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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..6833f05 --- /dev/null +++ b/.gitattributes @@ -0,0 +1,3 @@ +* text=auto +*.txt text +*.md text 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, anęsthesia, 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 aėriform 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 ęsthetical 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, Thermopylę, 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] Lyrę. 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' + "Cyclopędia," 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 aėriform 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 (3·8) 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 +aėriform 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 aėriform 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 aėriform 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 aėriform 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 aėriform 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 formulę, +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 encyclopędic 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_·_a_:_n_·_b_:_p_·_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 +formulę 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_·_a_:_n_·_b_:_p_·_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_)·_a_:(1/_k_)·_b_:(1/_l_)·_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 formulę which express the +relations between the parts of a crystal. From the last proportion we +derive at once + + (1/_h_)·(_a_/_A_) = (1/_k_)·(_b_/_B_) = (1/_l_)·(_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_ = 1:2·340:1·233. + Crystals of gypsum have _a_:_b_:_c_ = 1:0·413:0·691. + Crystals of tin-stone have _a_:_b_:_c_ = 1:1:0·6724. + 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_)·cos _P X_ = (_b_/_k_)·cos _P Y_ = (_c_/_l_)·cos _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 + + u·_u_ + v·_v_ + w·_w_ = _o_, + +where _u_ _v_ and _w_ are the indices of the third plane, and u v w +have the values + + u = _k_·_r_ - _l_·_q_ + v = _l_·_p_ - _h_·_r_ + w = _h_·_q_ - _k_·_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 formulę 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 Athenęum, 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 ą vos travaux et vous +avez bien souvent admiré, comme moi, la haute intelligence et la tact +infini avec lesquels il savait imprimer ą nos discussions les formes +modérées et courtoises inhérentes ą sa nature et ą son caractčre. Sous +ce rapport aussi la perte de Dumas est irréparable et crée dans +l'Académie un vide bien difficile ą combler. Aussi, longtemps encore +nous chercherons, ą 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 +aėriform 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 aėriform, 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 archęological 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 Cannę, 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 aėriform 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 aėriform, 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 11·11 per cent of hydrogen and 88·89 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, 11·11 +per cent of every molecule of water consists of hydrogen, while 88·89 +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 aėriform condition, it follows that the relative gas +volumes are proportional to the number of molecules of the aėriform +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 Palęontological 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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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) + + + + + + +</pre> + + + + + +<h1>SCIENTIFIC CULTURE,</h1> + +<p> </p> +<h3><i>AND OTHER ESSAYS</i>.</h3> +<p> </p> + +<h3><small>BY</small><br /> +<big>JOSIAH PARSONS COOKE, LL. D.,</big><br /> +<small>PROFESSOR OF CHEMISTRY AND MINERALOGY, IN HARVARD COLLEGE.</small></h3> + +<p> </p> +<h4><i>SECOND EDITION; WITH ADDITIONS.</i></h4> +<p> </p> + +<h4>NEW YORK:<br /> +<span class="g">D. APPLETON AND COMPANY,</span><br /> +<small>1, 3, <span class="smcap">and</span> 5 BOND STREET.</small><br /> +1885.</h4> + + + +<hr style="width: 65%;" /> +<p> </p> +<p class="center"><span class="smcap">Copyright</span>, 1881, 1885,<br /> +<span class="smcap">By JOSIAH PARSONS COOKE</span>.</p> +<p> </p> + + +<hr style="width: 65%;" /> +<p> </p> + +<h4>TO<br /> +<big>MY ASSOCIATES</big><br /> +IN<br /> +<span class="g">THE CHEMICAL LABORATORY</span><br /> +OF<br /> +<span class="g">HARVARD COLLEGE</span><br /> +THIS VOLUME<br /> +IS<br /> +AFFECTIONATELY DEDICATED.</h4> + +<p> </p> + +<hr style="width: 65%;" /> +<h2>PREFACE.</h2> + + +<p>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 +<span class='pagenum'>[Pg v]</span> +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.</p> + +<p>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.</p> + +<p>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 +<span class='pagenum'>[Pg vi]</span> +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.</p> +<p><span class='pagenum'>[Pg vii]</span></p> + + +<hr style="width: 65%;" /> +<h2>CONTENTS.</h2> + + + +<div class='center'> +<table border="0" cellpadding="0" cellspacing="0" summary=""> +<tr><td align='right' colspan='3'><small>PAGE</small></td></tr> +<tr><td align='right'><a href="#I">I.</a></td><td class='tdsc'>—Scientific Culture</td><td align='right'>5</td></tr> +<tr><td align='right'><a href="#II">II.</a></td><td class='tdsc'>—The Nobility of Knowledge</td><td align='right'>45</td></tr> +<tr><td align='right'><a href="#III">III.</a></td><td class='tdsc'>—The Elementary Teaching of Physical Science</td><td align='right'>71</td></tr> +<tr><td align='right'><a href="#IV">IV.</a></td><td class='tdsc'>—The Radiometer</td><td align='right'>86</td></tr> +<tr><td align='right'><a href="#V">V.</a></td><td class='tdsc'>—Memoir of Thomas Graham</td><td align='right'>127</td></tr> +<tr><td align='right'><a href="#VI">VI.</a></td><td class='tdsc'>—Memoir of William Hallowes Miller</td><td align='right'>145</td></tr> +<tr><td align='right'><a href="#VII">VII.</a></td><td class='tdsc'>—William Barton Rogers</td><td align='right'>160</td></tr> +<tr><td align='right'><a href="#VIII">VIII.</a></td><td class='tdsc'>—Jean-Baptiste-André Dumas</td><td align='right'>181</td></tr> +<tr><td align='right'><a href="#IX">IX.</a></td><td class='tdsc'>—The Greek Question</td><td align='right'>203</td></tr> +<tr><td align='right'><a href="#X">X.</a></td><td class='tdsc'>—Further Remarks on the Greek Question</td><td align='right'>214</td></tr> +<tr><td align='right'><a href="#XI">XI.</a></td><td class='tdsc'>—Scientific Culture; its Spirit, its Aim, and its Methods</td><td align='right'> 227</td></tr> +<tr><td align='right'><a href="#XII">XII.</a></td><td class='tdsc'>—"Noblesse Oblige"</td><td align='right'>267</td></tr> +<tr><td align='right'><a href="#XIII">XIII.</a></td><td class='tdsc'>—The Spiritual Life</td><td align='right'>289</td></tr> +</table></div> + + +<hr style="width: 100%;" /> +<h1>ESSAYS.</h1> + + +<hr style="width: 100%;" /> +<h3><a name="I" id="I"></a>I.</h3> + +<h2>SCIENTIFIC CULTURE.</h2> + +<h4><i>An Address delivered July 7, 1875, at the Opening of the Summer +Courses of Instruction in Chemistry, at Harvard University.</i></h4> + + +<p>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.</p> + +<p>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 +<span class='pagenum'><a name="Page_5" id="Page_5">[Pg 5]</a></span> +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.</p> + +<p>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.</p> + +<p>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, anæsthe<span class='pagenum'><a name="Page_6" id="Page_6">[Pg 6]</a></span>sia, +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.</p> + +<p>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.</p> + +<p>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 prod<span class='pagenum'><a name="Page_7" id="Page_7">[Pg 7]</a></span>ucts +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_8" id="Page_8">[Pg 8]</a></span> +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:</p> + +<p>The, of old, universally accepted principle that all living +organisms are propagated by seeds or germs (<i>omnia +ex ovo</i>) 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.</p> + +<p>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<span class='pagenum'><a name="Page_9" id="Page_9">[Pg 9]</a></span> +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."</p> + +<p>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."</p> + +<p>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<span class='pagenum'><a name="Page_10" id="Page_10">[Pg 10]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_11" id="Page_11">[Pg 11]</a></span> +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.</p> + +<p>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 ex<span class='pagenum'><a name="Page_12" id="Page_12">[Pg 12]</a></span>perimental +evidence, and accordingly he set himself to +work to obtain the required proof.</p> + +<p>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 <i>muriatic</i> 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.</p> + +<p>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<span class='pagenum'><a name="Page_13" id="Page_13">[Pg 13]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_14" id="Page_14">[Pg 14]</a></span> +The proportion of alkali and acid was sensibly increased.</p> + +<p>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.</p> + +<p>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.</p> + +<p>On examining the alkali formed in this last experi<span class='pagenum'><a name="Page_15" id="Page_15">[Pg 15]</a></span>ment, +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.</p> + +<p>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 ex<span class='pagenum'><a name="Page_16" id="Page_16">[Pg 16]</a></span>hausted +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.</p> + +<p>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<span class='pagenum'><a name="Page_17" id="Page_17">[Pg 17]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_18" id="Page_18">[Pg 18]</a></span> +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.</p> + +<p>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.</p> + +<p>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 ex<span class='pagenum'><a name="Page_19" id="Page_19">[Pg 19]</a></span>perimental +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.</p> + +<p>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.</p> + +<p>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 ob<span class='pagenum'><a name="Page_20" id="Page_20">[Pg 20]</a></span>ject. +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?</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_21" id="Page_21">[Pg 21]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_22" id="Page_22">[Pg 22]</a></span></p> + +<p>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.</p> + +<p>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 schol<span class='pagenum'><a name="Page_23" id="Page_23">[Pg 23]</a></span>arship +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?</p> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_24" id="Page_24">[Pg 24]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_25" id="Page_25">[Pg 25]</a></span> +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.</p> + +<p>I come back now again to the moral of all this, to<span class='pagenum'><a name="Page_26" id="Page_26">[Pg 26]</a></span> +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.</p> + +<p>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. Objec<span class='pagenum'><a name="Page_27" id="Page_27">[Pg 27]</a></span>tively +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_28" id="Page_28">[Pg 28]</a></span> +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.</p> + +<p>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 ap<span class='pagenum'><a name="Page_29" id="Page_29">[Pg 29]</a></span>pearance +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_30" id="Page_30">[Pg 30]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_31" id="Page_31">[Pg 31]</a></span> +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.</p> + +<p>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.</p> + +<p>So among scientific students the power to keep the +mind unbiased, and not to color our observations in the<span class='pagenum'><a name="Page_32" id="Page_32">[Pg 32]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_33" id="Page_33">[Pg 33]</a></span> +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.<span class='pagenum'><a name="Page_34" id="Page_34">[Pg 34]</a></span></p> + +<p>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.</p> + +<p>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, dis<span class='pagenum'><a name="Page_35" id="Page_35">[Pg 35]</a></span>covering +the true nature of the substances under examination.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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 re<span class='pagenum'><a name="Page_36" id="Page_36">[Pg 36]</a></span>move +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_37" id="Page_37">[Pg 37]</a></span> +the mind for weighing the probable evidence by which +men are chiefly guided in the affairs of life.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_38" id="Page_38">[Pg 38]</a></span> +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.</p> + +<p>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 æsthetical faculties of +the mind, the tastes, and the imagination, than the study +of natural science.</p> + +<p>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;<span class='pagenum'><a name="Page_39" id="Page_39">[Pg 39]</a></span> +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.</p> + +<p>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.</p> + +<p>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 adapta<span class='pagenum'><a name="Page_40" id="Page_40">[Pg 40]</a></span>tions +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.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_41" id="Page_41">[Pg 41]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_42" id="Page_42">[Pg 42]</a></span> +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.</p> + +<p>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.</p> + +<p>We have improved our system of instruction in the<span class='pagenum'><a name="Page_43" id="Page_43">[Pg 43]</a></span> +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.<span class='pagenum'><a name="Page_44" id="Page_44">[Pg 44]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="II" id="II"></a>II.</h3> + +<h2>THE NOBILITY OF KNOWLEDGE.</h2> + +<h4><i>An Address delivered before the Free Institute at Worcester, Massachusetts, +July 28, 1874.</i></h4> + + +<p>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</p> + +<div class="poem"><div class="stanza"> +<span class="i0">"Builders wrought with greatest care<br /></span> +<span class="i0">Each minute and unseen part."<br /></span> +<span class='pagenum'><a name="Page_45" id="Page_45">[Pg 45]</a></span></div></div> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>"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<span class='pagenum'><a name="Page_46" id="Page_46">[Pg 46]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>It is only too true that these visions will become<span class='pagenum'><a name="Page_47" id="Page_47">[Pg 47]</a></span> +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.</p> + +<p>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.</p> + +<p>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 occu<span class='pagenum'><a name="Page_48" id="Page_48">[Pg 48]</a></span>pations +are adorned by it, and without it the most exalted +positions appear to true men mean and low.</p> + +<p>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.</p> + +<p>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.</p> + +<p>Harvard College, by cherishing and honoring the<span class='pagenum'><a name="Page_49" id="Page_49">[Pg 49]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_50" id="Page_50">[Pg 50]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>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?<span class='pagenum'><a name="Page_51" id="Page_51">[Pg 51]</a></span></p> + +<p>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?</p> + +<p>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, Thermopylæ, +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.</p> + +<p>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 di<span class='pagenum'><a name="Page_52" id="Page_52">[Pg 52]</a></span>rects +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?</p> + +<p>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 Aloy<span class='pagenum'><a name="Page_53" id="Page_53">[Pg 53]</a></span>sius +Galvani with that mode of electrical energy which +flashes through the wire cords that now unite the four +quarters of the globe.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_54" id="Page_54">[Pg 54]</a></span> +listlessly, against the iron railing, when, lo! the frog's +legs are convulsed.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_55" id="Page_55">[Pg 55]</a></span> +chief effects were due to a cause of which he was wholly +ignorant.</p> + +<p>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.</p> + +<p>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.</p> + +<p>This discussion created the liveliest interest throughout +Europe. Every scholar of science took sides with +one or the other of these eminent Italian philosophers,<span class='pagenum'><a name="Page_56" id="Page_56">[Pg 56]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_57" id="Page_57">[Pg 57]</a></span> +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?</p> + +<p>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 <i>electrician</i> is watching +a spot of light on the scale of an instrument which is +called a <i>galvanometer</i>. 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 +Ampère, 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.</p> + +<p>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 assist<span class='pagenum'><a name="Page_58" id="Page_58">[Pg 58]</a></span>ants +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.</p> + +<p>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.</p> + +<p>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 de<span class='pagenum'><a name="Page_59" id="Page_59">[Pg 59]</a></span>voted +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_60" id="Page_60">[Pg 60]</a></span> +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 <i>invenio</i> signifies <i>to meet with</i>, as well as to <i>find</i>, +and these great gifts of God are <i>met with</i> 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.</p> + +<p>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<span class='pagenum'><a name="Page_61" id="Page_61">[Pg 61]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>This man, old at seventy years, "bent and furrowed +with labor, but in whose eye the fire of genius was still<span class='pagenum'><a name="Page_62" id="Page_62">[Pg 62]</a></span> +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.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_63" id="Page_63">[Pg 63]</a></span> +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 +Cœlestium Revolutionibus"—destined to form the broad +basis of astronomical science.</p> + +<p>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:</p> + +<div class="poem"><div class="stanza"> +<span class="i0">"Nunc dimittis servum tuum, Domine."<br /></span> +</div></div> + +<p>Grand close of a noble life! The seed has been sown—what +could we desire more?<span class='pagenum'><a name="Page_64" id="Page_64">[Pg 64]</a></span></p> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_65" id="Page_65">[Pg 65]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_66" id="Page_66">[Pg 66]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>Do not smile at the enthusiasm which rates so high +a purely intellectual achievement? Go out with me<span class='pagenum'><a name="Page_67" id="Page_67">[Pg 67]</a></span> +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?</p> + +<p>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<span class='pagenum'><a name="Page_68" id="Page_68">[Pg 68]</a></span> +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.</p> + +<p>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 in<span class='pagenum'><a name="Page_69" id="Page_69">[Pg 69]</a></span>telligence. +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.</p> + +<div class="poem"><div class="stanza"> +<span class="i0">"And so the Word had breath, and wrought,<br /></span> +<span class="i2">With human hands, the creed of creeds,<br /></span> +<span class="i2">In loveliness of perfect deeds,<br /></span> +<span class="i0">More strong than all poetic thought—<br /></span> +</div><div class="stanza"> +<span class="i0">"Which he may read that binds the sheaf,<br /></span> +<span class="i2">Or builds the house, or digs the grave,<br /></span> +<span class="i2">And those wild eyes that watch the wave,<br /></span> +<span class="i0">In roarings round the coral reef."<br /></span> +<span class='pagenum'><a name="Page_70" id="Page_70">[Pg 70]</a></span></div></div> + + + +<hr style="width: 65%;" /> +<h3><a name="III" id="III"></a>III.</h3> + +<h2>THE ELEMENTARY TEACHING OF +PHYSICAL SCIENCE.</h2> + +<h4><i>An Address to the Schoolmasters of Boston, delivered +February 4, 1878.</i></h4> + + +<p>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<span class='pagenum'><a name="Page_71" id="Page_71">[Pg 71]</a></span> +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.</p> + +<p>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 "Con<span class='pagenum'><a name="Page_72" id="Page_72">[Pg 72]</a></span>versations +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.</p> + +<p>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,<span class='pagenum'><a name="Page_73" id="Page_73">[Pg 73]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_74" id="Page_74">[Pg 74]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_75" id="Page_75">[Pg 75]</a></span> +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.</p> + +<p>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?</p> + +<p>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 defini<span class='pagenum'><a name="Page_76" id="Page_76">[Pg 76]</a></span>tions +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<span class='pagenum'><a name="Page_77" id="Page_77">[Pg 77]</a></span> +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.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_78" id="Page_78">[Pg 78]</a></span> +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<span class='pagenum'><a name="Page_79" id="Page_79">[Pg 79]</a></span> +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 <i>force</i>. +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.</p> + +<p>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<span class='pagenum'><a name="Page_80" id="Page_80">[Pg 80]</a></span> +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.<span class='pagenum'><a name="Page_81" id="Page_81">[Pg 81]</a></span></p> + +<p>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.</p> + +<p>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 lec<span class='pagenum'><a name="Page_82" id="Page_82">[Pg 82]</a></span>tures +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.</p> + +<p>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<span class='pagenum'><a name="Page_83" id="Page_83">[Pg 83]</a></span> +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.</p> + +<p>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.</p> + +<p>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;<span class='pagenum'><a name="Page_84" id="Page_84">[Pg 84]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_85" id="Page_85">[Pg 85]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="IV" id="IV"></a>IV.</h3> + +<h2>THE RADIOMETER:</h2> + +<h4>A FRESH EVIDENCE OF A MOLECULAR UNIVERSE.</h4> + +<h4><i>A Lecture delivered in the Sanders Theatre of Harvard University, +March 6, 1878.</i></h4> + + +<p>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<span class='pagenum'><a name="Page_86" id="Page_86">[Pg 86]</a></span> +the familiar astronomical facts which the sight of the +starry heavens suggests!</p> + +<p>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!</p> + +<p>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<span class='pagenum'><a name="Page_87" id="Page_87">[Pg 87]</a></span> +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, α 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!</p> + +<p>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 Cœlestium Revolutionibus," which was +destined, ultimately, to overthrow the crude cosmography<span class='pagenum'><a name="Page_88" id="Page_88">[Pg 88]</a></span> +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 α Lyræ. The measurement of this parallax, +together with Bessel's determination of the parallax of +61 Cygni, and Henderson's that of α Centauri, at about +the same time, gave us our first accurate knowledge of +the distances of the fixed stars.</p> + +<p>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,<span class='pagenum'><a name="Page_89" id="Page_89">[Pg 89]</a></span> +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.</p> + +<p>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.</p> + +<p>The conception to which I refer will be at once suggested +to every scientific scholar by the word <i>molecule</i>. +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.</p> + +<p>In attempting to discover the original usage of the<span class='pagenum'><a name="Page_90" id="Page_90">[Pg 90]</a></span> +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, <i>develop</i> 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 <i>grow</i> into men.</p> + +<p>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:<span class='pagenum'><a name="Page_91" id="Page_91">[Pg 91]</a></span> +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, <i>inhere</i> in these +particles, which Buffon names <i>organic molecules</i>. 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.</p> + +<p>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<span class='pagenum'><a name="Page_92" id="Page_92">[Pg 92]</a></span> +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.</p> + +<p>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,<span class='pagenum'><a name="Page_93" id="Page_93">[Pg 93]</a></span> +and thus we come to the present chemical definition of a +molecule, "<i>The smallest particles of a substance in which +its qualities inhere</i>," which, as you see, is a reproduction +of Buffon's idea, although applied to matter and not to +organism.</p> + +<p>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.</p> + +<p>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 <i>a lump of sugar is a universe +of moving worlds</i>.</p> + +<p>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<span class='pagenum'><a name="Page_94" id="Page_94">[Pg 94]</a></span> +look into the molecular universe with the same facility +with which the telescope penetrates the depths of space.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_95" id="Page_95">[Pg 95]</a></span> +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.</p> + +<p>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 name="FNanchor_A_1" id="FNanchor_A_1"></a><a href="#Footnote_A_1" class="fnanchor">[A]</a></p> +<p><span class='pagenum'><a name="Page_96" id="Page_96">[Pg 96]</a></span></p> + +<p><i>Dimension of Hydrogen Molecules calculated for Temperature of +Melting Ice, and for the Mean Height of the Barometer of the +Sea Level:</i></p> + +<p class="blockquot"> +Mean velocity, 6,099 feet a second.<br /> +Mean path, 31 ten-millionths of an inch.<br /> +Collisions, 17,750 millions each second.<br /> +Diameter, 438,000, side by side, measure <sup>1</sup>⁄<sub>100</sub> of an inch.<br /> +Mass, 14 (millions<sup>3</sup>) weigh <sup>1</sup>⁄<sub>1000</sub> of a grain.<br /> +Gas-volume, 311 (millions<sup>3</sup>) fill one cubic inch.<br /> +</p> + +<p>To explain how the values here presented were +obtained would be out of place in a popular lec<span class='pagenum'><a name="Page_97" id="Page_97">[Pg 97]</a></span>ture,<a name="FNanchor_B_2" id="FNanchor_B_2"></a><a href="#Footnote_B_2" class="fnanchor">[B]</a> +but a few words in regard to two or three of +the data are required to elucidate the subject of this +lecture.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_98" id="Page_98">[Pg 98]</a></span> +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.</p> + +<p>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.</p> + +<p>But, if the velocity changes in this way, you may ask,<span class='pagenum'><a name="Page_99" id="Page_99">[Pg 99]</a></span> +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.</p> + +<p>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.</p> + +<p>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 (3·8) +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<span class='pagenum'><a name="Page_100" id="Page_100">[Pg 100]</a></span> +molecular projectiles are so small; they make up by +their number for what they want in size.</p> + +<p>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.</p> + +<p>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 be<span class='pagenum'><a name="Page_101" id="Page_101">[Pg 101]</a></span>comes +evident, as in the familiar experiments with an +air-pump.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_102" id="Page_102">[Pg 102]</a></span>-ball +would under similar circumstances, with a greatly +increased velocity, and it is this more rapid motion which +alone constitutes the higher temperature.</p> + +<p>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 <i>kicks</i>! +And so every surface from which molecules rebound +must <i>kick</i>; 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.</p> + +<p>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 tem<span class='pagenum'><a name="Page_103" id="Page_103">[Pg 103]</a></span>perature +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.</p> + +<p>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<span class='pagenum'><a name="Page_104" id="Page_104">[Pg 104]</a></span> +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.</p> + +<p>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 <i>the rate of diffusion</i>, as it is called, we have +the data from which we can calculate both the number<span class='pagenum'><a name="Page_105" id="Page_105">[Pg 105]</a></span> +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<a name="FNanchor_C_3" id="FNanchor_C_3"></a><a href="#Footnote_C_3" class="fnanchor">[C]</a> 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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_106" id="Page_106">[Pg 106]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_107" id="Page_107">[Pg 107]</a></span></p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_108" id="Page_108">[Pg 108]</a></span> +and makes its annual journey of some 550,000,000 miles +in 365 days, 6 hours, 9 seconds, and <sup>6</sup>⁄<sub>10</sub> 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.</p> + +<p>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<span class='pagenum'><a name="Page_109" id="Page_109">[Pg 109]</a></span> +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, +"<i>nulla actio in distans</i>," and which in our day have +culminated in the famous apothegm of the German +materialist, "Kein Phosphor kein Gedanke."</p> + +<p>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<span class='pagenum'><a name="Page_110" id="Page_110">[Pg 110]</a></span> +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.</p> + +<p>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 <sup>1</sup>⁄<sub>1000</sub> 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<span class='pagenum'><a name="Page_111" id="Page_111">[Pg 111]</a></span> +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.</p> + +<p>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."</p> + +<p>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<span class='pagenum'><a name="Page_112" id="Page_112">[Pg 112]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_113" id="Page_113">[Pg 113]</a></span> +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.</p> + +<p>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.</p> + +<p>This experiment, however, was not conclusive, as it +might still be said that the <i>heat</i>-giving rays acted <i>mechanically</i>, +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,<span class='pagenum'><a name="Page_114" id="Page_114">[Pg 114]</a></span> +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.</p> + +<p>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.</p> + +<p>In order to investigate the question thus presented, I +placed the radiometer before a common kerosene lamp,<span class='pagenum'><a name="Page_115" id="Page_115">[Pg 115]</a></span> +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:</p> + + +<div class='center'> +<table border="1" rules="cols" cellpadding="4" cellspacing="0" summary=""> +<tr><th class="bbox">CONDITIONS.</th><th class="bbox">Time of ten revolutions.</th><th class="bbox">No. of revolutions in same time.</th></tr> +<tr><td align='left'>Both faces exposed</td><td align='left'> 8 seconds.</td><td align='left'> 319</td></tr> +<tr><td align='left'>Blackened faces only</td><td align='left'> 11 "</td><td align='left'> 232</td></tr> +<tr><td align='left'>Mica faces only</td><td align='left'> 29 "</td><td align='left'> 88</td></tr> +</table></div> + +<p>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 instru<span class='pagenum'><a name="Page_116" id="Page_116">[Pg 116]</a></span>ment, +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.</p> + +<p>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 circum<span class='pagenum'><a name="Page_117" id="Page_117">[Pg 117]</a></span>stance +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.</p> + +<p>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<span class='pagenum'><a name="Page_118" id="Page_118">[Pg 118]</a></span> +condition I could suggest—<i>that the effect was due to the +same cause which determines gas pressure</i>, 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.<a name="FNanchor_D_4" id="FNanchor_D_4"></a><a href="#Footnote_D_4" class="fnanchor">[D]</a> But, after +our previous discussions, a few words will suffice to show +how the molecular theory explains the new phenomena.</p> + +<p>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<sup>7</sup>⁄<sub>10</sub> 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<span class='pagenum'><a name="Page_119" id="Page_119">[Pg 119]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_120" id="Page_120">[Pg 120]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_121" id="Page_121">[Pg 121]</a></span> +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.<a name="FNanchor_E_5" id="FNanchor_E_5"></a><a href="#Footnote_E_5" class="fnanchor">[E]</a></p> + +<p><span class='pagenum'><a name="Page_122" id="Page_122">[Pg 122]</a></span></p><p>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 <i>direct</i> 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.</p> + +<p>More than this can not be said of the steam-engine, +although, of course, in the older engine the measure<span class='pagenum'><a name="Page_123" id="Page_123">[Pg 123]</a></span>ments +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.</p> + +<p>And when we consider the vast scope of the molecu<span class='pagenum'><a name="Page_124" id="Page_124">[Pg 124]</a></span>lar +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?</p> + +<p>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,<a name="FNanchor_F_6" id="FNanchor_F_6"></a><a href="#Footnote_F_6" class="fnanchor">[F]</a> 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 +<span class='pagenum'><a name="Page_125" id="Page_125">[Pg 125]</a></span>by the intelligence which makes the whole creation his +own.</p> + +<p>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.</p> +<p><span class='pagenum'><a name="Page_126" id="Page_126">[Pg 126]</a></span></p> + + +<hr style="width: 65%;" /> +<h3><a name="V" id="V"></a>V.</h3> + +<h2>MEMOIR OF THOMAS GRAHAM.</h2> + +<h4><i>Reprinted from the "Proceedings of the American Academy of Arts +and Sciences," Vol. VIII, May 24, 1870.</i></h4> + + +<p>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<span class='pagenum'><a name="Page_127" id="Page_127">[Pg 127]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_128" id="Page_128">[Pg 128]</a></span></p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_129" id="Page_129">[Pg 129]</a></span> +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."</p> + +<p>By means of the diffusion tube, Graham was able to +measure accurately the relative times of diffusion of +different gases, and he found that <i>equal volumes of any +two gases interpenetrate each other in times which are +inversely proportional to the square roots of their respective +densities</i>; 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.</p> + +<p>It can be shown, on the principles of pneumatics,<span class='pagenum'><a name="Page_130" id="Page_130">[Pg 130]</a></span> +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 "<i>effusion</i>" 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."</p> + +<p>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<span class='pagenum'><a name="Page_131" id="Page_131">[Pg 131]</a></span> +mode of expressing the final result. Such has proved to +be the case.</p> + +<p>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 <i>vis +viva</i> of its molecules; and, since all molecules at a given +temperature have the same <i>vis viva</i>, 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 phe<span class='pagenum'><a name="Page_132" id="Page_132">[Pg 132]</a></span>nomena +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.</p> + +<p>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<span class='pagenum'><a name="Page_133" id="Page_133">[Pg 133]</a></span> +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.</p> + +<p>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:</p> + +<p>First. A material for the septum capable of forming +a feeble chemical union with the gas to be transferred.</p> + +<p>Secondly. An excess of the gas on one side of the film +and a deficiency on the other.</p> + +<p>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.</p> + +<p>One of the most remarkable results of Graham's study<span class='pagenum'><a name="Page_134" id="Page_134">[Pg 134]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_135" id="Page_135">[Pg 135]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_136" id="Page_136">[Pg 136]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_137" id="Page_137">[Pg 137]</a></span> +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.</p> + +<p>Simultaneously with the experiments on <i>gases</i>, 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 <i>liquid</i> +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<span class='pagenum'><a name="Page_138" id="Page_138">[Pg 138]</a></span> +he showed that the rate of diffusion of the several groups +bear to one another simple numerical ratios.</p> + +<p>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."</p> + +<p>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 col<span class='pagenum'><a name="Page_139" id="Page_139">[Pg 139]</a></span>loids, +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.</p> + +<p>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 re<span class='pagenum'><a name="Page_140" id="Page_140">[Pg 140]</a></span>quired. +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.</p> + +<p>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, in<span class='pagenum'><a name="Page_141" id="Page_141">[Pg 141]</a></span>soluble +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_142" id="Page_142">[Pg 142]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_143" id="Page_143">[Pg 143]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_144" id="Page_144">[Pg 144]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="VI" id="VI"></a>VI.</h3> + +<h2>MEMOIR OF WILLIAM HALLOWES +MILLER.</h2> + +<h4><i>Reprinted from the "Proceedings of the American Academy of Arts +and Sciences," Vol. XVI, May 24, 1881.</i></h4> + + +<p>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<span class='pagenum'><a name="Page_145" id="Page_145">[Pg 145]</a></span> +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 formulæ, while the accomplished +artist traced the magnificent outlines of the Dolomite +mountains, was a beautiful idyl of science.</p> + +<p>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<span class='pagenum'><a name="Page_146" id="Page_146">[Pg 146]</a></span> +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 Mètre." +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."</p> + +<p>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 encyclopædic +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.</p> + +<p>The foundations of crystallography had been laid long +before Miller's time. Haüy is usually regarded as the<span class='pagenum'><a name="Page_147" id="Page_147">[Pg 147]</a></span> +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 +<i>primitive forms</i> of crystals as a whole, but also the forms +of their <i>integrant molecules</i>, he endeavored to show that +all secondary forms might be derived from a few primary +forms, regarded as elements of nature, by means of <i>decrements</i> +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 Lèvy, is still used by the French +mineralogists.</p> + +<p>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 crystallogra<span class='pagenum'><a name="Page_148" id="Page_148">[Pg 148]</a></span>pher, +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.</p> + +<p>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 <i>a</i> : <i>b</i> : <i>c</i> 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 <i>m</i> <i>a</i> : <i>n</i> <i>b</i> : <i>p</i> <i>c</i>, in which <i>m</i>, <i>n</i>, <i>p</i> 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,<span class='pagenum'><a name="Page_149" id="Page_149">[Pg 149]</a></span> +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.</p> + +<p>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 formulæ are well adapted to calculation, and easily intelligible +to persons moderately disciplined in mathematics.<span class='pagenum'><a name="Page_150" id="Page_150">[Pg 150]</a></span></p> + +<p>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.</p> + +<p>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."</p> + +<p>Miller began his study of crystallography with the<span class='pagenum'><a name="Page_151" id="Page_151">[Pg 151]</a></span> +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.</p> + +<p>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 funda<span class='pagenum'><a name="Page_152" id="Page_152">[Pg 152]</a></span>mental +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.</p> + +<p>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 <i>a</i> : <i>b</i> : <i>c</i> represent +the ratio of the intercepts of any plane of a crystal on +the three axes <i>x</i>, <i>y</i>, and <i>z</i>, respectively, the intercepts of +any other possible plane must satisfy the proportion—</p> + +<p class="center"> +<i>A</i> : <i>B</i> : <i>C</i> = <i>m a</i> : <i>n b</i> : <i>p c</i>,<br /> +</p> + +<p>in which <i>m</i>, <i>n</i>, and <i>p</i> are simple whole numbers. The +irrational values <i>a</i>, <i>b</i>, and <i>c</i> are fundamental magnitudes +for every crystalline substance;<a name="FNanchor_G_7" id="FNanchor_G_7"></a><a href="#Footnote_G_7" class="fnanchor">[G]</a> and Miller called these +relative magnitudes the parameters of the crystals, while +he called the whole numbers, <i>m</i>, <i>n</i>, and <i>p</i>, the indices of +the respective planes. But, instead of writing the pro<span class='pagenum'><a name="Page_153" id="Page_153">[Pg 153]</a></span>portion +which expresses the law of crystallography as +above, he gave to it a slightly different form, thus:</p> + +<div class='center'> +<table border="0" cellpadding="1" cellspacing="1" summary=""> +<tr><td align='left'><i>A</i> : <i>B</i> : <i>C</i> =</td> +<td align='left'>1<br /><span class="o"><i>h</i></span></td><td align='left'><i>a</i> : </td> +<td align='left'>1<br /><span class="o"><i>k</i></span></td><td align='left'><i>b</i> : </td> +<td align='left'>1<br /><span class="o"><i>l</i> </span></td><td align='left'><i>c</i>,</td> +</tr> +</table></div> + +<p>and used in his system for the indices of a plane the +values <i>h</i> : <i>k</i> : <i>l</i>, which are also in the ratio of whole numbers, +and usually of simpler whole numbers than <i>m</i> : <i>n</i> : <i>p</i>. +This seems a small difference; for <i>h k l</i> in the last proportion +are obviously the reciprocals of <i>m n p</i> in the first; +but the difference, small as it is, causes a wonderful simplification +of the formulæ which express the relations between +the parts of a crystal. From the last proportion we +derive at once</p> + +<div class='center'> +<table border="0" cellpadding="1" cellspacing="1" summary=""> +<tr> +<td align='left'>1<br /><span class="o"><i>h</i></span></td><td align='left'> · </td><td align='left'><i>a</i><br /><span class="o"><i>A</i></span></td><td align='left'> = </td> +<td align='left'>1<br /><span class="o"><i>k</i></span></td><td align='left'> · </td><td align='left'><i>b</i><br /><span class="o"><i>B</i></span></td><td align='left'> = </td> +<td align='left'>1<br /><span class="o"><i>l</i> </span></td><td align='left'> · </td><td align='left'><i>c</i><br /><span class="o"><i>C</i></span></td><td align='left'>,</td> +</tr> +</table></div> + +<p>which is the form in which Miller stated his fundamental +law.</p> + +<p>If <i>P</i> represents the "pole" of a face whose "indices" +are <i>h k l</i>, 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 <i>X</i>, <i>Y</i>, <i>Z</i> represent the points +where the axes of the crystal meet the same spherical +surface,<a name="FNanchor_H_8" id="FNanchor_H_8"></a><a href="#Footnote_H_8" class="fnanchor">[H]</a> then it is evident that <i>X Y</i>, <i>X Z</i>, and <i>Y Z</i> are +<span class='pagenum'><a name="Page_154" id="Page_154">[Pg 154]</a></span>the arcs of great circles, which measure the inclination of +the axes to each other, and that <i>P X</i>, <i>P Y</i>, and <i>P Z</i> are +arcs of other great circles, which measure the inclination +of the plane (<i>h</i> <i>k</i> <i>l</i>) 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</p> + +<div class='center'> +<table border="0" cellpadding="1" cellspacing="1" summary=""> +<tr> +<td align='left'><i>a</i><br /><span class="o"><i>h</i></span></td><td align='left'> cos <i>P X</i></td><td align='left'> = </td> +<td align='left'><i>b</i><br /><span class="o"><i>k</i></span></td><td align='left'> cos <i>P Y</i></td><td align='left'> = </td> +<td align='left'><i>c</i><br /><span class="o"><i>l</i> </span></td><td align='left'> cos <i>P Z</i>,</td> +</tr> +</table></div> + +<p>and by means of this theorem we are able to reduce a +great many problems of crystallography to the solution of +spherical triangles.</p> + +<p>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, <i>h</i> <i>k</i> <i>l</i> and <i>p</i> <i>q</i> <i>r</i> 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</p> + +<p class="center"> +u <i>u</i> + v <i>v</i> + w <i>w</i> = <i>o</i>,<br /> +</p> + +<p>where <i>u</i> <i>v</i> and <i>w</i> are the indices of the third plane, and +u v w have the values</p> + +<p class="center">u = <i>k r</i> − <i>l q</i> v = <i>l p</i> − <i>h r</i> w = <i>h q</i> − <i>k p</i>.</p> +<p><span class='pagenum'><a name="Page_155" id="Page_155">[Pg 155]</a></span></p> + +<p>Since <i>h</i> <i>k</i> <i>l</i> and <i>p</i> <i>q</i> <i>r</i> 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.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_156" id="Page_156">[Pg 156]</a></span> +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 formulæ +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<span class='pagenum'><a name="Page_157" id="Page_157">[Pg 157]</a></span> +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?</p> + +<p>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."<a name="FNanchor_I_9" id="FNanchor_I_9"></a><a href="#Footnote_I_9" class="fnanchor">[I]</a> 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 +<span class='pagenum'><a name="Page_158" id="Page_158">[Pg 158]</a></span>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.</p> + +<p>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.</p> +<p><span class='pagenum'><a name="Page_159" id="Page_159">[Pg 159]</a></span></p> + + +<hr style="width: 65%;" /> +<h3><a name="VII" id="VII"></a>VII.</h3> + +<h2>WILLIAM BARTON ROGERS.</h2> + + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_160" id="Page_160">[Pg 160]</a></span></p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_161" id="Page_161">[Pg 161]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_162" id="Page_162">[Pg 162]</a></span> +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.</p> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_163" id="Page_163">[Pg 163]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_164" id="Page_164">[Pg 164]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_165" id="Page_165">[Pg 165]</a></span> +displacement depending on the strength of the disturbing +force."</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_166" id="Page_166">[Pg 166]</a></span> +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."</p> + +<p>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.<span class='pagenum'><a name="Page_167" id="Page_167">[Pg 167]</a></span> +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."</p> + +<p>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<span class='pagenum'><a name="Page_168" id="Page_168">[Pg 168]</a></span> +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.</p> + +<p>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. Return<span class='pagenum'><a name="Page_169" id="Page_169">[Pg 169]</a></span>ing +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;<a name="FNanchor_J_10" id="FNanchor_J_10"></a><a href="#Footnote_J_10" class="fnanchor">[J]</a> 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 +sci<span class='pagenum'><a name="Page_170" id="Page_170">[Pg 170]</a></span>ence; 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.</p> + +<p>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<span class='pagenum'><a name="Page_171" id="Page_171">[Pg 171]</a></span> +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.</p> + +<p>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."</p> + +<p>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<span class='pagenum'><a name="Page_172" id="Page_172">[Pg 172]</a></span> +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.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_173" id="Page_173">[Pg 173]</a></span> +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.</p> + +<p>It would be out of place, as it would be unnecessary, +to dwell in this connection on the various stages in the<span class='pagenum'><a name="Page_174" id="Page_174">[Pg 174]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_175" id="Page_175">[Pg 175]</a></span> +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:</p> + +<p>"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<span class='pagenum'><a name="Page_176" id="Page_176">[Pg 176]</a></span> +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....</p> + +<p>"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."</p> + +<p>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 wis<span class='pagenum'><a name="Page_177" id="Page_177">[Pg 177]</a></span>dom, +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<span class='pagenum'><a name="Page_178" id="Page_178">[Pg 178]</a></span> +though tearful witnesses when, after the final seal of +commendation was set, he fell back, and the great work +was done.</p> + +<p>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 dis<span class='pagenum'><a name="Page_179" id="Page_179">[Pg 179]</a></span>cords +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.</p> + +<p>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.<span class='pagenum'><a name="Page_180" id="Page_180">[Pg 180]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="VIII" id="VIII"></a>VIII.</h3> + +<h2>JEAN-BAPTISTE-ANDRÉ DUMAS.<a name="FNanchor_K_11" id="FNanchor_K_11"></a><a href="#Footnote_K_11" class="fnanchor">[K]</a></h2> + + +<p>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 +<span class='pagenum'><a name="Page_181" id="Page_181">[Pg 181]</a></span>in 1816, where he had relatives who gave him a friendly +welcome, and where he found employment in the pharmacy +of Le Royer.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_182" id="Page_182">[Pg 182]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_183" id="Page_183">[Pg 183]</a></span> +Hilaire, Arago, Ampère, 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 Athenæum, 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.</p> + +<p>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.</p> + +<p>In 1828-'29 Dumas united with Théodore Olivier and +Eugène 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<span class='pagenum'><a name="Page_184" id="Page_184">[Pg 184]</a></span> +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.</p> + +<p>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 Revolu<span class='pagenum'><a name="Page_185" id="Page_185">[Pg 185]</a></span>tion +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.</p> + +<p>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.</p> + +<p>In 1868 Dumas was appointed Master of the Mint of<span class='pagenum'><a name="Page_186" id="Page_186">[Pg 186]</a></span> +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.</p> + +<p>It was, however, as Permanent Secretary of the +Academy of Sciences that Dumas exerted during the<span class='pagenum'><a name="Page_187" id="Page_187">[Pg 187]</a></span> +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:</p> + +<p>"Vous savez la part considérable que Dumas prenait +à vos travaux et vous avez bien souvent admiré, comme +moi, la haute intelligence et la tact infini avec lesquels +il savait imprimer à nos discussions les formes modérées +et courtoises inhérentes à sa nature et à son caractère. +Sous ce rapport aussi la perte de Dumas est irréparable +et crée dans l'Académie un vide bien difficile à combler. +Aussi, longtemps encore nous chercherons, à la place +qu'il occupait au Bureau avec tant d'autorité, la figure +sympathique et vénérée de notre bienaimé Secrétaire +perpétuel."</p> + +<p>And while Dumas was still occupying his conspicuous +position in the Academy, one of the most distinguished +of his German contemporaries<a name="FNanchor_L_12" id="FNanchor_L_12"></a><a href="#Footnote_L_12" class="fnanchor">[L]</a> wrote of him: +"An ever-ready interpreter of the researches of others, +he always heightens the value of what he communi<span class='pagenum'><a name="Page_188" id="Page_188">[Pg 188]</a></span>cates +by adding from the rich stores of his own experience, +thus often conveying lights not noticed even by +the authors of those researches."</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_189" id="Page_189">[Pg 189]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_190" id="Page_190">[Pg 190]</a></span> +Moreover, on the physical side, Avogadro, and afterward +Ampère, 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.</p> + +<p>"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 Ampère"—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."</p> + +<p>Here, it is obvious, are the very conceptions which<span class='pagenum'><a name="Page_191" id="Page_191">[Pg 191]</a></span> +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.</p> + +<p>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 +<span class='pagenum'><a name="Page_192" id="Page_192">[Pg 192]</a></span>silicates and the sulphates, the formula SiO<sub>3</sub>, 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<sub>2</sub>, +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."<a name="FNanchor_M_13" id="FNanchor_M_13"></a><a href="#Footnote_M_13" class="fnanchor">[M]</a></p> + +<p>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 impor<span class='pagenum'><a name="Page_193" id="Page_193">[Pg 193]</a></span>tant +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.</p> + +<p>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<span class='pagenum'><a name="Page_194" id="Page_194">[Pg 194]</a></span> +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."</p> + +<p>By the second investigation, as by the first, although +Dumas gave a most fruitful conception to chemistry,<span class='pagenum'><a name="Page_195" id="Page_195">[Pg 195]</a></span> +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.</p> + +<p>The third great investigation of Dumas was his revision +of the atomic weights of many of the chemical<span class='pagenum'><a name="Page_196" id="Page_196">[Pg 196]</a></span> +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<span class='pagenum'><a name="Page_197" id="Page_197">[Pg 197]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_198" id="Page_198">[Pg 198]</a></span> +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.</p> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_199" id="Page_199">[Pg 199]</a></span></p> + +<p>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.</p> + +<p>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 homœopathy, he riveted the attention +of his colleagues as completely as he had entranced the +students at the Sorbonne.</p> + +<p>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<span class='pagenum'><a name="Page_200" id="Page_200">[Pg 200]</a></span> +influence rather than by the extent of the field which +it covers.</p> + +<p>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<span class='pagenum'><a name="Page_201" id="Page_201">[Pg 201]</a></span> +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."</p> + +<p>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</p> + +<p class="center">"<span class="smcap">Aux Grands Hommes la Patrie Reconnaissante.</span>"<span class='pagenum'><a name="Page_202" id="Page_202">[Pg 202]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="IX" id="IX"></a>IX.</h3> + +<h2>THE GREEK QUESTION.<a name="FNanchor_N_14" id="FNanchor_N_14"></a><a href="#Footnote_N_14" class="fnanchor">[N]</a></h2> + + +<p>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."</p> + +<p>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,<span class='pagenum'><a name="Page_203" id="Page_203">[Pg 203]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_204" id="Page_204">[Pg 204]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_205" id="Page_205">[Pg 205]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_206" id="Page_206">[Pg 206]</a></span> +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.</p> + +<p>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 meth<span class='pagenum'><a name="Page_207" id="Page_207">[Pg 207]</a></span>ods +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.</p> + +<p>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<span class='pagenum'><a name="Page_208" id="Page_208">[Pg 208]</a></span> +of observing, interpreting, and ruling natural phenomena.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_209" id="Page_209">[Pg 209]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_210" id="Page_210">[Pg 210]</a></span></p> + +<p>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.</p> + +<p>Is this heresy? Is this revolution? Is it not rather<span class='pagenum'><a name="Page_211" id="Page_211">[Pg 211]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_212" id="Page_212">[Pg 212]</a></span> +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?<span class='pagenum'><a name="Page_213" id="Page_213">[Pg 213]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="X" id="X"></a>X.</h3> + +<h2>FURTHER REMARKS ON THE GREEK +QUESTION.</h2> + + +<p>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<span class='pagenum'><a name="Page_214" id="Page_214">[Pg 214]</a></span> +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 archæological study, they +would be more charitable to those who differ with them +on this subject.</p> + +<p>There are, of course, two distinct elements in a liberal +education: the one the acquisition of useful knowl<span class='pagenum'><a name="Page_215" id="Page_215">[Pg 215]</a></span>edge, +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 in<span class='pagenum'><a name="Page_216" id="Page_216">[Pg 216]</a></span>terpret +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?</p> + +<p>In order to teach successfully the <i>results</i> 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<span class='pagenum'><a name="Page_217" id="Page_217">[Pg 217]</a></span> +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<span class='pagenum'><a name="Page_218" id="Page_218">[Pg 218]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_219" id="Page_219">[Pg 219]</a></span> +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.</p> + +<p>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 con<span class='pagenum'><a name="Page_220" id="Page_220">[Pg 220]</a></span>victs +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.<a name="FNanchor_O_15" id="FNanchor_O_15"></a><a href="#Footnote_O_15" class="fnanchor">[O]</a> +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 +<span class='pagenum'><a name="Page_221" id="Page_221">[Pg 221]</a></span>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.</p> + +<p>There has been a great deal said in this discussion +about the "humanities," and it has been assumed that,<span class='pagenum'><a name="Page_222" id="Page_222">[Pg 222]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_223" id="Page_223">[Pg 223]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_224" id="Page_224">[Pg 224]</a></span> +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<span class='pagenum'><a name="Page_225" id="Page_225">[Pg 225]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_226" id="Page_226">[Pg 226]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="XI" id="XI"></a>XI.</h3> + +<h2>SCIENTIFIC CULTURE;</h2> + +<h3>ITS SPIRIT, ITS AIM, AND ITS METHODS.<a name="FNanchor_P_16" id="FNanchor_P_16"></a><a href="#Footnote_P_16" class="fnanchor">[P]</a></h3> + + +<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> + +<p>At the very outset of this discussion we must be +careful to make a clear distinction between instruction<span class='pagenum'><a name="Page_227" id="Page_227">[Pg 227]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_228" id="Page_228">[Pg 228]</a></span> +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 Cannæ, 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.</p> + +<p>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;<span class='pagenum'><a name="Page_229" id="Page_229">[Pg 229]</a></span> +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.</p> + +<p>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 <i>memoriter</i> 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<span class='pagenum'><a name="Page_230" id="Page_230">[Pg 230]</a></span> +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.</p> + +<p>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,<span class='pagenum'><a name="Page_231" id="Page_231">[Pg 231]</a></span> +and to direct his attention to the phenomena of Nature.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_232" id="Page_232">[Pg 232]</a></span> +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.</p> + +<p>Let me not be understood as disparaging the retentive +memory and power of concentration which enable<span class='pagenum'><a name="Page_233" id="Page_233">[Pg 233]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_234" id="Page_234">[Pg 234]</a></span> +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.</p> + +<p>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 atten<span class='pagenum'><a name="Page_235" id="Page_235">[Pg 235]</a></span>tion +to what he sees, and the want of this power in students +who have been trained solely by literary studies +is most marked.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_236" id="Page_236">[Pg 236]</a></span> +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."</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_237" id="Page_237">[Pg 237]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_238" id="Page_238">[Pg 238]</a></span> +this idea by Mr. G. A. Hill forms an admirable introduction +to the study.</p> + +<p>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<span class='pagenum'><a name="Page_239" id="Page_239">[Pg 239]</a></span> +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.</p> + +<p>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 draw<span class='pagenum'><a name="Page_240" id="Page_240">[Pg 240]</a></span>ing +can hardly be exaggerated, and it should be made +one of the most important objects of school-work from +an early period.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_241" id="Page_241">[Pg 241]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_242" id="Page_242">[Pg 242]</a></span>-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.</p> + +<p>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<span class='pagenum'><a name="Page_243" id="Page_243">[Pg 243]</a></span> +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.</p> + +<p>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 con<span class='pagenum'><a name="Page_244" id="Page_244">[Pg 244]</a></span>nections +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.</p> + +<p>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 teach<span class='pagenum'><a name="Page_245" id="Page_245">[Pg 245]</a></span>ing +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.</p> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_246" id="Page_246">[Pg 246]</a></span></p> + +<p>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.</p> + +<p>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 knowl<span class='pagenum'><a name="Page_247" id="Page_247">[Pg 247]</a></span>edge, +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.</p> + +<p>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.</p> + +<p>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 sys<span class='pagenum'><a name="Page_248" id="Page_248">[Pg 248]</a></span>tem +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.</p> + +<p>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<span class='pagenum'><a name="Page_249" id="Page_249">[Pg 249]</a></span> +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.</p> + +<p>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;<span class='pagenum'><a name="Page_250" id="Page_250">[Pg 250]</a></span> +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.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_251" id="Page_251">[Pg 251]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_252" id="Page_252">[Pg 252]</a></span> +step. Every chemical process obeys three fundamental +laws:</p> + +<div class="blockquot"><p>The Law of Conservation of Mass.</p> + +<p>The Law of Definite Proportions.</p> + +<p>The Law of Definite Volumes.</p></div> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_253" id="Page_253">[Pg 253]</a></span></p> + +<p>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.</p> + +<p>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.<span class='pagenum'><a name="Page_254" id="Page_254">[Pg 254]</a></span></p> + +<p>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.<span class='pagenum'><a name="Page_255" id="Page_255">[Pg 255]</a></span></p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_256" id="Page_256">[Pg 256]</a></span> +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.</p> + +<p>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,<span class='pagenum'><a name="Page_257" id="Page_257">[Pg 257]</a></span> +the volume of the resulting nitrogen gas is one third +of that of the chlorine gas employed.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_258" id="Page_258">[Pg 258]</a></span> +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.</p> + +<p>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 oxy<span class='pagenum'><a name="Page_259" id="Page_259">[Pg 259]</a></span>gen +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_260" id="Page_260">[Pg 260]</a></span> +parts 11·11 per cent of hydrogen and 88·89 per cent of +oxygen.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_261" id="Page_261">[Pg 261]</a></span> +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, 11·11 per +cent of every molecule of water consists of hydrogen, +while 88·89 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.</p> + +<p>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 mole<span class='pagenum'><a name="Page_262" id="Page_262">[Pg 262]</a></span>cules +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.</p> + +<p>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.</p> + +<p>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 pro<span class='pagenum'><a name="Page_263" id="Page_263">[Pg 263]</a></span>portional +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.</p> + +<p>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:</p> + +<p>Why is the symbol of water H<sub>2</sub>O? What information +does the symbol CO<sub>2</sub> 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.</p> + +<p>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.</p> + +<p>But, besides teaching the general principles of chem<span class='pagenum'><a name="Page_264" id="Page_264">[Pg 264]</a></span>ical +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.</p> + +<p>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.<span class='pagenum'><a name="Page_265" id="Page_265">[Pg 265]</a></span></p> + +<p>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.<span class='pagenum'><a name="Page_266" id="Page_266">[Pg 266]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="XII" id="XII"></a>XII.</h3> + +<h2>"NOBLESSE OBLIGE."</h2> + + +<p>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,<span class='pagenum'><a name="Page_267" id="Page_267">[Pg 267]</a></span> +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.</p> + +<p>I have used the term scientific culture <i>rightly understood</i> +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<span class='pagenum'><a name="Page_268" id="Page_268">[Pg 268]</a></span> +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?</p> + +<p>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<span class='pagenum'><a name="Page_269" id="Page_269">[Pg 269]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_270" id="Page_270">[Pg 270]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_271" id="Page_271">[Pg 271]</a></span> +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.</p> + +<p>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.<span class='pagenum'><a name="Page_272" id="Page_272">[Pg 272]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_273" id="Page_273">[Pg 273]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_274" id="Page_274">[Pg 274]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_275" id="Page_275">[Pg 275]</a></span> +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.</p> + +<p>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,<span class='pagenum'><a name="Page_276" id="Page_276">[Pg 276]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_277" id="Page_277">[Pg 277]</a></span> +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.</p> + +<p>A more efficient means of cultivating science, and +one which is certain, in the long run, to yield a far more<span class='pagenum'><a name="Page_278" id="Page_278">[Pg 278]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_279" id="Page_279">[Pg 279]</a></span> +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.</p> + +<p>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 pro<span class='pagenum'><a name="Page_280" id="Page_280">[Pg 280]</a></span>fessor's +own work, there is no stimulus so great as that +which the association with a class of earnest students +supplies.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_281" id="Page_281">[Pg 281]</a></span> +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 <i>prima-facie</i>.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_282" id="Page_282">[Pg 282]</a></span> +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.</p> + +<p>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.</p> + +<p>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<span class='pagenum'><a name="Page_283" id="Page_283">[Pg 283]</a></span> +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.</p> + +<p>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<span class='pagenum'><a name="Page_284" id="Page_284">[Pg 284]</a></span> +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?</p> + +<p>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<span class='pagenum'><a name="Page_285" id="Page_285">[Pg 285]</a></span> +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.</p> + +<p>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.</p> + +<p>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 tran<span class='pagenum'><a name="Page_286" id="Page_286">[Pg 286]</a></span>scendent +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 <i>reductio ad absurdum</i>.</p> + +<p>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 ad<span class='pagenum'><a name="Page_287" id="Page_287">[Pg 287]</a></span>vancing +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.<span class='pagenum'><a name="Page_288" id="Page_288">[Pg 288]</a></span></p> + + + +<hr style="width: 65%;" /> +<h3><a name="XIII" id="XIII"></a>XIII.</h3> + +<h2>THE SPIRITUAL LIFE.<a name="FNanchor_Q_17" id="FNanchor_Q_17"></a><a href="#Footnote_Q_17" class="fnanchor">[Q]</a></h2> + + +<p>We have reached the end of our long journey, and +now we are ready to turn back and start for home.</p> + +<p>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.</p> + +<p><span class='pagenum'><a name="Page_289" id="Page_289">[Pg 289]</a></span></p><p>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.</p> + +<p>The pyramid-builders come, and erect those neighboring +piles to preserve their bodies when dead for that +glorious destiny in which they trust.</p> + +<p>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.</p> + +<p>Moses comes, and leads out of Egypt the chosen +people to prepare the way for the expected Messiah.</p> + +<p>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.</p> + +<p>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.</p> + +<p>The Romans come, and in this mystic land lay aside +their legal codes, and add their testimony to the same +great truth.</p> + +<p>The Christian hermits come, and make the storied +stones of the Pharaohs re-echo with their triumphant +songs.</p> + +<p>The Arab comes, and, as morning and evening he +gazes into the East, sees visions of the glorious Mecca<span class='pagenum'><a name="Page_290" id="Page_290">[Pg 290]</a></span> +of his hopes for which the Sphinx has looked so +long.</p> + +<p>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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>It is well to go away at times, that we may see +another aspect of human life, which still survives in the<span class='pagenum'><a name="Page_291" id="Page_291">[Pg 291]</a></span> +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.</p> + +<p>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.</p> + +<p>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.</p> + +<p>Do not believe in any such pessimism.</p> + +<p>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.</p> + +<p>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,<span class='pagenum'><a name="Page_292" id="Page_292">[Pg 292]</a></span> +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.</p> + +<p>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.</p> + + +<h4>THE END.</h4> +<p><span class='pagenum'><a name="Page_293" id="Page_293">[Pg 293]</a></span></p> + + + +<hr style="width: 100%;" /> +<h3>FOOTNOTES:</h3> + +<div class="footnote"><p><a name="Footnote_A_1" id="Footnote_A_1"></a><a href="#FNanchor_A_1"><span class="label">[A]</span></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.</p> +<p class="center"><i>Molecular Magnitudes at Standard Temperature and Pressure, 0° C. and +76 c. m.</i></p> + + +<div class='center'> +<table border="1" rules="cols" cellpadding="2" cellspacing="0" summary=""> +<tr><th class="bbox">RANK ACCORDING TO ACCURACY OF KNOWLEDGE.</th><th class="bbox">Hydrogen.</th><th class="bbox">Oxygen.</th><th class="bbox">Carbonic Oxide.</th><th class="bbox">Carbonic Dioxide.</th></tr> +<tr><td class='tdsc'><br />Rank I.</td><td align='right'></td><td align='right'></td><td align='right'></td><td align='right'></td></tr> +<tr><td align='left'>Relative mass</td><td align='right'> 1</td><td align='right'> 16</td><td align='right'> 14</td><td align='right'> 22</td></tr> +<tr><td align='left'>Velocity in metres per second</td><td align='right'> 1,859</td><td align='right'> 465</td><td align='right'> 497</td><td align='right'> 396</td></tr> +<tr><td class='tdsc'><br />Rank II.</td><td align='right'></td><td align='right'></td><td align='right'></td><td align='right'></td></tr> +<tr><td align='left'>Mean path in ten billionths (10<sup>-10</sup>) of a metre</td><td align='right'> 965</td><td align='right'> 560</td><td align='right'> 482</td><td align='right'> 379</td></tr> +<tr><td align='left'>Collisions each second—number of millions</td><td align='right'> 17,750</td><td align='right'> 7,646</td><td align='right'> 9,489</td><td align='right'> 9,720</td></tr> +<tr><td class='tdsc'><br />Rank III.</td><td align='right'></td><td align='right'></td><td align='right'></td><td align='right'></td></tr> +<tr><td align='left'>Diameter in hundred billionths (10<sup>-11</sup>) of a metre</td><td align='right'> 58</td><td align='right'> 76</td><td align='right'> 83</td><td align='right'> 93</td></tr> +<tr><td align='left'>Mass in ten million million million millionths (10<sup>-25</sup>) of a gramme</td><td align='right'> 46</td><td align='right'> 736</td><td align='right'> 644</td><td align='right'> 1,012</td></tr> +</table></div> +<p> +Number of molecules in one cubic centimetre of every gas is nineteen +million million million on 19 (10<sup>18</sup>). +</p><p> +Two million hydrogen molecules side by side measure a little over one +millimetre.</p> +</div> + +<div class="footnote"><p><a name="Footnote_B_2" id="Footnote_B_2"></a><a href="#FNanchor_B_2"><span class="label">[B]</span></a> <i>See</i> Professor Maxwell's lecture, <i>loc. cit.</i>; also, Appletons' "Cyclopædia," +article "Molecules."</p></div> + +<div class="footnote"><p><a name="Footnote_C_3" id="Footnote_C_3"></a><a href="#FNanchor_C_3"><span class="label">[C]</span></a> 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.</p></div> + +<div class="footnote"><p><a name="Footnote_D_4" id="Footnote_D_4"></a><a href="#FNanchor_D_4"><span class="label">[D]</span></a> See notice of these investigations by the author of this article, in +"American Journal of Science and Arts," September, 1877 (3), xiv, 231.</p></div> + +<div class="footnote"><p><a name="Footnote_E_5" id="Footnote_E_5"></a><a href="#FNanchor_E_5"><span class="label">[E]</span></a> 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 order to 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.</p></div> + +<div class="footnote"><p><a name="Footnote_F_6" id="Footnote_F_6"></a><a href="#FNanchor_F_6"><span class="label">[F]</span></a> "Nature," No. 22, March 31, 1870.</p></div> + +<div class="footnote"><p><a name="Footnote_G_7" id="Footnote_G_7"></a><a href="#FNanchor_G_7"><span class="label">[G]</span></a> +</p> +<table border="0" cellpadding="0" cellspacing="0" summary=""> +<tr><td align='left'>For example, the native crystals of sulphur have </td><td align='left'><i>a</i> : <i>b</i> : <i>c</i> = 1 : 2·340 : 1·233.</td></tr> +<tr><td align='left'>Crystals of gypsum have</td><td align='left'><i>a</i> : <i>b</i> : <i>c</i> = 1 : 0·413 : 0·691.</td></tr> +<tr><td align='left'>Crystals of tin-stone have</td><td align='left'><i>a</i> : <i>b</i> : <i>c</i> = 1 : 1 : 0·6724.</td></tr> +<tr><td align='left'>And crystals of common salt have</td><td align='left'><i>a</i> : <i>b</i> : <i>c</i> = 1 : 1 : 1.</td></tr> +</table></div> + +<div class="footnote"><p><a name="Footnote_H_8" id="Footnote_H_8"></a><a href="#FNanchor_H_8"><span class="label">[H]</span></a> The origin of the axes is always taken as the center of the sphere of +projection.</p></div> + +<div class="footnote"><p><a name="Footnote_I_9" id="Footnote_I_9"></a><a href="#FNanchor_I_9"><span class="label">[I]</span></a> "Obituary Notices from the Proceedings of the Royal Society," No. +206, 1880, to which the writer has been indebted for several biographical +details.</p></div> + +<div class="footnote"><p><a name="Footnote_J_10" id="Footnote_J_10"></a><a href="#FNanchor_J_10"><span class="label">[J]</span></a> This notice is reprinted from the Proceedings of the American +Academy of Arts and Sciences, vol. xviii, 1882-'83.</p></div> + +<div class="footnote"><p><a name="Footnote_K_11" id="Footnote_K_11"></a><a href="#FNanchor_K_11"><span class="label">[K]</span></a> Reprinted from the Proceedings of the American Academy of Arts +and Sciences, vol. xix, 1883-'84.</p></div> + +<div class="footnote"><p><a name="Footnote_L_12" id="Footnote_L_12"></a><a href="#FNanchor_L_12"><span class="label">[L]</span></a> 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.</p></div> + +<div class="footnote"><p><a name="Footnote_M_13" id="Footnote_M_13"></a><a href="#FNanchor_M_13"><span class="label">[M]</span></a> Hofmann, <i>loc. cit.</i></p></div> + +<div class="footnote"><p><a name="Footnote_N_14" id="Footnote_N_14"></a><a href="#FNanchor_N_14"><span class="label">[N]</span></a> Remarks made at the dinner of the Harvard Club of Rhode Island, +Newport, August 25, 1883.</p></div> + +<div class="footnote"><p><a name="Footnote_O_15" id="Footnote_O_15"></a><a href="#FNanchor_O_15"><span class="label">[O]</span></a> 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.</p></div> + +<div class="footnote"><p><a name="Footnote_P_16" id="Footnote_P_16"></a><a href="#FNanchor_P_16"><span class="label">[P]</span></a> An address delivered at the opening of the Summer School of Chemistry +at Harvard College, July 7, 1884.</p></div> + +<div class="footnote"><p><a name="Footnote_Q_17" id="Footnote_Q_17"></a><a href="#FNanchor_Q_17"><span class="label">[Q]</span></a> An Address to College Students at the close of a course of lectures on +Egypt and her Monuments. Illustrated by lantern photographs.</p></div> + + +<hr style="width: 100%;" /> +<div class="sblockquot"> +<h2><a name="SCIENTIFIC_LECTURES_AND_ESSAYS" id="SCIENTIFIC_LECTURES_AND_ESSAYS"></a>SCIENTIFIC LECTURES AND ESSAYS.</h2> + + +<p><span class="ft20">Popular Lectures on Scientific Subjects.</span> By H. +<span class="smcap">Helmholtz</span>, Professor of Physics in the University of Berlin. First +Series. Translated by E. <span class="smcap">Atkinson</span>, Ph. D., F. C. S. With an Introduction +by Professor <span class="smcap">Tyndall</span>. With 51 Illustrations. 12mo. +Cloth, $2.00.</p> + +<div class="blockquot"><p><i>CONTENTS.</i>—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.</p></div> + + +<p><span class="ft20">Popular Lectures on Scientific Subjects.</span> By H. +<span class="smcap">Helmholtz</span>. Second Series. 12mo. Cloth, $1.50.</p> + +<div class="blockquot"><p><i>CONTENTS.</i>—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.</p> + +<p>"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."—<i>Boston Traveler.</i></p></div> + + +<p><span class="ft20">Science and Culture, and other Essays.</span> By Professor +<span class="smcap">T. H. Huxley</span>, F. R. S. 12mo. Cloth, $1.50.</p> + +<div class="blockquot"><p>"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."—<i>London Academy.</i></p> + +<p>"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."—<i>London Spectator.</i></p></div> + + +<p><span class="ft20">Scientific Culture, and other Essays.</span> By <span class="smcap">Josiah +Parsons Cooke</span>, Professor of Chemistry and Mineralogy in Harvard +College. 12mo. Cloth, $1.00.</p> + +<div class="blockquot"><p>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."</p></div> + + + +<hr style="width: 15%;" /> +<h2>WORKS ON ASTRONOMY.</h2> + + +<p><span class="ft20">Elements of Astronomy.</span> By <span class="smcap">Robert Stowell Ball</span>, LL. D., +F. R. S., Andrews Professor of Astronomy in the University of Dublin, +Royal Astronomer of Ireland. With Illustrations. 16mo. Cloth, +$2.25.</p> + +<p><span class="ft20">Elementary Lessons in Astronomy.</span> By J. <span class="smcap">Norman +Lockyer</span>, 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.</p> + +<p><span class="ft20">Outlines of Astronomy.</span> By Sir J. J. W. <span class="smcap">Herschel</span>. With +Plates and Woodcuts. Eleventh edition. 8vo. Cloth, $4.00.</p> + +<p><span class="ft20">The Sun.</span> By C. A. <span class="smcap">Young</span>, Ph. D., LL. D., Professor of Astronomy +in the College of New Jersey. With numerous Illustrations. 12mo. +Cloth, $2.00.</p> + +<div class="blockquot"><p>"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."—<i>Popular Science Monthly.</i></p></div> + +<p><span class="ft20">Spectrum Analysis, in its Application to Terrestrial +Substances, and the Physical Constitution +of the Heavenly Bodies.</span> Familiarly explained +by Dr. H. <span class="smcap">Schellen</span>, Director der Realschule I. O. Cologne. Translated +from the second enlarged and revised German edition by <span class="smcap">Jane</span> +and <span class="smcap">Caroline Lassell</span>. Edited, with Notes, by <span class="smcap">William Huggins</span>, +LL. D. With numerous Woodcuts, Colored Plates, and Portraits; +also, Angström's and Kirchhoff's Maps. 8vo. Cloth, $6.00.</p> + +<div class="blockquot"><p>"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."—<i>The Chemical News.</i></p> + +<p>"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."—<i>Boston Globe.</i></p></div> + +<p><span class="ft20">Studies in Spectrum Analysis.</span> By J. <span class="smcap">Norman Lockyer</span>, +F. R. S., Correspondent of the Institute of France, etc. With Sixty +Illustrations. 12mo. Cloth, $2.50.</p> + +<div class="blockquot"><p>"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."—<i>New York Evening Express.</i></p></div> + +<p><span class="ft20">Origin of the Stars, and the Causes of their Motions +and their Light.</span> By <span class="smcap">Jacob Ennis</span>. 12mo. Cloth, +$2.00.</p> + +<p><span class="ft20">Astronomy and Geology Compared.</span> By Lord <span class="smcap">Ormathwaite</span>. +18mo. Tinted paper. Cloth, $1.00.</p> + +<p><span class="ft20">The Expanse of Heaven.</span> A Series of Essays on the Wonders +of the Firmament. By R. A. <span class="smcap">Proctor</span>. 12mo. 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Cloth, $2.50.</p> + +<p><span class="ft20">Our Place among Infinities.</span> 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. <span class="smcap">Proctor</span>. 12mo. Cloth, $1.75.</p> + + + +<hr style="width: 15%;" /> +<h2>WORKS ON GEOLOGY, Etc.</h2> + + +<p><span class="ft20">Principles of Geology; or, The Modern Changes +of the Earth and its Inhabitants, considered +as illustrative of Geology.</span> By Sir <span class="smcap">Charles Lyell</span>, +Bart. Illustrated with Maps, Plates, and Woodcuts. A new and +entirely revised edition. 2 vols. Royal 8vo. 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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: ASCII + +*** 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-ANDRE 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, anaesthesia, 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 aeriform 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 aesthetical 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, +zooelogy, 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 cooeperation 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, Thermopylae, 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 Ampere, 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 deg. 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] Lyrae. 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 deg. 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' + "Cyclopaedia," 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 aeriform 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 (3.8) 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 deg. 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 +aeriform 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 cooerdinated 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 aeriform 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 aeriform 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 aeriform 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 aeriform 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 formulae, +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 Metre." 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 encyclopaedic 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. Hauey 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. Hauey'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 +Hauey invented to express the relation of the secondary to the primary +forms, as modified and improved by Levy, is still used by the French +mineralogists. + +The system of Hauey, 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 Hauey 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_._a_:_n_._b_:_p_._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 Hauey, 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 Hauey 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 +formulae 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 Hauey, 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_._a_:_n_._b_:_p_._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_)._a_:(1/_k_)._b_:(1/_l_)._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 formulae which express the +relations between the parts of a crystal. From the last proportion we +derive at once + + (1/_h_).(_a_/_A_) = (1/_k_).(_b_/_B_) = (1/_l_).(_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_ = 1:2.340:1.233. + Crystals of gypsum have _a_:_b_:_c_ = 1:0.413:0.691. + Crystals of tin-stone have _a_:_b_:_c_ = 1:1:0.6724. + 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_).cos _P X_ = (_b_/_k_).cos _P Y_ = (_c_/_l_).cos _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 + + u._u_ + v._v_ + w._w_ = _o_, + +where _u_ _v_ and _w_ are the indices of the third plane, and u v w +have the values + + u = _k_._r_ - _l_._q_ + v = _l_._p_ - _h_._r_ + w = _h_._q_ - _k_._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 Hauey 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 Hauey 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 formulae 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-ANDRE DUMAS.[K] + + +Jean-Baptiste-Andre 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. Prevost, 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 Prevost 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, Ampere, and Poisson, all +manifested their interest in the young investigator. Dumas was soon +appointed Repetiteur de Chimie at the Ecole Polytechnique, and also +Lecturer at the Athenaeum, 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 Theodore Olivier and Eugene Peclet in +founding the Ecole 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 Ecole Polytechnique; and in 1839 he succeeded +Deyeux at the Ecole de Medecine. 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 Ecole +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 considerable que Dumas prenait a vos travaux et vous +avez bien souvent admire, comme moi, la haute intelligence et la tact +infini avec lesquels il savait imprimer a nos discussions les formes +moderees et courtoises inherentes a sa nature et a son caractere. Sous +ce rapport aussi la perte de Dumas est irreparable et cree dans +l'Academie un vide bien difficile a combler. Aussi, longtemps encore +nous chercherons, a la place qu'il occupait au Bureau avec tant +d'autorite, la figure sympathique et veneree de notre bienaime +Secretaire perpetuel." + +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 +aeriform 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 aeriform, the relative volumes preserve an +equally definite and still simpler ratio. Moreover, on the physical +side, Avogadro, and afterward Ampere, 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 Ampere"--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 "Traite de Chimie appliquee 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 "Credit Foncier," which +flourishes in great prosperity to this day; he also founded the "Caisse +de Retraite 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 archaeological 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 Cannae, 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 aeriform 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 aeriform, 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 11.11 per cent of hydrogen and 88.89 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, 11.11 +per cent of every molecule of water consists of hydrogen, while 88.89 +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 aeriform condition, it follows that the relative gas +volumes are proportional to the number of molecules of the aeriform +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 Ampere 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, + Angstroem'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 Palaeontological 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'antorite" corrected to "d'autorite" (page 188) + "resourses" corrected to "resources" (page 206) + +8. 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