DISSERTATION SIXTH. MATHEMATICAL AND PHYSICAL SCIENCE. (1.) Modern Advances in Science. (2.) Period 1450-1550. (3.) Period 1550-1650. CHAPTER I. § 1. On the Plan of this Dissertation. THE year 1850 may be said to complete the Third century of modern scientific progress, or the Fourth if we include its earliest dawn. To each of these ages of discovery may be assigned a peculiarity in the character of its improvements, and even in the methods which conduced to that improvement. Between 1450 and 1550 (a period so distinguished in letters and the arts), some great truths in physics and mathematics had presented themselves to a few precocious minds, yet they had not received any public acknowledgment, nor perhaps an adequate demonstration. Algebra then first became a science. Leonardo da Vinci made the earliest steps since the time of Archimedes, in rational mechanics, and Copernicus almost at the close of this period promulgated the true system of the world. But the next centenary (1550-1650) was the first of true scientific activity. Its characteristic feature was the vindication of observation and experiment as the prime essentials to the increase of natural knowledge, with the consequent repudiation of the dogmas of the schoolmen, and the baseless methods of à priori reasoning. The men of science formed a goodly array at this stirring time; and signal were their triumphs. Galileo was beyond all comparison the glory of his age. His sagacity, his knowledge, his versatility of talent, his ingenuity as an inventor, his success in prosecuting his discoveries, and his zeal and elcquence in making known their importance, gave him an enviable pre-eminence even amidst a mighty generation. Bacon laid down the canons of a new method in philosophy which Gilbert and Kepler, as well as Galileo, had already acted on. Napier and Descartes prepared for the general application of mathematics in the coming struggle. (4.) Period The hundred years which next succeeded (16501750) saw the triumphant application of mathema- 1650-1750. tics to Mechanics and Physics, and the establishment of the greatest mechanical theory of any age, that of Gravitation. The preparatory labours of a hundred and fifty years were brought, chiefly by the unparalleled sagacity and genius of Newton, to a speedy and dazzling climax. His success brought numerous and worthy labourers into the field, but they found enough to do in gathering in the harvest which he had prepared for them. 1750-1850. If we look for the distinguishing characteristic of (5.) the centenary period just elapsed (1750-1850), we Period find it in this, that it has drawn far more largely upon Experiment as a means of arriving at truth than had previously been done. By a natural conversion of the process, the knowledge thus acquired has been applied with more freedom and boldness to the exigencies of mankind, and to the farther investigation of the secrets of nature. If we compare the now extensive subjects of Heat, Electricity, and Magnetism, with the mere rudiments of these sciences as understood in 1750, or if we think of the astonishing revival of physical and experimental Optics (which had well nigh slumbered for more than a century) during the too short lives of Young and Fresnel, we shall be disposed to admit (6.) Limits of this Dissertation. of the 18th century. The Dissertation of Professor Playfair closes with the period of Newton; that of Sir John Leslie, professedly devoted to the history of the eighteenth century, embraces some matters which belong more properly to those which preceded and followed it. After considering how I might best carry out the plan of these essays, I have adopted the period from about the year 1775 to 1850 as the general limit of my review. We may imagine this period, of three quarters of a century preceding the present time, to be divided into three lesser intervals of 25 years each, which have also some peculiar features of their own. (7.) From 1775 to 1800 many branches of science still Character continued in the comparatively inert state which chaof the close racterized a great part of the eighteenth century. There were, however, two or three notable exceptions. One was the continued successful solution of the outstanding difficulties of the Theory of Gravity applied to the moon and planets, a task in which the continental mathematicians, and of these, in chief, Lagrange and Laplace, had no rivals, or even coadjutors, on this side of the channel: Another was the foundation of Sidereal Astronomy by Sir William Herschel ; and the last was the commencement of a system of Chemical Philosophy based on new and important experiments, and including the laws of heat in combination with matter, which at that period very naturally ranged themselves within the province of the chemist. In this department two British and one foreign name stand conspicuous, Black, Cavendish, and Lavoisier. I do not of course mean to affirm that other branches of science were not cultivated with success within the exact period of which we speak. Electricity, for instance, first statical, afterwards that of the pile, had a share in the discoveries and speculations of the time. But these were rather the mere extension of what had previously been thought of; or the first dawn of future important results, whose development fills a large space in the succeeding story. Volta and his inventions belong rather to the nineteenth than to the eighteenth century. (8.) The first quarter of the present century attained Character a higher and more universal celebrity. Scarcely a of the branch of physical science but received important period 1800-1825, and even capital additions. Physical Astronomy indeed, no longer filled so large a space in the page of discovery, simply because the exhaustive labours of the geometers of the former period had brought it to a stage of perfection nearly co-ordinate with the means Céleste. of observation, and because, by the publication of the Mécanique Céleste, Laplace had rendered available Mécanique and precise the masses of scattered research accumulated by the labours of a century since the close of Newton's career of discovery. It was in some sense a new book of " Principia," not, indeed, the work of one, but of many; nor of a few years, but of two generations at least. Still there it was, a great monument of successful toil, which, like its prototype, was for many years to be studied, even by minds of the highest order, rather than to be enlarged. mental But the other branches of Natural Philosophy (9.) were now to make a stride, such as perhaps no pre- Expericeding time had witnessed. The science of Optics Physics. was speedily expanded almost twofold, both in its facts and in its doctrines. Galvanic Electricity disclosed a series of phenomena not less brilliant and unexpected in themselves than important from the new light they threw on the still dawning science of chemistry, and from the power of the tool which they placed in the hands of philosophers. Before the first quarter of the present century closed, the important and long suspected connection between Electricity and Magnetism was revealed, and its immediate consequences had been traced out with almost unparalleled ingenuity and expedition. The basis of the science of Radiant Heat, slightly anticipated by the philosophers of the eighteenth and even the seventeenth centuries (Lambert and Mariotte), was finally laid in a distinct form, assigning to the agent, heat, an independent position dissociated from grosser matter, such as light had long enjoyed. Astronomy, though enriched on the very first night of the new century by the discovery of a small planet, the herald of so many more of the same class, made perhaps less signal progress; but Chemistry, besides the aid it received from the invention of the pile, had a triumph peculiarly its own in the addition of the comprehensive doctrine of Definite Proportions, destined to throw at some later time a steady light on the vexed question of the constitution of matter. The great number of scientific names of the first order of merit concerned in these numerous discoveries marks the extraordinary fertility of the period. They are imperfectly comprehended in the following list: Young, Malus, Sir David Brewster, Fresnel, and Arago; Volta, Dalton, Davy, and Oersted; Prevost, Leslie, and Fourier; Gauss, Ivory, Olbers, Bessel, and Encke. Of the twenty-five years just elapsed, it is not so easy to speak with precision. The voice of criticism may be fairly uttered with that reserve which every one must feel in speaking of his immediate contemporaries. Yet it may perhaps be stated without just cause either of offence or regret, that it has not on the whole been characterized by the full maturity of so many commanding minds. Of the great discoverers of the former period, several survived and continued their efficient labours during no small por (10.) Period 1825-1850. y the com of th rise, und, to tempor ances hicl d, as it were, ref ss of the Mechanical uch called them forth are some in those which are active in more Rough scarcely more difficult, studies. - phil opber the al department, made the most unbroken period of diseat, too, has been successfully ours comparable perhaps to those is rst rise as a science, and some connected with heat have risen into practical consequence. Astronomy has secuted with a systematic assiduity and sucespecially at the British and Russian national servatories, which yields to that of no former periol, whilst physical astronomy has been cultivated by methods of still improved analysis, and has achieved one triumph which France need not grudge to England, nor England to France, so signal as to be placed by common consent in a position superior to any since the first publication of the theory of gravitation, more than a century and a half before. This was the prediction of the position in space of a planet whose existence was unknown except by the disturbance which it produced in the Magnetism. movements of another. Terrestrial Magnetism has, for the first time, aspired to the rank of an exact science. In an illustrious philosopher of Germany, it has found its Kepler; and the combination of national efforts in collecting reliable data from the remotest corners of the globe is characteristic of the Chemistry. practical energy of the age. Pure Chemistry has been cultivated with extraordinary assiduity; but though some general principles have emerged, none are comparable, from their importance, to the discovery of Dalton. To cite, then, at present, but a few names, amongst the most conspicuous benefac VOL. I. Having thus briefly reviewed the course of disco- (12.) Review of very since the latter portion of the eighteenth century, the History I proceed in the succeeding chapters to attempt to of Science sketch it more in detail, dividing the sciences into in this groups, and in each of these endeavouring to present Essay. a lively view of its progress by connecting it with the individnal career of the eminent men who have most contributed thereto, and introducing collaterally the chief results obtained by their contemporaries. In this manner I hope, on the one hand, to escape the formality of a history of science, and the meagre detail which our limits would prescribe to so vast a subject; and on the other to be enabled to impress upon the reader (as seems to be the design of these Essays) the leading facts and features of discovery in every age, together with the intellectual characteristics of the greatest minds which contributed to it. (14.) ery atten that it is far of omission, than for the exceeding difficult undertaking. I have but one gro and that is so strong, that I trust. calmly to meet every just critical reflecti conscious of having written in a spirit of a impartiality whether as regards persons or sub and that I have exercised to the full amount of opportunities what powers of judgment I possess I have striven to speak judicially and historically whether of friend or stranger, the dead or the living, Englishman or Foreigner. What I have felt the most constant effort, has been the needful exclusion of meritorious names, far more numerous than those especially included and dwelt upon in these pages. But this has appeared to me the cardinal point of my whole plan. The labourers in science have been in these latter days so numerous, that had I noticed, even briefly every one who had made a real step in science, my pages must have been crowded by names and titles of books. Even with the extension of bulk to which this essay has gradually and unavoidably grown (nearly double of its projected amount), the reader would rather have been bewildered than led by the perusal of such a catalogue. Besides, since such a brief historical synopsis forms very generally an introduction to the several articles of the Encyclopædia, to repeat it all here would have been but a tedious redundancy. No one conversant with such matters will imagine that I have saved myself any labour by this particularity of selection. On the contrary, it would have cost no effort to enumerate under each subject the living or recently deceased authors upon it who are best known; such a detail must have left a vague and shadowy impression on the mind of the general reader, and when regard is paid to the necessary limits of the essay, and the multitude of technical details and technical words which there is no space to define and illustrate, it is plain that the perusal must have been rendered as dry and unpalatable to those who seek general and elementary yet clear ideas, as it would have been tantalizing and unsatisfactory to the accomplished student, or to the man of science in search of particular historical details. The end at which I have aimed is to select the more striking land-marks of progress in each subject in each age, and endeavour to connect them with the character and position of all the more eminent dis ar leave solely fo has been ... the compositro It will be s that I have devi scheme of my two dis composition of the Dissert Playfair and Sir John Leslie. mer, which is the more finished admirably adapted to the period science of which he had principally period, namely, of Galileo, Bacon, Leibnitz. But the amount of material w and the principle of selection was also much s The positive science of that age might almost be duced to two heads, Astronomy, including its mecha nical principles, and Optics. It was an age not more distinguished for the Truths it disclosed, than for the invention and right appreciation of the Methods of Discovery. Inductive Logic, and Mathematical Logic applied for the first time to dynamics, very justly claimed a place in a dissertation on the progress of science, in a period when these preliminary doctrines and discoveries were the stepping stones by which even the basement story of the Temple of Nature could alone be reached. The Philosophy of Bacon and the discovery of Fluxions, occupied therefore, with much reason, a large portion of Professor Playfair's beautiful Dissertation; and it is impossible to regret that an intellect so admirably qualified for tracing and displaying the intimate and historical connection of branches of knowledge so varied in their principles and character, should have been thus congenially employed, to the delight and edification of readers of every degree of acquirement from the highest to the humblest.1 1 In mentioning the name of my distinguished predecessor in the Chair of Natural Philosophy in the University of Edinburgh, I willingly take the opportunity of noticing, in a few words, his peculiar merits, to which the Dissertation contained in , to unite two of the Writings of éan the History and the and Mr Stuuctive Sciences. An English art Mill. derful versatility, industry, and a permanent monument to his à voluminous work bearing the pre de. A slight inspection of that work will show impracticable and self-destructive a plan it be ad have been to attempt anything like a syste- he undertaking, then, entering upon the cogistinct, subjects of the Logic ry and the progress of the Pure will bear an enduring testimony. Playfair's original contributions to science were not so marked and consi- Character me in including his name in the comparatively brief catalogue of discoverers chronicled in the succeeding of Professor efforts are, nevertheless, deserving of notice, and indirectly were perhaps hardly less beneficial. He was a most Playfair. d admiring student of the greatest mathematical writers of his time, and, when we consider the singularly backward hat science in Great Britain about the end of the last and commencement of the present century, it was of no slight imnce to find a man placed in the position of a public instructor able and willing to direct attention to the splendid achievents of the continental mathematicians. By his lectures both on Mathematics and Natural Philosophy-by his luminous articles n the Edinburgh Review-by some of his original papers in the Transactions of the Royal Society of Edinburgh-he contributed to this useful end, and would have done so still farther had he been enabled to complete the Dissertation which he so ably commenced. He had an excellent mathematical capacity, and mathematical taste, rather than power. His explanations, even of matters of inherent difficulty, are perspicuous and popular, qualities possessed by few of his contemporaries. His style has been pronounced by the highest authorities to be a model of clearness and eloquence. He was extensively read in subjects of metaphysics and morals, as well as of pure science; and by a combination of talent rare, I am inclined to say, in a high degree, his taste, though eminently mathematical, was also directed, with signal success (at first through his intimate friendship for Dr Hutton), to the very opposite studies of Geology and Physical Geography, which may be said to have been the subjects of his predilection during the last twenty years of his life. Nor were these labours of the closet merely; he was far more intimately versed in the mineral structure of the earth, from observation, than any except a few professed geologists; and he exceeded them all in the ability with which he expounded and maintained the striking doctrines of the Huttonian theory. Though professedly the "illustrator" of the principles specifically but obscurely laid down by Hutton, he certainly added much of his own. There is no reason to doubt that Playfair first apprehended the moving power of glaciers as geological agents in modifying the surface of Alpine countries, a matter which has of late been so earnestly discussed by the ablest geologists. What adds to the singularity of the combination of tastes and talents to which I have referred is, that he appears to have had the slightest possible taste for that art of experiment which he eloquently advocated, with Bacon, as the grand distinction of modern science. I may be wrong in stating it broadly, but I do not now recollect a single experimental novelty, much less discovery, which we owe to Playfair, I mean in the department of Natural Philosophy; for we cannot include barometrical measurements under this head, of which, indeed, it was the mathematical theory, and not the application to practice, which chiefly occupied him. The same was the case in Astronomy, which, of the mechanical sciences, interested him most. In two capacities he will be remembered, first, as the able, eloquent, and generally impartial and accurate Historian of Science; secondly, as the promoter, to so great a degree as to be considered a second founder, of modern Dynamical Geology. He was much beloved in private life, and was singularly free from the tendency to carping criticism and personal prejudices sometimes, unfortunately, found in men of letters. He was the intimate associate of Jeffrey and the other founders of the Edinburgh Review. His character has been drawn in three words by Sir James Mackintosh, and as happily contrasted with that of his illustrious friend :-" ... Playfair and Jeffrey; the first a person very remarkable for understanding, calmness, and simplicity, the second more lively, fertile, and brilliant than any Scotchman of letters" (Life of Sir James Mackintosh, ii. 251). 2 Mill's Logic, 2 vols. 8vo. 1 Whewell's History and Philosophy of the Inductive Sciences, 5 vols. 8vo. |