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diff --git a/37427-8.txt b/37427-8.txt new file mode 100644 index 0000000..fa89ea2 --- /dev/null +++ b/37427-8.txt @@ -0,0 +1,7166 @@ +The Project Gutenberg EBook of Scientific Culture, and Other Essays, by +Josiah Parsons Cooke + +This eBook is for the use of anyone anywhere at no cost and with +almost no restrictions whatsoever. You may copy it, give it away or +re-use it under the terms of the Project Gutenberg License included +with this eBook or online at www.gutenberg.org + + +Title: Scientific Culture, and Other Essays + Second Edition; with Additions + +Author: Josiah Parsons Cooke + +Release Date: September 15, 2011 [EBook #37427] + +Language: English + +Character set encoding: ISO-8859-1 + +*** START OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC CULTURE, AND *** + + + + +Produced by Sharon Joiner, Bryan Ness and the Online +Distributed Proofreading Team at http://www.pgdp.net (This +file was produced from images generously made available +by The Internet Archive/Canadian Libraries) + + + + + + + + + + SCIENTIFIC CULTURE, + _AND OTHER ESSAYS_. + + BY + JOSIAH PARSONS COOKE, LL. D., + PROFESSOR OF CHEMISTRY AND MINERALOGY, IN HARVARD COLLEGE. + + _SECOND EDITION; WITH ADDITIONS._ + + NEW YORK: + D. APPLETON AND COMPANY, + 1, 3, AND 5 BOND STREET. + 1885. + + + + COPYRIGHT, 1881, 1885, + BY JOSIAH PARSONS COOKE. + + + + TO + MY ASSOCIATES + IN + THE CHEMICAL LABORATORY + OF + HARVARD COLLEGE + THIS VOLUME + IS + AFFECTIONATELY DEDICATED. + + + + +PREFACE. + + +The essays collected in this volume, although written for special +occasions without reference to each other, have all a bearing on the +subject selected as the title of the volume, and are an outcome of a +somewhat large experience in teaching physical science to college +students. Thirty years ago, when the writer began his work at Cambridge, +instruction in the experimental sciences was given in our American +colleges solely by means of lectures and recitations. Chemistry and +Physics were allowed a limited space in the college curriculum as +branches of useful knowledge, but were regarded as wholly subordinate to +the classics and mathematics as a means of education; and as physical +science was then taught, there can be no question that the accepted +opinion was correct. Experimental science can never be made of value as +a means of education unless taught by its own methods, with the one +great aim in view to train the faculties of the mind so as to enable the +educated man to read the Book of Nature for himself. + +Since the period just referred to, the example early set at Cambridge of +making the student's own observations in the laboratory or cabinet the +basis of all teaching, either in experimental or natural history +science, has been generally followed. But in most centers of education +the old traditions so far survive that the great end of scientific +culture is lost in attempting to conform even laboratory instruction to +the old academic methods of recitations and examinations. These, as +usually conducted, are simply hindrances in a course of scientific +training, because they are no tests of the only ability or acquirement +which science values, and therefore set before the student a false aim. +To point out this error, and to claim for science teaching its +appropriate methods, was one object of the writer in these essays. + +It is, however, too often the case that, in following out our theories +of education, we avoid Scylla only to encounter Charybdis, and so, in +specializing our courses of laboratory instruction, there is great +danger of falling into the mechanical routine of a technical art, and +losing sight of those grand ideas and generalizations which give breadth +and dignity to scientific knowledge. That these great truths are as +important an element of scientific culture as experimental skill, the +author has also endeavored to illustrate, and he has added brief notices +of the lives of two noble men of science which may add force to the +illustrations. + + + + +CONTENTS. + + + PAGE + I.--SCIENTIFIC CULTURE 5 + II.--THE NOBILITY OF KNOWLEDGE 45 + III.--THE ELEMENTARY TEACHING OF PHYSICAL SCIENCE 71 + IV.--THE RADIOMETER 86 + V.--MEMOIR OF THOMAS GRAHAM 127 + VI.--MEMOIR OF WILLIAM HALLOWES MILLER 145 + VII.--WILLIAM BARTON ROGERS 160 + VIII.--JEAN-BAPTISTE-ANDRÉ DUMAS 181 + IX.--THE GREEK QUESTION 203 + X.--FURTHER REMARKS ON THE GREEK QUESTION 214 + XI.--SCIENTIFIC CULTURE; ITS SPIRIT, ITS AIM, AND ITS METHODS 227 + XII.--"NOBLESSE OBLIGE" 267 + XIII.--THE SPIRITUAL LIFE 289 + + + + +ESSAYS. + + + + +I. + +SCIENTIFIC CULTURE. + + _An Address delivered July 7, 1875, at the Opening of the Summer + Courses of Instruction in Chemistry, at Harvard University._ + + +You have come together this morning to begin various elementary courses +of instruction in chemistry and mineralogy. As I have been informed, +most of you are teachers by profession, and your chief object is to +become acquainted with the experimental methods of teaching physical +science, and to gain the advantages in your study which the large +apparatus of this university is capable of affording. + +In all this I hope you will not be disappointed. You, as teachers, know +perfectly well that success must depend, first of all, on your own +efforts; but, since the methods of studying Nature are so different from +those with which you are familiar in literary studies, I feel that the +best service I can render, in this introductory address, is to state, +as clearly as I can, the great objects which should be kept in view in +the courses on which you are now entering. + +By your very attendance on these courses you have given the strongest +evidence of your appreciation of the value of chemical studies as a part +of the system of education, and let me say, in the first place, that you +have not overvalued their importance. The elementary principles and more +conspicuous facts of chemistry are so intimately associated with the +experience of every-day life, and find such important applications in +the useful arts, that no man at the present day can be regarded as +educated who is ignorant of them. Not to know why the fire burns, or how +the sulphur trade affects the industries of the world, will be regarded, +by the generation of men among whom your pupils will have to win their +places in society, as a greater mark of ignorance than a false quantity +in Latin prosody or a solecism in grammar. + +Moreover, I need not tell you that physical science has become a great +power in the world. Indeed, after religion, it is the greatest power of +our modern civilization. Consider how much it has accomplished during +the last century toward increasing the comforts and enlarging the +intellectual vision of mankind. The railroad, the steamship, the +electric telegraph, photography, gaslights, petroleum oils, coal-tar +colors, chlorine bleaching, anćsthesia, are a few of its recent +material gifts to the world; and not only has it made one pair of hands +to do the work of twenty, but it has so improved and facilitated the old +industries that what were luxuries to the fathers of our republic have +become necessities to our generation. + +And when, passing from these material fruits, you consider the purely +intellectual triumphs of physical science, such as those which have been +gained with the telescope, the microscope, and the spectroscope, you can +not wonder at the esteem in which these branches of study are held in +this practical age of the world. + +Now, these immense results have been gained by the application to the +study of Nature of a method which was so admirably described by Lord +Bacon in his "Novum Organon," and which is now generally called the +experimental method. What we observe in Nature is an orderly succession +of phenomena. The ancients speculated about these phenomena as well as +ourselves, but they contented themselves with speculations, animating +Nature with the products of their wild fancies. Their great master, +Aristotle, has never been excelled in the art of dialectics; but his +method of logic applied to the external world was of very necessity an +utter failure. It is frequently said, in defense of the exclusive study +of the records of ancient learning, that they are the products of +thinking, loving, and hating men, like ourselves, and it is claimed that +the study of science can never rise to the same nobility because it +deals only with lifeless matter. But this is a mere play on words, a +repetition of the error of the old schoolmen. + +Physical science is noble because it does deal with thought, and with +the very noblest of all thought. Nature at once manifests and conceals +an Infinite Presence: her methods and orderly successions are the +manifestations of Omnipotent Will; her contrivances and laws the +embodiment of Omniscient Thought. The disciples of Aristotle so signally +failed simply because they could see in Nature only a reflection of +their idle fancies. The followers of Bacon have so gloriously succeeded +because they approached Nature as humble students, and, having first +learned how to question her, have been content to be taught and not +sought to teach. The ancient logic never relieved a moment of pain, or +lifted an ounce of the burden of human misery. The modern logic has made +a very large share of material comfort the common heritage of all +civilized men. + +In what, then, does this Baconian system consist? Simply in these +elements: 1. Careful observation of the conditions under which a given +phenomenon occurs; 2. The varying of these conditions by experiments, +and observing the effects produced by the variation. We thus find that +some of the conditions are merely accidental circumstances, having no +necessary connection with the phenomenon, while others are its +invariable antecedent. Having now discovered the true relations of the +phenomenon we are studying, a happy guess, suggested probably by +analogy, furnishes us with a clew to the real causes on which it +depends. We next test our guess by further experiments. If our +hypothesis is true, this or that must follow; and, if in all points the +theory holds, we have discovered the law of which we are in search. If, +however, these necessary inferences are not realized, then we must +abandon our hypothesis, make another guess, and test that in its turn. +Let me illustrate by two well-known examples: + +The, of old, universally accepted principle that all living organisms +are propagated by seeds or germs (_omnia ex ovo_) has been seriously +questioned by a modern school of naturalists. Various observers have +maintained that there were conditions under which the lower forms of +organic life were developed independently of all such accessories, but +other, and equally competent, naturalists, who have attempted to +investigate the subject, have obtained conflicting results. + +Thus it was observed that certain low forms of life were quite +constantly developed in beef juice that had been carefully prepared and +hermetically sealed in glass flasks, even after these flasks had been +exposed for a long time to the temperature of boiling water. "Here," +proclaims the new school, "is unmistakable evidence of spontaneous +generation; for, if past experience is any guide, all germs must have +been killed by the boiling water." "No," answer the more cautious +naturalists, "you have not yet proved your point. You have no right to +assume that all germs are killed at this temperature." + +The experiments, therefore, were repeated under various conditions and +at different temperatures, but with unsatisfactory results, until +Pasteur, a distinguished French physicist, devised a very simple mode of +testing the question. He reasoned thus: "If, as is generally believed, +the presence of invisible spores in the air is an essential condition of +the development of these lower growths, then their production must bear +some proportion to the abundance of these spores. Near the habitations +of animals and plants, where the spores are known to be in abundance, +the development would be naturally at a maximum, and we should expect +that the growth would diminish in proportion as the microscope indicated +that the spores diminished in the atmosphere." + +Accordingly, Pasteur selected a region in the Jura Mountains suitable +for his purpose, and repeated the well-known experiment with beef juice, +first at the inn of a town at the foot of the mountains, and then at +various elevations up to the bare rocks which covered the top of the +ridge, a height of some eight thousand feet. At each point he sealed up +beef juice in a large number of flasks, and watched the result. He found +that while in the town the animalcules were developed in almost all the +flasks, they appeared only in two or three out of a hundred cases where +the flasks had been sealed at the top of the mountain, and to a +proportionate extent in those sealed at the intermediate elevations. +What, now, did these experiments prove? Simply this, that the +development of these organic forms was in direct proportion to the +number of germs in the air. It did not settle the question of +spontaneous generation, but it showed that false conclusions had been +deduced from the experiments which had been cited to prove it. + +A still more striking illustration of the same method of questioning +Nature is to be found in the investigation of Sir Humphry Davy, on the +composition of water. The voltaic battery which works our telegraphs was +invented by Volta in 1800; and later, during the same year, it was +discovered in London, by Nicholson and Carlisle, that this remarkable +instrument had the power of decomposing water. These physicists at once +recognized that the chief products of the action of the battery on water +were hydrogen and oxygen gases, thus confirming the results of +Cavendish, who, in 1781, had obtained water by combining these +elementary substances; oxygen having been previously discovered in 1775, +and hydrogen, at least, as early as 1766. It was, however, very soon +also observed that there were always formed by the action of the battery +on water, besides these aëriform products, an alkali and an acid, the +alkali collecting around the negative pole, and the acid around the +positive pole of the electrical combination. In regard to the nature of +this acid and alkali, there was the greatest difference of opinion among +the early experimenters on this subject. Cruickshanks supposed that the +acid was nitrous acid, and the alkali ammonia. Desormes, a French +chemist, attempted to prove that the acid was muriatic acid; while +Brugnatelli asserted that a new and peculiar acid was formed, which he +called the electric acid. + +It was in this state of the question that Sir Humphry Davy began his +investigation. From the analogies of chemical science, as well as from +the previous experiments of Cavendish and Lavoisier, he was persuaded +that water consisted solely of oxygen and hydrogen gases, and that the +acid and alkali were merely adventitious products. This opinion was +undoubtedly well founded; but, great disciple of Bacon as he was, Davy +felt that his opinion was worth nothing unless substantiated by +experimental evidence, and accordingly he set himself to work to obtain +the required proof. + +In Davy's first experiments the two glass tubes which he used to contain +the water were connected together by an animal membrane, and he found, +on immersing the poles of his battery in their respective tubes, that, +besides the now well-known gases, there were really formed muriatic acid +in one tube, and a fixed alkali in the other. Davy at once, however, +suspected that the acid and alkali came from common salt contained in +the animal membrane, and he therefore rejected this material and +connected the glass tubes by carefully washed cotton fiber, when, on +submitting the water as before to the action of the voltaic current, and +continuing the experiment through a great length of time, no _muriatic_ +acid appeared; but he still found that the water in the one tube was +strongly alkaline, and in the other strongly acid, although the acid was +chiefly, at least, nitrous acid. A part of the acid evidently came from +the animal membrane, but not the whole, and the source of the alkali was +as obscure as before. + +Davy then made another guess. He knew that alkali was used in the +manufacture of glass; and it occurred to him that the glass of the +tubes, decomposed by the electric current, might be the origin of the +alkali in his experiments. He therefore substituted for the glass tubes +cups of agate, which contains no alkali, and repeated the experiment, +but still the troublesome acid and alkali appeared. Nevertheless, he +said, it is possible that these products may be derived from some +impurities existing in the agate cups, or adhering to them; and so, in +order to make his experiments as refined as possible, he rejected the +agate vessels and procured two conical cups of pure gold, but, on +repeating the experiments, the acid and alkali again appeared. + +And now let me ask who is there of us who would not have concluded at +this stage of the inquiry that the acid and alkali were essential +products of the decomposition of water? But not so with Davy. He knew +perfectly well that all the circumstances of his experiments had not +been tested, and until this had been done he had no right to draw such a +conclusion. He next turned to the water he was using. It was distilled +water, which he supposed to be pure, but still, he said, it is possible +that the impurities of the spring-water may be carried over to a slight +extent by the steam in the process of distillation, and may therefore +exist in my distilled water to a sufficient amount to have caused the +difficulty. Accordingly, he evaporated a quart of this water in a silver +dish, and obtained seven-tenths of a grain of dry residue. He then added +this residue to the small amount of water in the gold cones and again +repeated the experiment. The proportion of alkali and acid was sensibly +increased. + +You think he has found at last the source of the acid and alkali in the +impurities of the water. So thought Davy, but he was too faithful a +disciple of Bacon to leave this legitimate inference unverified. +Accordingly, he repeatedly distilled the water from a silver alembic +until it left absolutely no residue on evaporation, and then with water +which he knew to be pure, and contained in vessels of gold from which he +knew it could acquire no taint, he still again repeated the already +well-tried experiment. He dipped his test-paper into the vessel +connected with the positive pole, and the water was still decidedly +acid. He dipped the paper into the vessel connected with the negative +pole, and the water was still alkaline. + +You might well think that Davy would have been discouraged here. But not +in the least. The path to the great truths which Nature hides often +leads through a far denser and a more bewildering forest than this; but +then there is not infrequently a "blaze" on the trees which points out +the way, although it may require a sharp eye in a clear head to see the +marks. And Davy was well enough trained to observe a circumstance which +showed that he was now on the right path and heading straight for the +goal. + +On examining the alkali formed in this last experiment, he found that +it was not, as before, a fixed alkali, soda or potash, but the volatile +alkali ammonia. Evidently the fixed alkali came from the impurities of +the water, and when, on repeating the experiment with pure water in +agate cups or glass tubes, the same results followed, he felt assured +that so much at least had been established. There was still, however, +the production of the volatile alkali and of nitrous acid to be +accounted for. As these contain only the elements of air and water, Davy +thought that possibly they might be formed by the combination of +hydrogen at the one pole and of oxygen at the other with the nitrogen of +the air, which was necessarily dissolved in the water. In order, +therefore, to eliminate the effect of the air, he again repeated the +experiment under the receiver of an air-pump from which the atmosphere +had been exhausted, but still the acid and alkali appeared in the two +cups. + +Davy, however, was not discouraged by this, for the "blazes" on the +trees were becoming more numerous, and he now felt sure that he was fast +approaching the end. He observed that the quantity of acid and alkali +had been greatly diminished by exhausting the air, and this was all that +could be expected, for, as Davy knew perfectly well, the best air-pumps +do not remove all the air. He therefore, for the last experiment, not +only exhausted the air, but replaced it with pure hydrogen, and then +exhausted the hydrogen and refilled the receiver with the same gas +several times in succession, until he was perfectly sure that the last +traces of air had been as it were washed out. In this atmosphere of pure +hydrogen he allowed the battery to act on the water, and not until the +end of twenty-four hours did he disconnect the apparatus. He then dips +his test-paper into the water connected with the positive pole, and +there is no trace of acid; he dips it into the water at the negative +pole, and there is no alkali; and you may judge with what satisfaction +he withdraws those slips of test-paper, whose unaltered surfaces showed +that he had been guided at last to the truth, and that his perseverance +had been rewarded. + +The fame of Sir Humphry Davy rests on his discovery of the metals of the +alkalies and earths which first revealed the wonderful truth that the +crust of our globe consists of metallic cinders; but none of these +brilliant results show so great scientific merit or such eminent power +of investigating Nature as the experiments which I have just detailed. I +have not, however, described them here for the purpose of glorifying +that renowned man. His honored memory needs no such office at my hands. +My only object was to show you what is meant by the Baconian method of +science, and to give some idea of the nature of that modern logic which +within the last fifty years has produced more wonderful transformations +in human society than the author of Aladdin ever imagined in his wildest +dreams. In this short address I can of course give you but a very dim +and imperfect idea of what I have called the Baconian system of +experimental reasoning. Indeed, you can not form any clear conception of +it, until in some humble way you have attempted to use the method, each +one for himself, and you have come here in order that you may acquire +such experience. + +My object, however, will be gained if these illustrations serve to give +emphasis to the following statements, which I feel I ought to make at +the opening of these courses of instruction--statements which have an +especial appropriateness in this place, since I am addressing teachers, +who are in a position to exert an important influence on the system of +education in this country. + +In the first place, then, I must declare my conviction that no educated +man can expect to realize his best possibilities of usefulness without a +practical knowledge of the methods of experimental science. If he is to +be a physician, his whole success will depend on the skill with which he +can use these great tools of modern civilization. If he is to be a +lawyer, his advancement will in no small measure be determined by the +acuteness with which he can criticise the manner in which the same tools +have been used by his own or his opponent's clients. If he is to be a +clergyman, he must take sides in the great conflict between theology and +science which is now raging in the world, and, unless he wishes to play +the part of the doughty knight Don Quixote, and think he is winning +great victories by knocking down the imaginary adversaries which his +ignorance has set up, he must try the steel of his adversary's blade. + +Let me be fully understood. It is not to be expected or desired that +many of our students should become professional men of science. The +places of employment for scientific men are but few, and more in the +future than in the past they will naturally be secured by those whom +Nature has endowed with special aptitudes or tastes--usually the signs +of aptitudes--to investigate her laws. That our country will always +offer an honorable career to her men of genius, we have every reason to +expect, and these born students of Nature will usually follow the plain +indications of Providence without encouragement or direction from us. + +It is different, however, with the great body of earnest students who +are conscious of no special aptitudes, but who are desirous of doing the +best thing to fit themselves for usefulness in the world; and I feel +that any system of education is radically defective which does not +comprise a sufficient training in the methods of experimental science +to make the mass of our educated men familiar with this tool of modern +civilization: so that, when, hereafter, new conquests over matter are +announced and great discoveries are proclaimed, they may be able not +only to understand but also to criticise the methods by which the +assumed results have been reached, and thus be in a position to +distinguish between the true and the false. Whether we will or not, we +must live under the direction of this great power of modern society, and +the only question is whether we will be its ignorant slave or its +intelligent servant. + +In the second place, it seems fitting that I should state to you what I +regard as the true aims to be kept in view in a course of scientific +study, and to give my reasons for the methods we have adopted in +arranging the courses you are about beginning. + +In our day there has arisen a warm discussion as to the relative claims +of two kinds of culture, and attempts are made to create an antagonism +between them. But all culture is the same in spirit. Its object is to +awaken and strengthen the powers of the mind; for these, like the +muscles of the body, are developed and rendered strong and active only +by exercise; while, on the other hand, they may become atrophied from +mere want of use. Science culture differs in its methods from the old +classical culture, but it has the same spirit and the same object. You +must not, therefore, expect me to advocate the former at the expense of +the latter; for, although I have labored assiduously during a quarter of +a century to establish the methods of science teaching which have now +become general, I am far from believing that they are the only true +modes of obtaining a liberal education. So far from this, if it were +necessary to choose one of two systems, I should favor the classical; +and why? + +Language is the medium of thought, and can not be separated from it. He +who would think well must have a good command of language, and he who +has the best command of language I am almost tempted to say will think +the best. For this reason a certain amount of critical study of language +is essential for every educated man, and such study is not likely to be +gained except through the great ancient languages; the advocates of +classical scholarship frequently say, can not be gained. I am not ready +to accept this dictum; but I most willingly concede that in the present +state of our schools it is not likely to be gained. I never had any +taste myself for classical studies; but I know that I owe to the study a +great part of the mental culture which has enabled me to do the work +that has fallen to my share in life. + +But, while I concede all this, I do not believe, on the other hand, that +the classical is the only effective method of culture; you evidently do +not think so, for you would not be here if you did. But, in abandoning +the old tried method, which is known to be good, for the new, you must +be careful that you gain the advantages which the new offers; and you +will not gain the new culture you seek unless you study science in the +right way. In the classical departments the methods are so well +established, and have been so long tested by experience, that there can +hardly be a wrong way. But in science there is not only a wrong way, but +this wrong way is so easy and alluring that you will most certainly +stray into it unless you strive earnestly to keep out of it. Hence I am +most anxious to point out to you the right way, and do what I can to +keep you in it; and you will find that our courses and methods have been +devised with this object. + +When advocating in our mother University of Cambridge, in Old England, +the claims of scientific culture, I was pushed with an argument which +had very great weight with the eminent English scholars present, and +which you will be surprised to learn was regarded as fatal to the +success of the science "triposes" then under debate. The argument was +that the experimental sciences could not be made the subjects of +competitive examinations. Some may smile at such an objection; but, as +viewed from the English standpoint, there was really a great deal in it, +and the argument brought out the radical difference between scientific +and classical culture. + +The old method of culture may be said to have culminated in the +competitive examinations of the English universities. We have no such +examinations here. Success depends not simply on knowing your subject +thoroughly, but on having it at your fingers' ends, and those fingers so +agile that they can accomplish not only a prodigious amount of work in a +short time, but can do this work with absolute accuracy. For the only +approach we make to an experience of this kind, we must look to our +athletic contests. It may of course be doubted whether the ability, once +in a man's life, to perform such mental feats, is worth what it costs. +Still it implies a very high degree of mental culture, and it is +perfectly certain that the experimental sciences give no field for that +sort of mental prize-fights. It is easy to prepare written examinations +which will show whether the students have been faithful to their work, +but they can not be adapted to such competitions as I have described +without abandoning the true object of science culture. The ability of +the scientific student can only be shown by long-continued work at the +laboratory table, and by his success in investigating the problems which +Nature presents. + +We have here struck the true key-note of the scientific method. The +great object of all our study should be to study Nature, and all our +methods should be directed to this one object. This aim alone will +ennoble our scholarship as students, and will give dignity to our +scientific calling as men of science. It is this high aim, moreover, +which vindicates the worth of the mode of culture we have chosen. What +is it that ennobles literary culture but the great minds which, through +this culture, have honored the nations to which they belong? + +The culture we have chosen is capable of even greater things; not +because science is nobler than art, for both are equally noble--it is +the thought, the conception, which ennobles, and I care not whether it +be attained through one kind of exercise of the mental faculties or +another--but we are capable of grander and nobler thoughts than Plato, +Cicero, Shakespeare, or Newton, because we live in a later period of the +world's history, when, through science, the world has become richer in +great ideas. It is, I repeat, the great thought which ennobles, and it +ennobles because it raises to a higher plane that which is immortal in +our manhood. + +If I have made my meaning clear, and if you sympathize with my feelings, +you will understand why I regard culture as so important to the +individual and to the nation. The works of Shakespeare and of Bacon are +of more value to England to-day than the memories of Blenheim or +Trafalgar; and those great minds will still be living powers in the +world when Marlborough and Nelson are only remembered as historical +names. + +I therefore believe that it is the first duty of a country to foster the +highest culture, and that it should be the aim of every scholar to +promote this culture both by his own efforts and his active influence. A +nation can become really great in no other way. We live in a country of +great possibilities; and the danger is that, as with many men I have +known in college, of great potential abilities, the greatness will end +where it begins. The scholars of the country should have but one voice +in this matter, and urge upon the government and upon individuals the +duty of encouraging and supporting mental culture for its own sake. + +The time has passed when we can afford to limit the work of our higher +institutions of learning to teaching knowledge already acquired. +Henceforth the investigation of unsolved problems, and the discovery of +new truth, should be one of the main objects at our American +universities, and no cost grudged which is required to maintain at them +the most active minds, in every branch of knowledge which the country +can be stimulated to produce. + +I could urge this on the self-interest of the nation as an obvious +dictate of political economy. I could say, and say truly, that the +culture of science will help us to develop those latent resources of +which we are so proud; will enable us to grow two blades of grass where +one grew before; to extract a larger percentage of metal from our ores; +to economize our coal, and in general to direct our waiting energies so +that they may produce a more abundant pecuniary reward. I could tell of +Galvani studying for twenty long years, to no apparent purpose, the +twitching of frogs' hind-legs, and thus sowing the seed from which has +sprung the greatest invention of modern times. Or, if our Yankee +impatience would be unwilling to wait half a century for the fruit to +ripen, I could point to the purely theoretical investigations of organic +chemistry, which in less than five years have revolutionized one of the +great industries of Europe, and liberated thousands of acres for a more +beneficent agriculture. This is all true, and may be urged properly if +higher considerations will not prevail. It is an argument I have used in +other places, but I will not use it here; although I gladly acknowledge +the Providence which brings at last even material fruits to reward +conscientious labor for the advancement of knowledge and the +intellectual elevation of mankind. I would rather point to that far +greater multitude who worked in faith for the love of knowledge, and who +ennobled themselves and ennobled their nation, not because they added to +its material prosperity, but because they made themselves and made their +fellows more noble men. + +I come back now again to the moral of all this, to urge upon you, as +the noblest patriotism and the most enlightened self-interest, the duty +of striving for yourselves and encouraging in others the highest culture +in the studies you have chosen, and this culture with one end in view, +to advance knowledge. I am far, of course, from advising you to grapple +immaturely with unsolved problems, or, when you have gained the +knowledge with which you can dare to venture from the beaten track, to +undertake work beyond your power. Many a young scientific man has +suffered the fate of Icarus in attempting to soar too high. Moreover, I +am far from expecting that all or many of you will ever have the +opportunity of going beyond the well-explored fields of knowledge; but +you can all have the aim, and that aim will make your work more worthy +and more profitable to yourselves. Every American boy can not be +President of the United States, but if, as our English cousins allege, +he believes that he can be, the very belief makes him an abler man. + +We have dwelt long enough on these generalities, and it is time to come +down to commonplaces, and to inquire what are the essential conditions +of this scientific culture which shall fit us to investigate Nature; and +the first thought that occurs to me in this connection may be expressed +thus: Science presents to us two aspects, which I may call its objective +and its subjective aspect. Objectively it is a body of facts, which we +have to observe, and subjectively it is a body of truths, conclusions, +or inferences, deduced from these facts; and the two sides of the +subject should always be kept in view. + +I propose next to say a few words in regard to each of these two aspects +of our study, and in regard to the best means of training our faculties +so as to work successfully in each sphere. First, then, success in the +observation of phenomena implies three qualities at least, namely, +quickness and sharpness of perception, accuracy in details, and +truthfulness; and on its power to cultivate these qualities a large part +of the value of science, as a means of education, depends. + +To begin with the cultivation of our perceptions. We are all gifted with +senses, but how few of us use them to the best advantage! "We have eyes +and see not"; for, although the light paints the picture on the retina, +our dull perceptions give no attention to the details, and we retain +only a confused impression of what has passed before our eyes. "But +how," you may ask, "are we to cultivate this sharpness of perception?" I +answer, only by making a conscious effort to fix our attention on the +objects we study until the habit becomes a second nature. I have often +noticed, with surprise, the power which uneducated miners frequently +possess of recognizing many minerals at sight. This they have acquired +by long experience and close familiarity with such objects, and such +power of observation is with them so purely a habit that they are +frequently unable to state clearly the grounds on which their +conclusions are based. They recognize the minerals by what in common +language is called their "looks" and they notice delicate differences in +the "looks" to which most men are blind. It is, however, the business of +the scientific mineralogist to analyze these "looks," and to point out +in what the differences consist; so that by fixing his attention on +these points the student may gain, by a few hours' study, the power +which the miner acquires only after long experience. + +The chief difficulty, however, which we find in teaching mineralogy is, +that the students do not readily see the differences when they are +pointed out, or, if they see them, do not remember them with sufficient +precision to render their subsequent observations conclusive and +precise. This either arises from a failure to cultivate the powers of +observation in childhood, or the subsequent blunting of them by disuse. +The ladies will scout the idea that a brooch of cut-glass is as +ornamental as one of diamond, and yet I venture to assert that there is +not one person in fifty, at least of those who have not made a study of +the subject, who can tell the difference between the two. The external +appearance depends simply on what we call lustre. The lustre of glass +is vitreous, that of the diamond adamantine; and I know of no other +distinction which it is more difficult for students to recognize than +this. Those of you who study mineralogy will experience this difficulty, +and it can be overcome only by giving careful attention to the subject. +The teacher can do nothing more than put in your hands the specimens +which illustrate the point, and you must study these specimens until you +see the difference. It is a question of sight, not of understanding, and +all the optical theories of the cause of the lustre will not help you in +the least toward seeing the difference between diamond and glass, or +anglesite and heavy spar. + +Another illustration of the same fact is the constant failure of +students to distinguish by the eye alone between the two minerals called +copper-glance and gray copper. There is a difference of color and lustre +which, although usually well marked, it requires an educated eye to +distinguish. + +Mineralogy undoubtedly demands a more careful cultivation of the +perceptions than the other branches of chemistry; but still you will +find abundant practice for close observation in them all. I have often +known students to reach erroneous results in qualitative analysis by +mistaking a white precipitate in a colored liquid for a colored +precipitate, or by not attending to similar broad distinctions, which +would have been obvious to any careful observer; and so in quantitative +analysis, mere delicacy of touch or handling is a great element of +success. + +But I must pass on to speak of the importance in the study of Nature of +accuracy in detail, which is the second condition of successful +observation of which I spoke. We must cultivate not only accuracy in +observing details, but also accuracy in following details which have +been laid down by others for our guidance. In science we can not draw +correct conclusions from our premises unless we are sure that we have +all the facts, and what seemed at first an unimportant detail often +proves to be the determining condition of the result; and, again, if we +are told that under certain conditions a certain sign is the proof of +the presence of a certain substance, we have no right to assume that the +sign is of any value unless the conditions are fulfilled. A black +precipitate, for example, obtained under certain conditions, is a proof +of the presence of nickel, but we can not assert that we have found +nickel unless we have followed out those details in every particular. + +Of course, we must avoid empiricism as far as we can. We must seek to +learn the reasons of the details, and such knowledge will not only +render our work intelligent, but will also frequently enable us to +judge how far the details are essential, and to what extent our +processes may be varied with safety. We must also avoid trifling, and, +above all, "the straining at a gnat and swallowing a camel," as is the +habit with triflers. Large knowledge and good judgment will avoid all +such errors; but, if we must choose between fussiness and carelessness, +the first is the least evil. Slovenly work means slovenly results, and +habits of carefulness, neatness, and order produce as excellent fruits +in the laboratory as in the home. + +Last in order but first in importance of the conditions of successful +observation, mentioned above, stands truthfulness. Here you may think I +am approaching a delicate subject, of which even to speak might seem to +cast a reproach. But not so at all. I am not speaking here of conscious +deception, for I assume that no one who aspires to be a student of +Nature can be guilty of that. But I am speaking of a quality whose +absence is not necessarily a mark of sinfulness, but whose possession, +in a high degree, is a characteristic of the greatest scientific talent. +As every lawyer knows, he is a rare man whose testimony is not colored +by his interests, and a very large amount of self-deception is +compatible with conscious honesty of purpose. + +So among scientific students the power to keep the mind unbiased, and +not to color our observations in the least degree, is one of the rarest +as it is one of the noblest of qualities. It is a quality we must strive +after with all our might, and we shall not attain it unless we strive. +Remember, our observations are our data, and, unless accurate, +everything deduced from them must have the taint of our deception. We +can not deceive Nature, however much we may deceive ourselves; and there +is many a student who would cut off his right hand rather than be guilty +of a conscious untruth, who is yet constantly untruthful to himself. +Every year students of mineralogy present to me written descriptions of +mineral specimens which particularize, as observed, characters that do +not appear on the specimen given them to determine, although they may be +the correct characters of some other mineral. + +There is usually no want of honesty in this, but, deceived by some +accident, the student has made a wrong guess, and then imagined that he +saw on the specimen those characters which he knew from the descriptions +ought to appear on the assumed mineral. So, also, it not unfrequently +happens that a student in qualitative analysis, who has obtained some +hints in regard to the composition of his solution, will torture his +observations until they seem to him to confirm his erroneous inferences; +and again the student in quantitative analysis, who finds out the exact +weight he ought to obtain, is often insensibly influenced by this +knowledge--in the washing and ignition of his precipitate, or in some +other way--and thus obtains results whose only apparent fault may be a +too close agreement with theory, but which, nevertheless, are not +accurate because not true. It is evident how fatal such faults as these +must be to the investigation of truth, and they are equally destructive +of all scientific scholarship. Their effect on the student is so marked +that, although he may deceive himself, he will rarely deceive his +teacher. That he should lose confidence in his own results is, to the +teacher, one of the most marked indications of such false methods of +study, but the student usually refers his want of success to any cause +but the real one--his own untruthfulness. He will complain of the +teacher, or of the methods of instruction, and may even persuade himself +that all scientific results are as uncertain as his own. As I have said, +mere ordinary truthfulness, which spurns any conscious deception, will +not save us from falling into such faults. Our scientific study demands +a much higher order of truthfulness than this. We should so love the +truth above all price as to strive for it with single-hearted and +unswerving purpose. We must be constantly on our guard to avoid any +circumstance which would tend to bias our minds or warp our judgments, +and we must make the attainment of the truth our sole motive, guide, and +end. + +It remains for me, before closing this address, to say a few words on +what I have called the subjective aspect of scientific study. Science +offers us not only a mass of phenomena to be observed, but also a body +of truths which have been deduced from these observations; and, without +the power of drawing correct inferences from the data acquired, exact +observations would be of little value. I have already described the +inductive method of reasoning, and illustrated it by two noteworthy +examples, and, in a humbler measure, we must apply the same method in +our daily work in the laboratory. We must learn how to vary our +experiments so as to eliminate the accidental circumstances, and make +evident the essential conditions of the phenomena we are studying. Such +power can only be acquired by practice, and a somewhat long experience +in active teaching has convinced me that there is no better means of +training this logical faculty than the study of qualitative chemical +analysis in which many of you are to engage. + +The results of the processes of qualitative analysis are perfectly +definite and trustworthy; but they are only reached by following out the +indications of experiments which are frequently obscure, and even +apparently contradictory; reconciling by new experiments the seeming +discrepancies, and, at last, having eliminated all other possible causes +of the phenomena observed, discovering the true nature of the +substances under examination. + +The study of mineralogy affords an almost equally good practice, +although in a somewhat different form. By comparing carefully many +specimens of the same mineral, you learn to distinguish the accidental +from the essential characters, and on this distinction you must base +your inferences in regard to the nature of the specimens you may be +called upon to determine. A single remark occurs to me which may aid you +in cultivating this scientific logic. + +Do not attempt to reason on insufficient data. Multiply your +observations or experiments, and when your premises are ample, the +conclusion will generally take care of itself. Are you in doubt in +regard to a mineral specimen? Repeat your observations again and again, +multiply them with the aid of the blow-pipe or goniometer, compare the +specimen with known specimens which it resembles, until either your +doubts are removed or you are satisfied that you are unequal to the +task; and remember that, in many cases, the last is the only honest +conclusion. + +Are you in doubt in regard to the reactions of the substance you are +analyzing, whether they are really those of a metal you suspect to be +present? Do not rest in such a frame of mind, and, above all, do not try +to remove the doubt by comparing your experience with that of your +neighbor, but multiply your own experiments; procure some compound of +the metal, and compare its reactions with those you have observed until +you reach either a positive or a negative result. + +Remember that the way to remove your doubts is to widen your own +knowledge, and not to depend on the knowledge of others. When your +knowledge of the facts is ample, your inferences will be satisfactory, +and then an unexplained phenomenon is the guide to a new discovery. Do +not be discouraged if you have to labor long in the dark before the day +begins to dawn. It will at last dawn to you, as it has dawned to others +before, and, when the morning breaks, you will be satisfied with the +result of your labor. + +Moreover, I feel confident that such experience will very greatly tend +to increase your appreciation of the value of scientific studies in +training the reasoning faculties of the mind. This, as every one must +admit, is the best test of their utility in a scheme of education, and +it is precisely here that I claim for them the very highest place. It +has generally been admitted that mathematical studies are peculiarly +well adapted to train the logical faculties, but still many persons have +maintained that, since the mathematics deal wholly with absolute +certainties, an exclusive devotion to this class of subjects unfits the +mind for weighing the probable evidence by which men are chiefly guided +in the affairs of life. + +But, without attempting to discuss this question, on which much might be +said on both sides, it is certain that no such objection can be urged +against the study of the physical sciences if conducted in the manner I +have attempted to describe. These subjects present to the consideration +of the student every degree of probable evidence, accustoming him to +weigh all the evidence for or against a given conclusion, and to reject +or to provisionally accept only on the balance of probabilities. +Moreover, in practical science, the student is taught to follow out a +chain of probable evidence with care and caution, to eliminate all +accidental phenomena, and supply, by experiment or observation, the +missing links, until he reaches the final conclusion--an intellectual +process which, though based wholly on probable evidence, may have all +the force and certainty of a mathematical demonstration. + +Indeed, that highly valued scientific acumen and skill which enables the +student to brush away the accidental circumstances by which the laws of +Nature are always concealed until the truth stands out in bold relief, +is but a higher phase of the same talent which marks professional skill +in all the higher walks of life. The physician who looks through the +external symptoms of his patient to the real disease which lurks +beneath; the lawyer, who disentangles a mass of conflicting testimony, +and follows out the truth successfully to the end; the statesman, who +sees beneath the froth of political life the great fundamental +principles which will inevitably rule the conduct of the state, and thus +foresees and provides for the coming change; the general, who discovers +amid the confusion of the battlefield the weak point of his enemy's +front; the merchant, even, who can interpret the signs of the unsettled +market--employ the same faculty, and frequently in not a much lower +degree, that discovered the law of gravitation, and which, since the +days of Newton, has worked so successfully to unveil the mysteries of +the material creation. + +Moreover, I hope, my friends, that you will come to value scientific +studies, not simply because they cultivate the perceptive and reasoning +faculties, but also because they fill the mind with lofty ideals, +elevated conceptions, and noble thoughts. Indeed, I claim that there is +no better school in which to train the ćsthetical faculties of the mind, +the tastes, and the imagination, than the study of natural science. + +The beauty of Nature is infinite, and the more we study her works the +more her loveliness unfolds. The upheaved mountain, with its mantle of +eternal snow; the majestic cataract, with its whirl and roar of waters; +the sunset cloud, with its blending of gorgeous hues, lose nothing of +their beauty for him who knows the mystery they conceal. On the +contrary, they become, one and all, irradiated by the Infinite Presence +which shines through them, and fill the mind with grander conceptions +and nobler ideas than your uneducated child of Nature could ever attain. + +Remember that I am not recommending an exclusive devotion to the natural +sciences. I am only claiming for them their proper place in the scheme +of education, and I do not, of course, deny the unquestionable value of +both the ancient and the modern classics in cultivating a pure and +elevated taste. But I do say that the poet-laureate of England has drawn +a deeper inspiration from Nature interpreted by science than any of his +predecessors of the classical school; and I do also affirm that the +pre-Raphaelite school of painting, with all its grotesque mimicry of +Nature, embodies a truer and purer ideal than that of any Roman fable or +Grecian dream. + +And what shall we say of the imagination? Where can you find a wider +field for its exercise than that opened by the discoveries of modern +science? And as the mind wanders over the vast expanse, crossing +boundless spaces, dwelling in illimitable time, witnessing the displays +of immeasurable power, and studying the adaptations of Omniscient +skill, it lives in a realm of beauty, of wonder, and of awe, such as no +artist has ever attained to in word, in sound, in color, or in form. And +if such a life does not lead man to feel his own dependence, to yearn +toward the Infinite Father, and to rest on the bosom of Infinite Love, +it is simply because it is not the noble in intellect, not the great in +talent, not the profound in knowledge, not the rich in experience, not +the lofty in aspiration, not the gifted in imagery, but solely the pure +in heart, who see God. + +Such, then, is a very imperfect presentation of what I believe to be the +value of scientific studies as a means of education. In what I have +stated I have implied that, for these studies to be of any real value, +the end must be constantly kept in view, and everything made subservient +to the one great object. + +To study the natural sciences merely as a collection of interesting +facts which it is well for every educated man to know, seldom serves a +useful purpose. The young mind becomes wearied with the details, and +soon forgets what it has never more than half acquired. The lessons +become an exercise of the memory and of nothing more; and if, as is too +frequently the case, an attempt is made to cram the half-formed mind in +a single school-year with an epitome of half the natural +sciences--natural philosophy, astronomy, and chemistry, physiology, +zoölogy, botany, and mineralogy, following each other in rapid +succession--these studies become a great evil, an actual nuisance, which +I should be the first to vote to abate. The tone of mind is not only not +improved, but seriously impaired, and the best product is a superficial, +smattering smartness, which is the crying evil not only of our schools +but also of our country. + +In order that the sciences should be of value in our educational system, +they must be taught more from things than from books, and never from +books without the things. They must be taught, also, by real living +teachers, who are themselves interested in what they teach, are +interested also in their pupils, and understand how to direct them +aright. Above all, the teachers must see to it that their pupils study +with the understanding, and not solely with the memory, not permitting a +single lesson to be recited which is not thoroughly understood, taking +the greatest care not to load the memory with any useless lumber, and +eschewing merely memorized rules as they would deadly poison. The great +difficulty against which the teachers of natural science have to contend +in the colleges are the wretched tread-mill habits the students bring +with them from the schools. Allow our students to memorize their +lessons, and they will appear respectably well, but you might as easily +remove a mountain as to make many of them think. They will solve an +involved equation of algebra readily enough so long as they can do it by +turning their mental crank, when they will break down on the simplest +practical problem of arithmetic which requires of them only thought +enough to decide whether they shall multiply or divide. + +Many a boy of good capabilities has been irretrievably ruined, as a +scholar, by being compelled to learn the Latin grammar by rote at an age +when he was incapable of understanding it; and I fear that schools may +still be found where young minds are tortured by this stupefying +exercise. Those of us who have faith in the educational value of +scientific studies are most anxious that the students who resort to our +colleges should be as well fitted in the physical sciences as in the +classics, for otherwise the best results of scientific culture can not +be expected. As it is, our students come to the university, not only +with no preparation in physical science, but with their perceptive and +reasoning faculties so undeveloped that the acquisition of the +elementary principles of science is burdensome and distasteful; and good +scholars, who are ambitious of distinction, can more readily win their +laurels on the old familiar track than on an untried course of which +they know nothing, and for which they must begin their training anew. + +We have improved our system of instruction in the college as fast as we +could obtain the means, but we are persuaded that the best results can +not be reached without the coöperation of the schools. We feel, +therefore, that it is incumbent upon us, in the first place, to do +everything in our power to prove to the teachers of this country how +great is the educational value of the physical sciences, when properly +taught; and secondly, to aid them in acquiring the best methods of +teaching these subjects. It is with such aims that our summer courses +have been instituted, and your presence here in such numbers is the best +evidence that they have met a real want of the community. We welcome you +to the university and to such advantages as it can afford, and we shall +do all in our power to render your brief residence here fruitful, both +in experience and in knowledge; hoping, also, that the university may +become to you, as she has to so many others, a bright light shining +calmly over the troubled sea of active life, ever suggesting lofty +thoughts, encouraging noble endeavors, and inciting all her children to +work together toward those great ends, the advancement of knowledge and +the education of mankind. + + + + +II. + +THE NOBILITY OF KNOWLEDGE. + + _An Address delivered before the Free Institute at Worcester, + Massachusetts, July 28, 1874._ + + +Within a comparatively few years schools for the instruction of artisans +have become a prominent feature in the educational systems both of this +country and of Europe, and seem destined to supersede the old system of +apprenticeships. The establishment of these schools has been an +important step in human progress, not because any great advantage has +been gained in the cultivation of mechanical skill, but because here the +future mechanic acquires culture of the mind as well as skill of the +hand. Indeed, it may be doubted whether our utilitarian age can ever +successfully compete with those "elder days of art" when + + "Builders wrought with greatest care + Each minute and unseen part." + +But, if our industrial schools do not make better mechanics than the +workshops of the olden time, they certainly educate better men, and, by +adding to skill, knowledge, they are elevating the mechanic and +ennobling his calling. + +If, therefore, these schools are the representatives in our age of the +workshops with their bands of apprentices in the days of yore, then that +by which the schools are distinguished, that which they have added to +the old system, is not art but mental culture; and therefore, when asked +to address you on this occasion, I could think of no more appropriate +subject than the Nobility of Knowledge. + +Identified with an institution in which mental culture is the chief aim, +I felt that I was asked to address a body of cultivated working-men with +whom, though employed in the mechanic arts, the acquisition of knowledge +was also a privilege and a pride. I felt, moreover, that a proper +appreciation of the true dignity of knowledge, in itself considered, and +apart from all economical considerations, is one of the great wants of +our age and of our country. + +"Knowledge is power." "Knowledge is wealth." These trite maxims are +sufficiently esteemed in our community, and need not that they be +enforced by any one. So far as knowledge will yield immediate +distinction or gain, it is sought and fostered by multitudes. But, when +the aim is low, the attainment is low, and too many of our students are +satisfied with superficiality, if it only glitters, and with +charlatanry, if it only brings gold. + +Let me not be understood to depreciate the material advantages of +learning. I rejoice that in this world knowledge frequently yields +wealth and fame, and I should have little hope for human progress were +the prizes of scholarship less than they are. Power and wealth are noble +aims, and when rightly used may be the means of conferring unmeasured +blessings on mankind; but I desire at this time to impress upon you, my +friends, the fact that knowledge has nobler fruits than these, and that +the worth of your knowledge is to be measured not by the credits it will +add to your account in the ledger, or the position it may give you among +men, but by the extent to which it educates your higher nature, and +elevates you in the scale of manhood. + +I address young men who are just entering on life, who are at an age +when the mystery of our being usually presses most closely upon the +soul, and whose aspirations for higher culture and clearer vision have +not been deadened by the sordid damps of the world. Trust no croakers +who tell you that your youthful visions are illusions, which a little +contact with the real business of the world will dispel. + +It is only too true that these visions will become fainter and fainter, +if you allow the cares of the world to engross your thoughts; but, +unless your higher nature becomes wholly deadened, you will look back to +the time when the visions were brightest, as the golden period of your +life, and let me assure you that, if you only are true to the +aspirations of your youth, the visions will become clearer and clearer +to the last, and, as we firmly believe, will prove to be the dawn of the +perfect day. + +My friends, if you have seen these visions, "the nobility of knowledge" +has been a reality of your experience. You know that there is a life +lived in communion with the thoughts of great men or with the thoughts +of God as we can read them in Nature and Revelation, which is purer and +nobler than a life of money-making or political intrigue, and I would +that I could so bring you to appreciate not only the nobility, but also +the happiness, of such a life as to induce you to try to live it. + +Do you tell me that it is only granted to a few men to become scholars, +and that you have been educated for some industrial pursuit? Remember, +as I said before, that it is your special privilege to have been +educated, to have added knowledge to your handicraft, and that this very +knowledge, if kept alive so far as you are able, will ennoble your life. +Knowledge, like the fairy's wand, ennobles whatever it touches. The +humblest occupations are adorned by it, and without it the most exalted +positions appear to true men mean and low. + +Nor is it the extent of the knowledge alone which ennobles, but much +more the spirit and aim with which it is cultivated, and that spirit and +aim you may carry into any occupation, however engrossing, and into any +condition of life, however obscure. + +And let me add that what I have said is true not only of the individual, +but also, and to an even greater degree, of the nation. Our people, for +the most part, look upon universities and other higher institutions of +learning as merely schools for recruiting the learned professions, and +estimate their efficiency solely by the amount of teaching work which +they perform. But, however important the teaching function of the +university may be, I need not tell you that this is not its only or +chief value to a community. The university should be the center of +scientific investigation and literary culture, the nursery of lofty +aspirations and noble thoughts, and thus should become the soul of the +higher life of the nation. For this and this chiefly it should be +sustained and honored, and no cost and no sacrifice can be too great +which are required to maintain its efficiency; and its success should be +measured by the amount of knowledge it produces rather than by the +amount of instruction it imparts. + +Harvard College, by cherishing and honoring the great naturalist she +has recently lost, has done more for Massachusetts than by educating +hosts of commonplace professional men. The simple title of teacher, +which in his last will Louis Agassiz wrote after his name, was a nobler +distinction than any earthly authority could confer; but remember he was +a teacher not of boys, but of men, and his influence depended not on the +instruction in natural history which he gave in his lecture-room, but on +his great discoveries, his far-reaching generalization, and his noble +thoughts. Although that man died poor, as the world counts poverty, yet +the bequest which he left to this people can not be estimated in coin. + +It is a sorry confession to make, but it is nevertheless the truth, +that, if we compare our American universities, in point of literary or +scientific productiveness, with those of the Old World, they will appear +lamentably deficient. Let me add, however, that this deficiency arises +not from any want of proper aims in our scholars, but simply from the +circumstance that our people do not sufficiently appreciate the value of +the higher forms of literary and scientific work to bear the burden +which the production necessary entails. Scholars must live, as well as +other men, and in a style which is in harmony with their surroundings +and cultivated tastes, and their best efforts can not be devoted to the +extension of knowledge unless they are relieved from anxiety in regard +to their daily bread. + +In our colleges the professors are paid for teaching and for teaching +only, while in a foreign university the teaching is wholly secondary, +and the professor is expected to announce in his lectures the results of +his own study, and not the thoughts of other men. Until the whole status +of the professors in our chief universities can be changed, very little +original thought or investigation can be expected, and these +institutions can not become what they should be, the soul of the higher +life of the nation. + +It is in your power, however, to bring about this change, but the reform +can be effected in only one way. You must give to your universities the +means of supporting fully and generously those men of genius who have +shown themselves capable of extending the boundaries of human knowledge, +and demand of them, only, that they devote their lives to study and +research, and let me assure you that no money can be spent which will +yield a larger or more valuable return. + +If you do not look beyond your material interests, the higher life of +the nation, which you will thus serve to cherish and foster, will guard +your honor and protect your home; and, on the other hand, what can you +expect in a nation whose highest ideal is the dollar or what the dollar +will buy, but venality, corruption, and ultimate ruin? + +But, rising at once to the noblest considerations, and regarding only +the welfare of your country and the education of your race, what higher +service can you render than by sustaining and cherishing the grandest +thought, the purest ideals, and the loftiest aspirations which humanity +has reached, and making your universities the altars where the holy fire +shall be kept ever burning bright and warm? + +Do you think me an enthusiast? Look back through history, and see for +yourselves what has made the nations great and glorious. Why is it that, +after twenty centuries, the memory of ancient Greece is still enshrined +among the most cherished traditions of our race? Is it not because Homer +sang, Phidias wrought, and Plato, Aristotle, Demosthenes, Thucydides, +with a host of others, thought and wrote? Or, if for you the military +exploits of that classic age have the greater charm, do not forget that +were it not for Grecian literature, Thermopylć, Marathon, and Salamis +would have been long since forgotten, and that the bravery, +self-devotion, and patriotism which these names embalm were the direct +fruits of that higher life which those great thinkers illustrated and +sustained. + +And, coming down to modern times, what are the shrines in our mother +country which we chiefly venerate, and to which the transatlantic +pilgrim oftenest directs his steps? Is it her battlefields, her castles +and baronial halls, or such spots as Stratford-on-Avon, Abbotsford, and +Rydal Mount? Why, then, will we not learn the lesson which history so +plainly teaches, and strive for those achievements in knowledge and +mental culture which will be remembered with gratitude when all local +distinctions and political differences shall have passed away and been +forgotten? + +While I was considering the line of discourse which I should follow on +this occasion, an incident occurred suggesting an historical parallel, +which will illustrate, better than any reflections of mine, the truth I +would enforce. The ship Faraday arrived on our coast after laying over +the bed of the Atlantic another of those electric nerves through which +pulsate the thoughts of two continents, and as I read the description of +that noble ship, fitted out with all the appliances which modern science +had created to insure the successful accomplishment of the enterprise, I +remembered that not a century had elapsed since the first obscure +phenomena were observed, whose conscientious study, pursued with the +unselfish spirit of the scientific investigator, had led to these +momentous results, and my imagination carried me back to an autumn day +of the year 1786, in the old city of Bologna, in Italy, and I seemed to +assist at the memorable experiment which has associated the name of +Aloysius Galvani with that mode of electrical energy which flashes +through the wire cords that now unite the four quarters of the globe. + +Galvani is Professor of Anatomy in the University of Bologna, and there +is hanging from the iron balcony of his house a small animal +preparation, which is not an unfamiliar sight in Southern Europe, where +it is regarded as a delicacy of the table. It is the hind-legs of a +frog, from which the skin had been removed, and the great nerve of the +back exposed. Six years before, his attention had been called to the +fact that the muscles of the frog were convulsed by the indirect action +of an electrical machine, under conditions which he had found very +difficult to interpret. He had connected the phenomenon with a theory of +his own: that electricity--that is, common friction electricity, the +only mode of electrical action then known--was the medium of all nervous +action; and this had led him into a protracted investigation of the +subject, during which he had varied the original experiment in a +thousand ways, and he had now suspended the frog's legs to the iron +balcony, in order to discover if atmospheric electricity would have any +effect on the muscles of the animal. + +Galvani has spent a long day in fruitless watching, when, while holding +in his hand a brass wire, connected with the muscles of the frog, he +rubs the end, apparently listlessly, against the iron railing, when, +lo! the frog's legs are convulsed. + +The patient waiting had been rewarded, for this observation was the +beginning of a line of discovery which was ere long to revolutionize the +world. But Galvani was not destined to follow far the new path he had +thus opened. The remarkable fact observed was this: The convulsions of +the frog's legs could be produced without the intervention of +electricity, or, at least, of the one kind of electricity then known, +and Galvani soon found out that the only condition necessary to produce +the result was, that the nerve of the frog should be connected with the +muscle of the leg by some good electrical conductor. + +But, although Galvani followed up this observation with the greatest +zeal, and showed remarkable sagacity throughout his whole investigation, +yet he was too strongly wedded to his own theory to interpret correctly +the facts he observed. He supposed, to the end of his life, that the +whole effect was caused by animal electricity flowing through the +conductor from the nerve to the muscle, and his experiments were chiefly +interesting to himself and to his contemporaries from the light they +were supposed to throw on the mysterious principle of life. We now know +that animal electricity played only a small part in the phenomena he +observed, and that the chief effects were due to a cause of which he +was wholly ignorant. + +Galvani published his observations in 1791, in a monograph entitled "The +Action of Electricity in Muscular Motion." This publication excited the +most marked attention, and, within a year, all Europe was experimenting +on frogs' legs. The phenomena were everywhere reproduced, but Galvani's +explanation of the phenomena was by no means so universally accepted. +His theory was controverted in many quarters, and by no one more +successfully than by Alexander Volta, Professor of Physics in the +neighboring University of Pavia. + +Volta, while admitting, with Galvani, that the muscular contractions +were caused by electricity, explained the origin of the electricity in a +wholly different way. According to Volta, the electricity originated not +in the animal, but in the contact of the dissimilar metals or other +materials used in the experiment. This difference of opinion led to one +of the most remarkable controversies in the history of science, and for +six years, until his death in 1798, Galvani was occupied in defending +his theory of animal electricity against the assaults of his +distinguished countryman. + +This discussion created the liveliest interest throughout Europe. Every +scholar of science took sides with one or the other of these eminent +Italian philosophers, and the scientific world became divided into the +school of Galvani and the school of Volta. Yet, so far at least as the +fundamental experiment was concerned, both were wrong. The electricity +came neither from the body of the frog nor from the contact of +dissimilar kinds of matter, but was the result of chemical action, which +both had equally overlooked. + +But, nevertheless, the controversy led to the most important results: +for Volta, while endeavoring to sustain his false theory by experimental +proofs, was led to the discovery of the Voltaic pile, or, as we now call +it, the Voltaic battery, an instrument whose influence on civilization +can be compared only with the printing-press and the steam-engine. Yet, +although the whole action of the battery was in direct contradiction to +his pet theory, still, to the last, Volta persistently defended the +erroneous doctrine he had espoused in his controversy with Galvani +thirty years before, and he died in 1827, without realizing how great a +boon he had been instrumental in conferring on mankind; so true it is +that Providence works out his bright designs even through the blindness +and mistakes of man. + +But there is another lesson to be learned from this history, which can +not be too often rehearsed in this self-sufficient age, which boasts so +proudly of its practical wisdom. There were, doubtless, many practical +men in that city of Bologna to smile at their sage professor, who had +spent ten long years in studying, to little apparent purpose, the +twitchings of frogs' hind-legs, and there was many a jest among the +courtiers of Europe at the expense of the learned philosophers who +"wasted" so much time in discussing the cause of such trivial phenomena. +But how is it now? + +Less than a century has passed since Galvani's death, and in a small hut +on the shores of Valentia Bay may be seen one of the most skillful of a +new class of practical men, representing a profession which owes its +origin to Galvani and Volta. The _electrician_ is watching a spot of +light on the scale of an instrument which is called a _galvanometer_. +Since the fathers fell asleep, the field of knowledge which they first +entered has spread out wider and wider before the untiring explorers who +have succeeded them. Oersted and Seebeck, Arago and Ampčre, Faraday and +our own Henry, have made wonderful discoveries in that field; and other +great men, like Steinheil, Wheatstone, Morse, and Thomson, have invented +ingenious instruments and appliances, by which these discoveries might +be made to yield great practical results. + +The spot of light, which the electrician is watching, is reflected from +one of the latest of these inventions, the reflecting galvanometer of +Thomson. He and his assistants had been watching by turns the same spot +for several days, since the Great Eastern had steamed from the bay, +paying out a cable of insulated wire. These electricians had no anxiety +as to the result, for daily signals had been exchanged between the ship +and the shore, as hundreds after hundreds of miles of this electrical +conductor had been laid on the bed of the broad ocean. The coast of +Newfoundland had already been reached, and they were only waiting for +the landing of the cable at the now far-distant end. + +At length the light quivers, and the spot begins to move. It answers to +concerted signals. And soon the operator spells out the joyful message. +The ocean has been spanned with an electric nerve, and the New World +responds to the greetings of the Old. + +Here is something practical, which all can appreciate, and all are ready +to honor. We honor the courage which conceived, the skill which +executed, and, above all, the success which crowned the undertaking. But +do we not forget that professor of Bologna, with his frogs' legs, who +sowed the seed from which all this has sprung? He labored without hope +of temporal reward, stimulated by the pure love of truth, and the grain +which he planted has brought forth this abundant harvest. Do we not +forget, also, that succession of equally noble men, Volta, and Oersted, +and Faraday, with many other not less devoted investigators of +electrical science, without whose unselfish labors the great result +never could have been achieved? Such men, of course, need no recognition +at our hands, and I ask the question not for their sakes, but for ours. +The intellectual elevation of the lives they led was their +all-sufficient reward. + +It is, however, of the utmost importance for us, citizens of a country +with almost unlimited resources, that we should recognize what are the +real springs of true national greatness and enduring influence. In this +age of material interests, the hand is too ready to say to the head, "I +have no need of thee"; and, amid the ephemeral applause which follows +the realization of some triumph over matter, we are apt to be deceived, +and not observe whence the power came. We associate the great invention +with some man of affairs man who overcame the last material obstacle, +and who, although worthy of all praise, probably added very little to +the total wealth of knowledge of which the invention was an immediate +consequence; and, not seeing the antecedents, we are apt to underrate +the part which the student or scientific investigator may have +contributed to the result. + +It is idle, for example, to speak of the electric telegraph as invented +by any single man. It was a growth of time, and many of the men who +contributed to win this great victory of mind over space "builded far +better than they knew." As I view the subject, that invention is as +much a gift of Providence as if the details had been supernaturally +revealed. But, whatever may be our speculative views, it is of the +utmost importance to the welfare of our community that we should realize +the fact that purely theoretical scientific study, pursued for truth's +sake, is the essential prerequisite for such inventions. Knowledge is +the condition of invention. The old Latin word _invenio_ signifies _to +meet with_, as well as to _find_, and these great gifts of God are _met +with_ along the pathway of civilization; but the throng of the world +passes them unnoticed, for only those can recognize the treasure whose +minds have been stored with the knowledge which the scholar has +discovered and made known. + +If, then, as no one will deny, science and scholarship are the powers by +which improvements in the useful arts are made, I might appeal to your +self-interest to support and cherish them. But I should despise myself +for appealing to such a motive, and you for requiring it. The supreme +importance of science and scholarship to a nation does not depend in the +least on the circumstance that important practical results may follow. +When, as in the case of Galvani's frogs, they come in the order of +Providence, let us thank God for them as a gift which we had no right +either to expect or demand. Science, if studied successfully, must be +studied for the pure love of truth; and, if we serve her solely for +mercenary ends, her truths, the only gold she offers, will turn to dross +in our hands, and we shall degrade ourselves in proportion as we +dishonor her. + +Galvani, and Volta, and Oersted, who discovered the truths of which the +electric telegraph is a simple application, sure to be made as soon as +the time was ripe, are not the less to be honored because they died +before the fullness of that time had come. We honor them for the truths +they discovered, and the lustre of their consecrated lives could be +neither enhanced nor impaired by subsequent events; and it is because I +am persuaded that such lives are the salt of the world, the saviours of +society, that I would lead you to cherish and sustain them; and, that I +may enforce this conclusion, allow me to ask your attention to another +historical incident, which presents a striking parallelism to the last. + +I must take you back to a period which we, of a nation born but +yesterday, regard as distant, but which was one of the most noted epochs +of modern history--the age of Luther and the Reformation. I must ask you +to accompany me to the small town of Allenstein, near Frauenberg, in +Eastern Prussia, where, on May 23, 1543, there lay dying one of the +great benefactors of mankind. + +This man, old at seventy years, "bent and furrowed with labor, but in +whose eye the fire of genius was still glowing," was then known as one +of the most learned men of his time. Doctor of medicine as well as of +theology, Canon of Frauenberg, Honorary Professor of Bologna and Rome, +while devoting his leisure to study, he had passed a life of active +benevolence in administering to the bodily as well as the spiritual +wants of the ignorant people among whom his lot had been cast. He was +also a great mechanical genius, and, by various labor-saving machines, +of his own invention, he had contributed greatly to the welfare of the +surrounding country. + +But the superstitious peasants, although they had hitherto reverenced +the great man as their best friend and benefactor, had been recently +incited by his enemies and rivals in the church to curse him as a +heretic and a wizard. A few days back he had been the unwilling witness +of one of those out-of-door spectacles, so common at that time, in which +his scientific opinions had been travestied, his charities ridiculed, +and his devoted life made the object of slander and reproach. This +ingratitude of his flock had broken his heart, and he could not recover +from the blow. + +The occasion of this outburst of fanaticism was the approaching +publication of a work in which he had dared to question the received +opinions of theologians and schoolmen, in regard to cosmogony. He had, +forsooth, denied that the visible firmament was a solid azure-colored +shell, to which the sun and planets were fastened, and through whose +opened doors the rain descended. He had proved that the sun was the +center of the system, around which the earth and planets revolved, and, +with his clear scientific vision, he had been able to gain glimpses, at +least, of the grand conceptions of modern astronomy: For this man was +Nicolas Copernicus, and the expected book was his great work--"De Orbium +Coelestium Revolutionibus"--destined to form the broad basis of +astronomical science. + +The work was printing at Nuremberg, and the last proofs had been +returned; but reports had come that a similar outburst of fanaticism was +raging at that place, that a mob had burned the manuscript on the public +square, and had threatened to break the press should the printing +proceed. But, thanks to God! the old man was not to die before the hour +of triumph came. While still conscious, a horse, covered with foam, +gallops to the door of his humble dwelling, and an armed messenger +enters the chamber, who, breathless with haste, places in the hands of +the dying man a volume still wet from the press. He has only strength to +return a smile of recognition, and murmur the last words: + + "Nunc dimittis servum tuum, Domine." + +Grand close of a noble life! The seed has been sown--what could we +desire more? + +Again the centuries roll on--not one, but three--while the seed grows to +a great tree, which overshadows the nations. Great minds have never been +wanting to cherish and prime it, like Tycho Brahe and Kepler, Galileo +and Newton, Laplace and Lagrange; and although at times some, while +lingering in the deep shade of the foliage, may have lost sight of the +summit, the noble tree has ever pointed upward to direct aspiration and +encourage hope. + +On the evening of the 24th of September, 1846, in the Observatory of +Berlin, a trained astronomical observer was carefully measuring the +position of a faint star in the constellation Capricorn. Only the day +before, he had received from Le Verrier a letter announcing the result +of that remarkable investigation which has made the name of this +distinguished French astronomer so justly celebrated. By the studies of +the great men who succeeded Copernicus, his system had become so +perfected as to enable the astronomer to predict, with unerring +certainty, the paths of the planets through the heavens. But there was +one failing case. The planet Uranus, then supposed to be the outer +planet of the solar system, wandered from the path which theory assigned +to it; and although the deviations were but small, yet any discrepancy +between theory and observation in so accurate a science as astronomy +could not be overlooked. + +Long before this, the hypothesis had been advanced that the deviations +were caused by the attractive force of an unseen and still more distant +planet; but, as no such planet had been discovered, the hypothesis had +remained until now wholly barren. The hypothesis, however, was +reasonable, and furnished the only conceivable explanation of the facts; +and, moreover, if true, the received system of astronomy ought to be +able to assign the position and magnitude of the disturbing body, the +magnitude and direction of the displacements being given. + +This possibility was generally appreciated by astronomers, and the very +great length and difficulty of the mathematical calculation which the +investigation involved was probably the reason that no one had hitherto +undertaken it. Le Verrier, however, had both the courage and the +youthful strength required for the work. And now the great work had been +done; and, on the 18th of September, Le Verrier had sent to the +Observatory of Berlin his communication announcing the final result, +namely, that the planet would be found about 5° to the east of the star +Delta of Capricorn. + +The letter containing this announcement was received by Galle, at +Berlin, on the 23d, and it was Galle whom we left measuring the position +of that faint star on the evening of the 24th. It so happened that a +chart of that portion of the heavens had recently been prepared by the +Berlin Observatory, and was on the eve of publication; and, on the very +evening he received the letter, Galle had found, near the position +assigned by Le Verrier, a faint star, which was not marked on this +chart. The object differed in appearance from the surrounding stars, but +still it was perfectly possible that it might be a fixed star which had +escaped previous observation. + +But, if a fixed star, its position in the constellation would not vary, +while, if a planet, a single night would show a perceptible change of +place. Hence, you may conceive of the interest with which Galle was +measuring anew its position on the evening of the 24th. + +The star had moved, and in the direction which theory indicated; and for +once, at least, the world rang with applause at a brilliant scientific +conquest from which there was not one cent of money to be made. Yet, was +that conquest any less important to the world? What had it secured? It +had confirmed the theory of astronomy which Copernicus and his +successors had built up, and it had clinched the last nail in the proof +that those grand conceptions of modern astronomy, now household +thoughts, are realities, and not dreams. Certainly no military conquest +can compare with this. + +Do not smile at the enthusiasm which rates so high a purely intellectual +achievement? Go out with me under the heavens, in some starlight night, +and, looking up into the depths of space, recall the truths you have +learned in regard to that immensity, and allow the imagination free +scope as it stretches out into the infinitudes of time, space, and +power, carrying the mind on, bound by bound, through the limitless +expanse, until even the imagination refuses to follow, and fairly quails +before the mighty form of the Infinite, which rises to confront it! +Remember now that your forefathers, of only a few centuries back, saw +there nothing but a solid dome hemming in the earth and skies, and that +you are able to look upon this grand spectacle only because great minds +have lived who have opened your intellectual eyes; and then answer me, +is not this result worth all the labor, all the sacrifice, all the +treasure it has cost? + +Every educated man, who has not sold his birthright for a mess of +pottage, lives a grander and nobler life, because the great astronomers +have thought and taught, and this elevation of human life is the +greatest achievement of which man can boast. Before it all material +conquests appear of little worth, and the lustre of all military or +civil glory grows dim. Cherish this intellectual life; foster it; +sustain it; do what you can by your own spirit and influence, and, if +you are blessed with riches, give of your abundance to support and +encourage those who, by genius, talent, and devotion, will widen the +intellectual kingdom. Be assured you will thus help to confer an +inestimable boon on your race and on your country; and the influence for +good will not be felt by the intellectual life of the nation only. That +corruption which is now festering at the heart of our body politic, and +threatening its destruction, can in no way be fought and conquered so +effectually as by keeping constantly before the nation noble and high +ideals; for, where the higher life is cherished and honored, the +mercenary and sensual motives of action, which both invite and shield +corruption, lose much of their force and power. + +But you may tell me that there is a life higher than the intellectual +life, and that I have ascribed to science and scholarship influences +which come only from a source which I have forgotten, or left out of +view. My friends, all truth is one and inseparable, and I have therefore +made no distinction in this address between the truths of science and +truths of religion. The grand old word knowledge, as I have used it, +includes both, and, in just the proportion that you reverence religion, +you must reverence also true science. All truth is God's truth, and, in +praying for the coming of his kingdom, you certainly do not expect that +Nature will be divorced from Grace. If the truths of religion required a +special revelation, it must be expected that they would transcend human +intelligence. These very conditions imply conflict, but the conflict +comes not from the knowledge, but from the ignorance and conceit of men; +and the only proper attitude for the devout scholar is "to labor and to +wait." And what more wonderful confirmation could we have of the +essential unity of the two phases of truth than is to be found in the +fact that the characteristic of science, which I have been endeavoring +to illustrate in this address, is the great prominent feature of +Christianity? Christianity was revealed in a life, and ever abides a +life in the soul of man, to purify, ennoble, and redeem humanity. + + "And so the Word had breath, and wrought, + With human hands, the creed of creeds, + In loveliness of perfect deeds, + More strong than all poetic thought-- + + "Which he may read that binds the sheaf, + Or builds the house, or digs the grave, + And those wild eyes that watch the wave, + In roarings round the coral reef." + + + + +III. + +THE ELEMENTARY TEACHING OF PHYSICAL SCIENCE. + + _An Address to the Schoolmasters of Boston, delivered + February 4, 1878._ + + +I felt a great reluctance at accepting the invitation of your excellent +superintendent to address you on this occasion; for, although I could +claim an unusually long experience in presenting the elements of +physical science to college students, I was fully conscious that I knew +little of the conditions under which such subjects must be studied, if +at all, in the elementary schools, and was therefore in danger of +appearing in a capacity which I should most sedulously shun, that of a +babbler about impracticable theories of education. It is very easy to +criticize another man's labor, and such criticisms, however plausible, +do the grossest injustice when, as is often the case, they leave out of +view the necessary conditions and limitations under which the work must +be done. While, however, I felt most keenly my incapacity to deal with +many of the practical problems which you have to solve, yet, on +consideration, I concluded that it was my duty under the circumstances +to state as clearly and forcibly as I could the very definite opinions +which I had formed on the subject you are discussing, knowing that you +will only give such weight to these opinions as your mature judgment can +allow. In stating the results of my experience, I can not avoid a +certain personal element, which would be wholly inexcusable were it not +that the facts, as I think you will admit, form the basis of my +argument. + +I am a Boston boy, born in this immediate neighborhood, and fitted for +college at the "Latin School." It so happened that, while I was very +unsuccessfully endeavoring to commit to memory, in the old school-house +on School Street, Andrews and Stoddard's Latin grammar, not one word of +which I could understand, the "Lowell Institute" lectures were opened at +the "Odeon" on Congress Street. At those lectures I got my first taste +of real knowledge, and that taste awakened an appetite which has never +yet been satisfied. As a boy, I eagerly sought the small amount of +popular science which the English literature of that day afforded; and I +can now distinctly recall almost every page of Mrs. Marcet's +"Conversations on Chemistry," which was the first book on my science +that I ever read. More to the point than this, a boy's pertinacity, +favored by a kind father's indulgence, found the means of repeating, in +a small way, most of the experiments first seen at the Lowell Institute +lecture; and thus it came to pass that, before I entered college, I had +acquired a real, available knowledge of the facts of chemistry; +although, with much labor and intense weariness, I had gained only a +formal knowledge of those subjects which were then regarded as the only +essential preparation for the college course. In college, my attention +was almost exclusively devoted to other studies--for, in my day at +Cambridge, chemistry was one of the lost arts. But when, the year after +I graduated, I was most unexpectedly called upon to give my first course +of lectures, the only laboratory in which I had worked was the shed of +my father's house on Winthrop Place, and the only apparatus at my +command was what this boy's laboratory contained. With these simple +tools, or, as I should rather say, because they were so simple, I gained +that measure of success which determined my subsequent career. + +I feel that I owe you a constant apology for these personal details, and +I should not be guilty of them did I not believe that they establish two +points more conclusively than I could prove them in any other way. +First, that it is perfectly possible for a child before fifteen years +of age to acquire a real and living knowledge of the fundamental facts +of nature on which physical science is based. Secondly, that this +knowledge can be effectually gained by the use of the simplest tools. +Let me add that this is not a question of natural endowments or special +aptitudes, for every one who has studied from the love of knowledge has +had the same experience; and I do not believe that, if my first taste of +real knowledge had been of history, nay, I will even say, of philology, +instead of chemistry, the circumstance would have materially influenced +my success in life, however different the direction into which it might +have turned my study. My early tastes were utterly at variance with all +my surroundings and all my inheritances, and were simply determined by +the accident which first satisfied that natural thirst for knowledge +which every child experiences to a greater or less degree--a desire most +rudely repressed in our usual methods of teaching. + +My bitter experience as a pupil in the Boston Latin School and my +subsequent more fortunate experience of thirty years as a teacher in +Harvard College have impressed me most profoundly with the conviction +that the only way to arouse and sustain a love for knowledge in children +is to cultivate their perceptive faculties. To present the rudiments of +knowledge to immature minds in an abstract form, whether the subject be +grammar or physical science, is, in my judgment, not only culpable +folly, but also downright wrong. And, if, to those who have been +accustomed to the long established routine of our public school, my +opinions may appear revolutionary and extreme, I am, nevertheless, sure +that they would receive the universal assent of the men whom all would +recognize as the foremost scientific teachers of the world. I can well +remember that when, many years ago, the late Professor Agassiz declared +in my hearing that he would have no text-books used in his museum, I +thought his plan of pure object-teaching chimerical in the extreme, and +yet experience has not only convinced me of the wisdom of his judgment +in regard to the teaching of natural history, but brought me to a +similar conclusion in regard to the elementary teaching both of natural +philosophy and of chemistry. + +Allow me then to express my firm persuasion that it is not only useless +but injurious to the education of young minds to present to them at the +outset any department of physical science as a body of definitions, +principles, laws, or theories; and that in elementary schools only such +facts should be taught as can be verified by the experience of the +pupil, or by such simple experiments as the pupils can try for +themselves. The usual method of committing by heart the words of a +school-book, and repeating them at the dictation of a teacher, may +afford a good exercise for the memory, but it is absurd to regard such a +task as a lesson in physical science, and this kind of study can be +spent with vastly greater profit on the spelling-book. + +There is one department of physical science which has been taught in +this absurd way in our schools from time immemorial. I refer, of course, +to the study of geography, and I leave for you to judge whether the +result is worth the one hundredth part of the toil and drudgery spent in +obtaining it. Let us suppose that your child is able to give you the +names of all the rivers, bays, and capes from Greenland to Patagonia, +how much more does that child know of the structure and social relations +of this globe on which its lot has been cast than it did before this +senseless feat was attempted, a feat, moreover, to which only a child's +memory would be equal? And, when you turn to your own experience, what +is the outcome of all the time and labor spent on geography? Is it not +solely just that portion of your knowledge which, in spite of the +system, was direct object-teaching--the images you insensibly acquired +from the maps and pictures in the school-books? + +But there is a very different way of teaching geography, by which the +study may be made a pleasure, not a task. The teacher does not begin +with abstract definitions of rivers, and bays, and oceans, which convey +no definite meaning to a child, but with Charles River, Boston Harbor, +and the Atlantic Ocean, which are to him real things, however imperfect +his conceptions of their extent. The child is first shown, not a map of +the globe, which he can not by any possibility understand, but a map of +a very limited region around his own home. He is taught how to find the +north and south, the east and west directions. He is encouraged to make +excursions to verify the map, or to add to its details, and such +excursions may be made to have for him all the zest of voyages of +discovery; and when thus the rudiments of geographical science have been +mastered, not in technical terms, but in substance, then the teacher may +begin to expand the horizon of the pupil's knowledge, judiciously +omitting details in proportion as distance increases, until at length +the general survey embraces the globe. Of course, such teaching as this +can only be given orally with the help of proper apparatus, such as wall +maps, and globes, and photographs. It must take the interrogative form, +and the questions should be directed to bring out the child's already +acquired knowledge, and to lead him to observe facts which had hitherto +escaped his notice. What a child reads in a book, or even what you tell +him, is never one half learnt, unless his interest is aroused. But what +a child observes for himself he never forgets, and when you have thus +aroused his interest you can associate a large number of facts with one +observation, and these all crystallize in his memory around this +nucleus. + +This is no mere theory, no untried method which I am advocating. So far +from it, I am describing the precise method which has been used for many +years in Germany, where the science of education is far better +understood than with us, and where economy both of time and labor in +teaching is most carefully studied. If our school committees could +attend and understand a single exercise in geography, such as are daily +given in the elementary schools of Prussia, I am sure that at least one +form of child torture would soon disappear from the primary schools of +this country. Indeed, I already see evidence of a growing public opinion +on this subject, an effect which I trace in no small measure to the +influence of the Department of Education of the Exhibition at +Philadelphia in 1876. + +That which is true of geography applies with still greater force to such +subjects as physics and chemistry, since the abstract conceptions which +these sciences involve are more abstruse, and the language by which the +conceptions are expressed or defined far less plain than is the case +with the older and more descriptive branch of knowledge. Hence, as +sciences, properly so called, that is, as philosophical systems, they +have no place whatever in elementary education. But, underlying these +systems, there is a great multitude of phenomena which a child can be +led to observe and apprehend as readily as the facts of geography. Take +that subject--mechanics--which our ordinary school-books very +philosophically but most unpractically place at the beginning of what +they call "Natural" Philosophy. How many of the fundamental facts of +this difficult subject can be made familiar to a child? Select, as an +example, Newton's "First Law of Motion." Suppose you make a boy memorize +the ordinary rule, "Every body continues in a state of rest or of +uniform motion in a straight line until acted upon by some external +force," how much will he know about it? Suppose you make him do a lot of +problems involving distances, velocities, and times, will he know any +more about it? But ask him, "Can you pitch a ball as well as your +playmate?" and he answers at once, "No; John is stronger than I am." And +then, if again you ask, "Can you catch John's ball?" he will probably +reply, "Of course, not! It requires a boy as strong as John to catch his +balls." And thus, by a few well-directed questions, you would bring that +boy to learn a lesson which he would never forget, and which he would +recall every time he played base-ball; namely, that John's swift balls +could not be set in motion without an expenditure of a definite amount +of muscular effort, and could not be stopped without the exertion of an +equal amount of what, after a while, you could get him to call _force_. +From the ball you would naturally pass to the railroad train or the +steamboat, and I should not wonder if, with a little patience, you could +bring even a boy to understand that motion can not be maintained against +a resistance, in other words, that work can not be done without a +constant expenditure of muscular effort, or of some other source of +power; and it is a fond hope of mine that by the time these boys grow +into men our intelligent New England community might become so far +educated in the elementary principles of mechanics that no +self-sustained motors, nor other mechanical nostrums which claim to have +superseded the primeval curse--if that law was a curse, which compels +man to earn his bread with the sweat of his brow--will receive the +sanction of our respectable journals; and then--if they have not +previously learned the lesson by dire experience--we may hope to +persuade our people of the parallel and equally elementary principle of +political economy, that value can not be legislated into rags. + +But, my friends, our subject gives no occasion for banter, and presents +aspects too serious to be treated lightly or in jests. As inhabitants of +a not over-fruitful land, and, therefore, members of a community which +must excel, if at all, solely by its enterprise and intelligence, we +have a duty to our children which we can not avoid, if we would, and for +which we shall be held responsible by our posterity. These children are +entering life surrounded not only by all the wonders and glories of +nature, but, also, by giant conditions, which, whether stationed on +their path as a blessing or a curse, will inevitably strike if their +behests are not obeyed. So far as science has been able to define these +giant forms, it is our duty, as it is our privilege, to point them out +to those we are bound to protect and guide; and in many cases it is in +our power to change the curse into a blessing, and to transform the +destructive demon into a guardian angel. After that command of language +which the necessities of civilized life imperatively require, there is +no acquisition which we can give our children that will exert so +important an influence on their material welfare as a knowledge of the +laws of nature, under which they must live and to which they must +conform; and throughout whose universal dominion the only question is +whether men shall grovel as ignorant slaves or shall rule as intelligent +servants. Yes; rule by obeying. "Ich Dien"; for only under that motto, +which, five hundred years ago, the great Black Prince bore so +victoriously through the fields of Cressy and Poitiers, can man ever +rule in Nature's kingdom. + +I regard it, therefore, as the highest duty and the most enlightened +self-interest of a community like this to provide the best means for the +instruction of its children in the elements of physical science; and I +was, therefore, most anxious to do all in my power to second the +enlightened efforts of your eminent Superintendent in this direction. +You must remember, however, that the best tools are worthless in +themselves, and can secure no valuable results unless judiciously used. +Indeed, there is danger in too many tools, and I have a great horror of +that array of brass-work which is usually miscalled "philosophical" +apparatus. The greater part of this is, in my opinion, a mere hindrance +to the teacher, because it at once erects a barrier between the scholar +and the simple facts of nature, and the child inevitably associates with +the phenomenon illustrated some legerdemain, and looks on your +experiments very much as he would on the exhibition of a Houdin or a +Signor Blitz. The secret of success in teaching physical science is to +use the simplest and most familiar means to illustrate your point. + +When a very young man I was favored with an introduction to Michael +Faraday, and had the privilege of attending a portion of a course of +lectures which this noble man was then in the habit of giving every +Christmas season to a juvenile auditory at the Royal Institution of +London. As a boy, I had become familiar with lectures on chemistry at +the Lowell Institute, where they did not lack the pomp of circumstance +or the display of apparatus, and I had come to associate these elements +with the conditions of success in lectures of this kind. What, then, was +my surprise to find Faraday, the acknowledged leader of the world in his +science, and who had every means of illustration at his command, using +the plainest language and the simplest tools. When, in my youthful +admiration at the result, I expressed, after one of the lectures, my +surprise at the simplicity of the means employed, the great master +replied: "That is the whole secret of interesting these young people. I +always use the simplest means, but I never leave a point not +illustrated. If I mention the force of gravitation I take up a stone and +let it drop." At this distance of time, I can not be sure that I quote +his exact language, but the lesson and the illustration I could not +forget; and to this lesson, more than to any other one thing, I owe +whatever success I have had as a teacher of physical science. + +I repeat, therefore, it is not only useless but injurious in the +education of young minds to present any department of physical science +as a body of definitions, principles, laws, or theories; and that in +elementary schools such facts only should be taught as can be verified +either by the experience of the pupils or by the simplest experiments, +which the pupils can repeat by themselves; and now, after this +discussion, I add, that the teacher must depend on his own ingenuity for +his experiments, and on his intercourse with his pupils for his +instruction. + +But you will tell me all this involves grave difficulties, and +conditions incompatible with our ordinary school life. I freely admit +the difficulties, but I am none the less sure that, unless science can +be taught on the principles I have endeavored to illustrate, it had +better not be taught at all. I know very well that the proper teaching +of physical science is wholly incompatible with our usual school +methods. But this only proves to me that these methods ought to be +changed, and I am persuaded that the changes required will benefit the +literary and classical as well as the scientific courses of study. For +do not the same general principles apply to the acquisition of knowledge +in all subjects? And when a child's perceptive faculties have been duly +stimulated, and his intelligence fully awakened, he will find interest +in grammar, in literature, or in history, as well as in science. + +In repelling the reproach of narrowness, to which our elective system at +Cambridge undoubtedly frequently leads, how often have I urged the +self-evident proposition that to arouse a love of study in any subject, +I care not how subordinate its importance or how limited its scope, is +to take the first step toward making your man a scholar; while to fail +to gain his interest in any study is to lose the whole end of +education--and what is true of the man is still more true of the child. +Classical culture on the one hand and scientific culture on the other +are excellent things, but, if your boy can not be made to take an +interest either in classics or in science, how plain it is that such +treasures are not for him, and, in the absence of the one condition +which can give value to any study, how idle and inconsequent all +questions in regard to the relative merits of these studies appear! On +the other hand, a love of study once gained, all studies are alike good. + +And as with the pupil, so with the teacher. No teaching is of any real +value that does not come directly from the intelligence, and heart of +the teacher, and thus appeals to the intelligence and heart of the +pupil. It, of course, implies more acquisition, and it requires far more +energy to teach from one's own knowledge than to teach from a book, but +then, just in proportion to the difficulties overcome, does the teacher +raise his profession and ennoble himself. There is no nobler service +than the life of a true teacher; but the mere task-master has no right +to the teacher's name, and can never attain the teacher's reward. + + + + +IV. + +THE RADIOMETER: A FRESH EVIDENCE OF A MOLECULAR UNIVERSE. + + _A Lecture delivered in the Sanders Theatre of Harvard + University, March 6, 1878._ + + +No one who is not familiar with the history of physical science can +appreciate how very modern are those grand conceptions which add so much +to the loftiness of scientific studies; and, of the many who, on one of +our starlit nights, look up into the depths of space, and are awed by +the thoughts of that immensity which come crowding upon the mind, there +are few, I imagine, who realize the fact that almost all the knowledge +which gives such great sublimity to that sight is the result of +comparatively recent scientific investigation; and that the most +elementary student can now gain conceptions of the immensity of the +universe of which the fathers of astronomy never dreamed. And how very +grand are the familiar astronomical facts which the sight of the starry +heavens suggests! + +Those brilliant points are all suns like the one which forms the center +of our system, and around which our earth revolves; yet so inconceivably +remote, that, although moving through space with an incredible velocity, +they have not materially changed their relative position since recorded +observations began. Compared with their distance, the distance of our +own sun--92,000,000 miles--seems as nothing; yet how inconceivable even +that distance is when we endeavor to mete it out with our terrestrial +standards! For if, when Copernicus--the great father of modern +astronomy--died, in 1543, just at the close of the Protestant +Reformation, a messenger had started for the sun, and traveled ever +since with the velocity of a railroad train--thirty miles an hour--he +would not yet have reached his destination! + +Evidently, then, no standards, which, like our ordinary measures, bear a +simple or at least a conceivable relation to the dimensions of our own +bodies, can help us to stretch a line in such a universe. We must seek +for some magnitude which is commensurate with these immensities of +space; and, in the wonderfully rapid motion of light, astronomy +furnishes us with a suitable standard. By the eclipses of Jupiter's +satellites the astronomers have determined that this mysterious +effluence reaches us from the sun in eight minutes and a half, and +therefore must travel through space with the incredible velocity--shall +I dare to name it?--of 186,000 miles in a second of time! Yet, +inconceivably rapid as this motion is, capable of girdling the earth +nearly eight times in a single second, the very nearest of the fixed +stars, [alpha] Centauri, is so remote that the light by which it will +be seen in the southern heavens to-night, near that magnificent +constellation, the Southern Cross, must have started on its journey +three years and a half ago. But this light comes from merely the +threshold of the stellar universe; and the telescope reveals to us stars +so distant that, had they been blotted out of existence when history +began, the tidings of the event could not yet have reached the earth! + +Compare now with these grand conceptions the popular belief of only a +few centuries back. Where we look into the infinite depths, our Puritan +forefathers saw only a solid dome hemming in the earth and skies, and +through whose opened doors the rain descended. They regarded the sun and +moon merely as great luminaries set in this firmament to rule the day +and night, and to their understandings the stars served no better +purpose than the spangles which glitter on the azure ceiling of many a +modern church. The great work of Copernicus, "De Orbium Coelestium +Revolutionibus," which was destined, ultimately, to overthrow the crude +cosmography which Christianity had inherited from Judaism, was not +published until just at the close of the author's life in 1543, the date +before mentioned. The telescope, which was required to fully convince +the world of its previous error, was not invented until more than half a +century later, and it was not until 1835 that Struve detected the +parallax of [alpha] Lyrć. The measurement of this parallax, together +with Bessel's determination of the parallax of 61 Cygni, and Henderson's +that of [alpha] Centauri, at about the same time, gave us our first +accurate knowledge of the distances of the fixed stars. + +To the thought I have endeavored to express, I must add another, before +I can draw the lesson which I wish to teach. Great scientific truths +become popularized very slowly, and, after they have been thoroughly +worked out by the investigators, it is often many years before they +become a part of the current knowledge of mankind. It was fully a +century after Copernicus died, with his great volume--still wet from the +press of Nuremberg--in his hands, before the Copernican theory was +generally accepted even by the learned; and the intolerant spirit with +which this work was received and the persecution which Galileo +encountered more than half a century later were due solely to the +circumstance that the new theory tended to subvert the popular faith in +the cosmography of the Church. In modern times, with the many popular +expositors of science, the diffusion of new truth is more rapid; but +even now there is always a long interval after any great discovery in +abstract science before the new conception is translated into the +language of common life, so that it can be apprehended by the mass even +of educated men. + +I have thus dwelt on what must be familiar facts in the past history of +astronomy, because they illustrate and will help you to realize the +present condition of a much younger branch of physical science; for, in +the transition period I have described, there exists now a conception +which opens a vision into the microcosmos beneath us as extensive and as +grand as that which the Copernican theory revealed into the macrocosmos +above us. + +The conception to which I refer will be at once suggested to every +scientific scholar by the word _molecule_. This word is a Latin +diminutive, which means, primarily, a small mass of matter; and, +although heretofore often applied in mechanics to the indefinitely small +particles of a body between which the attractive or repulsive forces +might be supposed to act, it has only recently acquired the exact +significance with which we now use it. + +In attempting to discover the original usage of the word molecule, I +was surprised to find that it was apparently first introduced into +science by the great French naturalist, Buffon, who employed the term in +a very peculiar sense. Buffon does not seem to have been troubled with +the problem which so engrosses our modern naturalists--how the vegetable +and animal kingdoms were developed into their present condition--but he +was greatly exercised by an equally difficult problem, which seems to +have been lost sight of in the present controversy, and which is just as +obscure to-day as it was in Buffon's time, at the close of the last +century, and that is, Why species are so persistent in Nature; why the +acorn always grows into the oak, and why every creature always produces +of its kind. And, if you will reflect upon it, I am sure you will +conclude that this last is by far the more fundamental problem of the +two, and one which necessarily includes the first. That, of two eggs, in +which no anatomist can discover any structural difference, the one +should, in a few short years, _develop_ an intelligence like Newton's, +while the other soon ends in a Guinea-pig, is certainly a greater +mystery than that, in the course of unnumbered ages, monkeys, by +insensible gradations, should _grow_ into men. + +In order to explain the remarkable constancy of species, Buffon advanced +a theory which, when freed from a good deal that was fanciful, may be +expressed thus: The attributes of every species, whether of plants or +of animals, reside in their ultimate particles, or, to use a more +philosophical but less familiar word, _inhere_ in these particles, which +Buffon names _organic molecules_. According to Buffon, the oak owes all +the peculiarities of its organization to the special oak molecules of +which it consists; and so all the differences in the vegetable or animal +kingdom, from the lowest to the highest species, depend on fundamental +peculiarities with which their respective molecules were primarily +endowed. There must, of course, be as many kinds of molecules as there +are different species of living beings; but, while the molecules of the +same species were supposed to be exactly alike, and to have a strong +affinity or attraction for each other, those of different species were +assumed to be inherently distinct and to have no such affinities. Buffon +further assumed that these molecules of organic nature were diffused +more or less widely through the atmosphere and through the soil, and +that the acorn grew to the oak simply because, consisting itself of oak +molecules, it could draw only oak molecules from the surrounding media. + +With our present knowledge of the chemical constitution of organic +beings, we can find a great deal that is both fantastic and absurd in +this theory of Buffon; but it must be remembered that the science of +chemistry is almost wholly a growth of the present century, while +Buffon died in 1788; and, if we look at the theory solely from the +standpoint of his knowledge, we shall find in it much that was worthy of +this great man. Indeed, in our time, the essential features of the +theory of Buffon have been transferred from natural history to chemistry +almost unchanged. + +According to our modern chemistry, the qualities of every substance +reside or inhere in its molecules. Take this lump of sugar. It has +certain qualities with which every one is familiar. Are those qualities +attributes of the lump or of its parts? Certainly of its parts; for, if +we break up the lump, the smallest particles will still taste sweet and +show all the characteristics of sugar. Could we, then, carry on this +subdivision indefinitely, provided only we had senses or tests delicate +enough to recognize the qualities of sugar in the resulting particles? +To this question, modern chemistry answers decidedly, No! You would +before long reach the smallest mass that can have the qualities of +sugar. You would have no difficulty in breaking up these masses, but you +would then obtain, not smaller particles of sugar, but particles of +those utterly different substances which we call carbon, oxygen, and +hydrogen--in a word, particles of the elementary substances of which +sugar consists. These ultimate particles of sugar we call the molecules +of sugar, and thus we come to the present chemical definition of a +molecule, "_The smallest particles of a substance in which its qualities +inhere_," which, as you see, is a reproduction of Buffon's idea, +although applied to matter and not to organism. + +A lump of sugar, then, has its peculiar qualities because it is an +aggregate of molecules which have those qualities, and a lump of salt +differs from a lump of sugar simply because the molecules of salt differ +from those of sugar, and so with every other substance. There are as +many kinds of molecules in Nature as there are different substances, but +all the molecules of the same substance are absolutely alike in every +respect. + +Thus far, as you see, we are merely reviving in a different association +the old ideas of Buffon. But just at this point comes in a new +conception, which gives far greater grandeur to our modern theory: for +we conceive that those smallest particles in which the qualities of a +substance inhere are definite bodies or systems of bodies moving in +space, and that _a lump of sugar is a universe of moving worlds_. + +If on a clear night you direct a telescope to one of the many +star-clusters of our northern heavens, you will have presented to the +eye as good a diagram as we can at present draw of what we suppose +would, under certain circumstances, be seen in a lump of sugar if we +could look into the molecular universe with the same facility with +which the telescope penetrates the depths of space. + +Do you tell me that the absurdities of Buffon were wisdom when compared +with such wild speculations as these? The criticism is simply what I +expected, and I must remind you that, as I intimated at the outset, this +conception of modern science is in the transition period of which I then +spoke, and, although very familiar to scientific scholars, has not yet +been grasped by the popular mind. I can further only add that, wild as +it may appear, the idea is the growth of legitimate scientific +investigation, and express my conviction that it will soon become as +much a part of the popular belief as those grand conceptions of +astronomy to which I have referred. + +Do you rejoin that we can see the suns in a stellar cluster, but can not +even begin to see the molecules? I must again remind you that, in fact, +you only see points of light in the field of the telescope, and that +your knowledge that these points are immensely distant suns is an +inference of astronomical science; and, further, that our knowledge--if +I may so call our confident belief--that the lump of sugar is an +aggregate of moving molecules is an equally legitimate inference of +molecular mechanics, a science which, although so much newer, is as +positive a field of study as astronomy. Moreover, sight is not the only +avenue to knowledge; and, although our material limitations forbid us to +expect that the microscope will ever be able to penetrate the molecular +universe, yet we feel assured that we have been able by strictly +experimental methods to weigh molecular masses and measure molecular +magnitudes with as much accuracy as those of the fixed stars. + +Of all forms of matter the gas has the simplest molecular structure, +and, as might be anticipated, our knowledge of molecular magnitudes is +as yet chiefly confined to materials of this class. I have given below +some of the results which have been obtained in regard to the molecular +magnitudes of hydrogen gas, one of the best studied of this class of +substances; and, although the vast numbers are as inconceivable as are +those of astronomy, they can not fail to impress you with the reality of +the magnitudes they represent. I take hydrogen gas for my illustration +rather than air, because our atmosphere is a mixture of two gases, +oxygen and nitrogen, and therefore its condition is less simple than +that of a perfectly homogeneous material like hydrogen. The molecular +dimensions of other substances, although varying very greatly in their +relative values, are of the same order of magnitude as these.[A] + + [A] As some of the readers of this volume may be interested to + compare these values, we reproduce the "Table of Molecular Data" + from Professor Clerk Maxwell's lecture on "Molecules," delivered + before the British Association at Bradford, and published in + "Nature," September 25, 1873. + + _Molecular Magnitudes at Standard Temperature and Pressure, 0° C. + and 76 c. m._ + + -----------------------+-----------+---------+----------+--------- + RANK ACCORDING TO | Hydrogen. | Oxygen. | Carbonic | Carbonic + ACCURACY OF KNOWLEDGE. | | | Oxide. | Dioxide. + -----------------------+-----------+---------+----------+--------- + RANK I. | | | | + Relative mass | 1 | 16 | 14 | 22 + Velocity in metres | | | | + per second | 1,859 | 465 | 497 | 396 + | | | | + RANK II. | | | | + Mean path in ten | | | | + billionths (10^{-10})| | | | + of a metre | 965 | 560 | 482 | 379 + Collisions each | | | | + second--number of | | | | + millions | 17,750 | 7,646 | 9,489 | 9,720 + | | | | + RANK III. | | | | + Diameter in hundred | | | | + billionths (10^{-11})| | | | + of a metre | 58 | 76 | 83 | 93 + Mass in ten million | | | | + million million | | | | + millionths (10^{-25})| | | | + of a gramme | 46 | 736 | 644 | 1,012 + -----------------------+-----------+---------+----------+--------- + + Number of molecules in one cubic centimetre of every gas is + nineteen million million million on 19 (10^{18}). + + Two million hydrogen molecules side by side measure a little + over one millimetre. + +_Dimension of Hydrogen Molecules calculated for Temperature of Melting +Ice, and for the Mean Height of the Barometer of the Sea Level:_ + + Mean velocity, 6,099 feet a second. + Mean path, 31 ten-millionths of an inch. + Collisions, 17,750 millions each second. + Diameter, 438,000, side by side, measure 1/100 of an inch. + Mass, 14 (millions^3) weigh 1/1000 of a grain. + Gas-volume, 311 (millions^3) fill one cubic inch. + +To explain how the values here presented were obtained would be out of +place in a popular lecture,[B] but a few words in regard to two or +three of the data are required to elucidate the subject of this lecture. + + [B] _See_ Professor Maxwell's lecture, _loc. cit._; also, Appletons' + "Cyclopćdia," article "Molecules." + +First, then, in regard to the mass or weight of the molecules. So far as +their relative values are concerned, chemistry gives us the means of +determining the molecular weights with very great accuracy; but when we +attempt to estimate their weights in fractions of a grain--the smallest +of our common standards--we can not expect precision, simply because the +magnitudes compared are of such a different order; and the same is true +of most of the other absolute dimensions, such as the diameter and +volume of the molecules. We only regard the values given in our table as +a very rough estimate, but still we have good grounds for believing that +they are sufficiently accurate to give us a true idea of the order of +the quantities with which we are dealing; and it will be seen that, +although the numbers required to express the relations to our ordinary +standards are so large, these molecular magnitudes are no more removed +from us on the one side than are those of astronomy on the other. + +Passing next to the velocity of the molecular motion, we find in that a +quantity which, although large, is commensurate with the velocity of +sound, the velocity of a rifle-ball, and the velocities of many other +motions with which we are familiar. We are, therefore, not comparing, as +before, quantities of an utterly different order, and we have confidence +that we have been able to determine the value within very narrow limits +of error. But how surprising the result is! Those molecules of hydrogen +are constantly moving to and fro with this great velocity, and not only +are the molecules of all aëriform substances moving at similar, although +differing rates, but the same is equally true of the molecules of every +substance, whatever may be its state of aggregation. + +The gas is the simplest molecular condition of matter, because in this +state the molecules are so far separated from each other that their +motions are not influenced by mutual attractions. Hence, in accordance +with the well-known laws of motion, gas molecules must always move in +straight lines and with a constant velocity until they collide with each +other or strike against the walls of the containing vessel, when, in +consequence of their elasticity, they at once rebound and start on a new +path with a new velocity. In these collisions, however, there is no loss +of motion, for, as the molecules have the same weight and are perfectly +elastic, they simply change velocities, and whatever one may lose the +other must gain. + +But, if the velocity changes in this way, you may ask, What meaning has +the definite value given in our table? The answer is, that this is the +mean value of the velocity of all the molecules in a mass of hydrogen +gas under the assumed conditions; and, by the principle just stated, the +mean value can not be changed by the collisions of the molecules among +themselves, however great may be the change in the motion of the +individuals. + +In both liquids and solids the molecular motions are undoubtedly as +active as in a gas, but they must be greatly influenced by the mutual +attractions which hold the particles together, and hence the conditions +are far more complicated, and present a problem which we have been able +to solve only very imperfectly, and with which, fortunately, we have not +at present to deal. + +Limiting, then, our study to the molecular condition of a gas, picture +to yourselves what must be the condition of our atmosphere, with its +molecules flying about in all directions. Conceive what a molecular +storm must be raging about us, and how it must beat against our bodies +and against every exposed surface. The molecules of our atmosphere move, +on an average, nearly four (3ˇ8) times slower than those of hydrogen +under the same conditions; but then they weigh, on an average, fourteen +and a half times more than hydrogen molecules, and therefore strike with +as great energy. And do not think that the effect of these blows is +insignificant because the molecular projectiles are so small; they make +up by their number for what they want in size. + +Consider, for example, a cubic yard of air, which, if measured at the +freezing-point, weighs considerably over two pounds. That cubic yard of +material contains over two pounds of molecules, which are moving with an +average velocity of 1,605 feet a second, and this motion is equivalent, +in every respect, to that of a cannon-ball of equal weight rushing along +its path at the same tremendous rate. Of course, this is true of every +cubic yard of air at the same temperature; and, if the motion of the +molecules of the atmosphere around us could by any means be turned into +one and the same direction, the result would be a hurricane sweeping +over the earth with this velocity--that is, at the rate of 1,094 miles +an hour--whose destructive violence not even the Pyramids could +withstand. + +Living as we do in the midst of a molecular tornado capable of such +effects, our safety lies wholly in the circumstance that the storm beats +equally in all directions at the same time, and the force is thus so +exactly balanced that we are wholly unconscious of the tumult. Not even +the aspen-leaf is stirred, nor the most delicate membrane broken; but +let us remove the air from one of the surfaces of such a membrane, and +then the power of the molecular storm becomes evident, as in the +familiar experiments with an air-pump. + +As has already been intimated, the values of the velocities both of +hydrogen and of air molecules given above were measured at a definite +temperature, 32° of our Fahrenheit thermometer, the freezing point of +water; and this introduces a very important point bearing on our +subject, namely, that the molecular velocities vary very greatly with +the temperature. Indeed, according to our theory, this very molecular +motion constitutes that state or condition of matter which we call +temperature. A hot body is one whose molecules are moving comparatively +rapidly, and a cold body one in which they are moving comparatively +slowly. Without, however, entering into further details, which would +involve the whole mechanical theory of heat, let me call your attention +to a single consequence of the principle I have stated. + +When we heat hydrogen, air, or any mass of gas, we simply increase the +velocity of its moving molecules. When we cool the gas, we simply lessen +the velocity of the same molecules. Take a current of air which enters a +room through a furnace. In passing it comes in contact with heated iron, +and, as we say, is heated. But, as we view the process, the molecules of +the air, while in contact with the hot iron, collide with the very +rapidly oscillating metallic molecules, and fly back as a billiard-ball +would under similar circumstances, with a greatly increased velocity, +and it is this more rapid motion which alone constitutes the higher +temperature. + +Consider, next, what must be the effect on the surface. A moment's +reflection will show that the normal pressure exerted by the molecular +storm, always raging in the atmosphere, is due not only to the impact of +the molecules, but also to the reaction caused by their rebound. When +the molecules rebound, they are, as it were, driven away from the +surface in virtue of the inherent elasticity both of the surface and of +the molecules. Now, what takes place when one mass of matter is driven +away from another--when a cannon-ball is driven out of a gun, for +example? Why, the gun _kicks_! And so every surface from which molecules +rebound must _kick_; and, if the velocity is not changed by the +collision, one half of the pressure caused by the molecular bombardment +is due to the recoil. From a heated surface, as we have said, the +molecules rebound with an increased velocity, and hence the recoil must +be proportionally increased, determining a greater pressure against the +surface. + +According to this theory, then, we should expect that the air would +press unequally against surfaces at different temperatures, and that, +other things being equal, the pressure exerted would be greater the +higher the temperature of the surface. Such a result, of course, is +wholly contrary to common experience, which tells us that a uniform mass +of air presses equally in all directions and against all surfaces of the +same area, whatever may be their condition. It would seem, then, at +first sight, as if we had here met with a conspicuous case in which our +theory fails. But further study will convince us that the result is just +what we should expect in a dense atmosphere like that in which we dwell; +and, in order that this may become evident, let me next call your +attention to another class of molecular magnitudes. + +It must seem strange indeed that we should be able to measure molecular +velocities; but the next point I have to bring to your notice is +stranger yet, for we are confident that we have been able to determine +with approximate accuracy for each kind of gas molecule the average +number of times one of these little bodies runs against its neighbors in +a second, assuming, of course, that the conditions of the gas are given. +Knowing, now, the molecular velocity and the number of collisions a +second, we can readily calculate the mean path of the molecule--that is, +the average distance it moves, under the same conditions, between two +successive collisions. Of course, for any one molecule, this path must +be constantly varying; since, while at one time the molecule may find a +clear coast and make a long run, the very next time it may hardly start +before its course is arrested. Still, taking a mass of gas under +constant conditions, the doctrine of averages shows that the mean path +must have a definite value, and an illustration will give an idea of the +manner in which we have been able to estimate it. + +The nauseous, smelling gas we call sulphide of hydrogen has a density +only a little greater than that of air, and its molecules must therefore +move with very nearly as great velocity as the average air +molecule--that is to say, about fourteen hundred and eighty feet a +second; and we might therefore expect that, on opening a jar of the gas, +its molecules would spread instantly through the surrounding atmosphere. +But, so far from this, if the air is quiet, so that the gas is not +transported by currents, a very considerable time will elapse before the +characteristic odor is perceived on the opposite side of an ordinary +room. The reason is obvious: the molecules must elbow their way through +the crowd of air molecules which already occupy the space, and can +therefore advance only slowly; and it is obvious that, the oftener they +come into collision with their neighbors, the slower their progress must +be. Knowing, then, the mean velocity of the molecular motion, and being +able to measure by appropriate means _the rate of diffusion_, as it is +called, we have the data from which we can calculate both the number of +collisions in a second and also the mean path between two successive +collisions. The results, as we must expect, are of the same order as the +other molecular magnitudes. But, inconceivably short as the free[C] path +of a molecule certainly is, it is still, in the case of hydrogen gas, +136 times the diameter of the moving body, which would certainly be +regarded among men as quite ample elbow-room. + + [C] There is an obvious distinction between the free and the + disturbed path of a molecule, and we can not overlook in + our calculations the perturbations which the collisions + necessarily entail. Such considerations greatly complicate + the problem, which is far more difficult than would appear + from the superficial view of the subject that can alone be + given in a popular lecture. + +Although, in this lecture, I have as yet had no occasion to mention the +radiometer, I have by no means forgotten my main subject, and everything +which has been said has had a direct bearing on the theory of this +remarkable instrument; and still, before you can understand the great +interest with which it is regarded, we must follow out another line of +thought, converging on the same point. + +One of the most remarkable results of modern science is the discovery +that all energy at work on the surface of this planet comes from the +sun. Most of you probably saw, at our Centennial Exhibition, that great +artificial cascade in Machinery Hall, and were impressed with the power +of the steam-pump which could keep flowing such a mass of water. But, +also, when you stood before the falls at Niagara, did you realize the +fact that the enormous floods of water which you saw surging over those +cliffs were in like manner supplied by an all-powerful pump, and that +pump the sun? And not only is this true, but it is equally true that +every drop of water that falls, every wave that beats, every wind that +blows, every creature that moves on the surface of the earth, one and +all, are animated by that mysterious effluence we call the sunbeam. I +say mysterious effluence; for how that power is transmitted over those +92,000,000 miles between the earth and the sun is still one of the +greatest mysteries of Nature. + +In the science of optics, as is well known, the phenomena of light are +explained by the assumption that the energy is transmitted in waves +through a medium which fills all space called the luminiferous ether, +and there is no question that this theory of Nature, known in science as +the Undulatory Theory of Light, is, as a working hypothesis, one of the +most comprehensive and searching which the human mind has ever framed. +It has both correlated known facts and pointed the way to remarkable +discoveries. But, the moment we attempt to apply it to the problem +before us, it demands conditions which tax even a philosopher's +credulity. + +As sad experience on the ocean only too frequently teaches, energy can +be transmitted by waves as well as in any other way. But every mechanic +will tell you that the transmission of energy, whatever be the means +employed, implies certain well-known conditions. Assume that the energy +is to be used to turn the spindles of a cotton mill. The engineer can +tell you just how many horse-power he must supply for every working-day, +and it is equally true that a definite amount of energy must come from +the sun to do each day's work on the surface of the globe. Further, the +engineer will also tell you that, in order to transmit the power from +his turbine or his steam-engine, he must have shafts and pulleys and +belts of adequate strength, and he knows in every case what is the +lowest limit of safety. In like manner, the medium through which the +energy which runs the world is transmitted must be strong enough to do +the immense work put upon it; and, if the energy is transmitted by +waves, this implies that the medium must have an enormously great +elasticity, an elasticity vastly greater than that of the best-tempered +steel. + +But turn now to the astronomers, and learn what they have to tell us in +regard to the assumed luminiferous ether through which all this energy +is supposed to be transmitted. Our planet is rushing in its orbit around +the sun at an average rate of over 1,000 miles a minute, and makes its +annual journey of some 550,000,000 miles in 365 days, 6 hours, 9 +seconds, and 6/10 of a second. Mark the tenths; for astronomical +observations are so accurate that, if the length of the year varied +permanently by the tenth of a second, we should know it; and you can +readily understand that, if there were a medium in space which offered +as much resistance to the motion of the earth as would gossamer threads +to a race-horse, the planet could never come up to time, year after +year, to the tenth of a second. + +How, then, can we save our theory by which we set so much, and rightly, +because it has helped us so effectively in studying Nature? If we may be +allowed such an extravagant solecism, let us suppose that the engineer +of our previous illustration was the hero of a fairy tale. He has built +a mill, set a steam-engine in the basement, arranged his spindles above, +and is connecting the pulleys by the usual belts, when some stern +necessity requires him to transmit all the energy with cobwebs. Of +course, a good fairy comes to his aid, and what does she do? Simply +makes the cobwebs indefinitely strong. So the physicists, not to be +outdone by any fairies, make their ether indefinitely elastic, and their +theory lands them just here, with a medium filling all space, thousands +of times more elastic than steel, and thousands on thousands of times +less dense than hydrogen gas. There must be a fallacy somewhere, and I +strongly suspect it is to be found in our ordinary materialistic notions +of causation, which involve the old metaphysical dogma, "_nulla actio in +distans_," and which in our day have culminated in the famous apothegm +of the German materialist, "Kein Phosphor kein Gedanke." + +But it is not my purpose to discuss the doctrines of causation, and I +have dwelt on the difficulty, which this subject presents in connection +with the undulatory theory, solely because I wished you to appreciate +the great interest with which scientific men have looked for some direct +manifestation of the mechanical action of light. It is true that the +ether waves must have dimensions similar to those of the molecules +discussed above, and we must expect, therefore, that they would act +primarily on the molecules and not on masses of matter. But still the +well-known principles of wave motion have led competent physicists to +maintain that a more or less considerable pressure ought to be exerted +by the ether waves on the surfaces against which they beat, as a partial +resultant of the molecular tremors first imparted. Already, in the last +century, attempts were made to discover some evidence of such action, +and in various experiments the sun's direct rays were concentrated on +films, delicately suspended and carefully protected from all other +extraneous influences, but without any apparent effect; and thus the +question remained until about three years ago, when the scientific world +were startled by the announcement of Mr. Crookes, of London, that, on +suspending a small piece of blackened alder pith in the very perfect +vacuum which can now be obtained with the mercury pump, invented by +Sprengel, he had seen this light body actually repelled by the sun's +rays; and they were still more startled, when, after a few further +experiments, he presented us with the instrument he called a radiometer, +in which the sun's rays do the no inconsiderable work of turning a small +wheel. Let us examine for a moment the construction of this remarkable +instrument. + +The moving part of the radiometer is a small horizontal wheel, to the +ends of whose arms are fastened vertical vanes, usually of mica, and +blackened on one side. A glass cap forms the hub, and by the +glass-blower's art the wheel is inclosed in a glass bulb, so that the +cap rests on the point of a cambric needle; and the wheel is so +delicately balanced on this pivot that it turns with the greatest +freedom. From the interior of the bulb the air is now exhausted by means +of the Sprengel pump, until less than 1/1000 of the original quantity is +left, and the only opening is then hermetically sealed. If, now, the +sun's light or even the light from a candle shines on the vanes, the +blackened surfaces--which are coated with lampblack--are repelled, and, +these being symmetrically placed around the wheel, the several forces +conspire to produce the rapid motion which results. The effect has all +the appearance of a direct mechanical action exerted by the light, and +for some time was so regarded by Mr. Crookes and other eminent +physicists, although in his published papers it should be added that Mr. +Crookes carefully abstained from speculating on the subject--aiming, as +he has since said, to keep himself unbiased by any theory, while he +accumulated the facts upon which a satisfactory explanation might be +based. + +Singularly, however, the first aspects of the new phenomena proved to be +wholly deceptive, and the motion, so far from being an effect of the +direct mechanical action of the waves of light, is now believed to be a +new and very striking manifestation of molecular motion. To this opinion +Mr. Crookes himself has come, and, in a recent article, he writes: +"Twelve months' research, however, has thrown much light on these +actions, and the explanation afforded by the dynamical theory of gases +makes what was a year ago obscure and contradictory now reasonable and +intelligible." + +As is frequently the case in Nature, the chief effect is here obscured +by various subordinate phenomena, and it is not surprising that a great +difference of opinion should have arisen in regard to the cause of the +motion. This would not be an appropriate place to describe the numerous +investigations occasioned by the controversy, many of which show in a +most striking manner how easily experimental evidence may be honestly +misinterpreted in support of a preconceived opinion. I will, however, +venture to trespass further on your patience, so far as to describe the +few experiments by which, very early in the controversy, I satisfied my +own mind on the subject. + +When, two years ago, I had for the first time an opportunity of +experimenting with a radiometer, the opinion was still prevalent that +the motion of the wheel was a direct mechanical effect of the waves of +light, and, therefore, that the impulses came from the outside of the +instrument, the waves passing freely through the glass envelope. At the +outset, this opinion did not seem to me to be reasonable, or in harmony +with well-known facts; for, knowing how great must be the molecular +disturbance caused by the sun's rays, as shown by their heating power, I +could not believe that a residual action, such as has been referred to, +would first appear in these delicate phenomena observed by Mr. Crookes, +and should only be manifested in the vacuum of a mercury pump. + +On examining the instrument, my attention was at once arrested by the +lampblack coating on the alternate surfaces of the vanes; and, from the +remarkable power of lampblack to absorb radiant heat, it was evident at +once that, whatever other effects the rays from the sun or from a flame +might cause, they must necessarily determine a constant difference of +temperature between the two surfaces of the vanes, and the thought at +once occurred that, after all, the motion might be a direct result of +this difference of temperature--in other words, that the radiometer +might be a small heat engine, whose motions, like those of every other +heat engine, depend on the difference of temperature between its parts. + +But, if this were true, the effect ought to be proportional solely to +the heating power of the rays, and a very easy means of roughly testing +this question was at hand. It is well known that an aqueous solution of +alum, although transmitting light as freely as the purest water, +powerfully absorbs those rays, of any source, which have the chief +heating power. Accordingly, I interposed what we call an alum cell in +the path of the rays shining on the radiometer, when, although the light +on the vanes was as bright as before, the motion was almost completely +arrested. + +This experiment, however, was not conclusive, as it might still be said +that the _heat_-giving rays acted _mechanically_, and it must be +admitted that the chief part of the energy in the rays, even from the +most brilliant luminous sources, always takes the form of heat. But, if +the action is mechanical, the reaction must be against the medium +through which the rays are transmitted, while, if the radiometer is +simply a heat engine, the action and reaction must be, ultimately at +least, between the heater and the cooler, which in this case are +respectively the blackened surfaces of the vanes and the glass walls of +the inclosing bulb; and here, again, a very easy method of testing the +actual condition at once suggested itself. + +If the motion of the radiometer wheel is an effect of mechanical +impulses transmitted in the direction of the beam of light, it was +certainly to be expected that the beam would act on the lustrous as well +as on the blackened mica surfaces, however large might be the difference +in the resultants producing mechanical motion, in consequence of the +great absorbing power of the lampblack. Moreover, since the instrument +is so constructed that, of two vanes on opposite sides of the wheel, one +always presents a blackened and the other a lustrous surface to an +incident beam, we should further expect to find in the motion of the +wheel a differential phenomenon, due to the unequal action of the light +on these surfaces. On the other hand, if the radiometer is a heat +engine, and the reaction takes place between the heated blackened +surfaces of the vanes and the colder glass, it is evident that the total +effect will be simply the sum of the effects at the several surfaces. + +In order to investigate the question thus presented, I placed the +radiometer before a common kerosene lamp, and observed, with a +stop-watch, the number of seconds that elapsed during ten revolutions of +the little wheel. Finding that this number was absolutely constant, I +next screened one half of the bulb, so that only the blackened faces +were exposed to the light as the wheel turned them into the beam. Again, +I several times observed the number of seconds during ten turns, which, +although equally constant, was greater than before. Lastly, I screened +the blackened surfaces so that, as the wheel turned, only the lustrous +surfaces of mica were exposed to the light, when, to my surprise, the +wheel continued to turn in the same direction as before, although much +more slowly. It appeared as if the lustrous surfaces were attracted by +the light. Again I observed the time of ten revolutions, and here I have +collected my results, reducing them, in the last column, so as to show +the corresponding number of revolutions in the same time: + + ----------------------+--------------------------+-------------------- + CONDITIONS. | Time of ten revolutions. | No. of revolutions + | | in same time. + ----------------------|--------------------------|-------------------- + Both faces exposed | 8 seconds. | 319 + Blackened faces only | 11 " | 232 + Mica faces only | 29 " | 88 + ----------------------+--------------------------+-------------------- + +It will be noticed that 88 + 232 equals very nearly 319. Evidently the +effect, so far from being differential, is concurrent. Hence, the action +which causes the motion must take place between the parts of the +instrument, and can not be a direct effect of impulses imparted by +ether waves; or else we are driven to the most improbable alternative, +that lampblack and mica should have such a remarkable selective power +that the impulses imparted by the light should exert a repulsive force +at one surface and an attractive force at the other. Were there, +however, such an improbable effect, it must be independent of the +thickness of the mica vanes; while, on the other hand, if, as seemed to +us now most probable, the whole effect depended on the difference of +temperature between the lampblack and the mica, and if the light +produced an effect on the mica surface only because, the mica plate +being diathermous to a very considerable extent, the lampblack became +heated through the plate more than the plate itself, then it would +follow that, if we used a thicker mica plate, which would absorb more of +the heat, we ought to obtain a marked difference of effect. Accordingly, +we repeated the experiment with an equally sensitive radiometer, which +we made for the purpose, with comparatively thick vanes, and with this +the effect of a beam of light on the mica surface was absolutely null, +the wheel revolving in the same time, whether these faces were protected +or not. + +But one thing was now wanting to make the demonstration complete. A heat +engine is reversible, and if the motion of the radiometer depended on +the circumstance that the temperature of the blackened faces of the +vanes was higher than that of the glass, then by reversing the +conditions we ought to reverse the motion. Accordingly, I carefully +heated the glass bulb over a lamp, until it was as hot as the hand would +bear, and then placed the instrument in a cold room, trusting to the +great radiating power of lampblack to maintain the temperature of the +blackened surfaces of the vanes below that of the glass. Immediately the +wheel began to turn in the opposite direction, and continued to turn +until the temperature of the glass came into equilibrium with the +surrounding objects. + +These early experiments have since been confirmed to the fullest extent, +and no physicist at the present day can reasonably doubt that the +radiometer is a very beautiful example of a heat engine, and it is the +first that has been made to work continuously by the heat of the +sunbeam. But it is one thing to show that the instrument is a heat +engine, and quite another thing to explain in detail the manner in which +it acts. In regard to the last point, there is still room for much +difference of opinion, although physicists are generally agreed in +referring the action to the residual gas that is left in the bulb. As +for myself, I became strongly persuaded--after experimenting with more +than one hundred of these instruments, made under my own eye, with every +variation of condition I could suggest--_that the effect was due to the +same cause which determines gas pressure_, and, according to the +dynamical theory of gases, this amounts to saying that the effect is due +to molecular motion. I have not time, however, to describe either my own +experiments on which this opinion was first based, or the far more +thorough investigations since made by others, which have served to +strengthen the first impression.[D] But, after our previous discussions, +a few words will suffice to show how the molecular theory explains the +new phenomena. + + [D] See notice of these investigations by the author of this + article, in "American Journal of Science and Arts," + September, 1877 (3), xiv, 231. + +Although the air in the bulb has been so nearly exhausted that less than +the one-thousandth part remains, yet it must be borne in mind that the +number of molecules left behind is by no means inconsiderable. As will +be seen by referring to our table, there must still be no less than +311,000 million million in every cubic inch. Moreover, the absolute +pressure which this residual gas exerts is a very appreciable quantity. +It is simply the one-thousandth of the normal pressure of the +atmosphere, that is, of 14-7/10 pounds on a square inch, which is +equivalent to a little over one hundred grains on the same area. Now, +the area of the blackened surfaces of the vanes of an ordinary +radiometer measures just about a square inch, and the wheel is mounted +so delicately that a constant pressure of one-tenth of a grain would be +sufficient to produce rapid motion. So that a difference of pressure on +the opposite faces of the vanes, equal to one one-thousandth of the +whole amount, is all that we need account for; and, as can easily be +calculated, a difference of temperature of less than half a degree +Fahrenheit would cause all this difference in the pressure of the +rarefied air. + +But you may ask, How can such a difference of pressure exist on +different surfaces exposed to one and the same medium? and your question +is a perfectly legitimate one; for it is just here that the new +phenomena seem to belie all our previous experience. If, however, you +followed me in my very partial exposition of the mechanical theory of +gases, you will easily see that on this theory it is a more difficult +question to explain why such a difference of pressure does not manifest +itself in every gas medium and under all conditions between any two +surfaces having different temperatures. + +We saw that gas pressure is a double effect, caused both by the impact +of molecules and by the recoil of the surface attending their rebound. +We also saw that when molecules strike a heated surface they rebound +with increased velocity, and hence produce an increased pressure against +the surface, the greater the higher the temperature. According to this +theory, then, we should expect to find the same atmosphere pressing +unequally on equal surfaces if at different temperatures; and the +difference in the pressure on the lampblack and mica surfaces of the +vanes, which the motion of the radiometer wheel necessarily implies, is +therefore simply the normal effect of the mechanical condition of every +gas medium. The real difficulty is, to explain why we must exhaust the +air so perfectly before the effect manifests itself. + +The new theory is equal to the emergency. As has been already pointed +out, in the ordinary state of the air the amplitude of the molecular +motion is exceedingly small, not over a few ten-millionths of an inch--a +very small fraction, therefore, of the height of the inequalities on the +lampblack surfaces of the vanes of a radiometer. Under such +circumstances, evidently the molecules would not leave the heated +surface, but simply bound back and forth between the vanes and the +surrounding mass of dense air, which, being almost absolutely a +non-conductor of heat, must act essentially like an elastic solid wall +confining the vanes on either side. For the time being, and until +replaced by convection currents, the oscillating molecules are as much a +part of the vanes as our atmosphere is a part of the earth; and on this +system, as a whole, the homogeneous dense air which surrounds it must +press equally from all directions. In proportion, however, as the air is +exhausted, the molecules find more room and the amplitude of the +molecular motion is increased, and, when a very high degree of +exhaustion is reached, the air particles no longer bound back and forth +on the vanes without change of condition, but they either bound off +entirely like a ball from a cannon, or else, having transferred a +portion of their momentum, return with diminished velocity, and in +either case the force of the reaction is felt.[E] + + [E] The reader will, of course, distinguish between the differential + action on the opposite faces of the vanes of the radiometer and + the reaction between the vanes and the glass which are the heater + and the cooler of the little engine. Nor will it be necessary to + remind any student that a popular view of such a complex subject + must be necessarily partial. In the present case we not only meet + with the usual difficulties in this respect, but, moreover, the + principles of molecular mechanics have not been so fully developed + as to preclude important differences of opinion between equally + competent authorities in regard to the details of the theory. To + avoid misapprehension, we may here add that, in orderto obtain in + the radiometer a reaction between the heater and the cooler, it + is not necessary that the space between them should actually be + crossed by the moving molecules. It is only necessary that the + momentum should be transferred across the space, and tide may + take place along lines consisting of many molecules each. The + theory, however, shows that such a transfer can only take place + in a highly rarefied medium. In an atmosphere of ordinary density, + the accession of heat which the vanes of a radiometer might + receive from a radiant source would be diffused through the mass + of the inclosed air. This amounts to saying that the momentum + would be so diffused, and hence, under such circumstances, the + molecular motion would not determine any reaction between the + vanes and the glass envelope. Indeed, a dense mass of gas presents + to the conduction of heat, which represents momentum, a wall far + more impenetrable than the surrounding glass, and the diffusion + of heat is almost wholly brought about by convection currents + which rise from the heated surfaces. It will thus be seen that + the great non-conducting power of air comes into play to prevent + not only the transfer of momentum from the vanes to the glass, + but also, almost entirely, any direct transfer to the surrounding + mass of gas. Hence, as stated above, the heated molecules bound + back and forth on the vanes without change of condition, and the + mass of the air retains its uniform tension in all parts of the + bulb, except in so far as this is slowly altered by the convection + currents just referred to. As the atmosphere, however, becomes + less dense, the diffusion of heat by convection diminishes, and + that by molecular motion (conduction) increases until the last + greatly predominates. When, now, the exhaustion reaches so great + a degree that the heat, or momentum, is rapidly transferred from + the heater to the cooler by an exaggeration, or, possibly, a + modification, of the mode of action we call conduction, then we + have the reaction on which the motion of the radiometer wheel + depends. + +Thus it appears that we have been able to show by very definite +experimental evidence that the radiometer is a heat engine. We have also +been able to show that such a difference of temperature as the radiation +must produce in the air in _direct_ contact with the opposite faces of +the vanes of the radiometer would determine a difference of tension, +which is sufficient to account for the motion of the wheel. Finally, we +have shown, as fully as is possible in a popular lecture, that, +according to the mechanical theory of gases, such a difference of +tension would have its normal effect only in a highly rarefied +atmosphere, and thus we have brought the new phenomena into harmony with +the general principles of molecular mechanics previously established. + +More than this can not be said of the steam-engine, although, of course, +in the older engine the measurements on which the theory is based are +vastly more accurate and complete. But the moment we attempt to go +beyond the general principles of heat engines, of which the steam-engine +is such a conspicuous illustration, and explain how the heat is +transformed into motion, we have to resort to the molecular theory just +as in the case of the radiometer; and the motion of the steam-engine +seems to us less wonderful than that of the radiometer only because it +is more familiar and more completely harmonized with the rest of our +knowledge. Moreover, the very molecular theory which we call upon to +explain the steam-engine involves consequences which, as we have seen, +have been first realized in the radiometer; and thus it is that this new +instrument, although disappointing the first expectations of its +discoverer, has furnished a very striking confirmation of this wonderful +theory. Indeed, the confirmation is so remote and yet so close, so +unexpected and yet so strong, that the new phenomena almost seem to be a +direct manifestation of the molecular motion which our theory assumes; +and when a new discovery thus confirms the accuracy of a previous +generalization, and gives us additional reason to believe that the +glimpses we have gained into the order of Nature are trustworthy, it +excites, with reason, among scientific scholars the warmest interest. + +And when we consider the vast scope of the molecular theory, the order +on order of existences which it opens to the imagination, how can we +fail to be impressed with the position in which it places man midway +between the molecular cosmos on the one side and the stellar cosmos on +the other--a position in which he is able, in some measure at least, to +study and interpret both? + +Since the time to which we referred at the beginning of this lecture, +when man's dwelling-place was looked at as the center of a creation +which was solely subservient to his wants, there has been a reaction to +the opposite extreme, and we have heard much of the utter insignificance +of the earth in a universe among whose immensities all human belongings +are but as a drop in the ocean. When now, however, we learn from Sir +William Thomson that the drop of water in our comparison is itself a +universe, consisting of units so small that, were the drop magnified to +the size of the earth, these units would not exceed in magnitude a +cricket-ball,[F] and when, on studying chemistry, we still further learn +that these units are not single masses but systems of atoms, we may +leave the illusions of the imagination from the one side to correct +those from the other, and all will teach us the great lesson that man's +place in Nature is not to be estimated by relations of magnitude, but +by the intelligence which makes the whole creation his own. + + [F] "Nature," No. 22, March 31, 1870. + +But, if it is man's privilege to follow both the atoms and the stars in +their courses, he finds that, while thus exercising the highest +attributes of his nature, he is ever in the presence of an immeasurably +superior intelligence, before which he must bow and adore, and thus come +to him both the assurance and the pledge of a kinship in which his only +real glory can be found. + + + + +V. + +MEMOIR OF THOMAS GRAHAM. + + _Reprinted from the "Proceedings of the American Academy + of Arts and Sciences," Vol. VIII, May 24, 1870._ + + +It would be difficult to find in the history of science a character more +simple, more noble, or more symmetrical in all its parts than that of +Thomas Graham, and he will always be remembered as one of the most +eminent of those great students of nature who have rendered our Saxon +race illustrious. He was born of Scotch parents in Glasgow in the year +1805, and in that city, where he received his education, all his early +life was passed. In 1837 he went to London as Professor of Chemistry in +the newly established London University, now called University College, +and he occupied this chair until the year 1855, when he succeeded Sir +John Herschel as Master of the Royal Mint, a post which he held to the +close of his life. His death, on the 16th of September last (1869), at +the age of sixty, was caused by no active disease, but was simply the +wearing out of a constitution enfeebled in youth by privations +voluntarily and courageously encountered that he might devote his life +to scientific study. As with all earnest students, that life was +uneventful, if judged by ordinary standards; and the records of his +discoveries form the only materials for his biography. + +Although one of the most successful investigators of physical science, +the late Master of the Mint had not that felicity of language or that +copiousness of illustration which added so much to the popular +reputation of his distinguished contemporary, Faraday; but his influence +on the progress of science was not less marked or less important. Both +of these eminent men were for a long period of years best known to the +English public as teachers of chemistry, but their investigations were +chiefly limited to physical problems; yet, although both cultivated the +border ground between chemistry and physics, they followed wholly +different lines of research. While Faraday was so successfully +developing the principles of electrical action, Graham with equal +success was investigating the laws of molecular motion. Each followed +with wonderful constancy, as well as skill, a single line of study from +first to last, and to this concentration of power their great +discoveries are largely due. + +One of the earliest and most important of Graham's investigations, and +the one which gave the direction to his subsequent course of study, was +that on the diffusion of gases. It had already been recognized that +impenetrability in its ordinary sense is not, as was formerly supposed, +a universal quality of matter. Dalton had not only recognized that +aëriform bodies exhibit a positive tendency to mix, or to penetrate +through each other, even in opposition to the force of gravity, but had +made this quality of gases the subject of experimental investigation. He +inferred, as the result of his inquiry, "that different gases afford no +resistance to each other; but that one gas spreads or expands into the +space occupied by another gas, as it would rush into a vacuum; at least, +that the resistance which the particles of one gas offer to those of +another is of a very imperfect kind, to be compared to the resistance +which stones in the channel of a stream oppose to the flow of running +water." But, although this theory of Dalton was essentially correct and +involved the whole truth, yet it was supported by no sufficient +evidence, and he failed to perceive the simple law which underlies this +whole class of phenomena. + +Graham, "on entering on this inquiry, found that gases diffuse into the +atmosphere with different degrees of ease and rapidity." This was first +observed by allowing each gas to diffuse from a bottle into the air +through a narrow tube in opposition to the solicitation of gravity. +Afterward an observation of Doebereiner on the escape of hydrogen gas by +a fissure or crack in a glass receiver caused him to vary the conditions +of his experiments, and led to the invention of the well-known +"diffusion tube." In this simple apparatus a thin septum of plaster of +Paris is used to separate the diffusing gases, which, while it arrests +in a great measure all direct currents between the two media, does not +interfere with the molecular motion. Much later, Graham found in +prepared graphite a material far better adapted to this purpose than the +plaster, and he used septa of this mineral to confirm his early results, +in answer to certain ill-considered criticisms in Bunsen's work on +gasometry. These septa he was in the habit of calling his "atomic +filters." + +By means of the diffusion tube, Graham was able to measure accurately +the relative times of diffusion of different gases, and he found that +_equal volumes of any two gases interpenetrate each other in times which +are inversely proportional to the square roots of their respective +densities_; and this fundamental law was the greatest discovery of our +late foreign associate. It is now universally recognized as one of the +few great cardinal principles which form the basis of physical science. + +It can be shown, on the principles of pneumatics, that gases should +rush into a vacuum with velocities corresponding to the numbers which +have been found to express their diffusion times; and, in a series of +experiments on what he calls the "_effusion_" of gases, Graham confirmed +by trial this deduction of theory. In these experiments a measured +volume of the gas was allowed to find its way into the vacuous jar +through a minute aperture in a thin metallic plate, and he carefully +distinguished between this class of phenomena and the flowing of gases +through capillary tubes into a vacuum, in which case, however short the +tube, the effects of friction materially modify the result. This last +class of phenomena Graham likewise investigated, and designated by the +term "transpiration." + +While, however, it thus appears that the results of Graham's +investigation were in strict accordance with Dalton's theory, it must +also be evident that Graham was the first to observe the exact numerical +relation which obtains in this class of phenomena, and that +all-important circumstance entitles him to be regarded as the discoverer +of the law of diffusion. The law, however, at first enunciated, was +purely empirical, and Graham himself says that something more must be +assumed than that gases are vacua to each other, in order to explain all +the phenomena observed; and according to his original view this +representation of the process was only a convenient mode of expressing +the final result. Such has proved to be the case. + +Like other great men, Graham built better than he knew. In the progress +of physical science during the last twenty-five years, two principles +have become more and more conspicuous, until at last they have +completely revolutionized the philosophy of chemistry. In the first +place, it has appeared that a host of chemical as well as of physical +facts are coördinated by the assumption that all substances in the state +of gas have the same molecular volume, or, in other words, contain the +same number of molecules in a given space; and in the second place, it +has become evident that the phenomena of heat are simply the +manifestations of molecular motion. According to this view, the +temperature of a body is the _vis viva_ of its molecules; and, since all +molecules at a given temperature have the same _vis viva_, it follows +that the molecules must move with velocities which are inversely +proportional to the square roots of the molecular weights. Moreover, +since the molecular volumes are equal, and the molecular weights +therefore proportional to the densities of the aëriform bodies in which +the molecules are the active units, it also follows that the velocities +of the molecules in any two gases are inversely proportional to the +square roots of their respective densities. Thus the simple numerical +relations first observed in the phenomena of diffusion are the direct +result of molecular motion; and it is now seen that Graham's empirical +law is included under the fundamental laws of motion. Thus Graham's +investigation has become the basis of the new science of molecular +mechanics, and his measurements of the rates of diffusion prove to be +the measures of molecular velocities. + +From the study of diffusion Graham passed by a natural transition to the +investigation of a class of phenomena which, although closely allied to +the first as to the effects produced, differ wholly in their essential +nature. Here also he followed in the footsteps of Dalton. This +distinguished chemist had noticed that a bubble of air separated by a +film of water from an atmosphere of carbonic anhydride gradually +expanded until it burst. In like manner a moist bladder, half filled +with air and tied, if suspended in an atmosphere of the same material, +becomes in time greatly distended by the insinuation of this gas through +its substance. This effect can not be the result of simple diffusion, +for it is to be remembered that the thinnest film of water, or of any +liquid, is absolutely impermeable to a gas as such, and, moreover, only +the carbonic anhydride passes through the film, very little or none of +the air escaping outward. The result depends, first, upon the solution +of the carbonic anhydride by the water on one surface of the film; +secondly, on the evaporation into the air, from the other surface, of +the gas thus absorbed. Similar experiments were made by Drs. Mitchell +and Faust, and others, in which gases passed through a film of +India-rubber, entering into a partial combination with the material on +one surface, and escaping from it on the other. + +Graham not only considerably extended our knowledge of this class of +phenomena, but also gave us a satisfactory explanation of the mode in +which these remarkable results are produced. He recognized in these +cases the action of a feeble chemical force, insufficient to produce a +definite compound, but still capable of determining a more or less +perfect union, as in the case of simple solution. He also distinguished +the influence of mass in causing the formation or decomposition of such +weak chemical compounds. The conditions of the phenomena under +consideration are simply these: + +First. A material for the septum capable of forming a feeble chemical +union with the gas to be transferred. + +Secondly. An excess of the gas on one side of the film and a deficiency +on the other. + +Thirdly. Such a temperature that the unstable compound may form at the +surface, where the aëriform constituent is present in large mass, while +it decomposes at the opposite surface, where the quantity is less +abundant. + +One of the most remarkable results of Graham's study of this peculiar +mode of transfer of aëriform matter through the very substance of solid +bodies was an ingenious method of separating the oxygen from the +atmosphere. The apparatus consisted simply of a bag of India-rubber kept +distended by an interior framework, while it was exhausted by a Sprengel +pump. Under these circumstances the selective affinity of the caoutchouc +determines such a difference in the rate of transfer of the two +constituents of the atmosphere that the amount of oxygen in the +transpired air rises to forty per cent., and by repeating the process +nearly pure oxygen may be obtained. It was at first hoped that this +method might find a valuable application in the arts, but in this Graham +was disappointed; for the same result has since been effected by purely +chemical methods, which are both cheaper and more rapid. + +These experiments on India-rubber naturally led to the study of similar +effects produced with metallic septa, which, although to some extent +previously observed in passing gases through heated metallic tubes, had +been only imperfectly understood. Thus, when a stream of hydrogen or +carbonic oxide is passed through a red-hot iron tube, a no +inconsiderable portion of the gas escapes through the walls. The same is +true to a still greater degree when hydrogen is passed through a red-hot +tube of platinum, and Graham showed that, through the walls of a tube +of palladium, hydrogen gas passes, under the same conditions, almost as +rapidly as water through a sieve. Moreover, our distinguished associate +proved that this rapid transfer of gas through these dense metallic +septa was due, as in the case of the India-rubber, to an actual chemical +combination of its material with the metal, formed at the surface, where +the gas is in excess, and as rapidly decomposed on the opposite face of +the septum. He not only recognized as belonging to this class of +phenomena the very great absorption of hydrogen by platinum plate and +sponge in the familiar experiment of the Doebereiner lamp, but also +showed that this gas is a definite constituent of meteoric iron--a fact +of great interest from its bearing on the meteoric theory. + +We are thus led to Graham's last important discovery, which was the +justification of the theory we have been considering, and the crowning +of this long line of investigation. As may be anticipated from what has +been said, the most marked example of that order of chemical compounds, +to which the metallic transpiration of aëriform matter we have been +considering is due, is the compound of palladium with hydrogen. Graham +showed that, when a plate of this metal is made the negative pole in the +electrolysis of water, it absorbs nearly one thousand times its volume +of hydrogen gas--a quantity approximatively equivalent to one atom of +hydrogen to each atom of palladium. He further showed that the metal +thus becomes so profoundly altered as to indicate that the product of +this union is a definite compound. Not only is the volume of the metal +increased, but its tenacity and conducting power for electricity are +diminished, and it acquires a slight susceptibility to magnetism, which +the pure metal does not possess. The chemical qualities of this product +are also remarkable. It precipitates mercury from a solution of its +chloride, and in general acts as a strong reducing agent. Exposed to the +action of chlorine, bromine, or iodine, the hydrogen leaves the +palladium and enters into direct union with these elements. Moreover, +although the compound is readily decomposed by heat, the gas can not be +expelled from the metal by simple mechanical means. + +These facts recall the similar relations frequently observed between the +qualities of an alloy and those of the constituent metals, and suggest +the inference made by Graham, that palladium charged with hydrogen is a +compound of the same class--a conclusion which harmonizes with the +theory long held by many chemists, that hydrogen gas is the vapor of a +very volatile metal. This element, however, when combined with +palladium, is in a peculiarly active state, which sustains somewhat the +same relation to the familiar gas that ozone bears to ordinary oxygen. +Hence Graham distinguished this condition of hydrogen by the term +"hydrogenium." Shortly before his death a medal was struck at the Royal +Mint from the hydrogen palladium alloy in honor of its discovery; but, +although this discovery attracted public attention chiefly on account of +the singular chemical relations of hydrogen, which it brought so +prominently to notice, it will be remembered in the history of science +rather as the beautiful termination of a life-long investigation, of +which the medal was the appropriate seal. + +Simultaneously with the experiments on _gases_, whose results we have +endeavored to present in the preceding pages, Graham carried forward a +parallel line of investigation of an allied class of phenomena, which +may be regarded as the manifestations of molecular motion in _liquid_ +bodies. The phenomena of diffusion reappear in liquids, and Graham +carefully observed the times in which equal weights of various salts +dissolved in water diffused from an open-mouth bottle into a large +volume of pure water, in which the bottle was immersed. He was not, +however, able to correlate the results of these experiments by such a +simple law as that which obtains with gases. It appeared, nevertheless, +that the rate of diffusion differs very greatly for the different +soluble salts, having some relation to the chemical composition of the +salt which he was unable to discover. But he found it possible to divide +the salts into groups of equi-diffusive substances, and he showed that +the rate of diffusion of the several groups bear to one another simple +numerical ratios. + +More important results were obtained from the study of a class of +phenomena corresponding to the transpiration of gases through +India-rubber or metallic septa. These phenomena, as manifested in the +transfer of liquids and of salts in solution through bladder or a +similar membrane, had previously been frequently studied under the names +of exosmose and endosmose, but to Graham we owe the first satisfactory +explanation. As in the case of gases, he referred these effects to the +influence of chemical force, combination taking place on one surface of +the membrane and the compound breaking up on the other, the difference +depending, as in the previous instance, on the influence of mass. He +also swept away the arbitrary distinctions made by previous +experimenters, showed that this whole class of phenomena are essentially +similar, and called this manifestation of power simply "osmose." + +While studying osmotic action, Graham was led to one of his most +important generalizations--the recognition of the crystalline and +amorphous states as fundamental distinctions in chemistry. Bodies in the +first state he called crystalloids; those in the last state, colloids +(resembling glue). That there is a difference in structure between +crystalloids, like sugar or felspar, and colloids, like barley candy or +glass, has of course always been evident to the most superficial +observer; but Graham was the first to recognize in these external +differences two fundamentally distinct conditions of matter not peculiar +to certain substances, but underlying all chemical differences, and +appearing to a greater or less degree in every substance. He showed that +the power of diffusion through liquids depends very much on these +fundamental differences of condition--sugar, one of the least diffusible +of the crystalloids, diffusing fourteen times more rapidly than caromel, +the corresponding colloid. He also showed that, in accordance with the +general chemical rule, while colloids readily combine with crystalloids, +bodies in the same condition manifest little or no tendency to chemical +union. Hence, in osmose, where the membranes employed are invariably +colloidal, the osmotic action is confined almost entirely to +crystalloids, since they alone are capable of entering into that +combination with the material of the septum on which the whole action +depends. + +On the above principles Graham based a simple method of separating +crystalloids from colloids, which he calls "dialysis," and which was a +most valuable addition to the means of chemical analysis. A shallow +tray, prepared by stretching parchment paper (an insoluble colloid) over +a gutta-percha hoop, is the only apparatus required. The solution to be +"dialyzed" is poured into this tray, which is then floated on pure +water, whose volume should be eight or ten times greater than that of +the solution. Under these conditions the crystalloids will diffuse +through the porus septum into the water, leaving the colloids on the +tray, and in the course of a few days a more or less complete separation +of the two classes of bodies will have taken place. In this way +arsenious acid and similar crystalloids may be separated from the +colloidal materials with which, in the case of poisoning, they are +usually found mixed in the animal juices or tissues. + +But, besides having these practical applications, the method of dialysis +in the hands of Graham yielded the most startling results, developing an +almost entirely new class of bodies, as the colloidal forms of our most +familiar substances, and justifying the conclusion that the colloidal as +well as the crystalline condition is an almost universal attribute of +matter. Thus, he was able to obtain solutions in water of the colloidal +states of aluminic, ferric, chromic, stannic, metastannic, titanic, +molybdic, tungstic, and silicic hydrates, all of which gelatinize under +definite conditions like a solution of glue. The wonderful nature of +these facts can be thoroughly appreciated only by those familiar with +the subject, but all may understand the surprise with which the chemist +saw such hard, insoluble bodies as flint dissolved abundantly in water +and converted into soft jellies. These facts are, without doubt, the +most important contributions of Dr. Graham to pure chemistry. + +In this sketch of the scientific career of our late associate, we have +followed the logical, rather than the chronological, order of events, +hoping thus to render the relations of the different parts of his work +more intelligible. It must be remembered, however, that the two lines of +investigation we have distinguished were in fact inter-woven, and that +the beautiful harmony which his completed life presents was the result, +not of a preconceived plan, but of a constant devotion to truth, and a +childlike faith, which unhesitatingly pressed forward whenever nature +pointed out the way. + +Although the investigations of the phenomena connected with the +molecular motion in gases and liquids were by far the most important of +Dr. Graham's labors, he also contributed to chemistry many researches +which can not be included under this head. Of these, which we may regard +as his detached efforts, the most important was his investigation of the +hydrates and other salts of phosphorus. It is true that the +interpretation he gave of the results has been materially modified by +the modern chemical philosophy, yet the facts which he established form +an important part of the basis on which that philosophy rests. Indeed, +it seems as if he almost anticipated the later doctrines of types and +polybasic acids, and in none of his work did he show more discriminating +observation or acute reasoning. A subsequent investigation on the +condition of water in several crystalline salts and in the hydrates of +sulphuric acid is equally remarkable. Lastly, Graham also made +interesting observations on the combination of alcohol with salts, on +the process of etherification, on the slow oxidation of phosphorus, and +on the spontaneous inflammability of phosphureted hydrogen. It would +not, however, be appropriate in this place to do more than enumerate the +subjects of these less important studies; and we have therefore only +aimed in this sketch to give a general view of the character of the +field which this eminent student of nature chiefly cultivated, and to +show how abundant was the harvest of truth which we owe to his faithful +toil. + +Graham was not a voluminous writer. His scientific papers were all very +brief, but comprehensive, and his "Elements of Chemistry" was his only +large work. This was an admirable exposition of chemical physics, as +well as of pure chemistry, and gave a more philosophical account of the +theory of the galvanic battery than had previously appeared. Our late +associate was fortunate in receiving during life a generous recognition +of the value of his labors. His membership was sought by almost all the +chief scientific societies of the world, and he enjoyed to a high degree +the confidence and esteem of his associates. Indeed, he was singularly +elevated above the petty jealousies and belittling quarrels which so +often mar the beauty of a student's life, while the great loveliness and +kindliness of his nature closely endeared him to his friends. + +In concluding, we must not forget to mention that most genial trait of +Graham's character, his sympathy with young men, which gave him great +influence as a teacher in the college with which he was long associated. +There are many now prominent in the scientific world who have found in +his encouragement the strongest incentive to perseverance, and in his +approval and friendship the best reward of success. + + + + +VI. + +MEMOIR OF WILLIAM HALLOWES MILLER. + + _Reprinted from the "Proceedings of the American Academy of + Arts and Sciences," Vol. XVI, May 24, 1881._ + + +William Hallowes Miller, who was elected Foreign Honorary Member of this +Academy in the place of C. F. Naumann, May 26, 1874, died at his +residence in Cambridge, England, on the 20th of May, 1880, at the age of +seventy-nine, having been born at Velindre, in Wales, April 5, 1801. His +life was singularly uneventful, even for a scholar. Graduating with +mathematical honors at Cambridge in 1826, he became a fellow of his +college (St. John's) in 1829, and was elected Professor of Mineralogy in +the University in 1832. Under the influence of the calm and elegant +associations of this ancient English university, Miller passed a long +and tranquil life--crowded with useful labors, honored by the respect +and love of his associates, and blessed by congenial family ties. This +quiet student-life was exactly suited to his nature, which shunned the +bustle and unrest of our modern world. For relaxation, even, he loved to +seek the retired valleys of the Eastern Alps; and the description which +he once gave to the writer, of himself sitting at the side of his wife +amid the grand scenery, intent on developing crystallographic formulć, +while the accomplished artist traced the magnificent outlines of the +Dolomite mountains, was a beautiful idyl of science. + +Miller's activities, however, were not confined to the University. In +1838 he became a Fellow of the Royal Society, and in 1856 he was +appointed its Foreign Secretary--a post for which he was eminently +fitted, and which he filled for many years. In 1843 he was selected one +of a committee to superintend the construction of the new Parliamentary +standards of length and weight, to replace those which had been lost in +the fire which consumed the Houses of Parliament in 1834, and to +Professor Miller was confided the construction of the new standard of +weight. His work on this important committee, described in an extended +paper published in the "Philosophical Transactions" for 1856, was a +model of conscientious investigation and scientific accuracy. Professor +Miller was subsequently a member of a new Royal Commission for +"examining into and reporting on the state of the secondary standards, +and for considering every question which could affect the primary, +secondary, and local standards"; and in 1870 he was appointed a member +of the "Commission Internationale du Mčtre." His services on this +commission were of great value, and it has been said that "there was no +member whose opinions had greater weight in influencing a decision upon +any intricate and delicate question." + +Valuable, however, as were Professor Miller's public services on these +various commissions, his chief work was at the University. His teacher, +Dr. William Whewell--afterward the Master of Trinity College--was his +immediate predecessor in the Professorship of Mineralogy at Cambridge. +This great scholar, whose encyclopćdic mind could not long be confined +in so narrow a field, held the professorship only four years; but during +this period he devoted himself with his usual enthusiasm to the study of +crystallography, and he accomplished a most important work in attracting +to the same study young Miller, who brought his mathematical training to +its elucidation. It was the privilege of Professor Miller to accomplish +a unique work, for the like of which a more advanced science, with its +multiplicity of details, will offer few opportunities. + +The foundations of crystallography had been laid long before Miller's +time. Haüy is usually regarded as the founder of the science; for he +first discovered the importance of cleavage, and classed the known facts +under a definite system. Taking cleavage as his guide, and assuming that +the forms of cleavage were not only the _primitive forms_ of crystals as +a whole, but also the forms of their _integrant molecules_, he +endeavored to show that all secondary forms might be derived from a few +primary forms, regarded as elements of nature, by means of _decrements_ +of molecules at their edges. In like manner he showed that all the forms +of a given mineral, like fluor-spar or calcite, might be built up from +the integrant molecules by skillfully placing together the primitive +forms. Haüy's dissection of crystals, in a manner which appeared to lead +to their ultimate crystalline elements, gained for his system great +popular attention and applause. The system was developed with great +perspicuity and completeness in a work remarkable for the vivacity of +its style and the felicity of its illustration. Moreover, a simple +mathematical expression was given to the system, and the notation which +Haüy invented to express the relation of the secondary to the primary +forms, as modified and improved by Lčvy, is still used by the French +mineralogists. + +The system of Haüy, however, was highly artificial, and only prepared +the way for a simpler and more general expression of the facts. The +German crystallographer, Weiss, seems to be the first to have +recognized the truth that the decrements of Haüy were merely a +mechanical mode of representing the fact that all the secondary faces of +a crystal make intercepts on the edges of the primitive form which are +simple multiples of each other; and, this general conception once +gained, it was soon seen that these ratios could be as simply measured +on the axes of symmetry of the crystal as on the edges of the +fundamental forms; and, moreover, that, when crystal forms are viewed in +their relation to these axes, a more general law becomes evident, and +the artificial distinction between primary and secondary forms +disappears. + +Thus became slowly evolved the conception of a crystal as a group of +similar planes symmetrically disposed around certain definite and +obvious systems of axes, and so placed that the intercepts, or +parameters, on these axes bore to each other a simple numerical ratio. +Representing by _a_:_b_:_c_ the ratio of the intercepts of a plane +on the three axes of a crystal of a given substance, then the intercepts +of every other plane of this, or of any other crystal of the same +substance, conform to the general proportion _m_ˇ_a_:_n_ˇ_b_:_p_ˇ_c_, +in which _m_, _n_, _p_ are three simple whole numbers. This simple +notation, devised by Weiss, expressed the fundamental law of +crystallography; and the conception of a crystal as a system of planes, +symmetrically distributed according to this law, was a great advance +beyond the decrements of Haüy, an advance not unlike that of astronomy +from the system of vortices to the law of gravitation. Yet, as the +mechanism of vortices was a natural prelude to the law of Newton, so the +decrements of Haüy prepared the way for the wider views of the German +crystallographers. + +Whether Weiss or Mohs contributed most to advance crystallography to its +more philosophical stage, it is not important here to inquire. Each of +these eminent scholars did an important work in developing and diffusing +the larger ideas, and in showing by their investigations that the facts +of nature corresponded to the new conceptions. But to Carl Friedrich +Naumann, Professor at the time in the "Bergakademie zu Freiberg," +belongs the merit of first developing a complete system of theoretical +crystallography based on the laws of symmetry and axial ratios. His +"Lehrbuch der reinen und angewandten Krystallographie," published in two +volumes at Leipzig in 1830, was a remarkable production, and seemed to +grasp the whole theory of the external forms of crystals. Naumann used +the obvious and direct methods of analytical geometry to express the +quantitative relations between the parts of a crystal; and, although his +methods are often unnecessarily prolix and his notation awkward, his +formulć are well adapted to calculation, and easily intelligible to +persons moderately disciplined in mathematics. + +But, however comprehensive and perfect in its details, the system of +Naumann was cumbrous, and lacked elegance of mathematical form. This +arose chiefly from the fact that the old methods of analytical geometry +were unsuited to the problems of crystallography; but it resulted also +from a habit of the German mind to dwell on details and give importance +to systems of classification. To Naumann the six crystalline systems +were as much realities of nature as were the forms of the integrant +molecules to Haüy, and he failed to grasp the larger thought which +includes all partial systems in one comprehensive plan. + +Our late colleague, Professor Miller, on the other hand, had that power +of mathematical generalization which enabled him to properly subordinate +the parts to the whole, and to develop a system of mathematical +crystallography of such simplicity and beauty of form that it leaves +little to be desired. This was the great work of his life, and a work +worthy of the university which had produced the "Principia." It was +published in 1839, under the title, "A Treatise on Crystallography"; and +in 1863 the substance of the work was reproduced in a more perfect form, +still more condensed and generalized, in a thin volume of only +eighty-six pages, which the author modestly called, "A Tract on +Crystallography." + +Miller began his study of crystallography with the same materials as +Naumann; but, in addition, he adopted the beautiful method of Franz +Ernst Neumann of referring the faces of a crystal to the surface of a +circumscribed sphere by means of radii drawn perpendicular to the faces. +The points where the radii meet the spherical surface are the poles of +the faces, and the arcs of great circles connecting these poles may +obviously be used as a measure of the angles between the crystal faces. +This invention of Neumann's was the germ of Miller's system of +crystallography, for it enabled the English mathematician to apply the +elegant and compendious methods of spherical trigonometry to the +solution of crystallographic problems; and Professor Miller always +expressed his great indebtedness to Neumann, not only for this simple +mode of defining the position of the faces of a crystal, but also for +his method of representing the relative position of the poles of the +faces on a plane surface by a beautiful application of the methods of +stereo-graphic and gnomonic projection. This method of representing a +crystal shows very clearly the relations of the parts, and was +undoubtedly of great aid to Miller in assisting him to generalize his +deductions. + +From the outset, Professor Miller apprehended more clearly than any +previous writer the all-embracing scope of the great law of +crystallography. He opens his treatise with its enunciation, and, from +this law as the fundamental principle of the subject, the whole of his +system of crystallography is logically developed. Beyond this, all that +is peculiar to Miller's system is involved in two or three general +theorems. The rest of his treatise consists of deductions from these +principles and their application to particular cases. + +One of the most important of these principles, and one which in the +treatise is involved in the enunciation of the fundamental law of +crystallography, is in its essence nothing but an analytical device. +As we have already stated, Weiss had shown that, if _a_:_b_:_c_ +represent the ratio of the intercepts of any plane of a crystal on the +three axes _x_, _y_, and _z_, respectively, the intercepts of any other +possible plane must satisfy the proportion-- + + _A_:_B_:_C_ = _m_ˇ_a_:_n_ˇ_b_:_p_ˇ_c_, + +in which _m_, _n_, and _p_ are simple whole numbers. The irrational +values _a_, _b_, and _c_ are fundamental magnitudes for every +crystalline substance;[G] and Miller called these relative magnitudes +the parameters of the crystals, while he called the whole numbers, _m_, +_n_, and _p_, the indices of the respective planes. But, instead of +writing the proportion which expresses the law of crystallography as +above, he gave to it a slightly different form, thus: + + _A_:_B_:_C_ = (1/_h_)ˇ_a_:(1/_k_)ˇ_b_:(1/_l_)ˇ_c_, + +and used in his system for the indices of a plane the values +_h_:_k_:_l_, which are also in the ratio of whole numbers, and usually +of simpler whole numbers than _m_:_n_:_p_. This seems a small +difference; for _h_ _k_ _l_ in the last proportion are obviously the +reciprocals of _m_ _n_ _p_ in the first; but the difference, small as it +is, causes a wonderful simplification of the formulć which express the +relations between the parts of a crystal. From the last proportion we +derive at once + + (1/_h_)ˇ(_a_/_A_) = (1/_k_)ˇ(_b_/_B_) = (1/_l_)ˇ(_c_/_C_), + +which is the form in which Miller stated his fundamental law. + + [G] For example, the native crystals + of sulphur have _a_:_b_:_c_ = 1:2ˇ340:1ˇ233. + Crystals of gypsum have _a_:_b_:_c_ = 1:0ˇ413:0ˇ691. + Crystals of tin-stone have _a_:_b_:_c_ = 1:1:0ˇ6724. + And crystals of common salt have _a_:_b_:_c_ = 1:1:1. + +If _P_ represents the "pole" of a face whose "indices" are _h_ _k_ _l_, +that is, represents the point where the radius drawn normal to the face +meets the surface of the sphere circumscribed around the crystal (the +sphere of projection, as it is called), and if _X_, _Y_, _Z_ represent +the points where the axes of the crystal meet the same spherical +surface,[H] then it is evident that _X Y_, _X Z_, and _Y Z_ are the +arcs of great circles, which measure the inclination of the axes to each +other, and that _P X_, _P Y_, and _P Z_ are arcs of other great circles, +which measure the inclination of the plane (_h_ _k_ _l_) on planes +normal to the respective axes; and, also, that these several arcs form +the sides of spherical triangles thus drawn on the sphere of projection. +Now, it is very easily shown that + + (_a_/_h_)ˇcos _P X_ = (_b_/_k_)ˇcos _P Y_ = (_c_/_l_)ˇcos _P Z_; + +and by means of this theorem we are able to reduce a great many problems +of crystallography to the solution of spherical triangles. + + [H] The origin of the axes is always taken as the center of the + sphere of projection. + +Another very large class of problems in crystallography is based on the +relation of faces in a zone; that is, of faces which are all parallel +to one line called the zone axis, and whose mutual intersections, +therefore, are all parallel to each other. If, now, _h_ _k_ _l_ and +_p_ _q_ _r_ are the indices of any two planes of a zone (not parallel to +each other), any other plane in the same zone must fulfill the condition +expressed by the simple equation + + uˇ_u_ + vˇ_v_ + wˇ_w_ = _o_, + +where _u_ _v_ and _w_ are the indices of the third plane, and u v w +have the values + + u = _k_ˇ_r_ - _l_ˇ_q_ + v = _l_ˇ_p_ - _h_ˇ_r_ + w = _h_ˇ_q_ - _k_ˇ_p_. + +Since _h_ _k_ _l_ and _p_ _q_ _r_ are whole numbers, it is evident that +u v w must also be whole numbers, and these quantities are called the +indices of the zone. The three whole numbers which are the indices of a +plane when written in succession serve as a very convenient symbol of +that plane, and represent to the crystallographer all its relations; and +in like manner Miller used the indices of a zone inclosed in brackets as +the symbol of that zone. Thus 123, 531, 010 are symbols of planes, and +[111], [213], [001] symbols of zones. + +An additional theorem enables us to calculate the symbols of a fourth +plane in a zone when the angular distances between the four planes and +the symbols of three of them are known, but this problem can not be made +intelligible with a few words. + +The few propositions to which we have referred involve all that is +essential and peculiar to the system of Professor Miller. These given, +and the rest could be at once developed by any scholar who was familiar +with the facts of crystallography; and the circumstance that its +essential features can be so briefly stated is sufficient to show how +exceedingly simple the system is. At the same time, it is wonderfully +comprehensive, and the student who has mastered it feels that it +presents to him in one grand view the entire scheme of crystal forms, +and that it greatly helps him to comprehend the scheme as a whole, and +not simply as the sum of certain distinct parts. So felt Professor +Miller himself; and, while he regarded the six systems of crystals of +the German crystallographers as natural divisions of the field, he +considered that they were bounded by artificial lines which have no +deeper significance than the boundary lines on a map. How great the +unfolding of the science from Haüy to Miller, and yet now we can see the +great fundamental ideas shining through the obscurity from the first! +What we now call the parameters of a crystal were to Haüy the +fundamental dimensions of his "integrant molecules," our indices were +his "decrements," and our conceptions of symmetry his "fundamental +forms." There has been nothing peculiar, however, in the growth of +crystallography. This growth has followed the usual order of science, +and here as elsewhere the early, gross, material conceptions have been +the stepping-stones by which men rose to higher things. In sciences like +chemistry, which are obviously still in the earlier stages of their +development, it would be well if students would bear in mind this truth +of history, and not attach undue importance to structural formulć and +similar mechanical devices, which, although useful for aiding the +memory, are simply hindrances to progress as soon as the necessity of +such assistance is passed. And, when the life of a great master of +science has ended, it is well to look back over the road he has +traveled, and, while we take courage in his success, consider well the +lesson which his experience has to teach; and, as progress in this +world's knowledge has ever been from the gross to the spiritual, may we +not rejoice as those who have a great hope? + +Although the exceeding merit of the "Treatise on Crystallography" casts +into the shade all that was subordinate, we must not omit to mention +that Professor Miller published an early work on hydrostatics, and +numerous shorter papers on mineralogy and physics, which were all +valuable, and constantly contained important additions to knowledge. +Moreover, the "New Edition of Phillips's Mineralogy," which he published +in 1852 in connection with H. J. Brooke, owed its chief value to a mass +of crystallographic observations which he had made with his usual +accuracy and patience during many years, and there tabulated in his +concise manner. As has been said by one of his associates in the Royal +Society, "it is a monument to Miller's name, although he almost expunged +that name from it."[I] It is due to Professor Miller's memory that his +works should be collated, and especially that by a suitable commentary +his "Tract on Crystallography" should be made accessible to the great +body of the students of physical science, who have not, as a rule, the +ability or training which enables them to apprehend a generalization +when solely expressed in mathematical terms. The very merits of +Professor Miller's book as a scientific work render it very difficult to +the average student, although it only involves the simplest forms of +algebra and trigonometry. + + [I] "Obituary Notices from the Proceedings of the Royal Society," + No. 206, 1880, to which the writer has been indebted for + several biographical details. + +Independence, breadth, accuracy, simplicity, humility, courtesy, are +luminous words which express the character of Professor Miller. In his +genial presence the young student felt encouraged to express his +immature thoughts, which were sure to be treated with consideration, +while from a wealth of knowledge the great master made the error evident +by making the truth resplendent. It was the greatest satisfaction to the +inexperienced investigator when his observations had been confirmed by +Professor Miller, and he was never made to feel discouraged when his +mistakes were corrected. The writer of this notice regards it as one of +the great privileges of his youth, and one of the most important +elements of his education, to have been the recipient of the courtesies +and counsel of three great English men of science, who have always been +"his own ideal knights," and these noble knights were Faraday, Graham, +and Miller. + + + + +VII. + +WILLIAM BARTON ROGERS. + + +William Barton Rogers was born at Philadelphia, on the 7th of December, +1804. His father, Patrick Kerr Rogers, was a native of Newton Stewart, +in the north of Ireland; but while a student at Trinity College, Dublin, +becoming an object of suspicion on account of his sympathy with the +Rebellion of 1798, he emigrated to this country, and finished his +education in the University of Pennsylvania, at Philadelphia, where he +received the degree of Doctor of Medicine. + +Here he married Hannah Blythe, a Scotch lady--who was at the time living +with her aunt, Mrs. Ramsay--and settled himself in his profession in a +house on Ninth Street, opposite to the University; and in this house +William B. Rogers was born. He was the second of four sons--James, +William, Henry, and Robert--all of whom became distinguished as men of +science. + +Patrick Kerr Rogers, finding that his prospects of medical practice in +Philadelphia had been lessened in consequence of a protracted absence in +Ireland, made necessary by the death of his father, removed to +Baltimore; but soon afterward accepted the Professorship of Chemistry +and Physics in William and Mary College, Virginia, made vacant by the +resignation of the late Robert Hare; and it is a fact worthy of notice +that, while he succeeded Dr. Hare at William and Mary College, his +eldest son, James, succeeded Dr. Hare at the University of Pennsylvania. +At William and Mary College the four brothers Rogers were educated; and +on the death of the father, at Ellicott Mills, in 1828, William B. +Rogers succeeded to the professorship thus made vacant. + +He had already earned a reputation as a teacher by a course of lectures +before the Maryland Institute in Baltimore during the previous year, and +after his appointment at once entered on his career as a scientific +investigator. At this period he published a paper on "Dew," and, in +connection with his brother Henry, another paper on the "Voltaic +Battery"--both subjects directly connected with his professorship. But +his attention was early directed to questions of chemical geology; and +he wrote, while at William and Mary College, a series of articles for +the "Farmer's Register" on the "Green Sands and Marls of Eastern +Virginia," and their value as fertilizers. Next we find the young +professor going before the Legislature of Virginia, and, while modestly +presenting his own discoveries, making them the occasion for urging upon +that body the importance of a systematic geological survey for +developing the resources of the State. So great was the scientific +reputation that Professor Rogers early acquired by such services, that +in 1835 he was called to fill the important Professorship of Natural +Philosophy and Geology in the University of Virginia; and during the +same year he was appointed State Geologist of Virginia, and began those +important investigations which will always associate his name with +American geology. + +Professor Rogers remained at the head of the Geological Survey of +Virginia until it was discontinued, in 1842, and published a series of +very valuable annual reports. As was anticipated, the survey led to a +large accumulation of material, and to numerous discoveries of great +local importance. As this was one of the earliest geological surveys +undertaken in the United States, its directors had in great measure to +devise the methods and lay out the plans of investigation which have +since become general. This is not the place, however, for such details; +but there are four or five general results of Professor Rogers's +geological work at this period which have exerted a permanent influence +on geological science, and which should therefore be briefly noticed. +Some of these results were first published in the "American Journal of +Science"; others were originally presented to the Association of +American Geologists and Naturalists, and published in its +"Transactions." Professor Rogers took a great interest in the +organization of this association in 1840, presided over its meeting in +1845, and again, two years later, when it was expanded into the American +Association for the Advancement of Science. + +In connection with his brother Robert, Professor William B. Rogers was +the first to investigate the solvent action of water--especially when +charged with carbonic acid--on various minerals and rocks; and by +showing the extent of this action in nature, and its influence in the +formation of mineral deposits of various kinds, he was one of the first +to observe and interpret the important class of facts which are the +basis of chemical geology. + +Another important result of Professor Rogers's geological work was to +show that the condition of any coal-bed stands in a close genetic +relation to the amount of disturbance to which the enclosing strata have +been submitted, the coal becoming harder and containing less volatile +matter as the evidence of disturbance increases. This generalization, +which seems to us now almost self-evident--understanding, as we do, more +of the history of the formation of coal--was with Professor Rogers an +induction from a great mass of observed facts. + +By far, however, the most memorable contribution of Professor Rogers to +geology was that made in connection with Henry D. Rogers, in a paper +entitled "The Laws of Structure of the more Disturbed Zones of the +Earth's Crust," presented by the two brothers at the meeting of the +Association of American Geologists and Naturalists, held at Boston in +1842. This paper was the first presentation of what may be called in +brief the "Wave Theory of Mountain Chains." This theory was deduced by +the brothers Rogers from an extended study of the Appalachian Chain in +Pennsylvania and Virginia, and was supported by numerous geological +sections and by a great mass of facts. The hypothesis which they offered +as an explanation of the origin of the great mountain waves may not be +generally received; but the general fact, that the structure of mountain +chains is alike in all the essential features which the brothers Rogers +first pointed out, has been confirmed by the observations of Murchison +in the Ural, of Darwin in the Andes, and of the Swiss geologists in the +Alps. "In the Appalachians the wave structure is very simple, and the +same is true in all corrugated districts where the crust movements have +been simple, and have acted in one direction only. But where the +elevating forces have acted in different directions at different times, +causing interference of waves like a chopped sea, as in the Swiss Alps +and the mountains of Wales or Cumberland, the undulations are disguised, +and are with extreme difficulty made out." The wave theory of mountain +chains was the first important contribution to dynamical and structural +geology which had been brought forward in this country. It excited at +the time great interest, as well from the novelty of the views as from +the eloquence with which they were set forth; and to-day it is still +regarded as one of the most important advances in orographic geology. + +A marked feature of mountain regions is that rupturing of the strata +called faults; and another of the striking geological generalizations of +the brothers Rogers is what may be called the law of the distribution of +faults. They showed that faults do not occur on gentle waves, but in the +most compressed flexures of the mountain chains, which in the act of +moving have snapped or given way at the summit where the bend is +sharpest, the less inclined side being shoved up on the plane of the +fault, this plane being generally parallel to, if it does not coincide +with, the axis plane; and, further, that "the direction of these faults +generally follows the run of the line of elevation of the mountains, the +length and vertical displacement depending on the strength of the +disturbing force." + +The last of the general geological results to which we referred above +was published under the name of William B. Rogers only. It was based on +the observed positions of more than fifty thermal springs in the +Appalachian belt, occurring in an area of about fifteen thousand square +miles, which were shown to issue from anticlinal axes and faults, or +from points very near such lines; and in connection with these springs +it was further shown that there was a great preponderance of nitrogen in +the gases which the waters held in solution. + +It must be remembered that, during the time when this geological work +was accomplished, Professor Rogers was an active teacher in the +University of Virginia, giving through a large part of the year almost +daily lectures either on physics or geology. Those who met him in his +after-life in various relations in Boston, and were often charmed by his +wonderful power of scientific exposition, can readily understand the +effect he must have produced, when in the prime of manhood, upon the +enthusiastic youths who were brought under his influence. His +lecture-room was always thronged. As one of his former students writes, +"All the aisles would be filled, and even the windows crowded from the +outside. In one instance I remember the crowd had assembled long before +the hour named for the lecture, and so filled the hall that the +professor could only gain admittance through a side entrance leading +from the rear of the hall through the apparatus-room. These facts show +how he was regarded by the students of the University of Virginia. His +manner of presenting the commonest subject in science--clothing his +thoughts, as he always did, with a marvelous fluency and clearness of +expression and beauty of diction--caused the warmest admiration, and +often aroused the excitable nature of Southern youths to the exhibition +of enthusiastic demonstrations of approbation. Throughout Virginia, and +indeed the entire South, his former students are scattered, who even now +regard it as one of the highest privileges of their lives to have +attended his lectures." + +Such was the impression which Professor Rogers left at the University of +Virginia, that, when he returned, thirty-five years later, to aid in the +celebration of the semi-centennial, he was met with a perfect ovation. +Although the memories of the civil war, which had intervened, and +Professor Rogers's known sympathies with the Northern cause, might well +have damped enthusiasm, yet the presence of the highly honored teacher +was sufficient to rekindle the former admiration; and, in the language +of a contemporary Virginia newspaper, "the old students beheld before +them the same William B. Rogers who thirty-five years before had held +them spellbound in his class of natural philosophy; and, as the great +orator warmed up, these men forgot their age; they were again young, and +showed their enthusiasm as wildly as when, in days of yore, enraptured +by his eloquence, they made the lecture-room of the University ring with +their applause." + +Besides his geological papers, Professor Rogers published, while at the +University of Virginia, a number of important chemical contributions, +relating chiefly to new and improved methods in chemical analysis and +research. These papers were published in connection with his youngest +brother, Robert E. Rogers, now become his colleague as Professor of +Chemistry and Materia Medica in the University; and such were the +singularly intimate relations between the brothers that it is often +impossible to dissociate their scientific work. Among these were papers +"On a New Process for obtaining Pure Chlorine"; "A New Process for +obtaining Formic Acid, Aldehyde, etc."; "On the Oxidation of the Diamond +in the Liquid Way"; "On New Instruments and Processes for the Analysis +of the Carbonates"; "On the Absorption of Carbonic Acid by Liquids"; +besides the extended investigation "On the Decomposition of Minerals and +Rocks by Carbonated and Meteoric Waters," to which we have referred +above. There was also at this time a large amount of chemical work +constantly on hand in connection with the Geological Survey, such as +analyses of mineral waters, ores, and the like. Moreover, while at the +University of Virginia, Professor Rogers published a short treatise on +"The Strength of Materials," and a volume on "The Elements of +Mechanics,"--books which, though long out of print, were very useful +text-books in their day, and are marked by the clearness of style and +felicity of explanation for which the author was so distinguished. + +The year 1853 formed a turning-point in Professor Rogers's life. Four +years previously he had married Miss Emma Savage, daughter of Hon. James +Savage, of Boston, the well-known author of the "New England +Genealogical Dictionary," and President of the Massachusetts Historical +Society. This connection proved to be the crowning blessing of his life. +Mrs. Rogers, by her energy, her intelligence, her cheerful equanimity, +her unfailing sympathy, became the promoter of his labors, the ornament +and solace of his middle life, and the devoted companion and support of +his declining years. Immediately after his marriage, June 20, 1849, he +visited Europe with his wife, and was present at the meeting of the +British Association for the Advancement of Science, held that year at +Birmingham, where he was received with great warmth, and made a most +marked impression. Returning home in the autumn, Professor Rogers +resumed his work at the University of Virginia; but the new family +relations which had been established led in 1853 to the transfer of his +residence to Boston, where a quite different, but even a more important, +sphere of usefulness surrounded him. His wide scientific reputation, as +well as his family connection, assured him a warm welcome in the most +cultivated circles of Boston society, where his strength of character, +his power of imparting knowledge, and his genial manners, soon commanded +universal respect and admiration. He at once took an active part in the +various scientific interests of the city. From 1845 he had been a Fellow +of this Academy;[J] and after taking up his residence among us he was a +frequent attendant at our meetings, often took part in our proceedings, +became a member of our Council, and from 1863 to 1869 acted as our +Corresponding Secretary. He took a similar interest in the Boston +Society of Natural History. He was a member, and for many years the +President, of the Thursday Evening Scientific Club, to which he imparted +new life and vigor, and which was rendered by him an important field of +influence. The members who were associated with him in that club will +never forget those masterly expositions of recent advances in physical +science; and will remember that, while he made clear their technical +importance to the wealthy business men around him, he never failed to +impress his auditors with the worth and dignity of scientific culture. + + [J] This notice is reprinted from the Proceedings of the American + Academy of Arts and Sciences, vol. xviii, 1882-'83. + +During the earlier years of his residence in Boston, Professor Rogers +occupied himself with a number of scientific problems, chiefly physical. +He studied the variations of ozone (or of what was then regarded as +ozone) in the atmosphere at the time when this subject was exciting +great attention. He was greatly interested in the improvements of the +Ruhmkorff Coil made by Mr. E. S. Ritchie; and in this connection +published a paper on the "Actinism of the Electric Discharge in Vacuum +Tubes." A study of the phenomena of binocular vision led to a paper +entitled "Experiments disproving by the Binocular Combination of Visual +Spectra Brewster's Theory of Successive Combinations of Corresponding +Points." A paper discussing the phenomena of smoke rings and rotating +rings in liquids appeared in the "American Journal of Science" for 1858, +with the description of a very simple but effective apparatus by which +the phenomena would be readily reproduced. In this paper Professor +Rogers anticipated some of the later results of Helmholtz and Sir +William Thomson. In the same year an ingenious illustration of the +properties of sonorous flames was exhibited to the Thursday Evening +Club above mentioned, in which Professor Rogers anticipated Count +Schafgottsch in the invention of a beautiful optical proof of the +discontinuity of the singing hydrogen flame. + +In 1861 Professor Rogers accepted from Governor Andrew the office of +Inspector of Gas and Gas-Meters for the State of Massachusetts, and +organized a system of inspection in which he aimed to apply the latest +scientific knowledge to this work; and in a visit he again made to +Europe in 1864 he presented, at the meeting of the British Association +at Bath, a paper entitled "An Account of Apparatus and Processes for +Chemical and Photometrical Testing of Illuminating Gas." + +During this period he gave several courses of lectures before the Lowell +Institute of Boston, which were listened to with the greatest +enthusiasm, and served very greatly to extend Professor Rogers's +reputation in this community. Night after night, crowded audiences, +consisting chiefly of teachers and working-people, were spellbound by +his wonderful power of exposition and illustration. There was a great +deal more in Professor Rogers's presentation of a subject than felicity +of expression, beauty of language, choice of epithets, or significance +of gesture. He had a power of marshaling facts, and bringing them all to +bear on the point he desired to illustrate, which rendered the +relations of his subject as clear as day. In listening to this powerful +oratory, one only felt that it might have had, if not a more useful, +still a more ambitious aim; for less power has moved senates and +determined the destinies of empires. + +The interest in Professor Rogers's lectures was not excited solely, +however, by the charm of his eloquence; for, although such was the +felicity of his presentations, and such the vividness of his +descriptions, that he could often dispense with the material aids so +essential to most teachers, yet when the means of illustration were at +his command he showed his power quite as much in the adaptation of +experiments as in the choice of language. He well knew that experiments, +to be effective, must be simple and to the point; and he also knew how +to impress his audience with the beauty of the phenomena and with the +grandeur of the powers of nature. He always seemed to enjoy any elegant +or striking illustration of a physical principle even more than his +auditors, and it was delightful to see the enthusiasm which he felt over +the simplest phenomena of science when presented in a novel way. + +We come now to the crowning and greatest work of Professor Rogers's +life, the founding of the Massachusetts Institute of Technology--an +achievement so important in its results, so far-reaching in its +prospects, and so complete in its details, that it overshadows all +else. A great preacher has said that "every man's life is a plan of +God's." The faithful workman can only make the best use of the +opportunities which every day offers; but he may be confident that work +faithfully done will not be for naught, and must trustingly leave the +issue to a higher power. Little did young Rogers think, when he began to +teach in Virginia, that he was to be the founder of a great institution +in the State of Massachusetts; and yet we can now see that the whole +work of his life was a preparation for this noble destiny. The very +eloquence he so early acquired was to be his great tool; his work on the +Geological Survey gave him a national reputation which was an essential +condition of success; his life at the University of Virginia, where he +was untrammeled by the traditions of the older universities, enabled him +to mature the practical methods of scientific teaching which were to +commend the future institution to a working community; and, most of all, +the force of character and large humanity developed by his varied +experience with the world were to give him the power, even in the +conservative State of his late adoption, to mold legislators and men of +affairs to his wise designs. + +It would be out of place, as it would be unnecessary, to dwell in this +connection on the various stages in the development of the Institute of +Technology. The facts are very generally known in this community, and +the story has been already well told. The conception was by no means a +sudden inspiration, but was slowly matured out of a far more general and +less specific plan, originating in a committee of large-minded citizens +of Boston, who, in 1859, and again in 1860, petitioned the Legislature +of Massachusetts to set apart a small portion of the land reclaimed from +the Back Bay "for the use of such scientific, industrial, and fine art +institutions as may associate together for the public good." The large +scheme failed; but from the failure arose two institutions which are the +honor and pride of Boston--the Museum of Fine Arts and the Institute of +Technology. In the further development of the Museum of Fine Arts, +Professor Rogers had only a secondary influence; but one of his +memorials to the Legislature contains a most eloquent statement, often +quoted, of the value of the fine arts in education, which attests at +once the breadth of his culture and the largeness of his sympathies. + +Although the committee of gentlemen above referred to had failed to +carry out their general plan, yet the discussions to which it gave rise +had developed such an interest in the establishment of an institution to +be devoted to industrial science and education that they determined upon +taking the preliminary steps toward the organization of such an +institution. A sub-committee was charged with preparing a plan; and the +result was a document, written by Professor Rogers, entitled "Objects +and Plan of an Institute of Technology." That document gave birth to the +Massachusetts Institute of Technology, for it enlisted sufficient +interest to authorize the committee to go forward. A charter with a +conditional grant of land was obtained from the Legislature in 1861, and +the institution was definitely organized, and Professor Rogers appointed +President, April 8, 1862. Still, the final plans were not matured, and +it was not until May 30, 1864, that the government of the new +institution adopted the report prepared by its president, entitled +"Scope and Plan of the School of Industrial Science of the Massachusetts +Institute of Technology," which Dr. Runkle has called the "intellectual +charter" of the institution, and which he states "has been followed in +all essential points to this very day." In striking confirmation of what +we have written above, Dr. Runkle further says: + +"In this document we see more clearly the breadth, depth, and variety of +Professor Rogers's scientific knowledge, and his large experience in +college teaching and discipline. It needed just this combination of +acquirements and experience to put his conceptions into working shape, +to group together those studies and exercises which naturally and +properly belong to each professional course, and thus enable others to +see the guiding-lines which must direct and limit their work in its +relations to the demands of other departments.... + +"The experimental element in our school--a feature which has been widely +recognized as characteristic--is undoubtedly due to the stress and +distinctness given to it in the 'Scope and Plan.' In our discipline we +must also give credit to the tact and large-heartedness of Professor +Rogers--in the fact that we are entirely free from all petty rules and +regulations relating to conduct, free from all antagonism between +teachers and students." + +The associates of Professor Rogers in this Academy--many of them his +associates also in the Institute of Technology, or in the Society of +Arts, which was so important a feature of the organization--will +remember with what admiration they watched the indefatigable care with +which its ever active president fostered the young life of the +institution he had created. They know how, during the earlier years, he +bore the whole weight of the responsibility of the trust he had +voluntarily and unselfishly assumed for the public good; how, while by +his personal influence obtaining means for the daily support of the +school, he gave a great part of the instruction, and extended a personal +regard to every individual student committed to his charge. They recall +with what wisdom, skill, tact, and patience he directed the increasing +means and expanding scope of the now vigorous institution, overcoming +obstacles, reconciling differences, and ingratiating public favor. They +will never forget how, when the great depression succeeded the unhealthy +business activity caused by the civil war, during which the institution +had its rise, the powerful influence of its great leader was able to +conduct it safely through the financial storm. They greatly grieved +when, in the autumn of 1868, the great man who had accomplished so much, +but on whom so much depended, his nerves fatigued by care and overwork, +was obliged to transfer the leadership to a younger man; and ten years +later were correspondingly rejoiced to see the honored chief come again +to the front, with his mental power unimpaired, and with adequate +strength to use his well-earned influence to secure those endowments +which the increased life of the institution required; and they rejoiced +with him when he was able to transfer to a worthy successor the +completed edifice, well established and equipped--an enduring monument +to the nobility of character and the consecration of talents. They have +been present also on that last occasion, and have united in the +acclamation which bestowed on him the title "Founder and Father +perpetual, by a patent indefeasible." They have heard his feeling but +modest response, and have been rejoicing though tearful witnesses when, +after the final seal of commendation was set, he fell back, and the +great work was done. + +We honor the successful teacher, we honor the investigator of Nature's +laws, we honor the upright director of affairs--and our late associate +had all these claims to our regard; but we honor most of all the noble +manhood--and of such make are the founders of great institutions. In +comparison, how empty are the ordinary titles of distinction of which +most men are proud! It seems now almost trivial to add that our +associate was decorated with a Doctor's degree, both by his own +university and also by the University at Cambridge; that he was sought +as a member by many learned societies; that he was twice called to +preside over the annual meetings of the American Association for the +Advancement of Science; and that, at the death of Professor Henry, he +was the one man of the country to whom all pointed as the President of +the National Academy of Science. This last honor, however, was one on +which it is a satisfaction to dwell for a moment, because it gave +satisfaction to Professor Rogers, and the office was one which he +greatly adorned, and for which his unusual oratorical abilities were so +well suited. He was a most admirable presiding officer of a learned +society. His breadth of soul and urbanity of manner insensibly resolved +the discords which often disturb the harmonies of scientific truth. He +had the delicate tact so to introduce a speaker as to win in advance the +attention of the audience, without intruding his own personality; and +when a paper was read, and the discussion closed, he would sum up the +argument with such clearness, and throw around the subject such a glow +of light, that abstruse results of scientific investigation were made +clear to the general comprehension, and a recognition gained for the +author which the shrinking investigator could never have secured for +himself. To Professor Rogers the truth was always beautiful, and he +could make it radiant. + +It is also a pleasure to record, in conclusion, that Professor Rogers's +declining years were passed in great comfort and tranquillity, amidst +all the amenities of life; that to the last he had the companionship of +her whom he so greatly loved; and that increasing infirmities were +guarded and the accidents of age warded off with a watchfulness that +only the tenderest love can keep. We delight to remember him in that +pleasant summer home at Newport, which he made so fully in reality as in +name the "Morning-side," that we never thought of him as old, and to +believe that the morning glow which he so often watched spreading above +the eastern ocean was the promise of the fuller day on which he has +entered. + + + + +VIII. + +JEAN-BAPTISTE-ANDRÉ DUMAS.[K] + + +Jean-Baptiste-André Dumas was born at Alais, in the south of France, +July 14, 1800. His father belonged to an ancient family, was a man of +culture, and held the position as clerk to the municipality of Alais. +The son was educated at the college of his native place, and appears to +have been destined by his parents for the naval service. But the anarchy +and bloodshed which attended the downfall of the First Empire produced +such an aversion to a military life that his parents abandoned their +plan, and apprenticed him to an apothecary of the town. He remained in +this situation, however, but a short time; for, owing to the same sad +causes, he had formed an earnest desire to leave his home, and, his +parents yielding to his wish, he traveled on foot to Geneva in 1816, +where he had relatives who gave him a friendly welcome, and where he +found employment in the pharmacy of Le Royer. + + [K] Reprinted from the Proceedings of the American Academy of + Arts and Sciences, vol. xix, 1883-'84. + +At that time Geneva was the center of much scientific activity, and +young Dumas, while discharging his duties in the pharmacy, had the +opportunity of attending lectures on botany by M. de Candolle, on +physics by M. Pictet, and on chemistry by M. Gaspard de la Rive; and +from these lectures he acquired an earnest zeal for scientific +investigation. The laboratory of the pharmacy gave him the necessary +opportunities for experimenting, and an observation which he made of the +definite proportions of water contained in various commercial salts, +although yielding no new results, gained for him the attention and +friendship of De la Rive. Soon after we find the young philosopher +attempting to deduce the volumes of the atoms in solid and liquid bodies +by carefully determining their specific gravities, and thus anticipating +a method which thirty years later was more fully developed by Hermann +Kopp. + +About this time young Dumas had the good fortune to render an important +service to one of the most distinguished physicians of Geneva, whose +name is associated with the beneficial uses of iodine in cases of +goitre. It had occurred to Dr. Coindet that burned sponge, then +generally used as a remedy for that disease, might owe its efficacy to +the presence of a small amount of iodine; and on referring the question +to Dumas, the young chemist not only proved the presence of iodine in +the sponge, but also indicated the best method of administering what +proved to be almost a specific remedy. It was in connection with this +investigation that Dumas's name first appears in public. The discovery +produced a great sensation, and for many years the manufacture of iodine +preparations brought both wealth and reputation to the pharmacy of Le +Royer. + +Soon after, Dumas formed an intimacy with Dr. J. L. Prévost, then +recently returned from pursuing his studies in Edinburgh and Dublin, and +was induced to undertake a series of physiological investigations, which +for a time withdrew him from his strictly chemical studies. Several +valuable papers on physiological subjects were published by Prévost and +Dumas, which attracted the notice of Alexander von Humboldt, who on +visiting Geneva, in 1822, sought out Dumas and awakened in him a desire +to seek a wider field of activity than his present position opened to +him. In consequence he removed to Paris in 1823, where the reputation he +had so deservedly earned at Geneva won for him a cordial reception at +what was then the chief center of scientific study in Europe. La Place, +Berthollet, Vauquelin, Gay-Lussac, Thenard, Alexandre Brongniart, +Cuvier, Geoffroy St. Hilaire, Arago, Ampčre, and Poisson, all +manifested their interest in the young investigator. Dumas was soon +appointed Répétiteur de Chimie at the École Polytechnique, and also +Lecturer at the Athenćum, an institution founded and maintained by +public subscription, for the purpose of exciting popular interest in +literature and science; and from this beginning his advancement to the +highest position which a man of science can occupy in France was +extremely rapid. + +In 1826 he married Mdlle. Herminie Brongniart, the eldest daughter of +Alexandre Brongniart, the illustrious geologist, an alliance which not +only brought him great happiness, and at the time greatly advanced his +social position, but also in after years made his house one of the chief +resorts of the scientific society of Paris. The many who have shared its +generous hospitality will appreciate how greatly, for more than half a +century, Madame Dumas has aided the work and extended the influence of +her noble husband. + +In 1828-'29 Dumas united with Théodore Olivier and Eugčne Péclet in +founding the École Centrale des Arts et Manufactures, an institution +which met with great success, and in which, as Professor of Chemistry, +Dumas rendered most efficient service for many years; and in 1878 had +the very good fortune to aid in celebrating the fiftieth anniversary of +his own foundation, and to see it acknowledged as among the most +important and efficient scientific institutions of the world. In 1832 +Dumas succeeded Gay-Lussac as Professor at the Sorbonne; in 1835 he +succeeded Thenard at the École Polytechnique; and in 1839 he succeeded +Deyeux at the École de Médecine. Thus before the age of forty he filled +successively, and for some time simultaneously, all the important +professorships of chemistry in Paris except one. This exception was that +of the College of France, with which he was never permanently connected, +although it was there that he delivered his famous course on the History +of Chemical Philosophy, when temporarily supplying the place of Thenard. + +Dumas early recognized the importance of laboratory instruction in +chemistry, for which there were no facilities at Paris when he first +came to what was then the center of the world's science; and in 1832 +founded a laboratory for research at his own expense. This laboratory, +first established at the Polytechnic School, was removed to the Rue +Cuvier in 1839, where it remained until broken up by the Revolution of +1848. The laboratory was small, and Dumas would receive only a few +advanced students, and these on terms wholly gratuitous. Among these +students were Piria, Stas, Melsens, Leblanc, Lalande, and Lewy, with +whose aid he carried on many of his important investigations. By the +Revolution of 1848 Dumas's activities were for a time diverted into +political channels; but under the Second Empire his laboratory was +re-established at the Sorbonne, and in 1868 was removed to the École +Centrale. + +The political episode of Dumas's life was the natural result of an +active mind with wide sympathies, which recognizes in the pressing +demands of society its highest duty. The political and social upheaval +of 1848 seemed at the time to endanger the stability in France of +everything which a cultivated and learned man holds most dear; and Dumas +was not one to consider his own preferences when he felt he could aid in +averting the calamities which threatened his country. Immediately after +the Revolution of February, he accepted a seat in the Legislative +Assembly offered him by the electors of the Arrondissement of +Valenciennes. Shortly afterward the President of the Republic called him +to fill the office of Minister of Agriculture and Commerce. During the +Second Empire he was elevated to the rank of Senator, and shortly after +his entrance into the Senate he became Vice-President of the High +Council of Education. In order to reform the abuses into which many of +the higher educational institutions of Paris had fallen, be accepted a +place in the Municipal Council of Paris, over which he subsequently +presided from 1859 to 1870. + +In 1868 Dumas was appointed Master of the Mint of France; but he +retained the office only during a short time, for with the fall of the +Second Empire, in 1870, his political career came to an abrupt +termination. The Senate had ceased to exist, and in the stormy days +which followed, the Municipal Council had naturally changed its +complexion; and even at the Mint, the man who had held such a +conspicuous position under the Imperial government was obliged to vacate +his place. Some years previously he had resigned his professorships +because his official positions were incompatible with his relations as +teacher, and now, at the age of seventy, he found himself for the first +time relieved from the daily routine of official duties, and free to +devote his leisure to the noble work of encouraging research, and thus +promoting the advancement of science. He had reached an age when active +investigation was almost an impossibility, but his commanding position +gave him the opportunity of exerting a most powerful influence, and this +he used with great effect. In early life he had been elected, in 1832, a +member of the Academy of Sciences in succession to Serullas; in 1868 he +had succeeded Flourens as its Permanent Secretary; and in 1875 he was +elected a member of the French Academy as successor to Guizot, a +distinction rarely attained by a man of science. + +It was, however, as Permanent Secretary of the Academy of Sciences that +Dumas exerted during the last years of his life his greatest influence. +He was the central figure and the ruling spirit of this distinguished +body. No important commission was complete without him, and on all +public occasions he was the orator of the body, always graceful, always +eloquent. In announcing Dumas's death to the Academy, M. Rolland, the +presiding officer, said: + +"Vous savez la part considérable que Dumas prenait ŕ vos travaux et vous +avez bien souvent admiré, comme moi, la haute intelligence et la tact +infini avec lesquels il savait imprimer ŕ nos discussions les formes +modérées et courtoises inhérentes ŕ sa nature et ŕ son caractčre. Sous +ce rapport aussi la perte de Dumas est irréparable et crée dans +l'Académie un vide bien difficile ŕ combler. Aussi, longtemps encore +nous chercherons, ŕ la place qu'il occupait au Bureau avec tant +d'autorité, la figure sympathique et vénérée de notre bienaimé +Secrétaire perpétuel." + +And while Dumas was still occupying his conspicuous position in the +Academy, one of the most distinguished of his German contemporaries[L] +wrote of him: "An ever-ready interpreter of the researches of others, he +always heightens the value of what he communicates by adding from the +rich stores of his own experience, thus often conveying lights not +noticed even by the authors of those researches." + + [L] A. W. Hofmann, in "Nature," February 6, 1880, to whose admirable + and extended biography the writer is indebted for much of the + material with which this notice has been prepared. + +When the writer last saw Dumas, in the winter of 1881-'82, the great +chemist had still all the vivacity of youth, and it was difficult to +realize his age. He took a lively interest in all questions of chemical +philosophy, which he discussed with great earnestness and warmth. There +was the same fire and the same exuberance of fancy which had enchanted +me in his lectures thirty years before. At an age when most men hold +speculation in small esteem, I was much struck with his criticism of a +contemporary, who, he said, had no imagination, although he spoke with +the highest praise of his experimental skill. At that time Dumas showed +no signs of impaired strength. But during the following year his health +began to fail, and he died on the 11th of April, at Cannes, where he had +sought a retreat from the severity of the winter climate of Paris. + +Dumas was one of the few men whose greatness can not be estimated from a +single point of view. He was not only eminent as an investigator of +nature, but even more eminent as a teacher and an administrator. +Beginning the study of chemistry at the culmination of the epoch of the +Lavoisierian system, and regarding, as he always did, the author of +that system with the greatest admiration, he nevertheless was the first +to discover the weak point in its armor and inflict the wound which led +to its overthrow. Without attempting to detail Dumas's numerous +contributions to chemical knowledge, we will here only refer to three +important investigations, which produced a marked influence in the +progress of chemical science. + +While still in Geneva, Dumas, as has been said, made numerous +determinations of the densities of allied substances, with a view to +discovering the relations of what he called their molecular or atomic +volumes; and it is no wonder to us that the problem proved too complex +to be solved at that time. After his removal to Paris he took up the +much simpler problem which the relations of the molecular volumes of +aëriform substances present, and his paper "On Some Points of the Atomic +Theory," which was published in the "Annales de Chimie et de Physique" +for 1826, had an important influence in developing our modern chemical +philosophy. Gay-Lussac had previously observed, not only that the +relative weights of the several factors and products concerned in a +chemical process bear to each other definite proportions, but also that, +when the materials are aëriform, the relative volumes preserve an +equally definite and still simpler ratio. Moreover, on the physical +side, Avogadro, and afterward Ampčre, had conceived the theory, that in +the state of gas all molecules must have the same volume. It was Dumas +who first saw that these principles furnished an important means of +verifying the molecular and atomic weights. + +"I am engaged," he writes, "in a series of experiments intended to fix +the atomic weights of a considerable number of bodies, by determining +their density in the state of gas or vapor. There remains in this case +but one hypothesis to be made, which is accepted by all physicists. It +consists in supposing that, in all elastic fluids observed under the +same conditions, the molecules are placed at equal distances, i. e., +that they are present in them in equal numbers. An immediate consequence +of this mode of looking at the question has already been the subject of +a learned discussion on the part of Ampčre"--and Avogadro, as the author +subsequently adds--"to which, however, chemists, with the exception +perhaps of M. Gay-Lussac, appear to have given as yet but little +attention. It consists in the necessity of considering the molecules of +the simplest gases as capable of a further division--a division +occurring in the moment of combination, and varying with the nature of +the compound." + +Here, it is obvious, are the very conceptions which form the basis of +our modern chemical philosophy; and at first we are surprised that they +did not lead Dumas at once to the full realization of the consequences +which the doctrine of equal molecular volumes involves in the +interpretation of the constitution of chemical compounds, and to the +clear distinction between "the physically smallest particles" and "the +chemically smallest particles," or the molecules and the atoms, as we +now call the physical and the chemical units. This distinction is +implied throughout Dumas's paper already quoted, and is illustrated by a +striking example in the introduction to his treatise on "Chemistry +applied to the Arts," published two years later; but the ground was not +yet prepared to receive the seed, and more than a quarter of a century +must pass before the full harvest of this fruitful hypothesis could be +reaped. + +There were, however, two important incidental results of this +investigation from which chemical science immediately profited. One was +a simple method of determining with accuracy the vapor densities of +volatile substances which has since been known by Dumas's name. The +other was a radical change in the formula of the silicates. On the +authority of Berzelius, who based his opinion chiefly on the analogy +between the silicates and the sulphates, the formula SiO_{3}, had been +accepted as representing the constitution of silica. But from the +density of both the chloride and the fluoride of silicon Dumas concluded +that the formula was SiO_{2}, a conclusion which is now seen to be in +complete harmony with the scheme of allied compounds. To Berzelius, +however, the new views appeared wholly out of harmony with the system of +chemistry which he had so greatly assisted in developing, and he opposed +them with the whole weight of his powerful influence, and so far +succeeded as to prevent their general adoption for many years. Still, +"the new mode of looking at the constitution of silicic acid slowly but +surely gained ground, and it is now so firmly rooted in our convictions, +that the younger generation of chemists will scarcely understand the +pertinacity with which this innovation was resisted."[M] + + [M] Hofmann, _loc. cit._ + +But if this investigation of gas and vapor densities brought a great +strain upon the dualistic system, the second of the three great +investigations of Dumas, to which we have referred, led to its complete +overthrow. The experimental results of this investigation would not be +regarded at the present day as remarkable, and can not be compared +either in breadth or intricacy with the results of numerous +investigations of a similar character which have since been made. The +most important of these results were the substitution products obtained +by the action of chlorine gas on acetic acid. They were published in a +series of papers entitled "Sur les Types Chimiques," and the capital +point made was that chlorine could be substituted in acetic acid for a +large part of the hydrogen without destroying the acid relations of the +product; and the inference was, that the qualities of a compound +substance depend not simply on the nature of the elements of which it +consists, but also on the manner or type according to which these +elements are combined. + +To the chemists of the present day these results and inferences seem so +natural that it is difficult to understand the spirit with which they +were received forty years ago. But it must be remembered that at that +time the conceptions of chemists were wholly molded in the dualistic +system. It was thought that chemical action depended upon the antagonism +between metals and metalloids, bases and acids, acid salts and basic +salts, and that the qualities of the products resulted from the blending +of such opposite virtues. That chlorine should unite with hydrogen was +natural, for no two substances could be more unlike; but that chlorine +should supply the place of hydrogen in a chemical compound was a +conception which the dualists scouted as absurd. Even Liebig, the +"father of organic chemistry," warmly controverted the interpretation +which Dumas had given to the facts he had discovered. Liebig himself had +successfully investigated the chemical relations of a large class of +organic products. He had, however, worked on the lines of the dualistic +system, showing that organic substances might be classed with similar +inorganic substances, if we assume that certain groups of atoms, which +he called "compound radicals," might take the place of elementary +substances. In the edition of the organic part of Turner's "Chemistry" +bearing his name, organic chemistry is defined as the "chemistry of +compound radicals," and the formulas of organic compounds are +represented on the dualistic system. Liebig's conceptions were therefore +naturally opposed to those advanced by Dumas; but it is pleasant to know +that the controversy which arose never disturbed the friendly relations +between these two noble men of science, who could approach the same +truth from different sides, and yet have faith that each was working for +the same great end. In his commemorative address on Pelouze, Dumas +expresses toward Liebig sentiments of affectionate regard, and Liebig +dedicates to Dumas, with equal warmth, the German edition of his +"Letters on Chemistry." + +By the second investigation, as by the first, although Dumas gave a most +fruitful conception to chemistry, he only took the first step in +developing it. His conception of chemical types was very indefinite, and +Laurent wrote of it, a few years later: "Dumas's theory is too general; +by its poetic coloring, it lends itself to false interpretations; it is +a programme of which we await the realization." Laurent himself helped +toward this realization, and in his early death left the work to his +associate and friend Gerhardt, who pushed it forward with great zeal, +classifying chemical compounds according to the four types of +hydrochloric acid, water, ammonia, and marsh-gas. Hofmann, Williamson, +Wurtz, and many others, greatly aided in this work by realizing many of +the possibilities which these types suggested; and thus modern +Structural Chemistry gradually grew up, in which the types of Dumas and +Gerhardt have been in their turn superseded by the larger views which +the doctrine of quantivalence has opened out to the scientific +imagination. It is a singular fact, however, that, while the growth +began in France, the harvest has been chiefly reaped by Germans; and +that, although in its inception the movement was strongly opposed in +Germany, its legitimate conclusions are now repudiated by the most +influential school of French chemists. + +The third great investigation of Dumas was his revision of the atomic +weights of many of the chemical elements, and in none of his work did +he show greater experimental skill. His determination of the atomic +weight of oxygen by the synthesis of water, and of that of carbon by the +synthesis of carbonic dioxide, are models of quantitative experimental +work. To this investigation, as to all his other work, Dumas was +directed by his vivid scientific imagination. In his teaching, from the +first, he had aimed to exhibit the relations of the elementary +substances by classing them in groups of allied bodies; and at the +meeting of the British Association in 1851 he had delighted the chemical +section by the eloquence and force with which he exhibited such +relations, especially triads of elementary substances; such as chlorine, +bromine, and iodine; oxygen, sulphur, and selenium; phosphorus, arsenic, +and antimony; calcium, barium, and strontium: in which not only the +atomic weight, but also the qualities of the middle member of the triad, +were the mean of those of the other two members. Later, he came to +regard these triads as parts of more extended series, in each of which +the atomic weights increased from the first to the last element of the +series, by determinate, but not always by equal differences, the values +being, if not exact multiples of the hydrogen atom according to the +hypothesis of Prout, at least multiples of one half or one quarter of +that weight. There can be no doubt that these speculations were more +fanciful than sound, and that Dumas did not do full justice to earlier +theories of the same kind; but with him these speculations were merely +the ornaments, not the substance of his work, and they led him to fix +more accurately the constants of chemistry, and thus to lay a +trustworthy foundation upon which the superstructure of science could +safely be built. + +That exuberance of fancy to which we have referred made Dumas one of the +most successful of teachers, and one of the most fascinating of +lecturers. It was the privilege of the writer to attend the larger part +of two of his courses of lectures given in Paris, in the winters of 1848 +and 1851, and he remembers distinctly the impression produced. Besides +the well-arranged material and the carefully prepared experiment, there +was an elegance and pomp of circumstance which added greatly to the +effect. The large theatre of the Sorbonne was filled to overflowing long +before the hour. The lecturer always entered at the exact moment, in +full evening dress, and held to the end of a two hours' lecture the +unflagging attention of his audience. The manipulations were entirely +left to the care of a number of assistants, who brought each experiment +to a conclusion at the exact moment when the illustration was required. +An elegance of diction, an appropriateness of illustration, and a +beauty of exposition, which could not be excelled, were displayed +throughout, and the enthusiasm of a French audience added to the +animation of the scene. + +To the writer the lectures of Dumas were brought in contrast to those of +Faraday. Both were perfect of their kind, but very different. Faraday's +method was far more simple and natural, and he excelled Dumas in +bringing home to young minds abstruse truths by the logic of +well-arranged consecutive experiment. With Dumas there was no attempt to +popularize science; he excelled in clearness and elegance of exposition. +He exhausted the subject which he treated, and was able to throw a glow +of interest around details which by most teachers would have been made +dry and profitless. + +Two volumes of Dumas's lectures have been published; one comprises his +course on the "Philosophy of Chemistry," delivered at the College of +France in 1836; the other contains only a single lecture, accompanied by +notes, entitled "The Balance of Organic Life," which was delivered at +the Medical School of Paris, August 20, 1841. In both these volumes will +be found the beauty of exposition and the elegance of diction of which +we have spoken, and they are models of literary style. But of course the +sympathetic enthusiasm of the great man's presence can not be reproduced +by written words. + +The lecture on "The Balance of Organic Life" was probably the most +remarkable of Dumas's literary efforts. It dealt simply with the +relations which the vegetable sustains to the animal kingdom through the +atmosphere, which, though now so familiar, were then not generally +understood; and the late Dr. Jeffries Wyman, who heard the lecture, +always spoke of it with the greatest enthusiasm. + +As might be expected, Dumas's oratory found an ample field in the +Chamber of Deputies and in the Senate; and whether setting forth a +project of recasting the copper coinage or a law of drainage, or +ridiculing the absurd theories of homoeopathy, he riveted the +attention of his colleagues as completely as he had entranced the +students at the Sorbonne. + +In the early part of his life, Dumas was a voluminous writer, and in +1828 published the "Traité de Chimie appliquée aux Arts," in eight large +octavo volumes, with an atlas of plates in quarto. But besides this +extended treatise, the two volumes of lectures just referred to are his +only important literary works. He published numerous papers in +scientific journals, which, as we have seen, produced a most marked +effect on the growth of chemical science. But the number of his +monographs is not large compared with those of many of his +contemporaries, and his work is to be judged by its importance and +influence rather than by the extent of the field which it covers. + +In his capacity of President of the Municipal Council at Paris, of +Minister of Agricultural Commerce, of Vice-President of the High Council +of Education, and of Perpetual Secretary of the Academy of Sciences, +Dumas had abundant opportunity for the exercise of his administrative +ability, and no one has questioned his great powers in this direction; +but in regard to his political career we could not expect the same +unanimity of opinion. That he was a liberal under Louis Philippe, and a +reactionist under Louis Napoleon, may possibly be reconciled with a +fixed political faith and an unswerving aim for the public good; but his +scheme for "civilian billeting" (by which wealthy people having rooms to +spare in their houses would have been compelled to billet artisans +employed in public works) leads one to infer that his statesmanship was +not equal to his science. Nevertheless, there can be no question about +his large-hearted charity. He instituted the "Crédit Foncier," which +flourishes in great prosperity to this day; he also founded the "Caisse +de Rétraite pour la Vieillesse," and several other agricultural +charities, which, though less successful, afford great assistance to +aged workmen. Louis Napoleon used to say in jest that the whole of the +War Minister's budget would not have been enough to realize M. Dumas's +benevolent schemes; and once, half-dazzled, half-amused, by one of the +chemist's vast sanitary projects, he called him "the poet of hygiene." + +It was to be expected that a man working with such eminent success in so +many spheres of activity, and at one of the chief centers of the world's +culture, should be loaded with medals, and marks of distinction of every +kind. It would be idle to enumerate the orders of knighthood, or the +learned societies, to which he belonged, for, so far from their honoring +him, he honored them in accepting their membership. It is a pleasure, +however, to remember that he lived to realize his highest ambitions and +to enjoy the fruits of his well-earned renown. France has added his name +in the Pantheon + + "AUX GRANDS HOMMES LA PATRIE RECONNAISSANTE." + + + + +IX. + +THE GREEK QUESTION.[N] + + +The question whether the college faculty ought to continue to insist on +a limited study of the ancient Greek language, as an essential +prerequisite of receiving the A. B. degree, has been under consideration +at Cambridge for a long time; and, since the opinions of those with whom +I naturally sympathize have been so greatly misrepresented in the +desultory discussion which has followed Mr. Adams's Phi Beta Kappa +oration, I am glad of the opportunity to say a few words on the "Greek +question." + + [N] Remarks made at the dinner of the Harvard Club of Rhode + Island, Newport, August 25, 1883. + +This question is by no means a new one. For the last ten years it has +been under discussion at most, if not at all, of the great universities +of the world; and, among others, the University of Berlin, which stands +in the very front rank, has already conceded to what we may call the new +culture all that can reasonably be asked. + +Let me begin by asserting that the responsible advocates of an expansion +of the old academic system do not wish in the least degree to diminish +the study of the Greek language, the Greek literature, or the Greek art. +On the contrary, they wish to encourage such studies by every legitimate +means. For myself I believe that the old classical culture is the best +culture yet known for the literary professions; and among the literary +professions I include both law and divinity. Fifty years ago I should +have said that it was the only culture worthy of the recognition of a +university. But we live in the present, not in the past, and a +half-century has wholly changed the relations of human knowledge. Regard +the change with favor or disfavor, as you please, the fact remains that +the natural sciences have become the chief factors of our modern +civilization; and--which is the important point in this connection--they +have given rise to new professions that more and more every year are +opening occupations to our educated men. The professions of the chemist, +of the mining engineer, and of the electrician, which have entirely +grown up during the lifetime of many here present, are just as "learned" +as the older professions, and are recognized as such by every +university. Moreover, the old profession of medicine, which, when, as +formerly, wholly ruled by authority or traditions, might have been +classed with the literary professions, has come to rest on a purely +scientific basis. + +In a word, the distinction between the literary and the scientific +professions has become definite and wide, and can no longer be ignored +in our systems of education. Now, while they would accord to their +classical associates the right to decide what is the best culture for a +literary calling, the scientific experts claim an equal right to decide +what is the best culture for a scientific calling. Ever since the +revival of Greek learning in Europe the literary scholars have been +working out an admirable system of education. In this system most of us +have been trained. I would pay it all honor, and I would here bear my +testimony to the acknowledged facts that in no departments of our own +university have the methods of teaching been so much improved during the +last few years as in the classical. I should resist as firmly as my +classical colleagues any attempt to emasculate the well-tried methods of +literary culture, and I have no sympathy whatever with the opinion that +the study of the modern languages as polite accomplishments can in any +degree take the place of the critical study of the great languages of +antiquity. To compare German literature with the Greek, or, what is +worse, French literature with the Latin, as means of culture, implies, +as it seems to me, a forgetfulness of the true spirit of literary +culture. + +But literature and science are very different things, and "what is one +man's meat may be another man's poison," and the scientific teachers +claim the right to direct the training of their own men. It is not their +aim to educate men to clothe thought in beautiful and suggestive +language, to weave argument into correct and persuasive forms, or to +kindle enthusiasm by eloquence. But it is their object to prepare men to +unravel the mysteries of the universe, to probe the secrets of disease, +to direct the forces of nature, and to develop the resources of this +earth. These last aims may be less spiritual, lower on your arbitrary +intellectual scale, if you please, than the first; but they are none the +less legitimate aims which society demands of educated men: and all we +claim is that the astronomers, the physicists, the chemists, the +biologists, the physicians, and the engineers, who have shown that they +are able to answer these demands of society, should be intrusted with +the training of those who are to follow them in the same work. + +Now, such is the artificial condition of our schools, and so completely +are they ruled by prescription, that, when we attempt to lay out a +proper course of training for the scientific professions, we are met at +the very outset by the Greek question. Greek is a requisition for +admission to college, and the only schools in which a scientific +training can be had do not teach Greek, and, what is more, can not be +expected to teach it. + +This brings us to the root of the whole difficulty with which the +teachers of natural science have been contending, and which is the cause +of the present movement. We can not obtain any proper scientific +training from the classical schools, and the present requisitions for +admission to college practically exclude students prepared at any +others. At Cambridge we have vainly tried to secure some small measure +of scientific training in the classical schools: first, by establishing +summer courses in practical science especially designed for training +teachers, and chiefly resorted to by such persons; and, secondly, by +introducing some science requisitions into the admission examinations. +But the attempt has been an utter failure. The science requisitions have +been simply "crammed," and the result has been worse than useless; +because, instead of securing any training in the methods of science, it +has in most cases given a distaste for the whole subject. True +science-teaching is so utterly foreign to all their methods that the +requisitions have merely hampered the classical schools, and the sooner +they are abandoned the better. Both the methods and the spirit of +literary and scientific culture are so completely at variance that we +can not expect them to be successfully united in the same preparatory +school. + +We look, therefore, to entirely different schools for the two kinds of +preparation for the university which modern society demands--schools, +which for the want of better distinctive names, we may call classical +and scientific schools. In the classical school the aim should be, as it +has always been, literary culture, and the end should be that power of +clothing thought in words which awakens thought. Of course, the results +of natural science must to a certain extent be taught; for even literary +men can not afford to be wholly ignorant of the great powers that move +the world. But the natural sciences should be studied as useful +knowledge, not as a discipline, and such teaching should not be +permitted in the least degree to interfere with the serious business of +the place. In the scientific school, on the other hand, while language +must be taught, it should be taught as a means, not as an end. The +educated man of science must command at least French and German--and for +the present a limited amount of Latin--as well as his mother-tongue, +because science is cosmopolitan. But these languages should be acquired +as tools, and studied no further than they are essential to the one +great end in view, that knowledge which is the essential condition of +the power of observing, interpreting, and ruling natural phenomena. + +In such a course as this it is obvious that the study of Greek would +have no place, even if there were time to devote to it, and we can not +alter the appointed span of human life, even out of respect to this most +honored and worthy representative of the highest literary culture. Of +course, no one will question that the scholar who can command both the +literary and scientific culture will be thereby so much the stronger and +more useful man; and certainly let us give every opportunity to the +"double firsts" to cultivate all their abilities, and so the more +efficiently to benefit the world. But such powers are rare, and the +great body of the scientific professions must be made up of men who can +only do well the special class of work in which they have been trained; +and, if you make certain formal and arbitrary requisitions, like a small +amount of Greek, obstacles in the way of their advancement, or of that +social recognition to which they feel themselves entitled as educated +men, those requisitions must necessarily be slighted, and your policy +will give rise to that cry of "fetich" of which recently we have heard +so much. + +Now, all the schools which prepare students for Harvard College are +classical schools. We do not wish to alter these schools in any respect, +unless to make them more thorough in their special work. As I have +already said, the small amount of study of natural science which we have +forced upon them has proved to be a wretched failure, and the sooner +this hindrance is got out of their way the better. We do not wish to +alter the studies of such schools as the Boston and Roxbury Latin +Schools, the Exeter and Andover Academies, the St. Paul's and the St. +Mark's Schools, and the other great feeders of the college. No--not in +the least degree! We do not ask for any change which in our opinion will +diminish the number of those coming to the college with a classical +preparation by a single man. We look for our scientific recruits to +wholly different and entirely new sources. For, although we think that +there are many students now coming to us through the classical schools +who would run a better chance of becoming useful men if they were +trained from the beginning in a different way, yet such is the social +prestige of the old classical schools and of the old classical culture +that, whatever new relations might be established, the class of students +which alone we now have would, I am confident, all continue to come +through the old channels. + +This is not a mere opinion; for only a very few men avail themselves +of the limited option which we now permit at the entrance +examinations--nine, at least, out of ten, offering what is called +maximum in classics. + +We look, then, for no change in the classical schools. Our only +expectation is to affiliate the college with a wholly different class of +schools, which will send us a wholly different class of students, with +wholly different aims, and trained according to a wholly different +method. At the outset we shall look to the best of our New England +high-schools for a limited supply of scientific students, and hope by +constant pressure to improve the methods of teaching in these schools, +as our literary colleagues have within ten years vastly improved the +methods in the classical schools. In time we hope to bring about the +establishment of special academies which will do for science-culture +what Exeter and St. Paul's are doing for classical culture. We expect to +establish a set of requisitions just as difficult as the classical +requisitions--only they will be requisitions which have a different +motive, a different spirit, and a different aim; and all we ask is, that +they should be regarded as the equivalents of the classical requisitions +so far as college standing is concerned. We do not at once expect to +draw many students through these new channels. To improve methods of +teaching and build up new schools is a work of years. But we have the +greatest confidence that in time we shall thus be able to increase very +greatly both the clientage and the usefulness of the university. + +Is this heresy? Is this revolution? Is it not rather the scientific +method seeking to work out the best results in education as elsewhere by +careful observation and cautious experimenting, unterrified by authority +or superstition? Certainly, the philologist must respect our method; for +of all the conquests of natural science none is more remarkable than its +conquest of the philologists themselves. They have adopted the +scientific methods as well as the scientific spirit of investigation; +but, while thus widening and classifying their knowledge, they have +rendered the critical study of language more abstruse and more +difficult; and this is the chief reason why the time of preparation for +our college has been so greatly extended during the last twenty-five +years. Nominally, the classical schools cover no more ground than +formerly, but they cultivate that ground in a vastly more thorough and +scientific way. + +These increased requirements of modern literary culture suggest another +consideration, which we can barely mention on this occasion. How long +will the condition of our new country permit its youths to remain in +pupilage until the age of twenty-three or twenty-four; on an average at +least three years later than in any of the older countries of the +civilized world? It is all very well that every educated man should have +a certain acquaintance with what have been called the "humanities." But +when your system comes to its present results, and demands of the +physician, the chemist, and the engineer--whose birthright is a certain +social status, which by accident you temporarily control--that he shall +pass fully four years of the training period of his life upon +technicalities, which, however important to a literary man, are +worthless in his future calling, is it not plain that your conservatism +has become an artificial barrier which the progress of society must +sooner or later sweep away? Is it not the part of wisdom, however much +pain it may cost, to sacrifice your traditional preferences gracefully +when you can direct the impending change, and not to wait until the rush +of the stream can not be controlled? + + + + +X. + +FURTHER REMARKS ON THE GREEK QUESTION. + + +In a former essay I endeavored to make prominent the essential +difference between a system of education based on scientific culture and +the generally prevailing system which is based on linguistic training. I +maintained that there is not only a difference of subject-matter, but a +difference of method, a difference of spirit, and a difference of aim; +and I argued that, as the conditions of success under the two modes of +culture are so unlike, there was no danger, even with the amplest +freedom, that the study of the physical sciences would supplant or +seriously interfere with linguistic studies. But, although the drift of +my argument was plain, this essay has been quoted in order to show that +not only Greek, but also all linguistic study, would be neglected by the +students of natural science as soon as it ceased to be useful in their +profession; and my attempt to point out a basis of agreement and +co-operation has been made the occasion of reiterating the extreme +doctrine that there can be no liberal education not based on the study +of language. It has been thus assumed that scientific culture can not +supply such a basis, and in this whole discussion the value of the study +of Nature in education, except in so far as this study may yield a fund +of useful knowledge, has been entirely ignored by the advocates of the +old system. Not only has there been no recognition of the value of the +study of material forms and physical phenomena as a mode of liberal +culture, but it has been assumed throughout that--to use the now +familiar form of words--"no sense for conduct" and "no sense for beauty" +can be acquired except through that special type of linguistic training +that has so long limited elementary education. Those who demand a place +for science-culture certainly have not shown the same contemptuous +spirit; and I venture to suggest that, if classical students were as +familiar with the methods of natural science as are the students of +Nature with philological and archćological study, they would be more +charitable to those who differ with them on this subject. + +There are, of course, two distinct elements in a liberal education: the +one the acquisition of useful knowledge, the other a training or +culture of the intellectual faculties. The first should be made as broad +as possible, the second, in the present state of knowledge, must +unfortunately be greatly restricted. While in the passage referred to I +have claimed that, in a system of education based upon science, +languages should be studied simply as tools, Mr. Matthew Arnold, in a +lecture which he has recently repeatedly delivered in this country, and +whose constant refrain was the phrases I have already quoted, has +claimed that, although scholars must use the results of science as so +much literary material, they need have nothing to do with its methods. +In my view, both positions are essentially sound. It has been said that +the Greek departments in our colleges could do without the scientific +students much better than scientific scholars could do without Greek, +and this remark admits of an evident rejoinder. Certainly in this age no +professional man can afford to be ignorant of the results of science, +and he will constantly be led into error if he does not know something +of its methods. It is perfectly well known that very few of the +investigators, who have coined the scientific terms derived from the +Greek, so often referred to, could read a page of Herodotus or Homer in +the original; and it is equally true that Mr. Matthew Arnold, and his +compeer, Lord Tennyson, who have shown such large knowledge of the +results of science, could not interpret the complex relations in which +the simplest phenomena of Nature are presented to the observer. The +greater number of the students of Nature can only know the beauties of +Greek literature as they are feebly presented in translations, and so +the greater number of literary students can only know of the wonders of +Nature as they are inadequately described in popular works on science. +If it requires years of study to enable a student to master the meaning +of a Greek sentence, can we expect that in less time a student shall be +able to unravel the intricacies of natural phenomena? It has been said +that no Greek scholarship is possible for a student who begins the study +of that language in college. Is it supposed that scientific scholarship +is any more possible under such conditions? + +In order to teach successfully the _results_ of science to college +students, I have no desire that they should have any preliminary +preparation. It has been my duty for more than thirty years to present +the elements of chemistry to the youngest class in one of our colleges, +and I have never had any reason to complain of their want of interest in +the subject. Indeed, I regard it as a great privilege to be the first to +point out to enthusiastic young men the wonderful vistas which modern +science has opened to our view. So far as their temporary interest is +concerned, I should greatly prefer that they had never studied the +subject before coming to college. But even enthusiastic interest in +popular lectures is not scientific culture. A few men in every class +always have been, and will continue to be, so far interested as to make +the cultivation of science the business of their lives. But such men +always labor under the disadvantages resulting from a want of early +training, and these obstacles repel a large number whose natural tastes +and abilities would otherwise have fitted them for a scientific calling. +The change from one system of culture to another, at the age of +eighteen, has all the disadvantages of changing a profession late in +life. Nevertheless, the college will always continue to educate a number +of men of science in this way. Most of these men become teachers, and no +one questions that their previous linguistic training makes them all the +more forcible expositors of scientific truth. It is not for such persons +that I desire any change. I am, however, most anxious that the +university should do its part in educating that important class of men +who are to direct the industries and develop the material resources of +our country. Such men can be led to appreciate, and will give time to +acquire, an elegant use of language, but they will not devote four or +five years of their lives to purely linguistic training, and, if we do +not open our doors to them, they will be forced to content themselves +with such education as high-schools, or, at best, technical schools, +can offer. But, while they will thus lose the broader knowledge and +larger scope which a university education affords, the university will +also lose their sympathy and powerful support. Such students are now +wholly repelled from the university, and, under a more liberal policy, +they would form an important and clear addition to our numbers, and--as +I have said in another place--without diminishing by a single man the +number of those who come to college through the classical schools. + +But there is another class of young men with whom a system of education +based on the study of Nature would, as I am convinced, be more +successful than the prevailing system of linguistic culture: I refer to +those who now come to college, some of them through the influence of +family tradition, some of them through the expectation of social +advantage, and a still larger number on account of the attractions of +college-life. Many of these are men who, with poor verbal memories, or +want of aptitude for recognizing abstract relations, can never become +classical scholars with any exertion that they can be expected to make, +but who can often be educated with success through their perceptive +faculties. These men are the dunces of the classical department, they +add nothing to its strength, and in every classical school are a +hindrance to the better students; but some of them may become able and +useful men, if their interest can be aroused in objective realities. Of +our present students, it is only this class that the proposed changes +would really affect. Those who have tastes and aptitudes for linguistic +studies would continue to come through the old channels, and of such +only can classical scholars be made. + +I know very well it is said that, although the classical department +would be glad to be rid of this undesirable element, yet the change +could not be made without endangering the continuance of the study of +Greek in many of our classical schools. But can the university be +justified in continuing a requisition which is recognized to be opposed +to the best interests of an important class of its patrons? And +certainly it is not necessary to protect the study of Greek in this +country by any such questionable means. I have a great deal more faith +myself in the value of classical scholarship than many of my classical +colleagues appear to possess. Never has one word of disparagement been +heard from me. I honor true classical scholarship as much as I despise +the counterfeit. To maintain that the class of classical dunces, to whom +I have referred, appreciate the beauties of classical literature or +derive any real advantage from the study is, in my opinion, to maintain +a manifest absurdity. Fully as much do the convicts in a tread-mill +enjoy the beauties of the legal code under which they are compelled to +work; and if, as Chief-Justice Coleridge has recently maintained, in his +speech at New Haven, classical scholarship is the best preparation for +the highest distinctions in church and state, certainly its continuance +does not depend on the minimum requisition in Greek of this +university.[O] The "new culture," although a much "younger industry," +does not ask for any such artificial protection. It only asks for an +opportunity to show what it can accomplish, and this opportunity it has +never yet had. Even if the largest liberty were granted, those who seek +to promote a genuine education, based on natural science, would labor +under the greatest disadvantages. Not only is the apparatus required for +the new culture far more expensive than that of an ordinary classical +school, but also more personal attention must be given to each scholar, +and the ordinary labor-saving methods of the class-room are wholly +inapplicable. In the face of such obstacles as these conditions present, +the new culture can advance only very gradually; and, amid the rivalry +of the old system, it can only succeed by maintaining a very high degree +of efficiency. The new way will certainly not offer any easier mode of +admission to college than the old; and when it is remembered that the +classical system has the control of all the endowed secondary schools, +the prestige of past success, and the support of the most powerful +social influence, it is difficult to understand on what the opposition +to the free development of the "new education" is based. Are not +gentlemen, who have been talking of a revolution in education, taking +counsel of their fears rather than of their better judgment; and are +they not forgetting that the teachers of natural science have the same +interest in upholding the principles of sound education as have their +classical colleagues? Certainly there can be no question that, in the +future as in the past, they will ever seek to maintain the integrity of +all the great departments of the university unimpaired. It has happened +before this that the judgment, even of intelligent men, has been warped +by their class relations or supposed interests; but as, in this country, +the learned class has no control of government patronage, we may at +least hope that the discussion of the Greek question will never assume +with us the great bitterness that a similar controversy has aroused in +Germany. + + [O] This article was written and read to the Faculty of Harvard + College shortly after Lord Coleridge's visit to the United + States, in the autumn of 1883. + +There has been a great deal said in this discussion about the +"humanities," and it has been assumed that, while the analysis of the +Greek verb is "humanizing," the analysis of the phenomena of Nature is +"materializing." I can discover nothing humanizing in the one or the +other, except through the spirit with which they are studied, and I know +by experience that the spirit with which the study of the Latin and +Greek grammars is often enforced is most demoralizing. Those who have +been born with a facility for language may laugh at this statement; but +a boy who has been held up to ridicule for the want of a good verbal +memory, denied him by his Creator, long remembers the depressing effect +produced, if not the malignity aroused, by the cruelty. Many are the +men, now eminent in literature as well as science, who have experienced +the tyranny of a classical school, so graphically described in the +Autobiography of Anthony Trollope; and many are the boys who might have +been highly educated if their perceptive faculties had been cultivated, +whose career as scholars has been cut short by the same tyranny. + +Again, a great deal has been said about specialization at an early age, +as if the study of Nature were specializing while the study of Latin +metres and Greek accents was liberalizing. But how could specialization +be more strikingly illustrated than by a system which limits a boy's +attention between the ages of twelve and twenty to linguistic studies +to the almost entire exclusion of a knowledge of that universe in which +his life is to be passed, and which so limits his intellectual training +that his powers of observation are left undeveloped, his judgments in +respect to material relations unformed, and even his natural conceptions +of truth distorted? Now, although a special culture which has such +mischievous results as these may be necessary in order to command that +power over language which marks the highest literary excellence, and +although a university should foster this culture by all legitimate +means, yet to enforce it upon every boy who aspires to be a scholar, +whatever may be his natural talents, is as cruel as the Chinese practice +of cramping the feet of women in order to conform to a traditional ideal +of beauty. Indeed, an instructor in natural science has very much the +same difficulty in training classical scholars to observe that a +dancing-master would have in teaching a class of Chinese girls to waltz. + +Again, it has been said that while the opportunities for scientific +culture in college are ample, no one will oppose such a modification of +the requisitions for admission as the conditions of this culture demand, +provided only we label the product of such culture with a descriptive +name. Call the product of your scientific culture Bachelors of Science, +we have been told, and you may arrange the requisites of admission to +your own courses as you choose. I am forced to say that this argument, +however specious, is neither ingenuous nor charitable. If you will label +the product of a purely linguistic culture with an equally descriptive +name; if, following the French usage, you will call such graduates +Bachelors of Letters, we shall not object to the term Bachelors of +Science; or, without making so great an innovation, I, for one, should +have no objection to a distinction between Bachelors of Arts in Letters +and Bachelors of Arts in Science. But it is perfectly well understood +that in this community the degree of Bachelor of Arts is for most men +the one essential condition of admission to the noble fraternity of +scholars, to what has been called the "Guild of the Learned." To refuse +this degree to a certain class of our graduates is to exclude them from +such associations and from the privileges which they afford; and this is +just what is intended. Hence I say that the argument is not ingenuous, +and it is not charitable because it implies that a class of men who +profess to love the truth as their lives are seeking to appear under +false colors. To cite examples from my own profession only, I have +always maintained that such men as Davy, Dalton, and Faraday were as +truly learned, as highly cultivated, and as capable of expressing their +thoughts in appropriate language, as the most eminent of their literary +compeers, and I shall continue to maintain this proposition before our +American community, and I have no question that sooner or later my claim +will be allowed, and the doors of the "Guild of the Learned" will be +opened to all scholars who have acquired by cultivation the same power +which these great men held in such a pre-eminent degree by gift of +Nature. + +Lastly, I am persuaded that in a large body politic like this it is +unwise, and in the long run futile, to attempt to protect any special +form of culture at the expense of another. If one member suffers, all +the members suffer with it; and what is for the interest of the whole is +in the long run always for the interest of every part. I would welcome +every form of culture which has vindicated its efficiency and its value, +and in so doing I feel that I should best promote the interests of the +special department which I have in charge. + + + + +XI. + +SCIENTIFIC CULTURE; ITS SPIRIT, ITS AIM, AND ITS METHODS.[P] + + +I assume that most of those whom I address are teachers, and that you +have been drawn here by a desire to be instructed in the best methods of +teaching physical science. It has therefore seemed to me that I might +render a real service, in this introductory address, by giving the +results of my own experience and reflection on this subject; and my +thoughts have been recently especially directed to this topic by the +discussion in regard to the requisites for admission, which during the +past year have actively engaged the attention of the faculty of this +college. + + [P] An address delivered at the opening of the Summer School of + Chemistry at Harvard College, July 7, 1884. + +At the very outset of this discussion we must be careful to make a clear +distinction between instruction and education--between the acquisition +of knowledge and the cultivation of the faculties of the mind. Our +knowledge should be as broad as possible, but, in the short space of +human life, it is not, as a rule, practicable to cultivate, for +effective usefulness, the intellectual powers in more than one +direction. + +Let me illustrate what I mean from that department of knowledge which is +at once the most fundamental and the most essential. I refer to the +study of language. No person can be regarded as thoroughly educated who +has not the power of speaking and writing his mother-tongue accurately, +elegantly, and forcibly; and scholars of the present day must also +command, to a considerable extent, both the French and the German +languages. These three languages, at least, are the necessary tools of +the American scholar, whatever may be the special field of his +scholarship, and his end is gained if he has acquired thorough command +of these tools. But if he goes further, and studies the philology of +these languages, their structure, their derivation, their literature, +the study may occupy a lifetime, and be made the basis of severe +intellectual training. More frequently, and as most scholars think more +effectually, such linguistic training is obtained by the study of the +ancient languages, especially the Latin and the Greek, and no one +questions the value and efficiency of this form of mental discipline. +But obviously such a preparation is not necessary for the use of the +modern languages as tools, or in order to acquire a knowledge of ancient +history, of the modes of ancient life, or the results of ancient +thought. In recent discussions a great deal has been said about the +value of classical learning, and it has been argued that no man could be +regarded as thoroughly educated who had never heard of Homer or Virgil, +of Marathon or Cannć, of the Acropolis of Athens or the Forum of Rome. +Certainly not. But all this knowledge can be acquired without spending +six years in learning to read the Latin and Greek authors in the +original, or in writing Latin hexameters or Greek iambics. The +discipline acquired by this long study is undoubtedly of the highest +value, but its value depends upon the intellectual training which is the +essential result, and not upon the knowledge of ancient life and +thought, which is merely an incident. + +Now, this same distinction, which I have endeavored to illustrate on +familiar ground, must not be forgotten in considering the relations of +physical science to education. Physical science may also be studied from +two wholly different points of view: First, to acquire a knowledge of +facts and principles, which are among the most important factors of +modern life; secondly, as a means of developing and training some of +the most important intellectual faculties of the mind--for example, the +powers of observation, of conception, and of inductive reasoning. + +The experimental sciences must often be studied chiefly from the first +point of view. If no man can be regarded as thoroughly educated who is +ignorant of the outlines of Roman and Greek history: one who knows +nothing of the principles of the steam-engine, or of the electric +telegraph, is certainly equally deficient. I do not question that in our +high-schools the physical sciences must be taught, for the most part, as +funds of useful knowledge, and in regard to such teaching I have only a +few remarks to make. Assuming that information is the end to be +attained, the best method of securing the desired result is to present +the facts in such a way as will interest the scholar, and thus secure +the retention of these facts by his memory. I think it a very serious +mistake to attempt to teach such subjects by _memoriter_ recitations +from a text-book, however well prepared. This method at once makes the +subject a task; and, if in addition the preparation for an examination +is the great end in view, it is wonderful how small is the residuum +after the work is done. Such subjects can always be made intensely +interesting if presented by lectures, with the requisite illustrations, +and I do not believe that the cramming process required to pass an +examination adds much to the knowledge previously gained. Many teachers, +finding that the parrot-like learning of a text-book is unprofitable, +attempt to make the exercise more valuable by means of problems--usually +simple arithmetical problems--depending upon principles of physics or +chemistry. And there can be no doubt that such problems do serve to +enforce the principles they illustrate; but I am afraid they also more +frequently, by disgusting the student, stand in the way of the +acquisition of the desired knowledge. + +It must not be forgotten, in studying the results of science, that the +facts are never fully learned unless the learner is made to understand +the evidence on which the facts rest. The child who reads in his +physical geography that the world revolves on its axis, learns what to +him is a mere form of words, until he connects this astronomical fact +with his own observation that the sun rises in the east and sets in the +west; and so the scholar who reads that water is composed of oxygen and +hydrogen has acquired no real knowledge until he has seen the evidence +on which this fundamental conclusion rests. Let, then, the sciences be +taught as they have been in schools, as important parts of useful +knowledge, but let them so be taught as to engage the interest of the +scholar, and to direct his attention to the phenomena of Nature. + +All this, however, is not scientific culture, in the sense in which I +have constantly used the term, and does not afford any special training +for the intellectual faculties. For myself, I do not desire any study of +natural history, chemistry, or physics from this point of view as a +preparation for college; simply because, with the large apparatus of the +university, all these subjects can be presented more effectively, and be +made more interesting, than is possible in the schools. What I desire to +see accomplished by our schools is a training in physical science, +comparable in extent and efficiency with that which they now accomplish +in the ancient languages. And this brings me to another topic, namely, +scientific culture as a system of mental training. + +Before attempting to state in what scientific culture consists, we shall +do well, even at the expense of some repetition, to show that what often +passes for scientific culture is far different from the system of +education which we have so constantly advocated. The acquisition of +scientific knowledge, however extensive, does not in itself constitute +scientific culture, nor is the power of reproducing such knowledge, at a +competitive examination, any test of real scientific power. +Nevertheless, the examination papers which have been published by the +universities of England and of this country show that this is the sole +test of scientific scholarship on which most of these universities rely, +in awarding their highest honors to students in physical science. The +power of so mastering a subject as to be able to reproduce any portion +of it with accuracy, completeness, and elegance, at a written +examination, is the normal result of literary, not of scientific, +culture, and the power is of the same order, whether the subject-matter +be philology, literature, art, or science. Indeed, scientific are, as a +rule, much less adapted than literary subjects to the cultivation of +this power. Moreover, it is also true that scholars, having attained to +a very high degree of scholarship, may not possess this power of stating +clearly and concisely the knowledge they actually possess. We have all +of us known eminent men, possessing in a very high degree the power of +investigating Nature, who have been wholly unable to state clearly the +knowledge they have themselves discovered. Great harm has been done to +the cause of scientific culture by attempting to adapt the well-tried +methods of literary scholarship to scientific subjects: for, as I have +said in another place, competitive examinations are no test of real +attainment in physical science. + +Let me not be understood as disparaging the retentive memory and power +of concentration which enable the student to reproduce acquired +information with accuracy, rapidity, and elegance. This is a power of +the very highest order, and is the result of the cultivation to a high +degree of many of the noblest faculties of the mill. And I wish to +enforce is, that success in such examinations is no indication of +scientific culture, properly so called. + +What, then, are the tests of true scientific scholarship? The answer can +be made perfectly plain and intelligible. The real test is the power to +study and interpret natural phenomena. As in classical scholarship the +true test of attainment is the power to interpret the delicate shades of +meaning expressed by the classical authors, so in science the true test +is the power to read and interpret Nature; and this last power, like the +other, can as a rule only be acquired by careful and systematic +training. As some men have a remarkable facility for acquiring +languages, so also there are men who seem to be born investigators of +Nature; but by most men such powers can only be acquired through a +careful training and exercise of the faculties of the mind, on which +success depends. No man would be regarded as a classical scholar, +however broad and extended his knowledge, if that knowledge had been +acquired solely by reading English translations of the classical +authors, however excellent. So, no man can be regarded as a scientific +scholar whose knowledge of Nature has been solely derived from books. +In either case the real scholar must have been to the fountain-head and +drawn his knowledge from the original sources. In order, then, to +discover how scientific culture must be gained, we must consider the +conditions on which the successful study and interpretation of Nature +depend. + +Of the powers of the mind called into exercise in the investigation of +Nature, the most obvious and fundamental is the power of observation. By +power of observation is not meant simply the ability to see, to hear, to +taste, or to smell with delicacy, but the power of so concentrating the +attention on what we observe as to form a definite and lasting +impression on the mind. There are undoubtedly great differences among +men in the acuteness of their sensations, but successful observation +depends far less upon the acuteness of the senses than on the faculty of +the mind which clearly distinguishes and remembers what is seen and +heard. We say of a man that he walks through the world with his eyes +shut, meaning that, although the objects around him produce their normal +impression on the retina of his eye, he pays no attention to what he +sees. The power of the naturalist to distinguish slight differences of +form or feature in natural objects is simply the result of a habit, +acquired through long experience, of paying attention to what he sees, +and the want of this power in students who have been trained solely by +literary studies is most marked. + +An assistant, who was at the time conducting a class in mineralogy, once +said to me: "What am I to do? One of my class can not see the difference +between this piece of blende and this piece of quartz" (showing me two +specimens which bore a certain superficial resemblance in color and +general aspect). My answer was, "Let him look until he can see the +difference." And, after a while, he did see the difference. The +difficulty was not lack of vision, but want of attention. + +The power of observation, then, is simply the power of fixing the +attention upon our sensations, and this power of fixing the attention is +the one essential condition of scholarship in all departments of +learning. It is a power which ought to be cultivated at an early age, +and in a system of scientific culture the sciences of mineralogy and +botany afford the best field for its culture, and I should therefore +place them among the earliest studies of a scientific course. Minerals +and plants may be profitably studied in the youngest classes of our +secondary schools, but they should be studied solely from specimens, +which the scholar should examine until he can distinguish all the +characteristics of form, feature, or structure. I am told that in many +of our secondary schools both mineralogy and botany are studied with +great success and interest in the manner I have indicated. But a mistake +is frequently made in attempting to do too much. With mineralogy or +botany as classificatory sciences, our secondary schools should have +nothing to do. The discrimination between many, even of the commonest, +species of minerals or plants depends upon delicate distinctions which +are quite beyond the grasp of young minds, and the study of botany +frequently loses all its value, through the ambition of the teacher to +embrace so much of systematic botany as will enable scholars "to analyze +plants." + +If a child, twelve or fourteen years of age, is made to observe the +characteristic qualities of a few common minerals so as to enable it to +recognize them in the rocks, and is likewise led to examine the +structure of a few familiar flowers, not only will a new power have been +acquired, but a new interest will have been added to life. + +Of course, the faculty of observation thus early exercised in childhood +only attains the highest degree of development after long experience and +continued practice. The acuteness which practice gives is frequently +very remarkable, and rude men often surprise us by the extent to which +their power of observation has been cultivated in certain special +directions. The sailor who recognizes the outlines of to him a +well-known coast, where the ordinary traveler sees nothing but a bank of +clouds, or the miner who recognizes in the rock indications of valuable +ores, are illustrations which may give a clearer conception of the +nature of the power we have been attempting to describe. + +Naturally following the power of observation in the order of education +is the power of conception with the cognate power of abstraction; that +is, the power of forming in the mind distinct and accurate images of +objects, and relations, which have been previously apprehended either by +direct observation, or through description; and also the power of +confining the attention to certain features which these images may +present to the exclusion of all others. This is a power which depends +very greatly on the imagination and is capable of being cultivated to a +very high degree. There is no study which is so well suited to the +training both of the powers of conception and of abstraction as the +study of geometry. + +To this end the study of geometry should be begun at an early period in +school-life, and it should be studied at first not as a series of +propositions logically connected, but as a description of the properties +and relations of lines, surfaces, and solids--what has sometimes been +called "the science of form." A text-book prepared on this idea by Mr. +G. A. Hill forms an admirable introduction to the study. + +I esteem very highly the system of geometry of Euclid, either in its +original form or as it has been modified by modern writers, as a means +of developing the logical faculty. The completeness of the proof of the +successive propositions and their mutual dependence by means of which, +as on a series of steps, we mount from simple axiomatic truths to the +most complex relations, furnish an admirable discipline for the +reasoning power; but too often the whole value of this discipline is +lost by the failure of the pupil to form a clear conception of the very +relations about which he is reasoning, and the study becomes an exercise +of the memory and nothing more. Often have I seen a conscientious and +faithful student draw an excellent figure, and write out an accurate +demonstration, without noticing that the two were not mated; and in a +recent meeting of teachers of our best secondary schools it was gravely +asserted that solid geometry is the most difficult study with which the +teachers had to deal. In solid geometry, however, the reasoning is no +more difficult than in plane geometry, but the conceptions are far more +complex, and, if the teacher insisted that the pupil should not take a +single step until his conceptions were perfectly clear, all the +difficulties would disappear. Of this I am fully persuaded, for I have +had to encounter the same difficulties over and over again in teaching +crystallography. In beginning the study of geometry, of course the power +of conception should be helped in every possible way. Let your pupil +find out by actual measurement that the sum of the angles of a triangle +is equal to two right angles, and he will easily discover the proof of +the proposition himself. So, also, if he actually divides with his knife +a triangular prism made from a potato or an apple into three triangular +pyramids, he will find no difficulty in following the reasoning on which +the measurement of the solid contents of a sphere depends. Let me assure +teachers that the study of geometry, taught as I have indicated, is a +most valuable introduction to the study of science. But, as it has been +usually taught as a preparation for college, it is almost worthless in +this respect, however valuable it may be as a logical training. + +I consider practice in free-hand drawing from natural objects a most +valuable means of training both the power of observation and the power +of conception, besides giving a skill in delineation which is of the +greatest importance to the scientific student. Accuracy of drawing +requires accuracy in observation, and also the ability to seize upon +those features of the object which are the most prominent and +characteristic. Hence, in a course of scientific training, the +importance of practice in drawing can hardly be exaggerated, and it +should be made one of the most important objects of school-work from an +early period. + +To the scientific student the powers of observation and conception are +not sought as ends in themselves, but as means of studying Nature. The +precise portions of this wide field to which the attention of the +student shall be directed will be determined by many circumstances, and +it is not our purpose in this address to lay down a plan of study. To +most students the natural history subjects offer the most attractive +field; but all, I think, will admit that the experimental sciences +should form a considerable portion, at least, of the course of all +scientific students, whatever specialty may subsequently be chosen. That +on which I desire particularly to dwell is the spirit in which all these +studies should be pursued; and I can best illustrate what I mean by +confining my remarks to that subject in which I am most interested, and +in regard to which I have the greatest experience. + +In a course of scientific study, chemistry can not be dissociated from +physics, and the two sciences ought to be studied to a great extent in +connection with each other. Not only does the philosophy of chemistry +rest upon physical conceptions; but, moreover, chemical methods involve +physical principles. There is, however, a distinction to be made; for, +while some of the departments of physics are best studied as a +preparation for chemistry, there are other subjects which are best +deferred until the student has some knowledge of chemical facts. Among +the preliminary subjects we should mention elementary mechanics, +including hydrostatics and pneumatics, and also thermotics; while +electricity, acoustics, and optics, including the large subject of +radiant energy, may well be deferred until after the study of chemistry. + +In the study both of chemistry and physics there are of course two +definite objects to be kept in view: In the first place, a knowledge of +the facts of the science is to be acquired; in the second place, the +student must learn by experience how these facts have been discovered. +It would be obvious, from a moment's reflection, that a knowledge of the +circumstances under which the facts of Nature are revealed to the +student is essential to a complete apprehension of the facts themselves. +The child who is taught that the earth moves in an elliptical orbit +around the sun in one year does not in the least grasp the wonderful +fact thus stated, and will not come to realize it until he connects the +statement with the nightly procession of the stars in the heavens. And +it is just such a connection as this which the teacher must seek to +establish in all scientific teaching. In experimental science such a +connection is most readily established in the mind of the student by +means of a series of well-arranged experiments, which each one repeats +for himself at the laboratory table. Obviously, however, it is +impossible, in a limited course of teaching, to go over the whole ground +of chemistry and physics in this way, or even over that small portion of +the ground with which the average scientific student can expect to +become acquainted. Nor is this necessary; for, after one has realized +the connection between phenomena and conclusion in a number of +instances, the mind will fully comprehend that a similar connection +exists in other cases, and will understand the limitations with which +scientific conclusions are to be received. + +Hence, it seems to me that, in teaching chemistry or physics, it is best +to combine a course of lectures which should give a broad view of the +whole ground with a course of laboratory instruction, which must +necessarily be more or less restricted. Experimental lectures are, I am +convinced, much the best way of presenting these subjects as systematic +portions of knowledge. It is not necessary that the lectures should be +formal, but it is all-important that they should be given in such a way +that the interest of the student should be awakened, and that they +should be fully illustrated by specimens and experiments. What we read +in a book does not make one half the impression that is produced by the +words of a living teacher, nor can we realize the facts unless we see +the phenomena described. There is undoubtedly an advantage to be gained +in subsequently reviewing the subject as presented in a good text-book, +and such a book may be of great use in preparation for an examination. +But how far examinations are of value in enforcing the acquisition of +knowledge of an experimental science is a question on which I feel a +grave doubt. Certainly their value is very small if, as is too +frequently the case, they lead the student to defer all effort to make +his own the knowledge presented in the lectures, until a final cram. + +The management of lectures, text-books, and examinations, will not, +however, offer nearly so great difficulties to the teacher as the +management of the parallel experimental course of laboratory teaching. +In the last the methods are less well tried and demand of the teacher a +very considerable amount of invention and experimental skill. To follow +mechanically any text-book would result in a loss of the proper spirit +with which the course should be conducted and which constitutes its +chief value. No experiments are so good as those which have been devised +by the teacher, or, still better, by the pupils themselves. A mere +repetition of a process, according to a definite description, has no +more value than a repetition of a form of words in an ordinary school +recitation. The teacher must make sure that the student fully +understands what he is about, and comprehends all the connections +between observations and conclusions which it is his aim to establish. +Moreover, he must constantly encourage his students to think and work +for themselves, and direct them in the methods of inductive reasoning. +The failure of an experiment may be made most instructive if the student +is led to discover the cause of the failure. A leak in his apparatus may +be turned to a similar profit if the student is shown how to discover +the leak, by carefully eliminating one part after another until the weak +point is made evident. + +The direction of an experimental laboratory is no easy task. The teacher +must make each man's work his own, and follow his processes of thought +as well as his experiments with the most careful attention. With large +classes much time can be saved by going through each process on the +lecture-room table and giving the directions to the class as a whole; +but this does not supersede the personal attention and instruction which +each student requires at the laboratory table. Moreover, in laboratory +teaching the teacher must rely, as we have said, on his own resources, +and but few aids can be given. There are books, however, which will help +the teacher to prepare himself for his work, and I am happy to say that +a book entitled "The New Physics," prepared by my colleague, Professor +Trowbridge, is now being printed, which I hope will greatly promote the +laboratory teaching of physics. Nichols's abridgment of Eliot and +Storer's Manual has long served a similar valuable purpose in chemistry, +and there are many excellent works on "Qualitative Analysis," a study +which is admirably adapted to develop the power of inductive reasoning. + +There is, however, a danger with all laboratory manuals, which must be +sedulously avoided, and the danger is generally greater the more precise +the descriptions. They are apt to induce mechanical habits which are +fatal to the true spirit of laboratory teaching. Not long ago I asked a +student, who was working in our elementary laboratory, what he was +doing. He answered that he was doing No. 24, and immediately went to +find his book to see what No. 24 was. I fear that a great deal of +laboratory work is done in a way which this anecdote illustrates, and, +if so, it is a mere waste of time. + +When teaching qualitative analysis it was always with me a constant +struggle to prevent just such a result, and many of the excellent tables +which have been prepared to facilitate analysis simply encourage the +evil practice. It is an error to which college students, with their +exclusively literary preparation, are especially liable, and I have no +question that the proper conduct of our laboratories would be made much +easier if the students came with a previous scientific training. + +Thus far I have dealt solely with generalities, and my object has been +not so much to give definite directions as to make suggestions which +might lead to better systems of teaching. The details of these systems +may vary widely, and yet all may lead to the desired result if only the +true spirit of scientific teaching is preserved, and a teacher's own +system is generally the best system for him. This leads me to explain my +own system of teaching chemistry--which presents some novelties that may +be of interest, and, although it has been worked out in detail in the +revised edition of the "New Chemistry," just published, still a few +words of explanation may be of value at this time in setting forth its +salient points. + +Chemistry has been usually defined as the science which treats of the +composition of bodies, and in most text-books the aim has been to +develop the scheme of the chemical elements, and to show that, by +combining these elements, all natural and artificial substances may be +prepared. In the larger text-books, which aim to cover the whole ground +and to describe all known substances, such a method is both natural and +necessary. But, as an educational system, this mode of presenting the +subject is, as a rule, profitless and uninteresting. The student becomes +lost amid details which he can only very imperfectly grasp, and the +great principles of the science, as well as their relations to cognate +departments of knowledge, are lost sight of. Moreover, the system is +unphilosophical, because it presents the conclusions of chemistry before +the observations on which they are based. Any one who has attempted to +teach chemistry from the ordinary elementary text-books must have +experienced the truth of what I have said. + +A student learns a lesson about sodium and the various salts of this +metal, and, after glibly reciting the words of the text-book, how much +more does he know of the real relations of these bodies than he did +before? Thus: "Chloride of sodium, symbol NaCl. Crystallizes in cubes. +Soluble in water. Solubility only slightly increased by heat. Generally +obtained by evaporation of sea-water in pans. Also found in beds in +certain geological basins, from which it is extracted by mining. When +acted upon by sulphuric acid, hydrochloric acid is evolved and sodic +sulphate is formed, according to the following reaction," and so on. I +have known a student to recite all this and a great deal more, without +ever dreaming that he had been eating chloride of sodium on his food, +three times a day at least, since he was born. + +Now, the rational system of teaching chemistry is first to present to +the scholar's mind the phenomena of Nature with which the science deals. +Lead him to observe these phenomena for himself; then show him how the +conclusions which together constitute that system of knowledge we call +chemistry have been deduced from these fundamental facts. My plan is to +develop this system in the lecture-room in as much detail as the time +allotted will permit; to illustrate all the points by experiment, and in +addition to explain more in detail carefully selected fundamental +experiments, which the student subsequently repeats in the laboratory +himself. Thus I make the lecture-room instruction and the laboratory +demonstration go hand in hand as complementary parts of a single course +of teaching. + +I begin by directing the student to observe for himself the properties +of bodies by which substances are distinguished. I place in his hands a +bit of roll-brimstone. He first notices the color, the hardness, the +brittleness, and the electrical excitability of this material. He next +determines its density, its melting-point, its point of ignition, and, +if practicable, its boiling-point. Then he treats the brimstone with +various solvents, and finds that, while insoluble in water or alcohol, +it dissolves readily in sulphide of carbon. Afterward he evaporates the +solution thus made, and obtains definite crystals, whose forms he +studies, and compares with the forms of the crystals of the same +material which he also makes by fusion. Lastly, he observes the +remarkable change which follows when fused brimstone is heated above its +melting-point, and also the peculiar plastic condition which the +material assumes when the thickened mass is poured into water. He will +thus be led to see that the same material may assume different states, +and gain a clear conception of the substance we call sulphur. After this +I give the student pieces of two metals which externally resemble each +other, like lead and tin, in order that, after making another series of +observations and experiments, he may come to understand on what +comparatively slight differences of properties the distinction between +substances is frequently based. A comparison is next made of the +properties of two closely-allied liquids, like methylic and ethylic +alcohol; and by this time the student attains sufficient skill in +experimenting to make a comparison between two aëriform substances, like +oxygen gas and carbonic dioxide. + +After more or less of such preliminary work, we are prepared to take up +the subject-matter of chemistry. In the broad fields of Nature what +portion does this science cover? Natural phenomena may obviously be +divided into two great classes: First, those changes which do not +involve a transformation of substance; and, secondly, those changes +whose very essence consists in the change of one or more substances into +other substances having distinctive properties. The science of physics +deals with the phenomena of the first class; the science of chemistry +with those of the last. Any phenomenon of Nature which involves a change +of substance is a chemical change, and in every chemical change one or +more substances, called the factors, are converted into another +substance or into other substances called the products. The first point +to be made in teaching chemistry is, that a student should realize this +statement, and a number of experiments should be shown in the +lecture-room and repeated in the laboratory illustrating what is meant +by a chemical change. + +Here, of course, arises a difficulty in finding examples which shall be +at once simple and conclusive, for in almost all natural phenomena there +is a certain indefiniteness which obscures the simple process. The +familiar phenomena of combustion are most striking examples of this +fact, and men were not able to penetrate the mist which obscured them +until within a hundred years. To find chemical processes whose whole +course is obvious to an unpracticed observer, we are obliged to resort +to unfamiliar phenomena. + +A very simple example of a chemical process is a mixture of sulphur and +zinc in atomic proportions, which, when lighted with a match, is rapidly +converted into white sulphide of zinc, with appearance of flame. Another +example, a mixture of sulphur and fine iron-filings, which, when +moistened with a little water, rapidly changes into a black sulphide of +iron. Then some copper-filings, which, when heated on a saucer in the +open air, slowly change into black oxide of copper. Then a bit of +phosphorus, burned in dry air under a glass bell, yielding a white +oxide. Next, some zinc, dissolved in diluted sulphuric acid, yielding +hydrogen gas and sulphate of zinc. Then, a solution of chloride of +barium added to a solution of sulphate of soda, giving a precipitate of +sulphate of baryta, and leaving in solution common salt, which can be +recovered by evaporating the filtrate. + +In all these examples the student should be made to see and handle all +the factors and all the products of each process, and the experiments +should be selected so that he may become familiar with the different +conditions under which substances appear, and with various kinds of +chemical processes. He should also be made clearly to distinguish +between the essential features of the process and the different +accessories, which may be more or less accidental--such, for example, as +the water used in determining the combination of iron and sulphur, or +the flame which accompanies combustion. + +After a clear conception has been gained of a chemical process, with its +definite factors and definite products, we are prepared for the next +important step. Every chemical process obeys three fundamental laws: + + The Law of Conservation of Mass. + The Law of Definite Proportions. + The Law of Definite Volumes. + +According to the first law, the sum of the weights of the products of a +chemical process is always equal to the sum of the weights of the +factors. This law must now be illustrated by experiments, and +approximate quantitative determinations should be introduced thus early +into the course of study. All that is required for this purpose is a +common pair of scales, capable of weighing two or three hundred grammes, +and turning with a decigramme. We use in our laboratory some +platform-scales, made by the Fairbanks Company, which are inexpensive, +and serve a very useful purpose. + +A very satisfactory illustration of the law of conservation of mass can +be obtained by inserting in a glass flask a mixture of copper-filings +and sulphur in atomic proportions. The glass flask is first balanced in +the scale-pan; then removed and gently heated until the ignition which +spreads through the mass shows that chemical combination has taken +place. The flask is lastly allowed to cool, and on reweighing is found +not to have altered in weight. + +For a second experiment, a bit of phosphorus may, with the aid of some +simple contrivance, be burned inside a tightly-corked glass flask, of +sufficient volume to afford the requisite supply of oxygen. Of course, +on reweighing the flask, after the chemical change has taken place, and +the bottom of the flask covered with the white oxide formed, there will +be no change of weight, and this experiment may be made to enforce the +truth that, in this example of combustion at least, the chemical process +is attended with no loss of material. Open now the flask, and air will +rush in to supply the partial vacuum, proving that in the process of +combustion a portion of the material of the air has united to form the +white product. + +Make now a third experiment as an application of the general principle +which has been illustrated by the previous experiments. Burn some finely +divided iron (iron reduced by hydrogen) on a scale-pan, and show that +the process is attended by an increase of weight. What does this mean? +Why, that some material has united with the iron to form the new +product. Whence has this material come? Obviously from the air, for it +could come from nowhere else. And thus, besides illustrating the first +of the above laws, this experiment may be made to furnish an instructive +lesson in regard to the relations of the oxygen of the atmosphere to +chemical processes. + +The second law declares that in every chemical process the weights of +the several factors and products bear each to the others a definite +proportion. This law must next be made familiar by experimental +illustrations. A weighed amount of oxide of silver is placed in a glass +tube connected with a pneumatic trough. The tube is gently heated until +the oxide is decomposed and the oxygen gas collected in a glass bottle +of sufficient size. The metallic silver remaining in the tube is now +reweighed, and the volume of the oxygen gas in the bottle measured, and +from the volume of the gas its weight is deduced. The measurement is +easily made by simply marking with a gummed label the level at which the +water stands in the bottle. If, now, the bottle is removed from the +pneumatic trough and the weight of water found which fills the bottle to +the same height, the weight of the water in grammes will give the volume +of the gas in cubic centimetres, and, knowing the weight of a cubic +centimetre of oxygen, we easily calculate the weight of this gas +resulting from the chemical process. We have now the weights of the +oxide of silver, the silver, and the oxygen, the one factor and the two +products of the chemical process, and, by comparing the results of +different students making the same experiment, the constancy of the +proportion will be made evident to the class. + +For a second illustration of the same law, the solution of zinc in +dilute sulphuric acid, yielding sulphate of zinc and hydrogen gas, may +be selected, and the weight of the hydrogen, estimated as in the +previous example, shown to sustain a definite relation to the weight of +the zinc dissolved. + +Again, silver may be dissolved in nitric acid, and the weight of the +nitrate of silver obtained shown to sustain a definite relation to the +weight of the metal. + +Or, still further, as an experiment of a wholly different class, a known +weight of chloride of barium may be dissolved in water, and, after +precipitation with sulphuric acid, the baric sulphate collected by +filtration and weighed, when the definite relation between the weight of +the precipitate and the weight of the chloride of barium will appear. + +For a last experiment let the student neutralize a weighed amount of +dilute hydrochloric acid with aqua ammonia, noting approximately the +amount of ammonia required. Let him now evaporate the solution on a +water-bath, and weigh the resulting saline product; taking next the same +quantity of hydrochloric acid as before, and, having added twice the +previous quantity of ammonia, let him obtain and weigh the resulting +salammoniac as before. A third time let him begin with half the +quantity of hydrochloric acid, and, adding as much ammonia as in the +first case, again repeat the process. It is obvious what the result of +these experiments must be; but without telling the student what he is to +expect, it will be a good exercise to ask him to draw his own inferences +from the results. Of course, he must previously have so far been made +acquainted with the properties of hydrochloric acid and ammonia as to +know that the excess of either would escape when the saline solution is +evaporated over a water-bath. But with this limited knowledge he will be +able to deduce the law of definite proportions from the experimental +results thus simply obtained. + +The third of the fundamental laws of chemistry stated above (generally +known as the law of Gay-Lussac) declares that, when two or more of the +factors or products of a chemical process are aëriform, the volumes of +these gaseous substances bear to each other a very simple ratio. Here, +again, numerous experiments may be contrived to illustrate the law. +Water, when decomposed by electricity, yields hydrogen and oxygen gases +whose volumes bear to each other the ratio of two to one. When +hydrochloric-acid gas is decomposed by sodium amalgam, the volume of the +original gas bears to that of the residual hydrogen the ratio also of +two to one. When ammonia is decomposed by chlorine, the volume of the +resulting nitrogen gas is one third of that of the chlorine gas +employed. + +Having illustrated these three general laws, attention should be +directed to the fact that the nature of a chemical process and the laws +which it obeys are results of observation and involve no theory +whatsoever. On these facts the science of chemistry is built. The modern +system of chemistry, however, assumes what is known as the molecular +theory, and by means of this theory attempts to explain all these facts +and show their mutual relations. Here the distinction between fact and +theory must be insisted upon, and also the value of theory for +classifying facts and directing observation. + +A molecule is now defined, and, if the student has not studied physics +sufficiently to become acquainted with the outlines of the kinetic +theory of gases, this theory must be developed sufficiently to give the +student a knowledge of the three great laws of Mariotte, of Charles, and +of Avogadro. He must be made to understand how molecules are defined by +the physicist, and how their relative weights may be inferred by a +comparison of vapor densities. He should then be made to compare the +relative molecular weights, deduced by physical means, with the definite +proportions he has observed in chemical processes. He will thus himself +be led to the conclusion that these definite proportions are the +proportions of the molecular weights, and that the constancy of the law +arises from the fact that in every chemical process the action takes +place between molecules, and that the products of the process are new +molecules, preserving always, of course, their definite relative +weights. The student will thus be brought to the chemical conception of +the molecule as the smallest mass of any substance in which the +qualities inhere, and he will come to regard a chemical process as +always taking place between molecules. + +Thus far nothing has been said about the composition of matter. A +chemical process has been defined simply as certain factors yielding +certain products, but nothing has been determined about the relations of +these several substances except in so far as they are defined by the +three laws illustrated above. But now it must be shown that a study of +different chemical processes compels us to conclude that in some cases +two or more substances unite to form a compound, while in other cases a +compound is broken up into simpler parts. Thus, when copper-filings are +heated in the air, it is evident that the material of the copper has +united with that portion of the air we call oxygen to form the black +product we call oxide of copper; and again, when oxide of silver is +heated, it is evident that the resulting silver and oxygen gas were +formerly portions of the material of the oxide. So, when water is +decomposed by electricity, the conditions of the experiment show that +the resulting oxygen and hydrogen gases must have come from the material +of the water, and could have come from nothing else. + +Experiments should now be multiplied until the student has a perfectly +clear idea of the nature of the evidence on which our knowledge of the +composition of bodies depends. The decomposition of chlorate of potash +by heat, yielding chloride of potassium and oxygen gas; the +decomposition of nitrate of ammonium by heat, yielding nitrous oxide and +water; the decomposition of this resulting nitrous oxide, when the gas +is passed over heated metallic copper; and, lastly, the decomposition +already referred to, of water by electricity--are all striking +experiments by which the evidence of chemical composition may be +enforced. + +The distinction between elementary and compound substances having been +clearly defined by the course of reasoning already given in outline, the +next aim should be to lead the student to comprehend how substances are +analyzed and their composition expressed in percents. The reduction of +oxide of copper by hydrogen gives readily the data for determining the +composition of water, which is thus shown to contain in one hundred +parts 11ˇ11 per cent of hydrogen and 88ˇ89 per cent of oxygen. + +Another substance whose analysis can be very readily made by the student +is carbonate of magnesia. By igniting pure carbonate of magnesia in a +crucible (not of course the "magnesia alba" of the shops), the +proportions of carbonic acid and magnesia can be readily determined. +Then, by burning magnesium ribbon, and weighing the product, the student +easily finds the relative weight of magnesium and oxygen in the oxide. +And, lastly, the proportion of carbon and oxygen in carbonic dioxide is +easily deduced from the burning of a weighed amount of carbon. Here the +result may be expressed either in percents of oxide or magnesium and +carbonic dioxide, or else in percents of the elementary substances, +carbon, magnesium, and oxygen. + +After making a few analyses like these, the student will be prepared to +comprehend the actual position of the science. All known substances have +been analyzed, and the results tabulated, so that it is unnecessary to +repeat the work except in special cases. + +The teacher is now prepared to take a very important step in the +development of the subject. If the molecule is simply a small particle +of a substance in which the qualities of the substance inhere, then it +follows, of course, that the composition of the molecule is the same as +the composition of the substance. The percentage results of the analysis +of water, or of carbonate of magnesia, indicate the composition of a +molecule of water or a molecule of carbonate of magnesia. Thus, 11ˇ11 +per cent of every molecule of water consists of hydrogen, while 88ˇ89 +per cent consists of oxygen. Hence it follows that, in a chemical +process, the molecules must be divided, and these elementary parts of +molecules which analysis reveals are the atoms of chemistry. Moreover, +as we know the weights of molecules, both by physical and chemical +means, chemical analysis now gives us the weights of the atoms. We have +no time to dwell on the details of this reasoning, but the general +course to be followed will be evident, and it must be enforced by +numerous examples. + +Assuming that the student fully comprehends the distinction between +molecules and atoms--that is, between the physically smallest particles +and the chemically smallest particles--he is prepared to master the +symbolical nomenclature of chemistry, with a very few words of +explanation. The initial letters of the Latin names are selected to +represent the atoms of the seventy known elementary substances, and +these letters stand for the definite atomic weights which are tabulated +in all chemical text-books. The symbols of the atoms are simply grouped +together to form the symbols of the molecules of the various +substances; the number of atoms of each kind entering into the +composition of the molecule being indicated by a subscript numeral. +Lastly, in order to represent chemical processes, the symbols of the +molecules of the factors are written on one side and the symbols of the +molecules of the products are written on the other side of an equation, +the number of molecules of each substance involved being indicated by +numerical coefficients. + +The atomic symbols, as we have seen, stand for definite weights. In the +same way, the molecular symbols stand for definite weights, which are +the sums of the weights of the atoms of which each consists, and in +every chemical equation the weights of the molecules represented on one +side must necessarily equal the weights of the molecules represented on +the other. The chemical process consists merely in the breaking up of +certain molecules, and the rearrangement of the same constituent atoms +to form new molecules. Again, as the molecular symbols represent +definite weights, the equation also indicates that a definite proportion +by weight is preserved between the several factors and products of the +process represented. + +Again, since every molecular symbol represents the same volume when the +substance is in an aëriform condition, it follows that the relative gas +volumes are proportional to the number of molecules of the aëriform +substances involved in the reaction. Thus it is that these chemical +equations or reactions are a constant declaration of the three great +fundamental laws of chemistry. + +In order to enforce the above principles, a great number of examples +should now be given which should be so selected as to illustrate +familiar and important chemical processes, including the all-important +phenomena of combustion. In each case, the student, having made the +experiment, should write the equation or reaction which represents the +process, and should be made to solve a sufficient number of +stochio-metrical problems, involving both weights and volumes, to give +him a complete mastery of the subject. Such questions as these will test +the completeness of his knowledge: + +Why is the symbol of water H_{2}O? What information does the symbol +CO_{2} give in regard to carbonic-dioxide gas? Write the reaction of +hydrochloric acid on sodic carbonate, and state what information the +equation gives in regard to the process which it represents. + +Of course, such questions may be greatly multiplied, and I cite these +three only to call attention to the features of the method of +instruction I have been endeavoring to illustrate. + +But, besides teaching the general principles of chemical science, it is +important to give the student a more or less extended knowledge of +chemical facts and processes--especially such as play an important part +in daily life, or in the arts--and such knowledge can readily be given +in this connection. Beyond this I do not deem it desirable to go in an +elementary course of instruction. The way, however, is now opened to the +most advanced fields of the science. A comparison of symbols and +reactions leads at once to the doctrine of quantivalence, and to the +results of modern structural chemistry which this doctrine involves. +Among these results there is of course much that is fanciful, but there +is also a very large substratum of established truth; and if the student +thoroughly comprehends the symbolical language of chemistry, and +understands the facts it actually represents, he will be able to +realize, so far as is now possible, the truths which underlie the +conventional forms. + +The study of the structure of molecules naturally leads to the study of +their stability, and of the conditions which determine chemical changes, +and thus opens the recently explored field of thermo-chemistry. To be +able to predict the order and results of possible conditions of +association of materials, or of chemical changes under all +circumstances, is now the highest aim of our science, and we have +already made very considerable progress toward this end. + +But I have detained you too long, and I must refer to the "New +Chemistry" for a fuller exposition of this subject. My object has been +gained if I have been able to make clear to you that it is possible to +present the science of chemistry as a systematic body of truths +independent of the mass of details with which the science is usually +encumbered, and make the study a most valuable means of training the +power of inductive reasoning, and thus securing the great end of +scientific culture. + + + + +XII. + +"NOBLESSE OBLIGE." + + +In the former essays of this volume I have earnestly maintained that +scientific culture, rightly understood, is a suitable basis for a +liberal education; and I have maintained this thesis without in any way +attempting to disparage that literary culture hitherto so generally +regarded as the only basis on which the liberal arts could be built. +While, however, I have argued that, in the present condition of the +world, there is more than one basis of true scholarship, I have fully +admitted that for far the larger number of scholars, including all those +whose lives are to be occupied with literary pursuits, the old system of +education is still the best. Moreover, I have endeavored to point out +that scientific culture in no way conflicts with literary culture; that +it has a different spirit, a different method, and a different aim; and +I have only recommended it as suitable to those who are distinctly +preparing themselves for a scientific calling; but I have maintained +that for such men scientific studies, rightly followed, may lead to a +broad, a noble, and in the truest sense a liberal education. + +I have used the term scientific culture _rightly understood_ in order to +mark a distinction; because a great deal that passes for scientific +scholarship in the world does not imply true scientific culture. In all +departments of learning, and not less in scientific than in literary +studies, erudition does not necessarily imply a high degree of culture. +We all value the labors of the lexicographer, and the work may be so +done as to task the noblest intellectual power; but there is a higher +form of literary culture than that which dictionary-making usually +implies. So also in science, no amount of book-learning constitutes what +we have called scientific culture rightly understood. For example, the +ability to pass an examination on the facts and principles of science is +no test whatever of the form of culture we are advocating. Not that we +underrate the value of such tests, or of the knowledge they imply; but +the ability to master a subject as presented in a text-book, and to +state that knowledge in a concise and accurate form, is the normal +result of literary, not of scientific culture. The power to do +something well is involved in the very idea of culture, and the scholar +who can pass a successful written examination has acquired a power which +literary culture chiefly gives, and that this power may be applied to +scientific as well as literary subjects is obvious. Here is a most +important distinction in connection with our subject. Culture implies +the acquisition of some power of the mind in an eminent degree, and such +power is constantly associated with erudition, simply because it leads +to erudition. But when we see erudition without such power, as we often +do in every department of scholarship, we perceive at once upon how much +lower a level it stands. What very different things are classical +scholarship and classical erudition; and is not the power which the +great classical scholars possess of interpreting the thoughts of the +classical authors, and of reproducing their life, the great element of +difference between the two? + +So scientific culture implies the ability to interpret Nature, to +observe her phenomena, and to investigate her laws. The scholar, to whom +Nature presents merely an orderly succession of facts and phenomena, +knows nothing of true scientific culture. As there is a spirit in the +great writers of classical antiquity which ennobles the study of the +forms in which the thoughts of these authors were expressed, so also is +there a spirit in Nature without which facts and phenomena, however well +classified, create no intellectual elevation. The last century of the +world's history has been marked, more than by anything else, by the +increase of our knowledge of Nature, and it will be known in history as +the age of great discoveries; but valuable as the facts and principles +of science certainly are, greatly as they have promoted the well-being +of mankind, and important, therefore, as the knowledge of these facts +and principles must be to man, yet nevertheless I should never urge the +claims of physical science as a basis of liberal education if they could +be defended on no other grounds than these. It is here as elsewhere "the +spirit which giveth life"; and the power to interpret Nature, and to +commune with the intelligence that rules the universe, is the one +acquisition which, above all others, gives worth and dignity to the form +of culture we have endeavored to advocate in these essays. + +Those who regard science simply as utilitarianism, and who value +scientific studies solely because they teach men how to build railroads, +to explore mines, to extract the useful metals from their ores, or to +increase the yield of agriculture, have an even more imperfect +conception of what is meant by scientific culture than those to whom +science is merely a valuable erudition. It is true that physics and +chemistry may be studied as arts rather than as sciences, and we have no +desire to underrate the importance of such technical education; but the +difference between the two modes of study is as wide as the difference +between the artisan and the scholar. In asserting this we do not forget +that the occupations of the engineer, the electrician, and the +analytical chemist demand a very large amount of knowledge, judgment, +and skill, and are rightly regarded as learned professions. But let it +not be supposed that skill in such professions is the end or aim of +scientific culture; any more than legal skill is the end or aim of +literary culture. If literary scholars regard the study of science +solely from this point of view, it is no wonder that they think that the +tone of scholarship would be lowered if it rested solely on such a +utilitarian basis; and, on the other hand, if they could once realize +the sublimity of Nature, as Copernicus, Newton, Faraday, and unnumbered +others have realized it, this fear that devotion to science must degrade +scholarship would disappear. + +We are well aware that practical men frequently regard with undisguised +contempt the students of theoretical science, and that the greater +number of persons seeking a scientific education must look for +employment to the practical professions in which this tone too often +prevails. But, certainly, a narrow technical spirit prevails quite as +often in the professions in which literary scholars chiefly find +employment; and the new scientific professions are even more closely +dependent on the discussion of theoretical and abstract principles than +those which have hitherto been exclusively regarded as liberal. It is an +admitted fact, as we have shown in another place, that all the great +advances in practical science, all the great inventions, which during +the last century have so wonderfully increased the power of man over +Nature, may be traced directly to the results of theoretical study. For +this reason, if on no higher ground, we have claimed that it is both the +interest and the duty of the State to foster and reward scientific +investigation. The time is not far distant, if it is not already at +hand, when the scientific culture of a people will be one of the chief +factors in determining its position among the nations of the world. + +We can not leave this subject without giving prominence to another +thought, which has been ever present with us while writing these pages, +if not hitherto distinctly stated. Culture, as we have seen, implies +power, and the possession of power also involves corresponding +obligations. Among the many blessings which Christianity and its +attendant civilization have brought to mankind, the recognition of this +principle is most plainly marked. The principle is assumed in almost +every relation of life, even when not distinctly acknowledged; and +happily it can rarely now be disregarded without incurring the odium of +mankind. It leads the possessors of great wealth to devote no +inconsiderable share of their fortunes to the public good; it +stigmatizes as miserly any neglect of this obligation; and the best hope +of preserving our modern civilization against the destructive agencies +of socialism is to be found in the increasing recognition and +enforcement of this saving grace. + +But while this principle is, to a greater or less degree, acted upon in +all relations of life, it is enforced by public opinion with special +strictness upon those who assume to be the servants of the people. In +political life the obligations it imposes are already very generally +recognized; and still more strongly are they felt by the ministers of +religion. The politician who uses his high position to promote his +personal interests may sometimes escape his just deserts; but the +clergyman who prostitutes his influence for private gains is universally +condemned. So true is this, that a clergyman is debarred by his +profession from many of the industries and occupations of life which are +regarded as perfectly honorable callings for other men. A clergyman who +speculated in stocks, or even engaged in a mercantile pursuit, would, +with good reason, lose the respect of the very men who had gained their +wealth by the same ways which they deny to him. He may not, like the +members of the elder religious fraternities, take the vow of poverty, +but still he is held to a very strict rule of life; and on this is based +his claim to an adequate support from the people to whom he ministers. +Because "appointed to sow spiritual things," the clergy are entitled "to +reap worldly things" which they have not sown nor gathered; and evil +will be the days when this claim is disallowed. + +Now, we hold that the profession of a scientific teacher implies an +obligation not less binding than that which rests on the clergyman; and +this is especially true if the teacher has been placed in a conspicuous +and responsible position before the world. The teacher has been set +apart as truly as the clergyman, and, if he uses the influence of his +office merely as a means of accumulating wealth, he is not loyal to the +profession which he has voluntarily assumed. Let me not be +misunderstood. There are a thousand legitimate ways of earning a +livelihood and acquiring wealth by means of the knowledge which +scientific study gives; and a man has a right to use scientific +knowledge for his worldly advancement as freely as any other knowledge. +But the man who has accepted the post of a teacher, and receives the +support to which his position entitles him, is bound to do the work of a +teacher to the best of his ability, and to devote his whole energies to +extending the knowledge of the science which he professes to teach. It +is of the utmost importance that the community should be educated up to +this point, and should hold its teachers to their trusts and obligations +as strictly as it does its clergy. Indeed, the scientific even more than +the religious teacher requires the aid of a correct public sentiment to +maintain the tone of his profession. Scientific knowledge and acumen, +when centered on business relations, has often discovered direct avenues +to wealth; the temptation to make use of the opportunities thus offered +is of course very great, and in most of the relations of life the career +so opened may be perfectly legitimate and honorable. But no one can +expect to succeed in any business career without devoting his whole +energy to the work, and there are conditions under which such a course +would involve the betrayal of a trust. Nor are the words betrayal of a +trust too strong; for it is sometimes the case that, besides neglecting +his appropriate work, the scientific teacher sells the reputation of his +position, and commands a higher price because he barters the good name +of the institution with which he is connected. + +I am well aware that there is another side to this question. In many of +our colleges the professor has an inadequate support, and is expected or +even invited to supplement his income by what is technically called +"commercial work." Of course, in such cases the man can not be blamed; +but public opinion should be such as to prevent a respectable +institution from offering, or a respectable professor from accepting, +such a position. The workman is worthy of his hire, and the same +sentiment which demands from the scientific professor a whole-hearted +devotion to his work, demands also from the community for which he works +an adequate support. + +It is undoubtedly in consequence of the inadequate support which +scientific teachers generally receive in this country that public +sentiment tolerates with them practices which sober judgment must +condemn; and it must be remembered that under these circumstances a +teacher, if he is faithful to the routine of his office, may devote his +remaining energies to commercial work, not only without any +consciousness of wrong-doing, but even with the approbation of his +associates. Hence, it is the more important to establish firmly in the +public mind the well-founded opinion that the endowed professorships of +our higher institutions of learning are offices of public trust, to be +administered solely for the public good. There is no hardship in this +position; since perfectly legitimate and honorable avenues are opened to +the scientific scholar, on which he may expend his business energies, +and, at the same time, use his scientific knowledge; and for many men +these avenues lead in the directions in which they can not only most +effectually advance themselves in worldly prosperity, but also most +benefit their fellows. Among the men of practical ability who have +developed a new industry, or introduced a new invention, and who have +acquired wealth thereby, are to be found some of the greatest +benefactors of their race; and far would it be from me to institute a +comparison between the practical men and the scholars. All we claim is +that the men of affairs should resign the endowments intended for the +maintenance of scholars to those whose zeal is sufficient to induce them +to make gladly the sacrifices which the advancement of knowledge usually +entails. + +These considerations will appear still more forcible if viewed in +relation to the interest of the community in scientific culture to which +we have already referred. This interest has not been overlooked, and in +recent years a great many projects have been discussed for what is +termed the "endowment of research"; and already very considerable funds +are held by learned societies of the Old World, and smaller amounts by +several societies of this country, which have been devoted to this +object. But although means are thus furnished to a limited extent to pay +the expenses of scientific investigations, and very considerable prizes +are offered for the solution of important problems, yet it must be +confessed that as yet the results have been meager and have not answered +the expectations of the founders of the endowments; and the reason of +the small fruitage is not far to seek. A certain order of scientific +results can be purchased like other professional work for a price which +is to some extent proportionate to the skill required to obtain them. +Such, for example, are the daily observations at an astronomical or a +meteorological station; such also are chemical analyses and assays of +various kinds; such, again, is much of the routine work of a physical +laboratory. But the highest order of scientific results, such as leave a +permanent impress on the records of science--like Newton's law of +gravitation, Young's theory of light, Faraday's theory of electricity, +or Bunsen's methods of spectrum analysis--can no more be had to order +than could "Paradise Lost" or "In Memoriam" have been purchased by the +foot. Moreover, scientific progress follows a necessary law of +continuity, and important advances can not be made until the time is +ripe. The most that can be done with the direct endowments for research +is, to multiply trustworthy observations, and thus prepare the way for +discovery; and more than this can not be expected. + +A more efficient means of cultivating science, and one which is certain, +in the long run, to yield a far more abundant and richer harvest, is to +secure the conditions which are known to be favorable to scientific +discoveries, and to hold in honor such discoveries when made; and I +think there will be little difference of opinion among competent +scientific authorities that the one essential condition above all others +is a certain atmosphere which results from the association of men who +are engaged in scientific study. + +An association of scholars acts in many ways to favor either literary or +scientific production. In the first place, it leads to competition, +which, although a low motive, is a very potent one in all forms of human +activity. In the second place, the contact of minds engaged in similar +studies leads the student to take a broader view of his subject, and to +see it from the various points of view which the criticism of his +associates may point out. Above all, work done in such associations is +not done without observation, and there are present witnesses to attest +the results, and publish them with the authority which is required to +insure for them general acceptance. A great deal of scientific work is +lost to the world because done in a corner, and buried in the +transactions of local societies, from which it is not disinterred until +the work has been repeated. The advantages of such association are only +too evident to the numerous workers in science at the isolated colleges +of this country, who are forced to compare their opportunities with +those of their compeers in the great capitals of Europe; and the want of +scientific productiveness in the United States which we so greatly +lament is due chiefly to the want of the stimulus which combined action +so greatly gives. Happily, however, the conditions favorable for +scientific investigation are multiplying at home, and already there are +several centers at which the productiveness is rapidly increasing, and +gives great promise of the future. Moreover, this growth gives us a good +indication as to the points at which we can most advantageously apply +aid; and I am confident that there is no way in which we can so +effectively encourage scientific investigation as by establishing at the +institutions of learning, which are at present the chief centers of +scientific activity, more professorships and fellowships, in order to +give support to those who are ready to devote their lives to scientific +study. + +The teaching which a professorship implies, instead of being a +hindrance, ought to be a great stimulus to scientific investigation. Of +course, this influence is greatly impaired if, as in many of our +colleges, the available energies of the teacher are exhausted by the +daily routine of instruction, or by the outside work required to +supplement his meager salary. But, if the teaching is only moderate in +amount and in the direction of the professor's own work, there is no +stimulus so great as that which the association with a class of earnest +students supplies. + +Were it necessary to sustain the opinions here advanced by further +illustrations, we need only point to the Royal Institution of Great +Britain, which holds foundations like those we have advocated; for the +names of Davy, Young, Faraday, Tyndal, and Dewar, are a conspicuous +memorial of the very great success of such endowments in advancing +physical science. + +It is obvious, however, that the endowment of professorships and +fellowships will be of no value to the community unless it is understood +that the incumbents are set apart for their special work; and the +suggestion that such positions could be used to favor private ends, or +as the basis of mercantile transactions, is sufficient to show how +inconsistent such a practice is with the true conception of scientific +culture. + +Our patent laws have a very marked and not altogether a beneficial +influence on the scientific culture of the country. It is true that they +foster mechanical ingenuity and inventive talent in certain directions, +but they also set before the people a very low and mercenary standard of +scientific attainment, upon which the popular notion of the utilitarian +tendency of scientific studies is to a great extent based. No one can +question that the discoverer of a new process, or the inventor of a new +machine, has a right to keep his knowledge to himself, and to make the +best use he can of his good fortune to increase his wealth. But +certainly the motto at the head of this essay points to a more excellent +way, and it is at least an open question whether it is for the interest +of the community at large to encourage by its laws the more selfish +course. The argument by which the patent laws are usually defended by +legal writers--that it is for the benefit of the community to encourage +and therefore to protect inventive talent--is by no means so +unanswerable as it appears _prima-facie_. + +In the first place, it may be questioned whether, in the present +condition of our patent laws, they do not hinder more than they foster +invention. Any one who has attempted to perfect a machine, or improve a +chemical process, knows to what extent he is hampered on every side by +patent rights, which often have no value to the holders except that +which the new improvement may give to them. + +Again, the inventions which the patent laws foster are only those having +an immediate pecuniary value, and it is often exceedingly simple +contrivances--like the needle of a sewing-machine or a gaudy toy--which +yield the greatest return; simply because they have been accommodated to +present emergencies or to passing popular fancy. Such contrivances +usually manifest no extended knowledge and no special talent, and the +inventor owes his good luck to the sole circumstance that he was in a +position to recognize the want. + +Now, every scientific investigator knows that the ordinary work of a +physical or chemical laboratory frequently demands inventive ability of +a high order, and that few important scientific results have been +reached that have not involved inventions as worthy of admiration as the +sewing-machines and power-looms which are so frequently cited as +examples of the beneficent influence of our patent laws; and the +question arises, is it for the interest of the community to promote one +class of inventions more than the other? Certainly, if we consider +either the sacrifice involved, or the ultimate good which eventually +results to the community, there can not be a moment's question which +class is the most valuable or most worthy of commendation. Yet the +patent laws not only give their immense prizes solely to inventions of +immediate utility, but also tend to raise a false estimate of the +intrinsic value of such inventions in the public mind. + +Some writers have gone to the extreme of claiming that a man has the +same right in his inventions or discoveries that an author has in his +books; but this claim will not bear analysis. The first duty of a +government is to protect its citizens in the enjoyment of the results +of their lawful labor, and certainly any one who has written a book +knows that it is just as much the product of day-labor as any article of +merchandise. On the other hand, an invention or discovery may be the +result of a fortunate accident, and, although it may be the fruit of +superior knowledge and intelligence, it can not be regarded in the same +sense as a direct product of labor. It is much more frequently a free +gift of Nature. + +Moreover, it is seldom if ever the case that a useful invention, meeting +a popular want, and therefore having a large commercial value, is in any +sense the product of one man. As a general rule, the patentee who enjoys +the right to the invention has actually added to the old stock only a +single detail. It may be that this detail was the one thing required to +make the invention practically useful; but it is certain that the +addition could never have been made if the previous knowledge had not +existed, and it is at least an open question whether the community ought +to grant to the last man an exclusive right to the whole inheritance. +Volta discovered--invented, if you please--the mode of generating a +current of low-tension electricity, which has been ever since, with +certain modifications, in general use; Oersted and Ampére discovered the +magnetic effects of this electrical current; Faraday, again, learned how +to produce an electric current from a magnet, and invented the original +dynamo-machine; Henry discovered the conditions under which the magnetic +effects of an electric current might be produced at great distances from +the source of the power. All these men were inventors of the highest +order, whose inventions have never been excelled either in the ingenuity +displayed, or in the influence exerted on the welfare of mankind. +Moreover, these far-reaching inventions were a willing contribution to +the world's knowledge, for which no pecuniary compensation was either +asked or received. Is it not, then, a question if any man of the present +day has a right to the exclusive use of these inventions; for writing +messages at a distance, for transmitting sound over wires, or for any +purpose whatsoever? + +There is of course another side to the question, and I freely admit the +difficulty of the problem which our patent laws present; but I feel that +in their present condition they do more harm than good, and do injustice +more frequently than they protect right. I greatly doubt if it is safe +to grant by statute property in any invention or discovery beyond the +definite mechanical contrivance in which it is for the time embodied. To +grant the sole use of a well-known power of Nature to produce a specific +effect, although the effect be a novel one; to give the monopoly of a +process of Nature to the man who was the first to claim it; above all, +to grant the sole right to make a specified mixture of materials--is +certainly a policy which directly encourages vast monopolies, that tax +the public without rendering a corresponding benefit. + +In this connection it must be remembered that the discoverer or inventor +himself rarely reaps the fruit of his sagacity or skill; but his rights, +frequently purchased for a song, are made the basis of great business +enterprises in which he has little or no share. On such a slender basis +have frequently been built up huge monopolies, in which the patent laws +have been made the instruments of oppressive exactions, and have become +the nucleus of a most complex system of usages and legal decisions, by +which the original intent of the laws has been wholly overlaid, and to a +great extent nullified. + +Certainly, there ought to be some limit to the inventor's claims on a +grateful people. Admit to the utmost the inventor's merit; rank him in +the fore front of the long procession of the great benefactors of the +human race; rank him before Faraday, before Volta, and before Newton; +rank him before Washington and the Fathers of the Republic; rank him +before the patriots and martyrs who have died in the defense of human +rights, or in attestation of the truth: and yet, in virtue of these +transcendent merits, should he or his representatives be authorized to +tax his countrymen millions on millions of dollars a year? Surely, there +could not be a greater travesty of our motto, "Noblesse Oblige"; and a +system which gives a legal sanction to such abuses will soon force on +the public mind that most convincing of all proofs of perversion, the +_reductio ad absurdum_. + +It is not, however, our intention to discuss the abuses of the patent +laws, much less to suggest the required remedies. We clearly see the +difficulties of the subject, and we perceive that it involves questions, +both of political economy and of jurisprudence, with which we are not +competent to deal. Our interest is solely to maintain the dignity of +scientific culture, and to demand for it the respect to which it is +entitled; but which is seriously compromised by the mercenary and +utilitarian spirit that the patent laws encourage and make prominent. We +are most anxious that the intelligence of our people should fully +recognize the fact that, among the students of science in this practical +age, there is such a thing as devotion to the truth for the truth's +sake; that throughout the length and breadth of these United States may +be found many an earnest student of Nature who, under great +disadvantages, and often at great personal sacrifice, is devoting the +noblest intellectual power, and the highest inventive skill, to the sole +end of advancing knowledge: and we rejoice to believe that the time +will come when it will be plainly seen by all that these silent workers +have been laying broad and deep-enduring foundations, on which national +greatness can securely rest. + + + + +XIII. + +THE SPIRITUAL LIFE.[Q] + + +We have reached the end of our long journey, and now we are ready to +turn back and start for home. + + [Q] An Address to College Students at the close of a course of + lectures on Egypt and her Monuments. Illustrated by lantern + photographs. + +The Reis is at his helm, the great sail is furled and bound closely to +the long yard; for, as the wind during the early spring blows here +constantly from the north, we must depend on the rapid current of the +Nile to bear us back to civilization: a river which, flowing through so +many generations of men from the unknown to the unlimited, not unfitly +typifies the course of history; and as, in imagination, we drift with +this historical stream, we can not fail to learn the lesson which the +associations and the scenes are so calculated to teach. That lesson is +the grandeur, the glory, and the immortality of the spiritual life of +man. + +We go back six thousand years, and find the Sphinx, as to-day, looking +toward the rising sun, and pondering the problem of human destiny. + +The pyramid-builders come, and erect those neighboring piles to preserve +their bodies when dead for that glorious destiny in which they trust. + +The long procession of the Pharaohs passes, and each inscribes indelibly +on rocky walls his faith in the great God who holds human destiny in his +hands. + +Moses comes, and leads out of Egypt the chosen people to prepare the way +for the expected Messiah. + +The Assyrians and the Persians come, and, while seeking to read their +destiny in the courses of the stars, pay homage to the same great hope. + +The Greeks come, and, even amid gross licentiousness and idolatry, erect +magnificent temples, in attestation of a belief in human destiny which, +however degraded, still survived. + +The Romans come, and in this mystic land lay aside their legal codes, +and add their testimony to the same great truth. + +The Christian hermits come, and make the storied stones of the Pharaohs +re-echo with their triumphant songs. + +The Arab comes, and, as morning and evening he gazes into the East, sees +visions of the glorious Mecca of his hopes for which the Sphinx has +looked so long. + +Last of all, the modern traveler comes, and he journeys in vain if he +does not recognize in all this aspiration and all this yearning the +attestation of those spiritual truths which to him the risen Christ has +revealed. + +As in material nature every unemployed organ distinctly points to a +previous use or to a future fruition: so, in the spiritual world, every +striving is a promise of a possible good; and these yearnings of +humanity, which have come down through the ages, are as truly a promise +of the Eternal as were the words spoken to Abraham on the plains of +Mamre. + +Coming home from the East, we can not fail to see, more clearly than +before, how artificial are most of the conventionalities of our modern +civilization, and how greatly such cares of the world tend to obscure +the great distinction between the spiritual and the material which is +ever present to Oriental thought; and this is especially true in our own +country, where the demands of material nature are so pressing, and where +the physical wants, which our highly artificial life entails, so +completely engross the attention of us all. + +It is well to go away at times, that we may see another aspect of human +life, which still survives in the East, and to feel that influence +which led even the Christ into the wilderness to prepare for the +struggle with the animal nature of man. + +We need something of the experience of the anchorites of Egypt to +impress us with the great truth that the distinction between the +spiritual and the material remains broad and clear, even if with the +scalpel of our modern philosophy we can not completely dissect the two; +and this experience will give us courage to cherish our aspirations, +keep bright our hopes, and hold fast our Christian faith until the +consummation comes. + +My young friends, there are many who will tell you that the Sphinx has +merely propounded a riddle to the ages; and that the yearnings of your +young lives--like those of the early Egyptians, who set up this memorial +of their hopes--are merely a delusion and a snare. + +Do not believe in any such pessimism. + +It is merely the dying gasp of your animal nature! But give your utmost +efforts that these aspirations be not smothered by the cares and trials +which must come to you as they come to all. + +Have faith in the Eternal who implanted those cravings in your nature; +and remember that all knowledge rests on the assurance that the Eternal +can not be false. Be loyal to the truth of that witness in your hearts, +and advancing years will only bring you increased reliance on the +promises he ever whispers to those who trust him; and he will certainly +lead you, at last--as he has led the faithful in all ages--into the +clear light of the perfect day. + +My fellow-students, if these fleeting pictures of scenes which have +given me fresh courage, shall aid any of you in the conflict of life, my +object in these lectures will be gained, and however incongruous with +the associations of physical science such scenes may have appeared, you +will bear me witness that the great lesson they teach has constantly +been enforced in this place. The spiritual life of man recognizes its +exalted intellectual likeness in the life of Nature, and it is this +vision of the Omniscient which distinguishes and ennobles mental +culture, whether it be in the fields of science, of literature, or of +art. + + +THE END. + + + * * * * * + + +SCIENTIFIC LECTURES AND ESSAYS. + + Popular Lectures on Scientific Subjects. By H. HELMHOLTZ, Professor + of Physics in the University of Berlin. First Series. Translated by + E. ATKINSON, Ph. D., F. C. S. With an Introduction by Professor + TYNDALL. With 51 Illustrations. 12mo. Cloth, $2.00. + + _CONTENTS._--On the Relation of Natural Science to Science in + General.--On Goethe's Scientific Researches.--On the Physiological + Causes of Harmony in Music.--Ice and Glaciers.--Interaction of the + Natural Forces.--The Recent Progress of the Theory of Vision.--The + Conservation of Force.--Aim and Progress of Physical Science. + + Popular Lectures on Scientific Subjects. By H. HELMHOLTZ. Second + Series. 12mo. Cloth, $1.50. + + _CONTENTS._--Gustav Magnus.--In Memoriam.--The Origin and + Significance of Geometrical Axioms.--Relation of Optics to + Painting.--Origin of the Planetary System.--On Thought in + Medicine.--Academic Freedom in German Universities. + + "Professor Helmholtz's second series of 'Popular Lectures on + Scientific Subjects' forms a volume of singular interest and value. + He who anticipates a dry record of facts or a sequence of immature + generalization will find himself happily mistaken. In style and + method these discourses are models of excellence, and, since they + come from a man whose learning and authority are beyond dispute, + they may be accepted as presenting the conclusions of the best + thought of the times in scientific fields."--_Boston Traveler._ + + Science and Culture, and other Essays. By Professor T. H. HUXLEY, + F. R. S. 12mo. Cloth, $1.50. + + "Of the essays that have been collected by Professor Huxley in this + volume, the first four deal with some aspect of education. Most of + the remainder are expositions of the results of biological + research, and, at the same time, illustrations of the history of + scientific ideas. Some of these are among the most interesting of + Professor Huxley's contributions to the literature of + science."--_London Academy._ + + "It is refreshing to be brought into converse with one of the most + vigorous and acute thinkers of our time, who has the power of + putting his thoughts into language so clear and forcible."--_London + Spectator._ + + Scientific Culture, and other Essays. By JOSIAH PARSONS COOKE, + Professor of Chemistry and Mineralogy in Harvard College. 12mo. + Cloth, $1.00. + + These essays are an outcome of a somewhat large experience in + teaching physical science to college students. Cambridge, + Massachusetts, early set the example of making the student's own + observations in the laboratory or cabinet the basis of all + teaching, either in experimental or natural history science; and + this example has been generally followed. "But in most centers of + education," writes Professor Cooke "the old traditions so far + survive that the great end of scientific culture is lost in + attempting to conform even laboratory instruction to the old + academic methods of recitations and examination. To point out this + error, and to claim for science-teaching its appropriate methods, + was one object of writing these essays." + + +WORKS ON ASTRONOMY. + + Elements of Astronomy. By ROBERT STOWELL BALL, LL. D., F. R. S., + Andrews Professor of Astronomy in the University of Dublin, Royal + Astronomer of Ireland. With Illustrations. 16mo. Cloth, $2.25. + + Elementary Lessons in Astronomy. By J. NORMAN LOCKYER, F. R. S. + Richly illustrated, and embracing the Latest Discoveries. American + edition. Adapted to the Schools and Academies of the United States. + 12mo. Cloth, $1.50. + + Outlines of Astronomy. By Sir J. J. W. HERSCHEL. With Plates and + Woodcuts. Eleventh edition. 8vo. Cloth, $4.00. + + The Sun. By C. A. YOUNG, Ph. D., LL. D., Professor of Astronomy + in the College of New Jersey. With numerous Illustrations. 12mo. + Cloth, $2.00. + + "Professor Young is an authority on 'The Sun,' and writes from + intimate knowledge. He has studied that great luminary all his + life, invented and improved instruments for observing it, gone + to all quarters of the world in search of the best places and + opportunities to watch it, and has contributed important + discoveries that have extended our knowledge of it."--_Popular + Science Monthly._ + + Spectrum Analysis, in its Application to Terrestrial Substances, + and the Physical Constitution of the Heavenly Bodies. Familiarly + explained by Dr. H. SCHELLEN, Director der Realschule I. O. Cologne. + Translated from the second enlarged and revised German edition by + JANE and CAROLINE LASSELL. Edited, with Notes, by WILLIAM HUGGINS, + LL. D. With numerous Woodcuts, Colored Plates, and Portraits; also, + Angström's and Kirchhoff's Maps. 8vo. Cloth, $6.00. + + "This admirable work does credit to, or should we say is worthy of, + the author, the translators, and the editor. The first part treats + on the artificial sources of high degrees of heat and light; the + second on Spectrum Analysis in its application to the heavenly + bodies. We must approve the method followed in the translation and + by the editor. In many translations the views of the author are + suppressed, in order that the views of the translator or editor may + be expounded; but here Dr. Huggins, however leniently such a fault + might have been looked upon with him, has permitted the author's + views to remain intact, clearly stating his own and wherein lies + the difference."--_The Chemical News._ + + "Certainly, as regards mere knowledge, the 'Spectrum Analysis' has + let us into many secrets of the physical universe which Newton and + Laplace would have declared impossible for man's intellect to + attain. The science is still in its infancy, but it is prosecuted + by some of the ablest, most patient, and most enthusiastic + observers, and some of the keenest thinkers, at present existing + on our little, insignificant physical globe."--_Boston Globe._ + + Studies in Spectrum Analysis. By J. NORMAN LOCKYER, F. R. S., + Correspondent of the Institute of France, etc. With Sixty + Illustrations. 12mo. Cloth, $2.50. + + "The study of spectrum analysis is one fraught with a peculiar + fascination, and some of the author's experiments are exceedingly + picturesque in their results. They are so lucidly described, too, + that the reader keeps on, from page to page, never flagging in + interest in the matter before him, nor putting down the book until + the last page is reached."--_New York Evening Express._ + + Origin of the Stars, and the Causes of their Motions and their Light. + By JACOB ENNIS. 12mo. Cloth, $2.00. + + Astronomy and Geology Compared. By Lord ORMATHWAITE. 18mo. Tinted + paper. Cloth, $1.00. + + The Expanse of Heaven. A Series of Essays on the Wonders of the + Firmament. By R. A. PROCTOR. 12mo. Cloth, $2.00. + + "'The Expanse of Heaven' can not fail to be of immense use in + forwarding the work of education, even when it is read only for + amusement, so forcible is the impression it makes on the mind from + the importance of the subjects treated of, while the manner of + treatment is so good."--_Boston Traveller._ + + The Moon: Her Motions, Aspect, Scenery, and Physical Conditions, with + Two Lunar Photographs and many Illustrations. By R. A. PROCTOR. New + edition. 12mo. Cloth, $3.50. + + Other Worlds than Ours; the Plurality of Worlds, studied under the + Light of Recent Scientific Researches. By R. A. PROCTOR. With + Illustrations, some colored. 12mo. Cloth, $2.50. + + Our Place among Infinities. A Series of Essays contrasting our Little + Abode in Space and Time with the Infinities around us. To which are + added Essays on the Jewish Sabbath and Astrology. By R. A. PROCTOR. + 12mo. Cloth, $1.75. + + +WORKS ON GEOLOGY, Etc. + + Principles of Geology; or, The Modern Changes of the Earth and its + Inhabitants, considered as illustrative of Geology. By Sir CHARLES + LYELL, Bart. Illustrated with Maps, Plates, and Woodcuts. A new and + entirely revised edition. 2 vols. Royal 8vo. Cloth, $8.00. + + The "Principles of Geology" may be looked upon with pride, not only + as a representative of English science, but as without a rival of + its kind anywhere. Growing in fullness and accuracy with the growth + of experience and observation in every region of the world, the work + has incorporated with itself each established discovery, and has + been modified by every hypothesis of value which has been brought + to bear upon, or been evolved from, the most recent body of facts. + + Text-Book of Geology, for Schools and Colleges. By H. ALLEYNE + NICHOLSON, M. D. 12mo. Half roan, $1.30. + + The Ancient Life-History of the Earth. A Comprehensive Outline + of the Principles and Leading Facts of Palćontological Science. + By H. ALLEYNE NICHOLSON, M. D. With numerous Illustrations. + Small 8vo. Cloth, $2.00. + + Elements of Geology. A Text-Book for Colleges and for the General + Reader. By JOSEPH LE CONTE, LL. D., Professor of Geology and + Natural History in the University of California. With upward + of 900 Illustrations. Revised and enlarged edition. 12mo. + Cloth, $4.00. + + Town Geology. By the Rev. CHARLES KINGSLEY, F. L. S., F. G. S., + Canon of Chester. 12mo. Cloth, $1.50. + + The Study of Rocks. An Elementary Text-Book in Petrology. With + Illustrations. By FRANK RUTLEY, of the English Geological Survey. + 16mo. Cloth, $1.75. + + Great Ice Age, and its Relation to the Antiquity of Man. By JAMES + GEIKIE. With Maps and Illustrations. 12mo. Cloth, $2.50. + + Volcanoes: What they Are and what they Teach. By J. W. JUDD, + Professor of Geology in the Royal School of Mines (London). + With 96 Illustrations. 12mo. Cloth, $2.00. + + Climate and Time in their Geological Relations: A Theory of Secular + Changes of the Earth's Climate. By JAMES CROLL, of H. M. Geological + Survey of Scotland. With Maps and Illustrations. 12mo. Cloth, $2.50. + + Geology. By Professor ARCHIBALD GEIKIE, F. R. S. ("Science Primers.") + 18mo. Flexible cloth, 45 cents. + + +_For sale by all booksellers; or sent by mail, post-paid, on receipt +of price._ + + +New York: D. APPLETON & CO., 1, 3, & 5 Bond Street. + + + * * * * * + + + + +TRANSCRIBER'S NOTES + + +1. Passages in italics are surrounded by _underscores_. + +2. Footnotes have been reindexed and moved from the end of the page to +the closest paragraph break. + +3. Certain words use oe ligature in the original. + +4. Carat character (^) is used to indicate "raised to power". And the +underscore character (_) is used to represent subscript. + +5. The greek letter alpha is represented as [alpha] in this text. + +6. A mixed fraction is indicated with a hyphen and forward slash. For +example, 3-1/2 represents three and a half. + +7. The following misprints have been corrected: + "1/0000" corrected to "1/1000" (page 111) + "strucure" corrected to "structure" (page 139) + "fevric" corrected to "ferric" (page 141) + "d'antorité" corrected to "d'autorité" (page 188) + "resourses" corrected to "resources" (page 206) + +8. Other than the corrections listed above, printer's inconsistencies in +spelling, punctuation, and ligature usage have been retained. + + + + + + +End of the Project Gutenberg EBook of Scientific Culture, and Other Essays, by +Josiah Parsons Cooke + +*** END OF THIS PROJECT GUTENBERG EBOOK SCIENTIFIC CULTURE, AND *** + +***** This file should be named 37427-8.txt or 37427-8.zip ***** +This and all associated files of various formats will be found in: + http://www.gutenberg.org/3/7/4/2/37427/ + +Produced by Sharon Joiner, Bryan Ness and the Online +Distributed Proofreading Team at http://www.pgdp.net (This +file was produced from images generously made available +by The Internet Archive/Canadian Libraries) + + +Updated editions will replace the previous one--the old editions +will be renamed. + +Creating the works from public domain print editions means that no +one owns a United States copyright in these works, so the Foundation +(and you!) can copy and distribute it in the United States without +permission and without paying copyright royalties. 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