*u % DS-ANCn% ^l-UBRARY^ ^v *g i ir 1 ^ ^ 5 i 8 ? \ THE CORRELATION AND CONSERVATION OF FOECES: 0f PROF. GEOYE, PEOF. HELMHOLTZ, DR. MATEK, DR. FAEADAY, PROF. LIEBIG AND DR. CAEPENTEE. LVPRODUCTION AND BRIEF BIOGRAPHICAL NOTICES OF THE CHIEF PROMOTERS OF THE NEW VIEWH EDWAKD L. TOUMANS, M. D. - Tho highest law In physical science which our faculties permit us to percc'.ve tht Conservation of Force." DB. FABADAT. NEW YOEK: D. APPLETON AND COMPANY, 1, 3, AND 5 BOND STREET. 1886. 138131 , according to Act of Congress, in the year 13*J by D. APPLETON AND COMPANY, In tttj Cwrk s Office, of the District Court of the United States for tl) Southern District of New Toik. QCT3 TO JOHN WILLIAM DKAPER, M.D., LL.D. PROFESSOR OP CHEMISTRY AND PHYSIOLOOY IN Ifll UNIVERSITY OF NEW YORK. DEAR SIR: IT seems peculiarly appropriate that this volume should be dedicated to you. Knowing the eminent esteem in which you are held in the circles of European science, I cannot doubt that the distinguished authors of the fol- lowing essays would cordially approve this connection of your name with their introduction to the American public. There is, besides, a further reason for this in that large coincidence of purpose which is manifest in their labors and your own. For while the per- vading design of the present collection is to widen the range of thought by unfolding a broader philosophy of the energies of nature, your own compre- hensive course of research beginning with an extended series of experi- mental investigations in chemical physics and physiology, and rising to the consideration of that splendid problem, the bearing of science upon the His- tory of the Intellectual Development of Europe has powerfully contributed to the same noble end ; that of elevating the aim and enlarging the scope of scientific inquiry. I gladly avail myself of this occasion to say how greatly I am indebted to your writings, in which accurate and profound instruction is so often and happily blended with the charms of poetic eloquence. That you may live long to enjoy your well-won honors, and to contribute still further to the triumphant ad ranee of scientific truth, is the heartfelt wish of Tours truly, E. L. Y. , c3 PREFACE IN his address before the British Association for the Advance- ment of Science last year, the President remarked that tne new views of the Correlation and Conservation of Forces constitute the most important discovery of the present century. The remark is probably just, prolific as has been this period in grand scientific re- suits. No one can glance through the current scientific publica- tions without perceiving that these views are attracting the pro- found attention of the most thoughtful minds. The lively con- troversy that has been carried on for the last two or three years respecting the share that different men of different countries have had in their establishment, still further attests the estimate placed upon them in the scientific world. But little, however, has been published in this country upon the subject ; no complete work, I believe, except the admirable volume of Prof. Tyndall on " Heat as a Mode of Motion," in which the new philosophy is adopted, and applied to the explanation of ther- mal phenomena in a very clear and forcible manner. I have, there- fore, thought it would be a useful service to the public to reissue some of the ablest presentations of these views which have ap- peared in Europe, in a compact and convenient form. The selec- tion of these discussions has been determined by a desire to com- bine clearness of exposition with authority of statement. In the first of these respects the essays will speak for themselves ; in re- gard to the last I may remark that all the authors quoted stand high as founders of the new theory of forces. Although I am not VI PREFACE. aware that Prof. Liebig lias made any claims J n this direction, yet it can scarcely be doubted that his original researches in Animal Chemistry tended strongly toward the promotion of the science of vital dynamics. The work of Professor Grove, which is here reprinted in full, has a high European reputation, having passed to the fourth edi- tion in England, and been translated into several continental lan- guages. It is hardly to the credit of science in our country, that this is the first American edition. The eloquent and interesting paper of Helmholtz, though delivered as a popular lecture, waa translated for the Philosophical Magazine, and has been very highly appreciated in scientific circles. The three articles of Mayer, which were also translated for the Philosophical Magazine, will have interest not only because of the great ability with which the subjects are treated, but as emanating from a man who stands per- haps preeminent among the explorers in this new tract of inquiry. The researches of Faraday in this field have been conspicuous and important, and his argument is marked by the depth and clearness which characterize, in an eminent degree, the writings of this ex- traordinary man. The essay of Liebig forms a chapter in the last edition of his invaluable 'Familiar Letters on Chemistry,' which has not been republished here ; and, as it touches the relation of the subject to organic processes, it forms a fit introduction to the final article of the series by Dr. Carpenter, on the " Correlation of thb Physical and Vital Forces." The eminent English physiologist has worked out this branch of the subject independently, and the pa- per quoted gives evidence of being prepared with his usual care and ability. A certain amount of repetition is of course unavoida- ble in such a collection, yet the reader will find much less of this than he might be inclined to look for, as each writer, in elaborating the subject, has stamped it with his own originality, In the introduction I have attempted to bring forward certain facts in the history of these discoveries, in which we as Ameri- cans have a special interest, and also to indicate several applications of the new principles which are not treated in the volume. It seemed best to confine the general discussion to those aspects of the subject upon which most thought had been expended, and which may be regarded as settled among advanced scientific men. But there are other applications of the doctrine, of the highest interest, which though incomplete are yet certain, and these will be found PREFACE. Vl: briefly noticed in the introductory observations too briefly, I fear, to be satisfactory. Those, however, who desire to pursue still further this branch of the inquiry the correlation of the vital, mental, and social forces are referred to the last edition of Car- penter's " Principles of Hnman Physiology ; " MorelTs " Outlines of Mental Philosophy ; " Laycock's " Correlations of Consciousness and Organization ; " Sir J. K. Shuttleworth's address before the Social Science Congress of 1860, on the " Correlation of the Moral and Physical Forces;" Hinton's "Life in Nature," and "First Principles " of Herbert Spencer's new system of Philosophy. The first and last of these works are the only ones, it is believed, that have appeared in an American form, and the last is much the ablest of all ; I was chiefly indebted to it in preparing the latter part of the introduction. The biographical notices, brief and im- perfect as they are, it is hoped may enhance the reader's interest in the volume. I have been specially incited to procure the publication of a work of this kind, by the same motive that has impelled me to write upon the subject elsewhere ; a conviction of our educational needs in this direction. The treatment of a vast subject like this in ordinary school text-books, is at best quite too limited for the requirements of the active-minded teacher ; to such, a volume like the present may prove invaluable. But a more serious difficulty is that, until compelled by the de- mands of intelligent teachers, the compilers of school-books will pass new views entirely by, or give them a mere hasty and careless notice, while continuing to inculcate the old erroneous doctrines. And thus it is that from inveterate habit, or intellectual sluggish- ness, or a shrewd calculation of the indifference of teachers, out- worn and effete ideas continue to drag through school-books for half a century after they have been exploded in the world of liv- ing science. He who continues to teach the hypothesis of caloric, falsifies the present truth of science as absolutely as he would do in teaching the hypothesis of phlogiston; in fact, the reasons of- fered for persisting in the erroneous notions of the materiality of heat convenience of teaching, unsettledness of the new vocabu- lary, &c,, are precisely those that were offered for clinging to phlo- giston, and rejecting the Lavoiserian chemistry of combustion. Both conceptions have no doubt been of service, but both were transitional, and having done their work they become hindrances nil PREFACE. instead of helps. "We can no\v see that -when the true chemistrj of combustion was once reached, the notion of phlogiston was of no further use, and if retained could only produce confusion and prevent the reception of correct ideas. So with caloric, and those false conceptions of the materiality of forces, which it implies : not only are they errors, but the ideas they involve are radically in- compatible with the higher truths to which science has advanced o that while the errors are retained the truths cannot be received. Nor will it answer merely to mention the new views while adopting the old, on the plea that the facts are the same in both cases. The facts are very far from being the same in both cases. It is precisely because the old ideas are out of harmony with the facts, and can no longer correctly explain and express them, that new ideas are sought. "Was not phlogiston abandoned because it no longer agreed with the facts ? So with the conception of the materiality of the forces ; it contradicts the facts, and therefore, for scientific purposes, can no longer represent them. In the workshop it may perhaps be very well to magnify facts, and depreciate their theoreti- cal explanations, but not in the school-room ; the business is here not working, but thinking. It is the aim of art to use facts, but of sci- ence to understand them. And it is simply because science goes beyond the fact to its explanation, and is ever striving after the highest truth, that it is fitted to discipline the thinking and reason- ing faculties, and therefore has imperative educational claims. In therefore bringing forward these able and authoritative ex- positions in a form readily accessible to teachers, I trust I am not only doing them a helpful service, but that they will be led to re- quire of the preparers of school-books a more conscientious per- formance of their tasks, and that the interests of sound education will be thereby promoted. 3Tw YOBK, Oct. 1, 1861 CONTENTS. PREFACE, ..... v INTRODUCTION, ...... THE CORRELATION OF PHYSICAL FORCES, Br W. R GROVK. Preface, ....... Ji I. Introductory Remarks, .... 9 H. Motion, ...... 25 HI. Heat, 38 IV. Electricity, ...... 83 V. Light, 116 VI. Magnetism, . . . . . .142 VH. Chemical Affinity, . . . 152 VnL Other Modes of Force, . . .169 IK. Concluding Remarks, .- . .178 Notes and References, .... 2011 It was this country, widely reproached for being over-practical, trliich produced just that kind of working ability that was suited to translate this profound question from the barren to the fruitful field of inquiry. It is a matter of just national pride that the two men who first demonstrated the capital propositions of pure sci ence, that lightning is but a case of common electricity, and that heat is but a mode of motion who first converted these proposi- tions from conjectures of fancy to facts of science, were not only Americans by birth and education, but men eminently representa- tive of the peculiarities of American character Benjamin Frank- lin and Benjamin Thompson, afterwards known as Count Eumford. The latter philosopher is less known than the former, though his services to science and society were probably quite as great. The prominence which his name now occupies in connection with the new views of heat, and the relations of forces, make it desirable to glance briefly at his career. BENJAMIN THOMPSON was born at "Woburn, Mass., in 1753. He received the rudiments of a common school education ; became a merchant's apprentice at twelve, and subsequently taught school. Having a strong taste for mechanical and chemical studies, he cul- tivated them assiduously during his leisure time. At seventeen he took charge of an academy in the village of Rumford (now Con- cord), N. H., and in 1772 married a wealthy widow, by whom ho had one daughter. At the outbreak of revolutionary hostilities he applied for a commission in the American service, was charged with toryism, left the country in disgust, and went to England. His talents were there appreciated, and he took a responsible posi- tion under the government, which he held for some years. After receiving the honor of knighthood he left England and entered the service of the elector of Bavaria. He settled in Mu- nich in 1784, and was appointed aide-de-camp and chamberlain to the Prince. The labors which he now undertook were of the most extensive and laborious character, and could never have been ao- complished but for tlie rigorous habits of order which Le carried into all his pursuits. He reorganized the entire military establish- ment of Bavaria, introduced not only a simpler code of tactics, and a new system of order, discipline, and economy among the troops and industrial schools for the soldiers' children, but greatly im- proved the construction and modes of manufacture of arms and ordnance. He suppressed the system of beggary which, had grown Into a recognized profession in Bavaria, and become an enormous public evil one of the most remarkable social reforms on record. He also devoted himself to various ameliorations, such as improv- ing the construction and arrangement of the dwellings of the work- ing classes, providing for them a better education, organizing houses of industry, introducing superior breeds of horses and cattle, and promoting landscape-gardening, which he did by converting an old abandoned hunting-ground near Munich into a park, where, after his departure, the inhabitants erected a monument to his honor. For these services Sir Benjamin Thompson received many distinc- tions, and among others was made Count of the holy Roman Empire. On receiving this dignity he chose a title in remembrance of the country of his nativity, and was thenceforth known as Count of Rumford. His health failing from excessive labor and what he considered the unfavorable climate, he came back to England in 1798, and had serious thoughts of returning to the United States. Having re- ceived from the American government the compliment of a formal invitation to revisit his native land, he wrote to an old friend re- questing him to look out for a " little quiet retreat " for himself and daughter in the vicinity of Boston. This intention, however failed, as he shortly after became involved in the enterprise of founding the Royal Institution of England. There was in Rumford's character a happy combination of phi- Untliropic impulses, executive power in carrying out great projects, and versatility of talent in physical research. His scientific inves- tigations were largely gnided and determined by his Dhilanthrqpu SCIENTIFIC LABOKS OF COUNT KUHFOKD. XiX plans and public duties. His interest in the more needy classes led him to the assiduous study of the physical wants of mankind, and the best methods of relieving them ; the laws and domestic man- agement of heat accordingly engaged a large share of his attention, lie determined the amount of heat arising from the combustion of different kinds of fuel, by means of a calorimeter of his own in- vention. He reconstructed the fireplace, and so improved the methods of heating apartments and cooking food as to produce a saving in the precious element, varying from one-half to seven- eighths of the fuel previously consumed. He improved the con- struction of stoves, cooking ranges, coal grates, and chimneys; showed that the non-conducting power of cloth is due to the air enclosed among its fibres, and first pointed out that mode of action of heat called convection; indeed he was the first clearly to dis- criminate between the three modes of propagation of heat radia- tion, conduction, and convection. He determined the almost per- fect non-conduoting properties of liquids, investigated the produc- tion of light, and invented a mode of measuring it. He was the first to apply steam generally to the warming of fluids and the culinary art ; he experimented upon the use of gunpowder, the strength of materials, and the maximum density of water, and made many valuable and original observations upon an extensive range of subjects. Prof. James D. Forbes, in his able Dissertation on the recent Progress of the Mathematical and Physical Sciences, in the last edition of the Encyclopedia Britannica, gives a full account of Rum- ford's contributions to science, and remarks; " All Rumford's experiments were made with admirable precis- ion, and recorded with elaborate fidelity, and in the plainest lan- guage. Every thing with him was reduced to weight and meas- ure, and no pains were spared to attain the best results. " Rumford's name will be ever connected with the progress of science in England by two circumstances : first, by the foundation of a perpetual medal and prize in the gift of the council of the EC INTRODUCTION. Royal Society of London, for the reward of discoveries connected with heat and light; and secondly, by the establishment in 1800 of the Eoyal Institution in London, destined, primarily, for the pro- motion of original discovery, and, secondarily, for the diffusion of a taste for science among the educated classes. The plan was con- ceived with the sagacity which characterized Rumford, and its suc- cess has been greater than could have been anticipated. Davy was there brought into notice by Rumford himself, and furnished with the means of prosecuting his admirable experiments. He and Mr. Faraday have given to that institution its just celebrity with little intermission for half a century." Leaving England, Eumford took up his residence in France, and the estimation in which he was held may be judged of by the fact that he was elected one of the eight foreign associates of the Acad- emy of Sciences. Count Eumford bequeathed to Harvard University the funds for endowing its professorship of the Application of Science to the Art of Living, and instituted a prize to be awarded by the Ameri- can Academy of Sciences, for the most important discoveries and improvements relating to heat and light. In 1804 he married the widow of the celebrated chemist Lavoisier, and with her retired to the villa of Auteuil, the residence of her former husband, where he died in 1814. Having thus glanced briefly at his career, I now pass to the dis- covery upon which Count Bum ford's fame in the future will chiefly rest. It is described in a paper published in the transactions of the Royal Society for 1798. He was led to it while superintending the operations of the Munich arsenal, by observing the large amount of heat generated in boring brass cannon. Eeflecting upon this, he proposed to him- Belf the following questions : " Whence comes the heat produced m the mechanical operations above mentioned ? " " Is it furnish e 1 by the metalL'c chips which are separated from the metal ? " BUMFOEIXS EXPERIMENTAL INVESTIGATIONS. xxi The common hypothesis affirmed that the heat produced had been latent in the metal, and had been forced out by condensation of the chips. But if this were the case the capacity for heat of the parts of metal so reduced to chips ought not only to be changed, but the change undergone by them should be sufficiently great to account for all the heat produced. With a fine saw Kumford then cut away slices of the unheated metal, and found that they had ex- actly the same capacity for heat as the metallic chips. No change in this respect had occurred, and it was thus conclusively proved that the heat generated could not have been held latent in the chips. Having settled this preliminary point, Kumford proceeds to his principal experiments. With the intuition of the true investigator, he remarks that " very interesting philosophical experiments may often be made, almost without trouble or expense, by means of machinery con- trived for mere mechanical purposes of the arts and manufactures." Accordingly, he mounted a metallic cylinder weighing 113.13 pounds avoirdupois, in a horizontal position. At one end there was a cavity three and a half inches in diameter, and into this was in- troduced a borer, a flat piece of hardened steel, four inches long, 0.63 inches thick, and nearly as wide as the cavity, the area of con- tact of the borer with the cylinder being two and a half inches. To measure the heat developed, a small round hole was bored in the cylinder near the bottom of the cavity, for the insertion of a email mercurial thermometer. The borer was pressed against the base of the cavity with a force of 10,000 pounds, and the cylinder made to revolve by horse-power at the rate of tl irty-two times per minute. At the beginning of the experiment tne temperature of the air in the shade and also in the cylinder was GOT. at the end of thirty minutes, and! after the cylinder had made 960 revolutions the temperature was found to be 130T. Having taken away the borer, he found that 839 grains of me- tallic dust had been cut away. " Is it possible," he exclaims, " that .he very considerable quantity of heat produced in this experiment CSll INTRODUCTION. a quantity which actually raised the temperature of upward uf 113 pounds of gun metal at least 70, could have been furnished by BO inconsiderable a quantity of metallic dust, and this merely in consequence of a change in the capacity for heat? " To measure more precisely the heat produced, he next sur- rounded his cylinder by an oblong wooden box in such a manner that it could turn water-tight in the centre of the box, while the borer was pressed against the bottom. The box was filled with water until the entire cylinder was covered, and the apparatus was set in action. The temperature of the water on commencing was 60. He remarks, " The result of this beautiful experiment was very striking, and the pleasure it afforded amply repaid me for all the trouble I had taken in contriving and arranging the complicated machinery used in making it. The cylinder had been in motion but a short time when I perceived, by putting my hand into the water and touching the outside of the cylinder, that heat was gen- erated." As the work continued the temperature gradually rose ; at two hours and twenty minutes from the beginning of the operation, the water was at 200, and in ten minutes more it actually boiled ! Upon this result Kumford observes, " It would be difficult to de- scribe the surprise and astonishment expressed in the countenances of the bystanders, on seeing so large a quantity of water heated and actually made to boil without any fire. Though there was nothing that could be considered very surprising in this matter, yet I acknowledge fairly that it afforded me a degree of childish pleasure which, were I ambitious of the reputation of a grave phi- losopher, I ought most certainly rather to hide than to discover." Kumford estimated the total heat generated as sufficient to raise 26.58 pounds of ice-cold water 180, or to its boiling point; and he adds, " from the results of these computations, it appears that the quantity of heat produced equally or in a continuous stream, if I may use the expression, by the friction of the blunt steel borer against the bottom of the hollow metallic cylinder, was greater BUMFOED 7 S INFERENCES FEOM HIS EXPERIMENTS. XX111 than that produced in the combustion of nine wax candles, each three-quarters of an inch in diameter, all burning together with clear bright flames." " One horse would have been equal to the work performed, though two were actually employed. Heat may thus be produced merely by the strength of a horse, and in a case of necessity this might be used in cooking victuals. But no circumstances could be imagined in which this method of producing heat could be advan- tageous, for more heat might be obtained by using the fodder ne- cessary for the support of the horse, as fuel. " By meditating on the results of all these experiments, we are naturally brought to that great question which has so often been the subject of speculation among philosophers, namely, What is heat? Is there such a thing as an igneous fluid? Is there any thing that with propriety can be called caloric ? " We have seen that a very considerable quantity of heat may be excited by the friction of two metallic surfaces, and given off in a constant stream or flux in all directions, without interruption or intermission, and without any signs of diminution or exhaustion. In reasoning on this subject we must not forget that most remark able circumstance, that the source of the heat generated by friction in these experiments appeared evidently to be inexhaustible. (The italics are Eumford's.) It is hardly necessary to add, that any thing which any insulated body or system of bodies can continue to furnish without limitation, cannot possibly be a material sub- stance ; and it appears to me to be extremely difficult, if not quite impossible, to form any distinct idea of any thing capable of being excited and communicated in those experiments, except it be MO- TION." No one can read the remarkably able and lucid paper from which these extracts are taken, without being struck with the per- feet distinctness with which the problem to be solved was pre- sented, and the systematic and conclusive method of its treatment. Rmnford kept strictly within the limits of legitimate inquiry, which INTRODUCTION. - no man can define better than he did. " I am very far from pre- tending to know how, or by what means or mechanical contri- vances, that particular sind of motion in bodies, which has been supposed to constitute heat, is exerted, continued, and propagated, and I shall not presume to trouble the Society with new conjec- tures. But although the mechanism of heat should in part be ona one of those mysteries of nature, which are beyond the reach cf human intelligence, this ought by no means to discourage us, or even lessen our ardor in our attempts to investigate the laws of its operations. How far can we advance in any of the paths which science has opened to us, before we find ourselves enveloped in those thick mists, which on every side bound the horizon of the human intellect." Eumford's experiments completely annihilated the material hy- pothesis of heat, while the modern doctrine was stated in explicit terms. He moreover advanced the question to its quantitative and highest stage, proposing to find the numerical relation between mechanical power and heat, and obtained a result remarkably near to that finally established. The English unit of force is the foot- pound, that is, one pound falling through one foot of space ; the unit of heat is one pound of water heated 1 F. Just fifty yeara subsequently to the experiment of Eumford, Dr. J. P. Joule,* of Manchester, England, after a most delicate and elaborate series of experiments, determined that 772 units of force produce one unit of heat ; that is, 772 pounds falling through one foot produces suf- ficient heat to raise one pound of water 1 F. This law is known as the mechanical equivalent of heat. Now, when we throw Eum- ford's results into these terms, we find that about 940 units of force produced a unit of heat, and that, therefore, on a large scale, and at the very first trial, he came within twenty per cent, of the true * JAMES PEESCOTT JOTTLB, born December 24th, 1818, at Salford, near Manchester, England, where he pursued the occupation of a brewer. Long and deeply devoted to scientific investigation, he became a member of the Manchester Philosophical So dety In 1842, and of the Eoyal Society of London in 1850. SOMMAEY OF RUMFORD 8 CLAIMS. XXV itatement. No account was taken of the heat lost by radiation, which, considering the high temperature produced, and the dura- tion of the experiment, must have been considerable ; so that aa Rumford himself noticed, this value must be too high. The ear Host numerical results in science are rarely more than rough ap- proximations, yet they may guide to the establishment of great principles. Certainly no one could question Dalton's claim to the discovery of the law of definite proportions, because of the inac- curacy of the numbers upon which he first rested it. We are called further to note that Rumford's ideas upon the general subject of forces were far in advance of his age. He saw the relation of all friction to heat, and suggested that of fluids, by churning processes, as a means of producing it precisely the method finally employed by Joule in establishing the mechanical equivalent of heat. He furthermore regarded animals dynami- cally, considering their force as the derivative of their food, and therefore as not created. That Rumford held these views in the comprehensive and matured sense in which they are now enter- tained is, of course, not asserted. The advance from his day to ours has been prodigious. Whole sciences have been created, which afford the most beautiful exemplifications of the new doc- trines. Those doctrines have received their subsequent develop- ment in various directions by many minds, but we may be allowed to question if the contributions of any of their promoters will sur- pass, if indeed they will equal, the varae and importance which we must assign to the first great experimental step in the new direc- tion. The claims of Rumford may be summarized as follows : L Ho was the man who first took the question of the nature of heat out of the domain of metaphysics, where it had been speculated upon since the time of Aristotle, and placed it upon the true basis of physical experiment. II. He first proved the insufficiency of the current explanation* 2 SXV1 DJTBODTJCTTON. of the sources of heat, and demonstrated the falsity oi the prevaih'ng view of its materiality. HI. He first estimated the quantitative relation between the heat produced by friction and that by combustion. IV. He first showed the quantity of heat produced by a definite amount of mechanical work, and arrived at a result re- markably near the finally established law. V. He pointed out other methods to be employed in determining the amount of heat produced by the expenditure of me- chanical power, instancing particularly the agitation of water, or other liquids, as in churning. VI. He regarded the power of animals as due to their food, there fore as having a definite source and not created, and thus applied his views of force to the organic world. VII. Eumford was the first to demonstrate the quantitative con- vertibility of force in an important case, and the first to reach, experimentally, the fundamental conclusion that heat is but a mode of motion. In his late work upon heat, Prof. Tyndall, after quoting co- piously from Kumford's paper, remarks : " When the history of the dynamical theory of heat is written, the man who in opposition to the scientific belief of his time could experiment, and reason upon experiment, as did Eumford in the investigation here referred to, cannot be lightly passed over." Had other English writers been equally just, there would have been less necessity for the foregoing exposition of Kumford's labors and claims ; but there has been a manifest disposition in various quarters to obscure and depreciate them. Dr. "Whewell, in his history of the Inductive Sciences, ' treats the subject of thermotics without mentioning him. An em- inent Edinburgh professor, writing recently in the Philosophical Magazine, under the confessed influence of 'patriotism,' under- DAVY'S RELATION TO THE QUESTION. lakes to make the dynamical theory of heat an English monopoly, due to Sir Isaac Newton, Sir Humphry Davy, and Dr. J. P Joule ; while an able writer in a late number of the North British Review, in sketching the historic progress of the new views, puts Davy forward as their founder, and assigns to Eumford a minor and subsequent place. Sir Humphry Davy, it is well known, early rejected the caloric hypothesis. In 1799, at the age of twenty-one, he published a tract at Bristol, describing some ingenious experiments upon the subject. It was the publication of this pamphlet which brought him to Rumford's notice, and resulted in his subsequent connection with the Royal Institution. But Davy's ideas upon the question were far from clear, and will bear no comparison with those of Rumford, published the year before. Indeed his eulogist remarks : "It is certain that even Davy himself was led astray in his argu- ment by using the hypothesis of change of capacity as the basis of his reasoning, and that he might have been met successfully by any able calorist, who, though maintaining the materiality of heat, might have been willing to throw overboard one or two of the less essential tenets of his school of philosophy." It was not till 1812 that Davy wrote in his Chemical Philosophy, " The immediate cause of the phenomena of heat theft is motion, and the laws of its communication are precisely the same as those of the communica- tion of motion," When, therefore, we remember that Davy's first publication was subsequent to that of Rumford's, that he confined himself to the narrowest point of the subject, the simple question of the existence of caloric ; and that he nowhere gives evidence of having the slightest notion of the quantitative relation between mechanical force and heat, the futility of the claim which would make him the experimental founder of the dynamical theory, is abundantly apparent. The inquiries opened by Rumford and Davy were not formally pursued by the succeeding generation. Even the powerful adhe- sion of Dr. Thomas Young perhaps the greatest mind in science KV111 ZNTBODUCTIOW. since Newton failed to give currency to the new views. But the salient and impregnable demonstration of Kumford, and the ingen- ious experiments of Davy, facts which could neither be evaded nor harmonized with the prevailing errors, were not without influence. That there was a general, though unconscious tendency toward a new philosophy of forces, in the early inquiries of the present cen- tury, is shown by the fact that various scientific men of different nations, and with no knowledge of each other's labors, gave ex- pression to the same views at about the same time. Grove and Joule of England, Mayer of Germany, and Colding of Denmark, announced the general doctrine of the mutual relations of the forces, with more or less explication, about 1842, and Seguin of France, it is claimed, a little earlier. From this time the subject was closely pursued, and the names of Helmholtz, Holtzman, Clausius,* Faraday, Thompson, Eankine,t Tyndall, Carpenter, and others are intimately associated with its advancement. In this country Professors Henry J and Leconte have contributed to illustrate the organic phase of the doctrine. \ I cannot here attempt an estimate of the respective shares which these men have had in constructing the new theories ; the reader will gather various intimations upon this point from the succeeding essays. The foreign periodicals, both scientific and lit- erary, show that the question is being thoroughly sifted, and mate- rials accumulating for the future history of the subject. The para- mount claims are, however, those of Joule, Mayer, and Grove. * CuuTsnis, Rtn>OLPH Juutrs iMMAycra. was born at Coslin, Pommern, January 82, 1822. He became Professor of Philosophy and Physics in the Polytechnic School t Zurich in 1855, and then Professor of the Zurich University (1857). He was after- wards teacher of Physics and Artillery in the School of Berlin, and then privat* teacher of the University of that place. t BAJTEINB, WILLIAM JOHN MACQITOBS' was born at Edinburgh, July 5, 1820. Ha Is a civil engineer In Glasgow, a member of the Philosophical Society at that place, od of the Eoyal Society ot London. $ Se the article "Meteorology," in the Agricultural Beport of the Patent Off , fa tt*7. See the American Journal of Science for Nov. 1S59. CLAIMS OF JOULE, GKOVE, AND MAYEK. According to the strict rule of science, that in all those cases where experimental proof is possible, he who first supplies it is the true discoverer, Dr. Joule must be assigned the foremost place among the modern investigators of the subject. He dealt with the whole question upon the basis of experiment. He labored with great perseverance and skill to determine the mechanical equivalent of heat the corner-stone of the edifice ; and in accomplishing this result in 1850, he may be said to have matured the work of Kumford, and finally established upon an experimental basis the great law of thermo-dynamics, to remain a demonstration of science forever. Professor Grove has also worked out the subject in his own in- dependent way. Combining original experimental investigations of great acuteness, with the philosophic employment of the gen- eral results of science, he was the first to give complete and system- atic expression to the new views. His able work, which opens the present series, is an authoritative exposition, and an acknowl- edged classic upon the subject. Again, the claims of Dr. Mayer to an eminent and enviable place among the pioneers of this great scientific movement, are un- questionable. There has evidently been, on the part of some Eng- lish writers, an unworthy inclination to depreciate his merits, which has given rise to a sharp and searching controversy. The intellectual rights of the German philosopher have, however, been decisively vindicated by the chivalric pen of Prof. Tyndall ; and it is to the public interest thus excited, that we are indebted for the translation of Mayer's papers, which appear in this volume. Mayer did not experiment to the extent of Joule and Grove, yet he well knew its importance, and made such investigations as his apparatus and the duties of a laborious profession would allow. Yet his views were not therefore mere ingenious and probable conjectures. Master of the results of modern science, and of the mathematical methods of dealing with them, possessing a broad philosophic grasp, and an extraordinary mental pertinacity, Dr. Mayer entered early upon the inquiry, and not only has he developed many of its EC5. INTRODUCTION. prime applications in advance of any other thinker, but he has done his "work under circumstances and in a manner which awa- kens the highest admiration for his genius.* An eminent authority has remarked ' that tl ese discoveries open a region which promises possessions richer than any hitherto granted to the intellect of man.' Involving as they do a revolution of fundamental ideas, their consequences must he as comprehen- sive as the range of human thought. A principle has heen devel- oped of all-pervading appli cation, which brings the diverse and distant branches of knowledge into more intimate and harmonious alliance, and affords a profounder insight into the universal order. Not only is science itself deeply affected by the presentation of its questions, in new and suggestive lights, but its method is at once made universal. There is a crude notion in many minds, that it }g the business of science to occupy itself merely with the study of matter. When, hitherto, it has pressed its inquiries into the higher Prof. Tyndall remarks : " Mayer probably had not the means of making experi- ments himself, bat he ransacked the records of experimental science for his data, and thus conferred upon his writings a strength which mere speculation can never possess. From the extracts which I have given, the reader may infer his strong desire for quan- titative accuracy, the clearness of his insight, and the firmness of his grasp. Regard- ing the recognition which will be ultimately accorded to Dr. Mayer, a shade of trouble or doubt has never crossed my mind. Individuals may seek to pull him down, but their efforts will be unavailing as long as such evidence of his genius exists, and aa long as the general mind of humanity is influenced by considerations of justice and truth. u The paucity of facts in Mayer's time has been urged as if it were a reproach to him; but it ought to be remembered that the quantity of fact necessary to a generaliza- tion is different for different minds. A word to the wise is sufficient for them,' and a single feet in some minds bears fruit that a hundred cannot produce in others. Mayer's data were comparatively scanty, but his genius went far to supply the lack of experiment, by enabling him to see clearly the bearing of such facts as he possessed. They enablid him to think out the law of conservation, and his conclusions received the stamp of certainty from the subsequent experimental labors of Mr. Joule. In ref- erence to their comparative merits, I would say that as Seer and Generalizer, Mayer to ray opinion, stands first as experimental philoiopher, Joule." THE TRUE SCOPE OF SCIENCE. region of life, mind, society, history, and education, the traditional custodians of these subjects have bidden it keep within its limits and stick to matter. But science is not to he hampered by this narrow conception ; its office is nothing less than to investigate the laws and universal relations of force, and its domain is therefore coextensive with the display of power. Indeed, as we know noth ing of matter, except through its manifestation of forces, it is ob- vious that the study of matter itself is at last resolved into the study of forces. The establishment of a new philosophy of forces, therefore, by its vast extension of the scope and methods of sci- ence, constitutes a momentous event of intellectual progress. The discussions of the present volume will make fully apparent the importance of the new doctrines in relation to physical science, but their higher implications are hut partially unfolded. In the concluding article Dr. Carpenter has shown the applicability of the principle of correlation to vital phenomena. His argument is of interest, not only because of the facts and principles established, but as opening an inquiry which must lead to still larger results : for, if the principle be found operative in fundamental organic processes, it will undoubtedly be traced in those which are higher ; if in the lower sphere of life, then throughout that sphere. If the forces are correlated in organic growth and nutrition, they must be in organic action; and thus human activity, in all its forms, is brought within the operation of the law. As a creature of or- ganic nutrition, borrowing matter and force from the outward world ; as a being of feeling and sensibility, of intellectual power and multiform activities, man must be regarded as amenable to the great law that forces are convertible and indestructible; and as psychology and sociology the science of mind and the science of society have to deal constantly with different phases and forma of human energy, the new principle must be of the profoundest Import in relation to these great subjects. The forces manifested in the living system are of the most Taried and unlike character, mechanical, thermal, luminous, electric, LNTKOULO110.N. chemical, nervous, sensory, emotional, and intellectual. That these forces are perfectly coordinated that there is some definite relation among them which explains the marvellous dynamic unity of the living organism, does not admit of question. That this relation is of the same nature as that which is found tc exist among the purely physical forces, and which is expressed hy the term ' Correl- ation,' seems also abundantly evident. From the great complex- ity of the conditions, the same exactness will not, of course, be expected here as in the inorganic field, but this is one of the neces- sary limitations of all physiological and psychological inquiry ; thus qualified the proofs of the correlation of the nervous and mental forces with the physical, are as clear and decisive as those for the physical forces alone. If a current of electricity is passed through a small wire it produces heat, while if heat is applied to a certain combination of metals, it reproduces a current of electricity; these forces are, therefore, correlated. A current of electricity passed through a email portion of a motor or sensory nerve will excite the nerve force in the remainder, while, on the other hand, as is shown in the case of the torpedo, the nerve-force may generate electricity. Nerve-force may produce heat, light, electricity, and, as we con- stantly experience, mechanical power, and these in their turn may also excite nerve-force. This form of energy is therefore clearly entitled to a place in the order of correlated agencies. Again, if we take the highest form of mental action, viz. : will- power, we find that while it commands the movements of the sys- tem, it does not act directly upon the muscles, but upon the cerebral hemispheres of the brain. There is a dynamic chain of which voluntary power is but one link. The will is a power which excites nerve-force in the brain, which again excites mechanical power in the muscles. "Will-power is therefore correlated with nerve-power in the same manner as the latter is with muscular power. Dr. Carpenter well observes: "It is difficult to see that the dynamical agency which we term will is more removed from nerve-force or CORRELATION OF NERVOUS AND MENTAL FORCES. XXXlll the one hand than nerve-force is removed from motor force on the other. Each, in giving origin to the next, is itself expended or ceases to exist as such, and each bears, in its own intensity, a pre- cise relation to that of its antecedent and its consequent." We have here only space briefly to trace the principle in its applica- tion to sensations, motions, and intellectual operations. The physical agencies acting upon inanimate objects in the external world, change their form and state, and we regard these changes as transformed manifestations of the forces in action. A body is heated by hammering ; the heat is but transmuted mechani- cal force ; or a body is put in motion by heat, a certain quantity being transformed into mechanical effect, or motion cf the mass. And so it is held that no force can arise except by the expenditure of a preexisting force. Now, the living system is acted upon by the same agencies and under the same law. Impressions made upon the organs of sense give rise to sensations, and we have the same warrant in this, as in the former case, for regarding the effects as transformations of the forces in action. If the change of molecular state in a melted body represents the heat transformed in fusing it, so the sensation of warmth in a living body must represent the heat transformed in producing it. The impression on the retina, as well as that on the photographic tablet, results from the transmuted impulses of light. Ajid thus impressions made from moment to moment on all our organs of sense, are directly correlated with external physical forces. This correlation, further- more, is quantitative as well as qualitative. Not only does the light-force produce its peculiar sensations, but the intensity of these sensations corresponds with the intensity of the force ; not only is atmospheric vibration transmuted into the sense of sound, but the energy of the vibration determines its loudness. And so in all other cases ; the quantity of sensation depen is upon the quantity of the force acting to produce it. Moreover, sensations do not terminate in themselves, or come to nothing ; they produce certain correlated and equivalent effect* &XX1V INTRODUCTION. The feelings of light, heat, sound, odor, taste, pressure, are iin mediately followed by physiological effects, as secretion, musculai action, &c. Sensations increase the contractions of the heart, and it has heen lately maintained that every sensation contracts the muscular fibres throughout the whole vascular system. The res- piratory muscles also respond to sensations ; the rate of breathing being increased by both pleasurable and painful nerve-impressions. The quantity of sensation, moreover, controls the quantity of emo- tion. Loud sounds produce violent starts, disagreeable tastes cause wry faces, and sharp pains give rise to violent struggles. Even when groans and cries are suppressed, the clenched hands and set teeth show that the muscular excitement is only taking another direction. Between the emotions and bodily actions the correlation and equivalence are also equally clear. Moderate actions, like moderate sensations, excite the heart, the vascular system, and the glandular organs. As the emotions rise in strength, however, the various systems of muscles are thrown into action ; and when they reach a certain pitch of intensity, violent convulsive movements ensue. Anger frowns and stamps ; grief wrings its hands ; joy dances and leaps the amount of sensation determining the quantity of correla- tive movement. Dr. Carpenter, in his Physiology, has brought forward numerous exemplifications of this principle of the conversion of emotion into movement, as seen in the common workings of human nature. Most persons have experienced the difficulty of sitting still under high excitement of the feelings, and also the relief afforded by walking or active exercise ; while, on the other hand, repression of the movements protracts the emotional excitement. Many irascible persons get relief from their irritated feelings by a hearty explosion of oaths, others by a violent slamming of the door, or a prolonged 6t of grumbling. Demor strati ve persons habitually expend their feelings in action, while those who manifest them less retain then* longer: hence the former are more weak and transient in their CORRELATION OF PHYSICAL AND MENTAL FORCES. XXXV attachments than the latter, whose unexpended emotions become permanent elements of character. For the same reason, those wno are loud and vehement in their lamentations seldom die of grief; while the deep-seated emotions of sorrow which others cannot work off in violent demonstrations, depress the organic functions, and often wear out the life. The intellectual operations are also directly correlated with physical activities. As in the inorganic world we know nothing of forces except as exhibited by matter, so in the higher intellectual realm we know nothing of mind-force except through its material manifestations. Mental operations are dependent upon material changes in the nervous system ; and it may now be regarded as a fundamental physiological principle, that " no idea or feeling can arise, save as the result of some physical force expended in pro- ducing it." The directness of this dependence is proved by the fact that any disturbance of the train of cerebral transformations disturbs mentality, while their arrest destroys it. And here, also, the correlation is quantitative. Other things being equal there is a relation between the size of the nerve apparatus and the amount of mental action of which it is capable. Again, it is dependent upon the vigor of the circulation ; if this is arrested by the cessation of the heart's action, total unconsciousness results; if it is enfeebled, mental action is low ; while if it is quickened, mentality rises, even to delirium, when the cerebral activity becomes excessive. Again, the rate of brain activity is dependent upon the special chemical ingredients of the blood, oxygen and carbon. Increase of oxygen augments cerebral action, while increase of carbonic acid depresses it. The degree of mentality is also dependent upon the phosphatic constituents of the nervous system. The proportion of phosphorus In the brain is smallest in infancy, idiocy, and old age, and greatest during the prime of life ; while the quantity of alkaline phosphates excreted by the kidneys rises and falls with the variations of mental activity. The equivalence of physical agencies and mental effects is still further seen in the action of various substances, as alcohol, INTRODUCTION, opium, hashish, nitrons oxide, etc., when absorbed into the blood Within the limits of their peculiar action upon the nervous centres, the effect of each is strictly proportionate to the quantity taken. There is a constant ratio between the antecedents and consequents. " How this metamorphosis takes place how a force existing as motion, heat, or light, can become a mode of consciousness how it is possible for aerial vibrations to generate the sensation we call sound, or for the forces liberated by chemical changes in the train, to give rise to emotion, these are mysteries which it is im- possible to fathom. But they are not profounder mysteries than the transformation of the physical forces into each other. They are not more completely beyond our comprehension than the natures of mind and matter. They have simply the same insolu- bility as all other ultimate questions. "We can learn nothing more than that here is one of the uniformities in the order of phe- nomena." The law of correlation being thus applicable to human energy as well as to the powers of nature, it must also apply to society, where we constantly witness the conversion of forces on a compre- hensive scale. The powers of nature are transformed into the activ- ities of society; water-power, wind-power, steam-power, and electri- cal-power are pressed into the social service, reducing human labor, multiplying resources, and carrying on numberless industrial pro- cesses : indeed, the conversioo of these forces into social activiti.es i? one of the chief triumphs ot civilization. The universal forces of heat and light are transformed by the vegetable kingdom into the vital energy of organic compounds, and then, as food, are again converted into human beings and human power. The very exist- ence as well as the activity of society are obviously dependent upon the operations of vegetable growth. When that is abundant, popu- lati>n may become dense, and social activities multifarious and complicated, while a scanty vegetation entails sparse population and enfeebled social action. Any universal disturbance of the physical forces, as excessive rains or drouth, by reducing the har COKKELATION OF VITAL AND SOCIAL FOKCE3. XXXV11 fest, is felt throughout the entire social organism. "Where this effect is marked, and not counteracted by free communication with more fertile regions, the means of the community become restricted, business declines, manufactures are reduced, trade slackens, travel falls off, luxuries are diminished, education is neglected, marriages are fewer, and a thousand kindred results indicate decline of enter- prise and depression of the social energies. In a dynamical point of view there is a strict analogy between the individual and the social economies the same law of force governs the development of both. In the case of the individual, the amount of energy which he possesses at any time is limited, and when consumed for one purpose it cannot of course be had for another. An undue demand in one direction involves a corre- sponding deficiency elsewhere. For example, excessive action of the digestive system exhausts the muscular and cerebral systems, while excessive action of the muscular system is at the expense of the cerebral and digestive organs ; and again, excessive action of the brain depresses the digestive and muscular energies. If the fund of power in the growing constitutions of children is overdrawn in any special channel, as is often the case by excessive stimulation of the brain, the undue abstraction of energy from other portions of the system is sure to entail some form of physiological disaster. So with the social organism ; its forces being limited, there is but a definite amount of power to be consumed in the various social activities. Its appropriation in one way makes impossible its em- ployment in another, and it can only gain power to perform one function by the loss of it in other directions. This fact, that social force cannot be created by enactment, and that when dealing with the producing, distributing, and commercial activities of the com- munity, legislation can do little more than interfere with their natural courses, deserves to be more thoroughly appreciated by the public. But the law in question has yet higher bearings. More and more we are perceiving that the condition of humanity and th progress of civilization are direct resultants of the forces by wLich men are controlled. "What we terra the moral order of society, im- plies a strict regularity in the action of these forces. Modern sta- tistics disclose a remarkable constancy in the moral activities man- ifested in communities of men. Crimes, and even the modes of crime, have been observed to occur with a uniformity which admits of their prediction. Each period may therefore be said to have its definite amount of morality and justice. It has been maintained, for instance, with good reason, that " the degree of liberty a peo- ple is capable of in any given age, is a fixed quantity, and that any artificial extension of it in one direction brings about an equiva- lent limitation in some other direction. French revolutions show scarcely any more respect for individual rights than the despotisms they supplant; and French electors use their freedom to put themselves again in slavery. So in those communities where State restraint is feeble, we may expect to find it supplemented by the sterner restraints of public opinion." But society like the individual is progressive. Although at each stage of individual growth the forces of the organism, physi- ological, intellectual, and passional, "nave each a certain definite amount of strength, yet these ratios are constantly changing, and it is in this change that development essentially consists. So with society; the measured action of its forces gives rise to a fixed amount of morality and liberty in each age, but that amount in- creases with social evolution. The savage is one in whom certain classes of feelings and emotions predominate, and he becomes civil- ized just in proportion as these feelings are slowly replaced by oth- ers of a higher character. Yet the activities which determine human advancement are various. Not only must we regard the physiological forces, or those which pertain to man's physical or ganization and capacities, and the psychological, or those resulting from his intellectual and emotional constitution, but the influences of the external world, and those of the social state, are likewise to be considered. Man and society, therefore, as viewed by the ey SPENCER'S CONTETBUTION TO THE IXQTTIKT. xxxix of science, present a series of vast and complex dynamical problems, wrhich are to be studied in the future in the light of the great .aw by which, we have reason to believe, all forms and phases of force are governed. A further aspect of the subject remains still to be noticed. Mr. Herbert Spencer has the honor of crowning this sublime inquiry by showing that the law of the conservation, or as he prefers to term it the ' Persistence of Force,' .as it is the underlying principle of all be- ing, is also the fundamental truth of all philosophy. With masterly analytic skill he has shown that this principle of which the human mind has just become fully conscious, is itself the profoundest law of the human mind, the deepest foundation of consciousness. He has demonstrated that the law of the Persistence of Force, of which the most piercing intellects of past times had but partial and un- satisfying glimpses, and which the latest scientific research has disclosed as a great principle of nature, has a yet more transcendent character ; is, in fact, an d priori truth of the highest order a truth which is necessarily involved in our mental organization ; which is broader than any possible induction, and of higher validity than any other truth whatever. This principle, which is at once the highest result of scientific investigation and metaphysical analysis, Mr. Spencer has made the basis of his new and compre- hensive System of Philosophy ; and in the first work of the series, entitled " First Principles, " he has developed the doctrine in its broadest philosophic aspects. The lucid reasoning by which he reaches his conclusions cannot be presented here ; a brief extract or two will, however, serve to indicate the important place assigned to the law by this acute and profound inquirer: " We might, indeed, be certain, even in the absence ot at?y such analysis as the foregoing, that there must exist some principle which, as being the basis of science, cannot be established by sci- ence. All reasoned out conclusions whatever must rest on some postulate. As before shown, we cannot go on merging derivative truths in these wider and wider truths from which they are de- J ENTEODUCTION. rived, without reaching at last a widest truth which can be merged in no other, or derived from no other. And whoever contemplates the relation in which it stands to the truths of science in general, will see that this truth, transcending demonstration, is the Persist- ence of force." * * *