddenly, without any explanation, declared that he could, at will, impart to this water, though so transparent, the most sparkling colors; that he was capable of making it yellow as lemon peel, or crimson-red, while keeping it in its pure state, without mixing it with any foreign substance and without changing the ratio of its gaseous elements?

Will our physicist not be considered an utter liar if, after so strange an introduction, he adds that, in order for him to color the water, it is enough to obtain it in the form of a film; that “thin,” if one may put it so, is synonymous with “colored”; that the transition from any color to the color most sharply differing from it is a necessary consequence of a simple change in the thickness of the layer of liquid; that, in passing from red to green, this change does not amount to a thousandth part of the thickness of a hair. And yet these incredible conclusions inevitably follow from the phenomena of coloration that can be observed in bubbles made of liquid and even simply in thin layers of various substances.

The fact that these phenomena, for more than twenty centuries, were every hour presented to the eyes of physicists without arresting their attention can be explained only by nature’s niggardliness, which grants to few the precious faculty of wonder.

Boyle was the first to open this rich vein. He confined himself, however, to a detailed description of the circumstances that give rise to the rainbow. His collaborator Hooke did not stop there. He thought he had discovered the cause of the coloration that arises when rays are crossed, or, in his own words, when waves reflected by the two surfaces of a thin layer intersect. This was, as we shall see below, a flash of genius; but it could not bear fruit in an epoch when the complex nature of white light was still unknown.

The coloration of thin layers was, for Newton, a favorite subject of study. He devoted an entire book to it—his famous Opticks; he established the laws of its occurrence by means of an astonishing series of experiments that have not been surpassed to this day. Obtaining, with the aid of homogeneous light, the regular rainbows already mentioned by Hooke, which arise around the point of contact of two glass lenses placed one upon the other, he proved that for every simple color, in any thin layers, there exists a series of increasing thicknesses at which no light is reflected. This result was decisive; in it lay the key to all similar phenomena. Less successful were the theoretical conclusions drawn by Newton from this remarkable observation. To repeat after him, speaking of the reflected ray, that it is in a state favoring easy reflection (dans un accès de facile réflexion), and of the ray that passes entirely through the layer, that it is in a state favoring easy transmission—does this not mean repeating in confused expressions what the experiment with the two lenses has shown?

The theory of Thomas Young is free from such criticism. Here no states are taken as the fundamental property of rays. Moreover, a thin layer is in every respect likened to a thick mirror of the same substance. When in certain points a complete absence of light is observed, Young does not conclude that there are no reflections at them at all: he assumes that, in certain directions from these points, the rays reflected by the second surface, moving toward the rays reflected from the first, extinguish them completely. The author gave to this interpretation the now so well-known name of interference.

This is, without doubt, the strangest of hypotheses!

It was unexpected to see night in the midst of a clear day, at points freely reached by the sun’s rays; but who could have thought that light, adding itself to light, could produce darkness!

The physicist truly triumphs when he can announce a result that so greatly violates ordinary notions; but he must immediately support it with proofs, lest he resemble those Eastern writers whose whimsical fantasies entertained the Sultan Shahriyar for a thousand and one nights.

Young did not take this precaution. He showed at first that his theory was applicable to various phenomena, but only within the limits of possibility. Having later developed real proofs, he encountered the prejudice of the public and was unable to overcome it. Meanwhile, the experiment by which our colleague supported his memorable discovery this time could not have raised the slightest doubt. Two rays issuing from one and the same source traveled by somewhat different paths toward an intersection at a certain point in space. At this point a sheet of good paper was placed. Each ray separately imparted to it the brightest brilliance, but when the two rays were combined, when they fell upon the paper simultaneously, every sign of light disappeared: day was replaced by the deepest night.

Two rays are not always completely extinguished at the point of mutual intersection. Sometimes only a partial weakening can be noticed; at times, too, the rays are superposed upon one another. Here the decisive role is played by the differences in the length of the paths traveled, and everything is subject to very simple laws, the discovery of which would at all times have been sufficient to immortalize the name of a physicist.

The differences of paths as a result of which rays meet and are completely extinguished are not the same for rays of different colors. When two rays of white light intersect, it may happen that only one of the principal component colors, for example red, is under conditions of complete extinction. But white without red is green! Thus light interference manifests itself also in coloration; in such cases the different elementary colors reveal themselves without decomposition by means of a prism. It is now enough to observe that in space there will not be found a single point at which homogeneous rays, more or less obliquely reflected, would not intersect, and the whole vast unexplored region opened to the searching gaze of physicists by the theory of interference will immediately present itself to the eye. By the time Young published this theory, many phenomena of the periodic alternation of colors had already attracted the attention of investigators; it must be added, however, that they yielded to no explanation. Among these phenomena were the rings formed as a consequence of reflection not on thin films, but on slightly curved mirrors of thick glass; iridescent bands of varying width, bordering and sometimes covering the inner space of shadows cast by bodies, first noticed by Grimaldi, later troubling Newton’s genius, and subsequently fully explained by Fresnel; arcs, colored red and green, which can be observed directly beneath the seven spectral colors of the main rainbow and which seemed so resistant to any explanation that in the end they ceased to be mentioned in textbooks of physics; and, finally, coronas of sharply defined colors and of constantly changing diameter, which often appear around the moon and the sun.

Remembering how numerous are the people who value scientific theories only according to the possibility of their immediate application, me-

One would not wish to end the enumeration of phenomena characterized by a more or less extensive series of periodic colors without mentioning the rings, so remarkable for the regularity of their form and their clear brilliance, which we discern around any sufficiently bright source of light when viewing it through a mass of molecules or fibers of uniform size. These rings in fact inspired Young with the idea of constructing an exceedingly simple instrument, which he called the eriometer (ériomètre) and with the aid of which one can easily calculate the dimensions of the smallest bodies. The eriometer, still so little known to investigators, has, in comparison with the microscope, the enormous advantage that it immediately gives the mean size of millions of particles located in the field of view. It possesses, moreover, the strange property of giving no results when the particles differ too sharply from one another, or, in other words, when the problem of determining their dimensions has physically no meaning. Young used his eriometer to measure blood corpuscles in animals of various families; to measure pollen particles arising from various plant species; to measure the fineness of wool used in textile work, beginning with the most valuable—beaver wool—and ending with the wool of ordinary flocks of Sussex County, which, being on the last rungs of the ladder, consists of fibers four and a half times thicker than beaver wool.

Before Young, the named phenomena of coloration, in all their multiplicity, not only had found no explanation, but also remained outside any mutual connection. Newton, for example, who had studied them so thoroughly, noticed no kinship between the rings of thin layers and diffraction bands. Young established that bands of both kinds are a consequence of interference. Later, when chromatic polarization was discovered, he drew from certain measurements of thickness remarkable numerical analogies, from which it could be concluded with great probability that sooner or later this distinctive kind of polarization would reveal a connection with his doctrine. It must be confessed, however, that here a vast gap still remained to be filled. Complete ignorance of the most important properties of light did not at that time allow one to comprehend all those strange phenomena that arise under the action of double refraction, as a consequence of the extinction of light when rays are crossed in various crystals. Nevertheless, here too Young deserves the honor of having opened the way; he was the first to begin deciphering the hieroglyphs of optics.

Egyptian Hieroglyphs.—History of the First Exact Interpretation of Them

The word hieroglyph, if it is understood not metaphorically but in its natural meaning, carries us into a region that has already served as living soil for numerous and lively disputes. I experienced a moment of hesitation before coming face to face

with all the passions that had arisen around this question. The secretary of an academy wholly devoted to the exact sciences could indeed have entrusted this philological burden to judges more knowledgeable. Moreover, I confess, I was afraid of finding myself at odds on a whole series of important questions with a brilliant scholar whose works I had examined with genuine pleasure, without a single word of criticism having come from my pen. Yet all these doubts vanished after I took into account that the interpretation of Egyptian hieroglyphs is one of the finest discoveries of our century; that Young himself introduced my name into the discussions of which it was the subject; and that, having set myself the task of determining whether this new and glorious conquest truly belongs to France, I am broadening the mission I am carrying out at this moment, and acting as befits a citizen. I know in advance that precisely these sentiments will be taken for narrow-mindedness; I am aware that cosmopolitanism has its good sides, but what name would it deserve from me if, at a time when neighboring nations proudly enumerate the discoveries of their sons, I were forbidden to seek in the same circle, among compatriots whose modesty is inviolable to me, proofs that France has not fallen into decline, that she too each year contributes her glorious share to the vast repository of human knowledge.

And so I turn to the question of Egyptian writing. I approach it without any preconceived opinions, with the firm intention of observing justice, with an ardent desire to reconcile the rival claims of two scholars whose premature death gave all Europe such just cause for regret. Moreover, in this discussion of hieroglyphs I do not overstep the bounds prescribed to me, and I shall be happy if my audience, on whose indulgence I rely, should find that I have managed to cope with a subject whose intricacy has become proverbial. People have invented two completely different systems of writing. One of them is used among the Chinese; it is the hieroglyphic system; the other is at present in use among all other peoples and bears the name of the alphabetic, or phonetic, system. Strictly speaking, the Chinese have no letters. The signs they use for writing are genuine hieroglyphs: they represent not sounds, not phonetics, but ideas. Thus, the concept house is expressed by means of a single and special character, which would remain unchanged even if all Chinese, in oral speech, were to designate a house by a word entirely different from the one they pronounce at the present time. Does this result surprise you? Recall our numerals, which likewise are hieroglyphs. The idea of a unit added to itself seven times is expressed everywhere—in France, in England, in Spain, and so on—by means of two circles placed vertically one above the other and touching at only one point; yet, on seeing this ideographic sign, a Frenchman says huit, an Englishman eight, a Spaniard ocho. Everyone knows that the same applies to all

complex numbers. Thus, among other things, if the Chinese ideographic signs, like Arabic numerals, had been universally disseminated, then everyone would read any book in his own language, without needing to know even a single word of the language of the book’s author.

All this in no way applies to alphabetic writing.

He who instructed us in lofty matters
To trace the word and converse with the eye,

having observed, in general, that all the words of the richest language are composed of a very small number of elementary sounds, or articulations, devised signs, or letters, representing them, to the number of twenty-four or thirty. With the aid of various combinations of these signs he could write any word that touched his hearing, even without knowing what it meant.

Chinese, or hieroglyphic, writing appears to us to correspond to the childhood of art. It is incorrect, however, to hold the former notion that learning to read in China itself consumes the entire long life of an industrious mandarin. Rémusat, whose name every time reminds me of one of the cruelest losses suffered by scholarship in a long time, showed from his own experience and from the experience of his pupils that the Chinese language can be learned like any other. It is also incorrect to hold the original notion that hieroglyphic signs are capable of expressing only ideas: a few pages from the novel Yu-kiao-li, or “The Two Cousins,” would be sufficient to prove that Chinese writing is capable of conveying the most ingenious, the most refined abstractions. The chief shortcoming of this writing is the absence of means for expressing new names. A Cantonese scholar could have communicated in writing to Peking that on 14 June 1800 there took place a battle memorable for France, but he could not, by means of hieroglyphic signs alone, have conveyed to his correspondent that the plain on which this event occurred was near the village of Marengo and that the name of the general was Bonaparte. A people among whom the transmission of proper names from city to city can be carried out only with the help of a messenger must still remain at the first stages of civilization. This does not apply to the Chinese people. Hieroglyphic signs do indeed constitute the principal part of their writing, but in some cases, especially when it is necessary to write a proper name, they lose their hieroglyphic meaning and begin to express only sounds and articulations, becoming like ordinary letters.

After all these preliminary reflections, it will be easy for us to explain and analyze the question of priority that arose in connection with the decipherment of Egyptian writing. Indeed, in the hieroglyphs of the ancient people of the pharaohs we shall find all the devices that the Chinese use at the present time.

Many passages in Herodotus, Diodorus Siculus, and Saint Clement of Alexandria indicate that the Egyptians used two

or three kinds of writing and that, at least in one of them, symbolic signs or emblems of ideas play a large role.

Horapollo has preserved for us the meaning of some of these signs; thus, it is known that the hawk denoted the soul, the ibis—the heart, the dove (strange as it may seem)—a cruel person, the flute—an effeminate one, the number sixteen—sensuality, the frog—an incautious person, the ant—knowledge, the drawn-out loop—love, and so on.

These signs, preserved by Horapollo, constituted only a very small part of the eight or nine hundred letters deciphered in tomb inscriptions. Our contemporaries, among them Kircher, tried to increase the number of known signs. Their efforts led to no useful result, unless one counts as superfluous proof of the fact that the most educated people are capable of going astray when, in the search for facts, they trust their imagination without restraint. For lack of data, the decipherment of Egyptian writing had long seemed to all the luminaries of reason a completely insoluble problem; but in 1799 Mr. Boussard, an officer of the engineer troops, discovered, during excavations being carried out under his direction near Rosetta, a large stone covered with three rows of quite clear letters. One of the inscriptions was Greek. Despite some damage, it clearly reported that the authors of the monument had ordered one and the same inscription to be drawn in three kinds of letters, namely, in sacred, or hieroglyphic, Egyptian letters, in local, or everyday, letters, and finally in Greek; thus, thanks to unexpected good fortune, philologists received at their disposal a Greek text together with its translation into the Egyptian language or, at least, with two transcriptions that had been used in antiquity on the banks of the Nile.

This Rosetta Stone, which since then has become so widely known and which in its time was presented by Boussard as a gift to the Cairo Institute, was taken from that scholarly institution during the evacuation of the French troops from Egypt. At present it may be seen in the London Museum. Quite apart from its value, the famous physicist could add, without risking the appearance of partiality, that this invaluable bilingual monument also testifies to the advanced views that guided all the details of the memorable Egyptian expedition, as well as to the untiring zeal of the valiant scholars whose work, often carried out under grapeshot fire, brought glory to French science. In fact, they were so keenly aware of the importance of the Rosetta inscription that, not wishing to expose this treasure to the vicissitudes of a sea voyage, from the very beginning they persistently strove to reproduce it in the form of simple drawings, typographic impressions from a copper plate, or plaster and sulfur casts. Let us add, moreover, that antiquarians of all countries first became acquainted with the Rosetta Stone from the drawings of French scholars.

One of the most enlightened members of the Institute, Silvestre de Sacy, in 1802 was the first to set out upon the path opened to philologists by the bilingual inscription. However, he dealt only

by the Egyptian text written in cursive signs. In it he discovered groups representing various proper names, and established their phonetic character. Thus, at least in one of the two scripts named, the Egyptians had representations of sounds that were true letters. This important result ceased to provoke objections after the Swedish scholar Åkerblad, deepening our compatriot’s investigation, established, with probability close to certainty, the individual phonetic value of various letters used in the transcription of proper names, which could be recognized from the Greek text.

What remained was the purely hieroglyphic part of the inscription, or what was taken to be such. It remained entirely unexplored; no one dared to set about deciphering it.

And it is here that Thomas Young’s turn comes.

First of all, as if in a burst of inspiration, he declares that among the multitude of signs carved on the stone and depicting either animals or fantastic beings, as well as instruments, works of art, or geometric figures, the signs enclosed in an ellipse correspond to proper names in the Greek inscription; thus, in particular, proved to be the name of Ptolemy, the only one fully preserved in hieroglyphic transcription. Immediately after this Young points out that, in the special case of a frame or cartouche, the signs no longer represent ideas, but sounds, and, finally, by means of a careful and very subtle analysis, he tries to find an individual hieroglyph for each of the sounds perceived by the ear in the name Ptolemy on the Rosetta Stone and in the name Berenice—on another monument.

These, if I am not mistaken, are the three culminating points of Young’s investigation of the graphic systems of Egypt. It is commonly believed that before the English physicist no one had noticed them, or at least that no one had pointed them out. This opinion, although generally accepted, seems to me debatable. It is known that in 1766 de Guignes pointed out in a published work that all proper names in Egyptian inscriptions are framed by cartouches. In the same work you may find arguments supporting the learned Orientalist’s opinion concerning the invariably phonetic nature of Egyptian hieroglyphs. Thus priority belongs to Young on one point only: he was the first to attempt to break down the groups of cartouches into letters in order to establish the phonetic value of the hieroglyphs composing the name Ptolemy on the Rosetta Stone.

In this investigation, as was to be expected, Young gave new proof of his enormous insight; however, his efforts, entangled in a false system, did not lead to complete success. Thus, in some cases he ascribed to hieroglyphic letters a purely alphabetic value; in other cases he supposed in them syllables and even disyllabic combinations, not embarrassed by the strangeness of such a mixture of different symbols. Thus, the fragment of the alphabet published by Dr. Young,

contains within it both truths and errors, but the latter so prevail that, by means of the hieroglyphs deciphered in it, it is impossible to read anything except two proper names, from which they were extracted. The word impossible occurs so rarely in Young’s scholarly career that it is necessary to justify it at once. Thus, I shall point out that at the time of compiling his alphabet Young found in the vignette of an Egyptian monument the name Arsinoë (Arsinoé) in the place where subsequently his famous rival, with complete obviousness, deciphered the word autocrator; that it seemed to him—he read Evergetes (Evergète) in a group which should be read César!

Champollion’s work, where it concerns the discovery of the phonetic meaning of hieroglyphs, is clear, uniform, and, it seems, gives rise to no doubts. Each sign corresponds to a simple vowel or a simple consonant; its meaning is not arbitrary; each phonetic hieroglyph is the image of a physical object whose name in the Egyptian language begins with the vowel or consonant that is to be represented1.

Champollion’s alphabet, compiled with the help of the Rosetta Stone and two or three other monuments, makes it possible to read quite different inscriptions—for example, the name of Cleopatra on the obelisk of Philae (Philoe), long since transported to England, on which Dr. Young, with his alphabet, could make out nothing. In the temples of Karnak Champollion twice read the name of Alexander; on the Dendera zodiac—the Roman imperial title; on the large building above which the zodiac was placed—the names and epithets of the emperors Augustus, Tiberius, Claudius, Nero, Domitian, and others. Thus, among other things, on the one hand the revived dispute over the age of these monuments was cut short, and on the other it became indisputably clear that under Roman rule hieroglyphs were still in full use on the banks of the Nile.

Champollion calls homophonous (homophones) all those signs which, representing one and the same sound or even one and the same articulation, may at the same time replace one another arbitrarily. In the present state of the Egyptian alphabet I can note six or seven homophonous signs for the letter A and more than twelve for S, or, more precisely, for the Greek sigma.

Applying the alphabet, which had already yielded so many unexpected results, to the great Karnak obelisks and to other monuments known to belong to the time of the Pharaohs, we learn the names of various kings of this ancient race, the names of Egyptian deities, and even more—nouns, adjectives, and verbs of the Coptic language. Young, therefore, was mistaken in regarding phonetic hieroglyphs as a most recent invention, asserting that in Egypt they served only for writing proper names, and then only foreign ones. On the contrary, de Guignes and especially Étienne Quatremère, by indicating that modern Coptic is the language of the ancient subjects of Sesostris, thereby established a very important real fact, confirmed by indisputable proofs after the reading of the inscriptions of the Pharaohs.

The facts are now known. I may therefore confine myself to briefly supporting, by a few reflections, the circumstance which in my opinion inevitably follows from them.

Disputes about priority, even under the influence of national prejudices, would never become so acute if their resolution were based on any precise determinations. In some cases the decisive role is played by the first idea; in other cases the details present the chief difficulty. Sometimes, however, it seems that the principal merit lies not so much in the discovery of the theory as in its proof. One may judge what arbitrariness is possible in the choice of a point of view and, at the same time, what significance it has for the final resolution of the question.

In order to avoid this difficulty, I tried to find an example in which the roles of two persons claiming the invention could be compared with the roles of Champollion and Young, and which at the same time would not cause disagreement. It seemed to me that I found this example in the discovery of interference, without referring, in the question of hieroglyphs, to quotations from the work of de Guignes.

Hook asserted, indeed, even before Thomas Young, that light rays interfere, just as the latter, before Champollion, had assumed that Egyptian hieroglyphs sometimes possess phonetic value. Hook did not give direct proof of his hypothesis; the proof of the phonetic value ascribed by Young to various hieroglyphs could have been based only on a reading that had not and could not have been carried out.

Knowing nothing of the complex nature of white light, Hook had no exact conception of the essence of interference; in just the same way Young was mistaken in supposing that hieroglyphs represented syllables or double syllables.

Young was unanimously recognized as the author of the theory of interference; hence, I believe, it inevitably follows that Champollion must be recognized as the author of the decipherment of hieroglyphs.

I regret that I did not think of this comparison earlier. If Young, during his lifetime, had been faced with the alternative of remaining the creator of the doctrine of interferences, yielding the hieroglyphs to Champollion, or else of preserving the hieroglyphs, leaving Hook …

remarkable optical theory, he would undoubtedly have hastened to acknowledge the rights of our famous compatriot. However, he would have retained what belongs to him indisputably—the right to figure in the history of a memorable discovery, just as Kepler, Borelli, Hooke, and Wren figure in the history of the law of universal gravitation.

Young’s Miscellaneous Works

Lack of space does not allow me even to enumerate the titles of the countless number of works published by Dr. Young. And yet, a public reading of so rich a catalogue would, undoubtedly, have increased the glory of our confrère. Indeed, who would not think that before him was a list of the works of several academies, on hearing, for example, such a series of titles:

On factories producing iron.
On music and painting.
A study of the behavior of spiders and the system of Fabricius.
On the strength of bridge trusses.
On the atmosphere of the moon.
A mathematical theory of epicycloidal curves.
Restoration and translation of various Greek inscriptions.
On means of strengthening the frames of ships of the line.
On the role of the heart and arteries in the phenomenon of circulation.
The theory of tides.
On pulmonary diseases.
On friction in the axles of machines.
On yellow fever.
On how to calculate eclipses.
An experiment in grammar.

Young’s Character.—Medical Practice.—Collaboration in the Nautical Almanac.—Young’s Death

It would seem that such numerous and varied labors could only have been the result of the industrious and secluded life of one of those scholars, now encountered ever more rarely, who from early youth break off ties with their contemporaries in order to shut themselves up forever in their study.

Thomas Young, on the contrary, was what is commonly called a man of the world. He regularly frequented the most brilliant salons of London. The charm of his mind and the elegance of his manners would have been quite sufficient for him to stand out; but one need only imagine these crowded gatherings, where fifty different subjects are touched upon in turn over the course of a few minutes, and it will become clear what value was possessed by a library in human form, in which everyone, on any question, instantly found an exact, clear, substantial answer.

In his pursuits Young devoted great attention to the arts. Many of his works testify to a very early acquired-

deep knowledge of the theory of music. He also developed in himself, to a high degree, the talent of a performer, and I am almost certain that, among all known instruments, including even the Scottish bagpipe, there will be no more than two on which he would not have been able to play.

His interest in painting developed during his stay in Germany. The sumptuous collection of the Dresden gallery wholly absorbed him, since his aspirations were not limited to the inexpensive advantage of being able to assign the name of one artist or another to a given picture without error. The characteristic merits and shortcomings of the greatest masters, the changes of manner often observed in them, the materials they used in their work, the changes taking place in these materials, in particular in paints, under the action of time—all this consistently occupied his mind. In a word, Young studied painting in Saxony in the same way as earlier he had studied languages in his own country and as he devoted himself to the sciences. In his eyes, however, everything was a subject of reflection and investigation. The university companions of the great physicist recall a comic example of this mental bent: they relate that, on entering Young’s room on the day when he took his first minuet lesson in Edinburgh, they found him carefully tracing, with the aid of a ruler and compass, the intersecting paths of the two dancers, with various improvements which he thought it possible to introduce into these figures. From an early age Young had adopted the conviction, common among the Quakers to whom he then belonged, that the innate mental abilities of children differ from one another far less than is usually supposed. “Anyone could do what anyone else has done” became his favorite saying. He himself, moreover, did not shrink from a single test to which they wished to subject his system.

In England a physician who values the confidence of the public must abstain from all scientific-research or literary pursuits if they have no relation to medical practice. Young long made sacrifices to this prejudice. His works appeared under cover of a pseudonym. True, this cover was fairly transparent: two adjacent letters of a well-known Latin motto, taken consecutively, in the proper order, served as the signature of each of his works; but Young named the three Latin words to all his friends, both native and foreign, without at all requiring them to keep them secret from anyone. Who, moreover, could fail to know that the celebrated author of the theory of interference was secretary to the Royal Society of London for foreign correspondence; that he lectured in the halls of the Royal Institution on mathematical physics; that, together with Sir Humphry Davy, he published a scientific journal, and so on and so forth? In addition, it must be observed that anonymity was strictly maintained only in minor works. In important cases, as, for example, with the publication in 1807 of two volumes in quarto, each from 800 to 900 pages in size, in which all branches of natural philosophy were treated so profoundly and so newly, самო-

love of the author triumphed over the interests of the physician, and Young’s name, set in bold type, replaced another two small italic letters, which would have looked rather ridiculous at the head of an enormous work.

For this reason Young, as a practitioner, neither in London nor in Worthing, where he spent the sea-bathing season, ever had a very wide clientele. He was considered too learned! One must even admit that the courses in medicine that he delivered—for example, the course given at St George’s Hospital—were usually poorly attended. Someone said, in explanation of this fact, that his lessons were too densely packed, too substantial, and that they were not accessible to people of average ability.

But would it not be more correct to attribute this failure to the rare frankness with which Young pointed out the insurmountable difficulties that arise every hour in the study of the numerous disorders of our fragile organism?

Could one expect in Paris, and moreover in an age when everyone strives to reach his goal without any significant expenditure of time and effort, that a faculty professor would retain a large audience after beginning his course with the following words, taken down by me verbatim from Dr. Young:

“There is no science whose complexity exceeds that of medicine. It goes beyond the bounds of the human mind. The impulse to press forward at all costs, without attempting to understand what lies before one’s eyes, often leads the physician to the same place as does a passion for gradual generalizations based on observations, with respect to which every analogy would prove risky.”

And if, continuing in the same tone, one adds: “In the lotteries of medicine, the chances of the holder of ten tickets inevitably exceed the chances of those who have only five!”

Even after recognizing themselves as participants in a lottery, will the listeners—if they have not taken flight after the first phrase—wish to expend great efforts in order to obtain the greatest number of tickets, or, to explain the words of our confrère, the greatest amount of knowledge? Despite his knowledge, perhaps even precisely because of its colossal extent, Young was utterly lacking in confidence when he found himself at a patient’s bedside. At that moment his imagination presented to him all those harmful consequences that might accidentally arise from the action of even the medicine most appropriate to the case; and these considerations plunged him into a state of irresolution, quite understandable, but always perceived by the public in the very worst light. The same irresolution is noticeable in all of Young’s medical works. A man so astonishing in the boldness of his scientific judgments limits himself here to simple enumerations of facts. He is scarcely confident in the correctness of his thesis—both when denouncing the famous Dr. Radcliffe, the whole secret of whose brilliant and fortunate practice consisted, by his own admission, in the use of medicines contrary to common sense, and in his dispute with Dr. Brown, who asserted on the basis of

of the hospital’s records, run by distinguished physicians, that febrile illnesses, when left to their natural course, prove in the aggregate no more serious and no more protracted than under the best treatment.

In 1818, having received the title of secretary of the Bureau of Longitudes, Young almost entirely abandoned medical practice and took up the supervision of the famous periodical publication known as the Nautical Almanac. From that time onward, the journal of the Royal Institution began, in every quarter, to publish numerous papers on the most important problems of navigation and astronomy. The volume entitled Illustrations of Laplace’s Celestial Mechanics and the work on tides would, moreover, serve as quite weighty proof that Young did not regard the appointment he had accepted as a sinecure. Yet this post brought him nothing but deep disappointment. From its very first appearance the Nautical Almanac had been a work intended wholly for the service of maritime navigation; someone demanded that, in addition, it be made into a complete astronomical ephemeris. The Bureau of Longitudes, whether rightly or wrongly, not very willingly agreed to the proposed change and was suddenly subjected to the crudest attacks. Newspapers of every hue, Whig or Tory, took part in the battle. The assembly of Davys, Wollastons, Youngs, Herschels, Katers, and Ponds came to be seen as nothing more than a gathering of persons (I quote verbatim) subject to some obscure influence; the Nautical Almanac, formerly so renowned, became an object of shame to the English nation; the slightest misprints, inevitably present in any large collection of numbers, were represented as a possible cause of the destruction of the entire British fleet, from the smallest launch to enormous three-decked ships. It was said that the chief instigator of these wild exaggerations noticed such an abundance of serious errors in the Nautical Almanac only after his attempts to enter the Bureau of Longitudes had ended in failure. I do not know whether this is so. In any case, I do not consider it possible to repeat all the ridiculous comments that arose in connection with it; I must not forget that for several years the member of the Royal Society in question had already been generously sacrificing part of his ample fortune for the development of science. This honorable astronomer, concentrated, like many scholars, on a single subject, was guilty—and I am not inclined to excuse him—of overestimating the importance of his projects; but on his part it was altogether unforgivable to lose sight of the fact that his polemical exaggerations would be taken seriously, that in all countries and in all ages there have been enough people, reckless in the consciousness of their own insignificance, who seize upon every occasion for scandal as booty and, under the guise of striving for the public good, persecute contemporaries whose reputation enjoys respect. In Rome, the carrying of a triumphator was entrusted to a slave. In London, a celebrated scholar is cruelly insulted by a member of the House of Commons. Ora-

THOMAS YOUNG

Tory, famous for his prejudices, but who had previously poured out his venom only upon what was of French origin, chose as his target the best names in England and, before the face of the whole Parliament, with ridiculous solemnity brought against them childish and absurd accusations. The ministers, who spent hours practicing cheap eloquence on the subject of the privileges of a rotten borough, did not utter a single word in defense of genius; and as a result the Board of Longitude was reformed without objection. True, on the very next day the needs of vast maritime navigation raised an insistent voice, and one of the scholars who had just been dismissed, the former secretary of the Board, Dr. Young, was at last called upon to perform his former duties. A futile remedy! How could he be compensated for separation from his enlightened colleagues? And could a man of mind and heart forget that the noble fruits of human reason had just been assessed before the representatives of the country in guineas, shillings, and pence, as though they were pepper, sugar, or cinnamon? From that grievous moment the health of our colleague, already somewhat shaken, began to fail with terrifying rapidity. The experienced physicians who treated him soon lost all hope. Young himself was aware of the nearness of the end and watched its approach with astonishing calm. Until his last hour he worked continuously on the Egyptian dictionary, which was then in press and was published only after his death. When weakness no longer allowed him to rise and take up the pen, he corrected the proof-sheets in pencil. One of his last acts was to prevent the printing of a talented pamphlet, written by a friendly pen and directed against all those who had helped to destroy the Board of Longitude.

Young faded away in the circle of his adoring family on May 10, 1829, having scarcely reached the age of fifty-six.

The autopsy showed that he had suffered from ossification of the aorta.

If the task has not proved beyond my strength, if in particular I have managed to emphasize, as I wished, the importance and novelty of the remarkable law of light interferences, then Young must appear in your eyes as one of the most outstanding scholars of whom England could ever be proud. Anticipating my words in your thoughts, you foresee, in the concluding part of this historical note, an account of the well-deserved honors rendered to the author of so remarkable a discovery. I must, unfortunately, disappoint you. Young’s death did not call forth in his homeland any very notable response. The gates of Westminster Abbey, once so accessible to titled mediocrity, remained closed to a man of genius who was not a baronet. The remains of Thomas Young were laid in the village of Farnborough, in the modest place of repose belonging to his wife’s family. The indifference of the English nation toward works that occupy no last place in the treasury of its glory is a very unusual fact, the causes of which must arouse curiosity. I regret

I would sin against sincerity; I would be a panegyrist, not a historian, if I did not admit that Young, in general, did not spare his readers; that a large part of his scientific works is guilty of a certain obscurity. And yet the oblivion to which they were for a long time consigned cannot be explained by this reason alone.

The exact sciences possess, over the creations of art or imagination, one generally recognized advantage. The truths that constitute them live for centuries, suffering no damage either from the caprices of fashion or from the corruption of taste. But at the same time, are there many judges upon whom one could rely when rising beyond commonplaces? When Richelieu set upon the great Corneille a whole pack of people who could not tolerate another’s superiority, the Parisians hissed the zealous supporters of the cardinal-despot and greeted the poet with applause. Such a reward was denied to the geometer, the astronomer, the physicist, who cultivate science in its highest manifestations. The number of their informed judges in all Europe never reaches even eight or ten. Take into account the unjust, the indifferent, or the envious—for I suppose that there have been such people as well—and the public, forced to take things on trust, will not know that d’Alembert connected the great phenomenon of the precession of the equinoxes with the principle of universal gravitation; that Lagrange succeeded in determining the physical cause of the oscillations of the moon; that, after Laplace’s investigations, the acceleration of the motion of this luminary is associated with a particular change in the form of the earth’s orbit, and so on. Scientific journals, when conducted by people manifestly worthy of trust in certain questions, thereby acquire an influence that is often pernicious. It seems to me that such, at times, was the role of the journal Edinburgh Review.

Among the contributors to this famous journal there figured at first, in the foremost ranks, a young writer who regarded Newton’s discoveries with a feeling of profound admiration. This feeling, so natural, so just, unfortunately prevented him from appreciating all the wit, incontestability, and significance of the doctrine of interferences. Perhaps the author of this theory did not always take care to clothe his conclusions and criticisms in polite forms, which did no harm to the true right and, moreover, were an incontestable duty, since the matter concerned the immortal author of Natural Philosophy. For this a hundredfold was repaid to him; the Edinburgh Review fell upon the erudite scholar, the writer, the geometer, the experimentalist, with a heat and harshness of expression almost inadmissible in scientific disputes. The public usually feels distrust when it is addressed in so unrestrained a language, but this time it immediately agreed with the journalist’s opinion, and not at all lightly. Indeed, this journalist did not belong to the category of those unborn Aristarchuses whose appointment is justified by no scientific merit. Several excellent works, accepted by the Royal Society, testified to his mathematical gifts—

knowledge and won him an honored place among physicists engaged in experimental optics; in London he was already at that time considered one of the most brilliant lawyers; the Whigs of the House of Commons esteemed him as a rare orator, who in parliamentary struggles not infrequently appeared in the role of Canning’s fortunate opponent. He was, finally, the future chairman of the House of Lords and the present Lord Chancellor1.

What can be set against unjust criticism when it proceeds from such sources? I know how much firmness some minds draw from the consciousness of their rightness, from the confidence that sooner or later truth will triumph; but I also know that those act wisely who do not count too much on such exceptions.

Recall, for example, Galileo, saying under his breath after his recantation, “E pur si muove!”; but do not seek in these immortal words any thought of the future, since they expressed only the bitter grief experienced by the great old man. Young, too, revealed on several pages of the article he published as a reply to the Edinburgh Review a feeling of deep despondency. The vividness and heat of his expressions poorly concealed his oppressed feelings. And yet—I hasten to say it—justice, full justice, was finally rendered to the great physicist! For some time now the whole world has begun to see in him one of the principal glories of our age. France (as Young himself stated with satisfaction) gave the first signal for this belated recognition. I shall add that even in much more remote times, when the doctrine of interference still had no proselytes either in England or on the Continent, Young found in his own family a person who understood him and whose approval must have rewarded him for the public’s indifference. I hope that the remarkable person whom I shall name here, in order to direct toward her the gratitude of all European physicists, will generously forgive me if I supplement my modest hint.

In 1816 I traveled through England in the company of my learned friend, Mr. Gay-Lussac. At that time Fresnel had only just begun his scientific career by writing a work on diffraction. This work, which contained, in our opinion, solid data incompatible with the Newtonian theory of light, naturally became the chief subject of our conversations with Dr. Young. We were surprised at the numerous reservations that he introduced into our laudatory judgments, until he told us that the experiment which had seized

our attention, had already, in 1807, been set forth in his Natural Philosophy. This assertion seemed to us unfounded. It made our dispute long and detailed. Mrs. Young was present, apparently taking no part in it; but since we knew that the entirely childish fear of the ridiculous nickname “blue stocking” compels English ladies to behave with great restraint in the presence of foreigners, the awareness of our own tactlessness struck us only at the moment when Mrs. Young suddenly went out. We had already begun to pour out apologies to her husband, when she returned again with an enormous quarto volume in her hands. It was the first volume of the Natural Philosophy. She laid it on the table, opened it, without saying a word, to page 787, and pointed with her finger to the drawing on which the curvilinear path of the diffraction bands, which had been the subject of the dispute, was theoretically demonstrated.

I hope I shall be forgiven these details. Has not an abundance of examples accustomed the public to regard oblivion, injustice, persecution, and poverty as the natural reward of those who diligently devote their sleepless nights to the advancement of human knowledge? Let us not, then, pass over the exceptions when they occur. If we wish youth to devote themselves with enthusiasm to intellectual pursuits, let us convince them that to the glory associated with great discoveries there is sometimes joined a little peace and happiness. If possible, let us even tear from the history of the sciences all the pages that darken its brilliance. Let us try to assure ourselves that even in the dungeons of the inquisitors Galileo heard a friendly voice pronouncing those ardent words with which posterity honored his memory; that beyond the deaf walls of the Bastille, the news reached Fréret of the honorable place he was destined to occupy among the scholars who are the pride of France; that before dying in a hospital, Borelli sometimes found in the city of Rome shelter from bad weather and a little straw for a pillow; that, finally, Kepler, the great Kepler, never knew the torments of hunger!

it would have proved false. You might, I shall perhaps be told, when submitting your article for publication, have struck out entirely everything that had to do with so vexatious a polemic. I could indeed have done so, and the thought even came into my head, but I soon gave it up. I know too well the exalted feelings of my celebrated friend to fear that he would be offended by the frankness of my question, in which, I am deeply convinced, all the power of his mind did not save him from error. I believe that the tribute of respect which I pay to the noble character of Lord Brougham, by publishing without alteration this passage from Young’s biography, is so eloquent that any additions would be superfluous.

1. Since the newspapers have done me the honor of noting in several cases the numerous marks of favor and friendship shown to me by Lord Brougham in 1834 in Scotland and in Paris, I believe that a brief explanation is necessary here. Dr. Young’s eulogy was read at a public meeting of the Academy of Sciences on November 26, 1832; at that time I was not yet in any personal relations with the author of the Edinburgh Review; consequently, any accusation of ingratitude ↩↩↩