astronomer, Bradley, who noticed that the fixed stars did not really appear to be fixed, but describe in the heavens every year a little orbit resembling the earth's orbit. The result perplexed him, but Bradley had a mind open to suggestion, and capable of seeing, in the smallest fact, a picture of the largest. He was one day upon the Thames in a boat, and noticed that, as long as his course remained unchanged, the vane upon his mast-head showed the wind to be blowing constantly in the same direction, but that the wind appeared to vary with every change in the di-ery; but, like all barriers that rest upon rection of his boat. "Here," as Whewell says, "was the image of his case. The boat was the earth, moving in its orbit, and the vind was the light of a star." satisfy the scientific mind. We find, accordingly, in this career of optics, the greatest minds constantly yearning to pass from the phenomena to their causes-to explore them to their hidden roots. They thus entered the region of theory, and here Newton, though drawn from time to time towards the truth, was drawn still more strongly towards the error, and made it his substantial choice. His experiments are imperishable, but his theory has passed away. For a century it stood like a dam across the course of discovauthority, and not upon truth, the pressure from behind increased, and eventually swept the barrier away. This, as you know, was done mainly through the labors of Thomas Young, and his illustrious French fellowworker Fresnel. We may ask in passing, what, without the faculty which formed the "image," would Bradley's wind and vane have been to him? In 1808, Malus, looking through Iceland A wind and vane, and nothing more. You spar at the sun reflected from the window of will immediately understand the meaning of the Luxembourg Palace in Paris, discovered Bradley's discovery. Imagine yourself in a the polarization of light by reflection. In motionless railway-train with a shower of rain 1811 Arago discovered the splendid chro descending vertically downward. The mo-matic phenomena which we have had illusment the train begins to move, the rain-drops begin to slant, and the quicker the train the greater is the obliquity. In a precisely similar manner the rays from a star vertically overhead are caused to slant by the motion of the earth through space. Knowing the speed of the train, and the obliquity of the falling rain, the velocity of the drops may be calculated; and knowing the speed of the earth in her orbit, and the obliquity of the rays due to this cause, we can calculate just as easily the velocity of light. Bradley did this, and the "aberration of light," as his discovery is called, enabled him to assign to it a velocity almost identical with that deduced by Roemer from a totally different method of observation. Subsequently Fizeau, employing not planetary or stellar distances, but simply the breadth of the city of Paris, determined the veloci y of light: while after him Foucault-a man of the rarest mechanical genius-solved the problem without quitting his private room. Up to his demonstration of the composition of white light, Newton had been everywhere triumphant-triumphant in the heavens, triumphant on the earth, and his subsequent experimental work is for the most part of immortal value. But infallibility is not the gift of man, and, soon after his discovery of the nature of white light, Newton proved himself human. He supposed that refraction and dispersion went hand in hand, and that you could not abolish the one without at the same time abolishing the other. Here Dolland corrected him. But Newton committed a graver error than this. Science, as I sought to make clear to you in our second lecture, is only in part a thing of the senses. The roots of phenomena are embedded in a region beyond the reach of the sen-es, and less than the root of the matter will never trated by plates of gypsum in polarized light ; he also discovered the rotation of the plane of polarization by quartz-crystals. In 1813 Seebeck discovered the polarization of light by tourmaline. That same year Brewster discovered those magnificent bands of color that surround the axes of biaxal crystals. In 1814 Wollaston discovered the rings of Iceland spar. All these effects, which, without a theoretic clue, would leave the human mind in a hopeless jungle of phenomena without harmony or relation, were organically connected by the theory of undulation. The theory was applied and verified in all directions, Airy being especially conspicuous for the severity and conclusiveness of his proofs. The most remarkable verification fell to the lot of the late Sir William Hamilton, of Dublin, a profound mathematician, who, taking up the theory where Fresnel had left it, arrived at the conclusion that, at four special points at the surface of the ether-wave in double-refracting crystals, the ray was divided not into two parts, but into an infinite number of parts; forming at these points a continuous conical envelope instead of two images. No human eye had ever seen this envelope when Sir William Hamilton inferred its existence. Turning to his friend Dr. Lloyd, he asked him to test experimentally the truth of his theoretic conclusion. Lloyd, taking a crystal of arragonite, and following with the most scrupulous exactness the indications of theory, cutting the crystal where theory said it ought to be cut, observing it where theory said it ought to be observed, found the luminous envelope which had previously been a mere idea in the mind of the mathematician. Nevertheless this great theory of undula. tion, like many another truth, which in the long-run has proved a blessing to humanity, had to establish, by hot conflict, its right to existence. Great names were arrayed against it. It had been enunciated by Hooke, it had been applied by Huyghens, it had been defended by Euler. But they made no impression. And, indeed, the theory in their hands was more an analogy than a demonstration. It first took the form of a demonstrated verity in the hand of Thomas Young. He brought the waves of light to bear upon each other, causing them to support each other, and to extinguish each other at will. From their mutual actions he determined their lengths, and applied his determinations in all directions. He showed t at the standing difficulty of polarization might be embraced by the theory. After him came Fresnel, whose transcendent mathematical abilities enat led him to give the theory a generality unattained by Young. He grasped the theory in its entirety, followed the ether into its eddies and estuaries in the hearts of crystals of the most complicated structure, and into bodies subjected to strain and pressure. He showed that the facts discovered by Malus, Arago, Brewster, and Biot, were so many ganglia, so to speak, of his theoretic organism, deriv ing from it sustenance and explanation. With a mind too strong for the body with which it was associated, that body became a wreck long before it had become old, and Fresnel died, leaving, however, behind him a name immortal in the annals of science. retic truth, or the confirmation of a calcula tion by experiment." This, ladies and gentlemen, is the core of the whole matter as regards science. It must be cultivated for its own sake, for the pure love of truth, rather than for the applause or profit that it brings. And now my occupation in America is wellnigh gene. Still I will bespeak your tolerance for a few concluding remarks in reference to the men who have bequeathed to us the vast body of knowledge of which I have sought to give you some faint idea in these lectures. What was the motive that spurred them on? what the prize of their high calling for which they struggled so assiduously? What urged them to those battles and those victories over reticent Nature which have become the heritage of the human race? It is never to be forgotten that not one of those great investigators, from Aristotle down to Stokes and Kirchhoff, had any practical end in view, according to the ordinary definition of the word "practical." They did not propose to themselves money as an end, and knowledge as a means of obtaining it. For the most part, they nobly reversed this process, made knowledge their end, and such money as they possessed the means of obtaining it. 44 We may see to-day the issues of their work in a thousand practical forms, and this may be thought sufficient to justify it, if not ennoble their efforts. But they did not work One word more I should like to say regard- for such issues; their reward was of a totally ing Fresnel. There are things, ladies and different kind. We love clothes, we love gentlemen, better even than science. There luxuries, we love fine equipages, we love are matters of the character as well as matters money, and any man who can point to these of the intellect, and it is always a pleasure to as the result of tis efforts in lite justifies those who wish to think well or human na- these efforts before all the world. In Ameriture, when high intellect and upright charac-ca and England more especially he is a ter are combined. They were, I believe, combined in this young Frenchman. In those hot conflicts of the undulatory theory, he stood forth as a man of integrity, claiming no more than his right, and ready to concede their rights to others. He at once recognized and acknowledged the merits of Thomas Young. Indeed, it was he, and his fellowcountryman Arago, who first startled England into the consciousness of the injustice done to Young in the Edinburgh Review. I should like to read you a brief extract from a letter written by Fresnel to Young in 1824, as it throws a pleasant light upon the character of the Frenc philosopher. "For a long time,' says Fresnel, "that sensibility, or that vanity, which people call love of glory, has been much blunted in me. I labor much less to catch the suffrages of the public than Could we have seen these men at work to obtain that inward approval which has without any knowledge of the consequences always been the sweetest reward of my efforts. of their work, what should we have thought Without doubt, in moments of disgust and of them? To many of their contemporaries discouragement, I have often needed the spur it would have appeared simply ridiculous to of vanity to excite me to pursue my researches. see men, whose names are now stars in the But all the compliments I have received from firmanent of science, straining their attenArago, De la Place, and Biot, never gave me tion to observe an effect of experiment also much pleasure as the discovery of a theo-most too minute for detection. To the un practical" man. But I would appeal confidently to this assembly whether such things exhaust the demands of human nature? Th very presence here for six inclement nights of this audience, embodying so much of the mental force and refinement of this great city, is an answer to my question I need not tell such an assembly that there are joys of the intellect as well as joys of the body, or that these pleasures of the spirit constituted the reward of our great investigators. Led on by the whisperings of natural truth, through pain and self-denial, they often pursued their work. With the ruling passion strong in death, some of them, when no longer able to hold a pen, dictated to their friends the result of their labors, and then rested from them forever. Initiated, they might well appear as big children playing with not very amusing toys. It is so to this hour. Could you watch the true investigator-your Henry or your Draper, for example-in his laboratory, unless animated by his spirit, you could hardly understand what keeps him there. Many of the objects which rivet his attention might appear to you utterly trivial; and, if you were o step forward and ask him what is the use of his work, the chances are that you would confound him. He might not be able to express the use of it in intelligible terms. He might not be able to assure you that it will put a dollar into the pocket of any human being living or to come. That scientific discovery may put not only dollars into the poekets of individuals, but millions into the exchequers of nations, the history of science amply proves; but the hope of its doing so never was and never can be the motive power of the investigator. I know that I run some risk in speaking thus before practical men. I know what De Tocqueville says of you. "The man of the North," he says, "has not only experience, but knowledge. He, however, does not care for science as a pleasure, and only embraces with avidity when it leads to useful applications." But what, I would ask, are the hopes of useful applications which have drawn you so many times to this place in spite of snow-drifts and biting cold? What, I may ask, is the origin of that kindness which drew me from my work in London to address you here, and which, if I permitted it, would send me home a millionaire? Not because I had taught you to make a single cent by science, am I among you to-night, but because I tried to the best of my ability to present science to the world as an intellectual good. Surely no two terms were ever so distorted and misapplied with refe.ence to man in his higher relations as these terms useful and practical. As if there were no nakedness of the mind to be clothed as well as nakedness of the body-no hunger and thirst of the intellect to satisfy. Let us expand the definitions of these terms until they embrace all the needs of man, his highest intellectual needs inclusive. It is specially on this ground of its administering to the higher needs of intellect, it is mainly because I believe it to be wholesome as a source of knowledge, and as a means of discipline, that I urge the claims of science this evening upon your attention. But, with reference to material needs and joys, surely pure science has also a word to say. People sometimes speak as if steam had not been studied before James Watt, or electricity before Wheatstone and Morse; whereas, in point of fact, Watt and Wheatstone and Morse, with all their practicality, were the mere outcome of antecedent forces, which acted without reference to practical ends. This also, I think, me:its a moment's atten tion. You are delighted, and with good reason, with your electric telegraphs, proud of your steam-engines and your factories, and charmed with the productions of photography. You see daily, with just elation, the creation of new forms of industrynew powers of adding to the wealth and comfort of society. Industrial England is heaving with forces tending to this end, and the pulse of industry beats still stronger in the United States. And yet, when analyzed, what are industrial America and industrial England? If you can tolerate freedom of speech on my part, I will answer this question by an illustration. Strip a strong arm, and regard the knotted muscles when the hand is clenched and the arm bent. Is this exhibition of energy the work of the muscle alone? By no means. The muscle is the channel of an influence, without which it would be as powerless as a lump of plastic dough. It is the delicate unseen nerve that unlocks the power of the muscle. And, without those filaments of genius which have been shot like nerves through the body of society by the original discoverer, industrial America and industrial England would, I fear, be very much in the condition of that plastic dough. At the present time there is a cry in England for technical education, and it is the expression of a true national want; but there is no cry for original investigation. Still without this, as surely as the stream dwindles when the spring dries, so surely will "technical education" lose all force of growth, all power of reproduction. Our great investigators have given us sufficient work for a time, but, if their spirit die out, we shali find ourselves eventually in the condition of those Chinese mentioned by De Tocqueville, who, having forgotten the scientific origin of what they did, were at length compelled to copy without variation the inventions of an ancestry who, wiser than themselves, had drawn their inspiration direct from Nature. To keep society as regards science in healthy play, three classes of workers are necessary: Firstly, the investigator of natural truth, whose vocation it is to pursue that truth, and extend the field of discovery for the truth's own sake, and without reference to practical ends. Secondly, the teacher of natural truth, whose vocation it is to give public diffusion to the knowledge already won by the discoverer. Thirdly, the applier of natural truth, whose vocation it is to make scientific knowledge available for the needs, comforts, and luxuries of life. These three classes ought to coexist and interact. Now, the popular notion of science, both in this country and in England, often relates, not to science strictly so called, but to the applications of science. Such applications, espe cially on this continent, are so astoundingthey spread themselves so largely and umbrageously before the public eye-as to shut out from view those workers who are engaged in the quieter and profounder business of original investigation. Take the electric telegraph as an example, which has been repeatedly forced upon my attention of late. I am not here to attenuate in the slightest degree the services of those who, in England and America, have given the telegraph a form so wonderfully fitted for public use. They earned a great reward, and assuredly they have received it. But I should be untrue to you and to myself if I failed to tell you that, however high in particular respects their claims and qualities may be, practical men did not discover the electric telegraph. The discovery of the electric telegraph implies the discovery of electricity itself, and the development of its laws and phenomena. Such discoveries are not made by practical men, and they never will be made by them, because their minds are beset with ideas which, though of the highest value from one point of view, are not those which stimulate the original discoverer. Dif our peril. For I say again, that, behind all your practical applications, there is a region of intellectual action to which practical men have rarely contributed, but from which they draw all their supplies. Cut them off from this region, and they become eventually helpless. In no case is the adage truer, "Other men labored, but ye are entered in o their labors," than in the case of the discoverer and the applier of natural truth. But now a word on the other side. While I say that practical men are not the men to make the necessary antecedent discoveries, the cases are rare in which the discoverer knows how to turn his labors to practical account. ferent qualities of mind and different habits of thought are needed in the two cases; and, while I wish to give emphatic utterance to the claims of those whose claims, owing to the simple fact of their intellectual elevation, are often misunderstood, I am not here to exalt the one class of workers at the expense of the other. They are the necessary supplements of each other; but remember that one class is sure to be taken care of. All the material rewards of society are already within their reac.; but it is at our peril that we neglect to provide opportunity for those studies and pursuits which have no such rewards, and from which, therefore, the rising genius of the country is incessantly tempted away. The ancients discovered the electricity of amber; and Gilbert, in the year 1600, extended the force to other bodies. Then followed other inquirers, your own Franklin among the number. But this form of electricity, though tried, did not come into use for telegraphic purposes. Then appeared the great Italian, Volto, who discovered the Pasteur, one of the most eminent members source of electricity, which bears his name, of the Institute of France, in accounting for and applied the most profound insight and the disastrous overthrow of his country and the most delicate experimental skill to its de- the predominance of Germany in the late velopment. Then arose the man who added war, expresses himself thus: "Few persons to the powers of his intellect all the graces of comprehend the real origin of the marvels of the human heart, Michael Faraday, the dis-industry and the wealth of nations. I need coverer of the great domain of magneto- no further proof of this than the employment, electricity. Ersted discovered the deflection more and more frequent in official language, of the magnetic needle, and Arago and Stur- and in writing of all sorts, of the erroneous geon the magnetization of iron by the elec- expression applied science. The abandontric current. The voltaic circuit finally found ment of scientific careers by men capable of its theoretic Newton in Ohm, while Henry, pursuing them with distinction was recently of Princeton, who had the sagacity to recog- complained of in the presence of a minister nize the merits of Ohm while they were still of the greatest talent. This statesman endecried in his own country, was at this time deavored to show that we ought not to be in the van of experimental inquiry. surprised at this result, because in our day the reign of theoretic science yielded place to that of applied science. Nothing could be more erroneous than this opinion, nothing, I venture to say, more dangerous, even to practical life, than the consequences which might flow from these words. They have rested on my mind as a proof of the imperious necessity of reform in our superior edu cation. There exists no category of the sciences to which the name of applied science could be given. We have science, and the applications of science which are united together as the tree and its fruit." In the works of these men you have all the materials employed at this hour in all the forms of the electric telegraph. Nay, more; Gauss, the celebrated astronomer, and Weber, the celebrated natural philosopher, both professors in the University of Göttingen, wishing to establish a rapid mode of communication between the observatory and the physical cabinet of the university, did this by means of an electric telegraph. The force, in short, had been discovered, its laws investigated and made sure, the most complete mastery of its phenomena had been attained, nay, its applicability to telegraphic purposes demonstrated, by men whose sole reward for their labors was the noble joy of discovery, and before your practical men appeared at all upon the scene. Are we to ignore all this? We do so at And Cuvier, the great comparative anato mist, writes thus upon the same theme: "These grand practical innovations are the mere applications of truths of a higher order, not sought with a practical intent, but which were pursued for their own sake, and solely through an ardor for knowledge. Those who applied them could not have discovered them; those who discovered them had no inclination to pursue them to a practica. end. Engaged in the high regions whither their thoughts had carried them, they hardly perceived these practical issues, though born of their own deeds. These ris.ng workshops, these peopled colonies, those ships which furrow the seas-this abundance, this luxury, this tumult-all this comes from discoverers in science, and it all remains strange to them. At the point where science merges into practice they abandon it; it concerns them no more." words repeated, and, if necessary, laid to When the Pilgrim Fathers landed at Ply mouth Rock, and when Penn made his treaty with the Indians, the new-comers had to De Tocqueville evidently doubts the cabui'd their houses, to chasten the earth into pacity of a democracy to foster genius as it cultivation, and to take care of their souls. was fostered in the ancient aristocracies, In such a community, science, in its more "The future," he says, "wili prove whether abstract forms, was not to be thought cf. the passion for profound knowledge, so rare And, at the present hour, when your hardy and so fruitful, can be born and developed Western pioneers stand face to face with so readily in democractic societies as in arisstubborn Nature, piercing the mountains tocracies. As for me," he continues, "I and subduing the forest and the prairie, the can hardly believe it." He speaks of the unpursuit of science, for its own sake, is not to quiet feverishness of democratic commube expected. The first need of man is food nities, not in times of great excitement, for and shelter; but a vast portion of this con- such times may give an extraordinary impetinent is already raised far beyond this need. tus to ideas, but in times of peace. There The gentlemen of New York, Brooklyn, Bos- is then, he says, "a small and uncomfortable ton, Philadelphia, Baltimore, and Washing- agaitation, a sort of incessant attrition of ton, have already built their houses, and very man against man, which troubles and disbeautiful they are; they have also secured tracts the mind without imparting to it either their dinners, to the excellence of which I animation or elevation." It rests with you can also bear testimony. They have, in to prove whether these things are nece sarily fact, reached that precise condition of well-so-whether the highest scientific genius canbeirg and independence when a culture, as igh as humanity has yet reached, may be justly demanded at their hands. They have reached that maturity, as possessors of wealth and leisure, when the investigator of natural truth, for the truth's own sake, ought to find among them promoters and protectors. not find in the midst of you a tranquil home. Among the many grave problems before them they have this to solve, whether a re-scientific results are not achieved in Ameripublic is able to foster the highest forms of ca, it is not to the small agitations of society, genius. You are familiar with the writings that I should be disposed to ascribe the deof De Tocqueville, and must be aware of the fect, but to the fact that the men among you intense sympathy which he felt for your insti- who possess the endo vments necessary for tutions; and this sympathy is all the more scientific inquiry are laden with duties of advaluable, from the philosophic candor with ministration or tuition so heavy as to be which he points out, not only your merits, utterly incompatible with the continuous and but your defects and dangers. Now, if I tranquil meditation which original investicome here to speak of science in America in gation demands. It may well be aske a critical and captious spirit, an invisible whether Henry would have been transformed radiation from my words and manner will into an administrator, or whether Draper enable you to find me out, and will guide would have forsaken science to write history, your treatment of me to-night. But, if I, in if the original investigator had been honored no unfriendly spirit-in a spirit, indeed, th. as he ought to be in this land? I hardly reverse of unfriendly-venture to repeat be- think they would. Still I do not think this fore you what this great historian and analyst of democratic institutions said of America, I am persuaded that you will hear me out. He wrote some three-and-twenty years ago, and perhaps would not write the same 10-day; but it will du nobody any harm to have his *Il faut reconnaître, que parmis les peuples civilisés de nos jours, il en est peu. chez qui les hautes sciences aient fait moins de progrès qu'aux Etatsde poètes illustres, et d: cé obres écriva ns. (Us L Unis, ou qui aient fourni noins de grands artistes, Démocratie en Amérique, etc., tume in., p. 36.) |