Parade' CJTON. A MEN OF LETTERS AND SCIENCE TIME OF GEORGE III. ivlTAJllEll, TO SIR JOHN WILLIAMS, r ONE OF THE JUDGES OF THE COURT OF KING'S BENCH, THIS WORK IS INSCRIBED, AS A SMALL MEMORIAL OF ANCIENT FRIENDSHIP. PREFACE, THE reign of George III. may in somp important re- spects be justly regarded as the Augustan age of modern history. The greatest statesmen, the most consummate captains, the most finished orators, the first historians, all flourished during this period. For excellence in these departments it was unsurpassed in former times, nor had it even any rivals, if we except the warriors of Louis XIV.'s day, one or two states- men, and Bolingbroke and Massillon as orators. But its glories were not confined to those great departments of human genius. Though it could show no poet like Dante, Milton, Tasso, or Dryden ; no dramatist like Shakspeare or Corneille ; no philosopher to equal Bacon, Newton, or Locke, — it nevertheless in some branches, and these not the least important of natural science, very far surpassed the achievements of former days, while of political science, the most important of all, it first laid the foundations, and then reared the superstructure. The science of chemistry almost entirely, of political economy entirely, were the growth vlii PREFACE. of this remarkable era ; while even in the pure mathe- matics a progress was made which almost changed its aspect since the days of Leibnitz and Newton. The names of Black, Watt, Cavendish, Priestley, Lavoisier, Davy, may justly be placed far above the Boyles, the Stahls, the Hales, the Hookes of former times ; while Euler, Clairault, Lagrange, La Place, must be ranked as analysts close after Newton himself, and above Des- cartes, Leibnitz, or the Bernouillis ; and in economical science, Hume, Smith, and Quesnai really had no pa- rallel, hardly any forerunner. It would also be vain to deny great poetical and dramatic genius to Goldsmith, Voltaire, Alfieri, Monti, and the German school, how inferior soever to the older masters of song. But, above all, it must not be forgotten, that in our times the mighty revolution which has been effected in public affairs, and has placed the rights of the people throughout the civilized world upon a new and a firm foundation, was brought about, immediately in- deed by the efforts of statesmen, but prepared, and remotely caused, by the labours of philosophers and men of letters. The diffusion of knowledge among the community at large is the work of our own age, and it has made all the conquests of science both in recent and in older times of incalculably greater value, of in- comparably higher importance to the interests of man- kind, than they were while scientific study was con- fined within the narrow circles of the wealthy and the learned. PREFACE. ix Having, therefore, on retiring from office, more time left for literary pursuits than professional and judicial duties had before allowed me, I was not minded to waste, indolent and inactive, or enslaved by lower occupations, that excellent leisure: — "Non fuit consi- lium socordia atque desidid bonum otium conterere; neque vero agrum colendo, aut venando, servilibus offi- ciis intentum, eetatem agere. Statutum res gestas po- puli nostri carptim, ut quseque memoria digna videban- tur, perscribere ; eo magis quod mihi a spe, metu, par- tibus reipublicse, animus liber erat."* For I conceived that as portrait-painting is true historical painting in one sense, so the lives of eminent men, freely written, are truly the history of their times ; and that no more authentic account of any age, its transactions, the springs which impelled men's conduct, and the merits which different actors in its scenes possessed, can be obtained than by studying the biography of the per- sonages who mainly guided affairs, and examining their characters, which by their influence they im- pressed upon the times they flourished in. Such a work had moreover this advantage, that beside pre- serving the memory of past events, and the likeness of men who had passed from the stage, it afforded fre- quent opportunities of inculcating the sound principles of an enlightened and virtuous policy, of illustrating their tendency to promote human happiness, of exhi- * Sail., Cat., cap. iv. PREFACE. biting their power to raise the genuine glory as well of individuals as of nations. Though I could entertain no doubt that this plan was expedient, no one could more doubt than I did the capacity brought to its execution, or feel more dis- trustful of the pen held by a hand which had so long been lifted up only in the contentions of the Senate and the Forum. My only confidence was in the spirit of fairness and of truth with which I entered on the performance of the task ; and I now acknowledge with respectful gratitude the favour which the work has hitherto, so far above its deserts, experienced from the public, both at home, in spite of party opposition, and abroad, where no such unworthy influence could have place. It is fit that I also express my equal satisfac- tion at the testimony which has been borne to its strict impartiality by those whose opinions, and the opinions of whose political associates, differed the most widely from my own. That in composing the work I never made any sacrifice of those principles which have ever guided my public conduct, is certain ; that I never concealed them in the course of the book is equally true ; nay, this has been made a charge against it, as if I was at liberty to write the history of my own times, nay, of transactions in many of which I had borne a forward part, and not show what my own sentiments had been on those very affairs. But if my opinions were not sacrificed to the fear that I might offend the living by speaking plainly of the PREFACE. xi dead, so neither were truth and justice ever sacrificed to those opinions. The Statesmen of George the Third's age having thus formed the subject of the volumes already pub- lished, I now offer to the attention of the reader a more full and elaborate view of the Learned Men who flourished in the same period. In my opinion, these, the great teachers of the age, covered it with still greater glory than it drew from the Statesmen and the Warriors who ruled its affairs. It was neces- sary to enter much more into detail here than in the former branch of this work, because a mere general description of scientific or of literary merit is of ex- ceedingly little value, conveying no distinct or precise idea of the subject sought to be explained. It ap- peared the more necessary to discuss these matters minutely, because upon some of them much prejudice prevailed, and no attempt had hitherto been made to examine them completely, or even impartially. Of this a remarkable example is afforded by the want of any thing that deserves the name of a Life of Voltaire, and by the great prejudices, both favour- able and unfavourable to him, which, among differ- ent classes, exist on the subject. But it must also be observed that Dr. Black's discoveries have been far from attaining the reputation which they so well de- serve as the foundation of modern chemistry ; and justice to this illustrious philosopher required that the consequences arising from his modesty and his great PKEFACE. indifference to fame should be counteracted by a full history of his scientific labours, comparing the state of the science as he found it with that in which he left it. My own personal acquaintance with some of the great men whose history I have ventured to write, enabled me to throw additional light upon it ; and re- specting one, whom of course I could not have known, Mr. Hume, I have obtained information from good sources through the kindness of friends. The mate- rials of his life are, however, chiefly to be sought in his writings, and especially in his letters. The same remark is applicable to the life of Voltaire. Those who have written it, like the Marquis de Condorcet, without ever referring to the fourteen large volumes (containing nine thousand closely-printed pages) of his Correspondence, might just as well have undertaken to give a life of Rousseau without consulting his ' Con- fessions,' or of Hume without reading his ' Autobio- graphy.' — I have, besides, had access to valuable ori- ginal documents both of Voltaire, Robertson, and Cavendish ; to some respecting Watt and Simson. The course of this work has kept me, for the most part, at a distance from questions touching political affairs, or the constitution and progress of society, but not always. The reader will find that no opportunity has been left unimproved, as far as I was capable of seizing it with any effect, for inculcating or illustrat- ing the great doctrines of peace, freedom, and religious liberty. The observations on historical composition in PREFACE. xiii the life of Robertson, I especially consider as pointing to an improvement in that department of letters, highly important to the best interests of mankind, as well as to the character of historians. But although I have no political animosities to encounter, I fear my historical statements and my commentaries on some lives, as those of Voltaire, Rousseau, and Hume, may find enemies among the two great parties whose principles come in question. The Free-thinkers will object to the blame which I have ven- tured to pronounce upon their favourite authors ; the friends of the Church may take exception to the praises which I have occasionally bestowed, It may, however, be expected from the justice of both these conflicting bodies, that they will read with attention and with calm- ness before they condemn. From the former class I can expect no favour beyond what every one has a right to claim from avowed adversaries ; a fair hearing is all I desire. To the latter I would address a few words in the spirit of respectful kindness, as to those with whom I generally agree. Whoever feels disposed to treat as impious any writer that has the misfortune not to be among the great body of believers, like the celebrated men above named, should bear in mind that the author of these pages, while he does justice to their great literary merits, has himself published, whether anonymously or under his own name, nearly as much in de- fence of religion as they did against it ; and if, with xjv PREFACE. powers 90 infinitely below theirs, he may hope to have obtained some little success, and done some small service to the good cause, he can only ascribe this fortune to the intrinsic merits of that cause which he has ever supported.* He ventures thus to hope that no one will suspect him of being the less a friend to religion, merely because he has not permitted his sincere belief to make him blind regarding the literary merit of men whose opinions are opposed to his own. His censures of all indecorous, all unfair, all ribald or declamatory attacks, however set off by wit or graced by eloquence, he has never, on any occasion, been slow to pronounce. Chateau Eleanor-Louise (Provence), Jan. 8, 1845. * It has given me a most heartfelt satisfaction to receive many communications from persons both at home and abroad, which inti- mated their having been converted from irreligious opinions by the ' Commentaries and Illustrations of Paley,' published in 1835 and 1838.— It must be noted that the passage of the present work in which Dr. Lardner is mentioned as an orthodox writer, refers to the great question between Christians and Infidels. He was an Uni- tarian, undoubtedly ; but his defence of Revelation forms really the groundwork of Dr. Pajey's < Evidences.' C 0 N T E N T S, VOLTAIRE Page 1 ROUSSEAU . 143 HUME ....... . 195 ROBERTSON ...... . 256 BLACK ....... . 324 WATT . 352 PRIESTLEY ...... . 402 CAVENDISH ...... . 429 DAVY . 448 SlMSON 467 ERRATA. In page 3, line 13 from foot, after and insert it. „ 9, „ 7 from foot, for guides „ 17, „ 7, for 1769, read 1762. ,, 18, „ 9 from foot,/or sixty read a hundred. ,, 23, ,, 11 from foot, for regne dans 1' read commande en. ,, 39, ,, 3 from foot, for ses read son. ,, 46, ,, 13 from foot}
me personal spleen or individual interest, had suffered his judgment to be warped, and thus, as it were, lashed himself into disbelief of a system alto- gether pure, administered by a simple, a disinterested a venerable hierarchy. VOLTAIRE. 7 Let us for a moment, independent of what may be termed the political view of the question— independent of all that regards the priesthood — consider the posi- tion of a person endowed with strong natural faculties, and not under the absolute dominion of his spiritual guides, nor prevented by their authority from exercising his reason ; but, on the contrary, living at a moment when a spirit of free inquiry was beginning generally to prevail. He is told that the mystery of transubstan- tiation must be believed by him as a fact; he is told that there has been transmitted through a succession of ages from the apostles one of the Divine attributes, the power of pardoning sin, and that the laying a priest's hands on a layman gives him this miraculous power, to be exercised by him how guilty soever may be his own life, how absolutely null his own belief in the Divine being — nay, that this power has come through certain persons notorious atheists themselves, and whose lives were more scandalously profligate than anything that a modest tongue can describe. Presented to a vigorous mind, and not enforced by an authority which suffers no reasoning, or if enforced yet vainly so enforced, these dogmas and these claims became the subject of discussion, and were rejected almost as soon as they were understood. But in company with them were found many other doctrines and pretensions of a very different complexion, yet all of them were pro- nounced to have the same Divine original; and no greater sanctity, no higher authority, no deeper vene- ration was claimed for them than for the real presence of the Creator at the summons of the priest, or the VOLTAIRE. participation of that priest in the attributes of the God- head. Let us be just towards the youth who was placed in these circumstances, and let us not condemn him for hastily rejecting the wheat with the chaff, before we endeavour to place ourselves in the same situation, asking what effect would be produced on our minds by severe denunciations against us should we doubt the priest's power, or refuse an explicit assent to his dogmas, which our reason, nay our senses rejected, while he refused all access to the inspired volumes which contained, or were said to contain, their only warrant. Rejecting the false doctrines, the chances are many that our faith would be shaken in the true. How many Protestants were made in the sixteenth century by the sale of indulgences ! But how many unbelievers in Christianity have been made in all ages of the Church by the grosser errors of Rome, the exorbitant usurpations of her bishops, and the preposterous claims of her clergy ! It is also to be observed that Voltaire was, through his whole life, a sincere believer in the existence and attributes of the Deity. He was a firm and decided, and an openly declared unbeliever in Christianity, but he was, without any hesitation or any intermission, a theist. Then in examining the justice of the charge of blasphemy it is to be borne in mind that not one irreverent expression is to be found in all his number- less writings towards the Deity in whom he believed. > has more ably than most writers stated and illus- trated the arguments in favour of that belief. He has consecrated some of his noblest poetry to celebrate the VOLTAIRE. 9 powers of the Godhead.* Whatever exception to this assertion may seem to be found in those writings will, on consideration, prove to be only apparent. It will be found that he is speaking only of the Deity as represented in systems of religion which he dis- believed ; consequently he is there ridiculing only the idols, the work of men's hands, and the objects of superstitious worship, not the great Being in whom he believed and whom he adored. Even his ' Candide,' one of his greatest, perhaps his most perfect work, is only intended to expose the extravagance of the optimist doctrine ; and however we may lament its tone in some sort, it is certainly not chargeable with ridiculing any- thing which a philosophic theist must necessarily believe. But no one can exempt Voltaire from blame for the manner in which he attacked religious opinions, and outraged the feelings of believers. There he is without defence. Had all men been prepared to make the step * His dramatic compositions abound in such religious sentiments, clothed in the noblest language of poetical abstraction ; but his celebrated verses, said to have been written extempore in a com- pany that were admiring the firmament one summer's evening, may be placed by the side of the finest compositions in that kind — ••3Y9 lor j^i'mk 'I.'-? ;:.. — (viii. 269.) And— 44 VOLTAIRE. whereas Voltaire is" ready to commit this offence at every moment, and seems ever to take the view of each sub- ject that most easily lends itself to licentious allusions. But this is not all. The ' Pucelle' is one continued sneer at all that men do hold, and all that they ought to hold, sacred, from the highest to the least important subjects, in a moral view — from the greatest to the most indifferent, even in a critical view. Religion and its ministers and its professors — virtue, especially the virtues of a prudential cast — the feelings of humanity —the sense of beauty — the rules of poetical compo- sition — the very walks of literature in which Voltaire had most striven to excel — are all made the constant subjects of sneering contempt, or of ribald laughter ; sometimes by wit, sometimes by humour, not rarely by the broad grins of mere gross buffoonery. It is a sad thing to reflect that the three masterpieces of three such men as Voltaire, Rousseau, Byron, should all be the most immoral of their compositions. It seems as if their prurient nature had been affected by a bad but criminal excitement to make them exceed themselves. — Assuredly if such was not Voltaire's case, he well merits the blame ; for he scrupled not to read his ' Pucelle' to his niece, then a young woman.* And— Avrap «ywv tuc)oi/ui napa ^pvfftri A^po&r?/. — (viii. 342.) So when describing in the llth Odyssey Neptune's rape of Pyro, the old bard only says — Avf evil in this world, or to account for its inconsistency with the Divine goodness, await with patient resignation the light which will dawn upon them in another state of being, and by which all these difficulties will be explained.* The residence of Voltaire, first at the Delices, near Geneva, and, when the Calvinist metropolis obliged him to part with that place at a heavy loss, at Fer- ney within the French frontier, was for the remainder of his life far more tranquil and agreeable than during the more passionate and irritable period which pre- ceded. His literary occupation was as incessant as ever ; and, beside some of his lesser poems, the greater portion of his philosophical and critical works were written during this latter time.f His relaxation was * He appears to have disavowed this admirable work even more carefully than any of his far more exceptionable productions. To his most familiar friends we find him exceeding all the fair limits of denial within which authors writing anonymously should confine themselves. To M. Vernes, pastor at Geneva, with whom he was intimate, he writes, " J'ai lu enfin ' Candide ;' il faut avoir perdu le sens pour m'attribuer cette coi'onnerie : j'ai, Dieu merci ! demeil- leurs occupations" (Cor. Gen., v. 229). To Thibouville he says, " J'ai lu enfin ce ' Candide,' dont vous m'avez parle ; et plus il m'a fait rire, plus je suis fache qu'on me 1'attribue" (ib. 258). Even to his confidant and tool Theiriot he says — " Dieu me garde d'avoir eu la moindre part a cet ouvrage !" (ib. 258). t About twenty-eight of his works, beside some of the romances and some of the minor poems, were written and published after the year 1758; of the 'Dictionary,' eight volumes; of the « Philo- sophy' all the six, except half a volume ; of the ' Melanges Litte- raires,' more than one ; of the ' Melanges Historiques,' two ; ' Dialogues,' two ; « History of the Parliaments of Paris,' one ; nearly all the volumes of ' Faceties ;' all but half a volume of the three on * Politics and Legislation,' including his writings on the cases of VOLTAIRE. Ill the society of his friends and the amusements of the stage, a small theatre being formed in the chateau, and his niece, and occasionally himself, acting in the different pieces represented. Madame Denis had some talents for the stage, but he greatly exaggerated her merit, and even amused Marmontel, who relates the anecdote in his ' Memoirs/ with telling him on one oc- casion how much she had excelled Clairon. " J'avoue," says he, "j'ai trouve cela unpeu fort." Voltaire him- self had very humble pretensions as an actor, and laughs at himself, with much good humour, in his letters for these exhibitions. The Genevese purists were scandalised at the near neighbourhood of private theatricals, but they occasionally formed part of the audience in spite of Rousseau's exhortations against the stage. They also visited Voltaire without scruple at Ferney. He kept a hospitable house, befitting his affluent circumstances and generous disposition ; he received strangers who were properly introduced, and it may well be imagined that the inexhaustible resources of his learning and his wit, as varied as it was original, gave extraordinary delight to his guests. He was fond of assisting persons in distress, but chiefly young persons of ability struggling with difficult circumstances: thus the niece of Corneille, left in u destitute condition, was invited, about the year 1760, to Ferney, where she Galas and Debarre ; nearly the whole of the three volumes of ' Commentaries on Dramatic Works/ Beside these volumes there are eight or more thick volumes of his Correspondence ; and beside finishing and correcting some of his other historical works, he wrote the < Peter the Great' and the l Age of Louis XV.' during the same last twenty years of his life ; so that he wrote forty volumes during that period of his old age. 112 VOLTAIRE. remained for several years, and received her education. But, above all, he was the protector of the oppressed, whether by political or ecclesiastical tyranny. His fame rests on an imperishable foundation as a great writer— certainly the greatest of a highly polite and cultivated age; but these claims to our respect are mingled with sad regrets at the pernicious tendency of no small portion of his works. As the champion of injured virtue, the avenger of enormous public crimes, he claims a veneration which embalms his memory in the hearts of all good men ; and this part of his character untarnished by any stain, enfeebled by no failing, is justly to be set up against the charges to which other passages of his story are exposed, redeeming those passages from the dislike or the contempt which they are calculated to inspire towards their author. During the winter of 1761-62, a scene of mingled judicial bigotry, ignorance, and cruelty was enacted in Languedoc, the account of which reached Ferney, where the unhappy family of its victims sought refuge. A young man, twenty-eight years of age, Marc Antoine Galas, the son of a respectable old Calvinist, was found dead, having, it appears, hanged himself. There arose a suspicion nearly amounting to insanity in the mind of a fanatical magistrate of the name of David, that the young man had been hanged by the father to prevent him from becoming a Catholic. There was another son already converted, and whom the father, so far from repudiating, supplied with a hand- some allowance. There was a visitor of the family, a youth of nineteen years old, present at the time when the murder was supposed to have been committed ; as were VOLTAIRE. 113 the mother and brothers of the deceased, all of whom must have concurred in the diabolical act. The father had for some time, beside his age of sixty-nine, been reduced to great weakness by a paralytic complaint. The deceased was one of the most powerful men in the country, and nearly six feet high. He was also of dissolute habits, involved in pecuniary difficulties, and possessing and fond of reading books that defended suicide. Finally, it was certainly known that the notion of his wishing to become a Catholic was a pure fiction, and that he had never given the least intimation of such a desire. In the face of all this, amounting to proof of the magistrate's fancy being an absolute impossibility, he ordered the whole family to be cast into prison together with the father, as accomplices in the supposed murder. The populace immediately took up the subject thus sug- gested to them by authority, and considered the deceased as a martyr. The brotherhood of the White Penitents (Voltaire says at the desire of the magistrate) cele- brated a mass for his soul, exhibiting his figure with a palm-branch in one hand as the emblem of martyr- dom, and a pen in the other, the instrument where- with, as was represented, he intended to have signed his recantation of Calvinism. A report was industriously spread abroad that the Protestants regard the murder of children by their parents as a duty when they are minded to abjure the reformed faith ; but that, for the sake of greater certainty, and to prevent the escape of the convert, the sect assembles in a secret place, and elects at stated times a public executioner to perform this office. The court before whom the case was brought, I 114 VOLTAIRE. at first was disposed to put the whole family to the torture, never doubting that the murder would be confessed by one or other of them ; but they ended by only condemning the father to be broke alive upon the wheel. The Parliament of Toulouse, by a narrow majority, confirmed this atrocious sentence; and the wretched old man died in torments, declaring his per- fect innocence with his latest breath. The rest of the family were acquitted — an absurdity the most glaring, inasmuch as they were all his accomplices of absolute necessity if he was guilty. Loaded with grief, and suffering under the additional pangs of their blasted reputation, the wretched family came to Geneva, the head-quarters of their sect, and immediately applied to Voltaire. He at once devoted himself to their defence, and to obtaining the reversal of perhaps the most iniquitous sentence that ever a court professing or profaning the name of justice pronounced. He was nobly seconded by the Due de Choiseul, then Minister. The case was remitted to a Special Court of Judges appointed to investigate the whole matter. The preparation of memorials, the examination of evidence, a long correspondence with the authorities, were not the philosopher's only labours in this good cause : he revised all the pleadings of the advocates, made important additions to them, and infused a spirit into the whole proceedings the fruit of his genius, and worthy of his pious design. In 1765 the decree was reversed ; Galas was declared innocent, and his memory restored (rehabttite) ; and the Minister afforded to the family an ample pecuniary VOLTAIRE. 115 compensation, as far as any sum could repair such cruel wrongs.* This took place in the spring of 1766. The Parliament of Languedoc was, unfor- tunately, not compelled to recognise the justice of the act which reversed its decree, and it had the wretched meanness to refuse obstinately the only reparation it could make — indeed, the only step by which its own honour could be saved. When we hear considerable persons, as we used to hear Mr. Windham, argue from the example of the French tribunals that judicial places may safely be sold, let the case of Galas not be forgotten. No men who had risen to the Bench by their pro- fessional talents ever could have joined the ferocious David in committing this judicial murder. For him a signal and a just retribution was reserved. The reversal of the sentence either stung him with remorse, or, covering him with shame, affected his reason, and he died soon after in a mad-house. The efforts of Voltaire, crowned with success, gained him universal applause. Since the revocation of the Edict of Nantz, the Huguenots had never felt any security against persecution, They now felt that they ha!> *;P ri( '.'» . ,:t -V ...•, ,, . ^; i'r) RQTUSSEATU. KOUSSEAU. 145 Lausanne, where he afterwards married a second wife advanced in years, and had no children by her. His eldest son, seven or eight years older than Jean Jacques, had never been the favourite, though bred to his father's business ; he took a dissipated course, left the place, and went into Germany. Little pains were taken to stop or to trace him ; he never wrote to any one after his flight, and what became of him is not known. In all probability, he died before his bro- ther's name became well known, else he probably would have discovered himself. Beside the love of modern romances and of ancient history, accident gave him a fondness for music, which, with the other passion, accompanied him through life. His aunt, who took care of him, sang a great number of simple airs, chiefly popular ones, with a sweet small voice, which, aided by his attachment to her, made a deep impression upon him, and formed his taste in song as well as imbued him with a sensibility to its charms. After his father's departure for Lausanne, he was left to the care of his uncle Bertrand, who sent him for two years to Boissy, near Geneva, where he remained under the tuition of M. Lambercier, a pastor, and appears to have learnt a little Latin ; but when the Abbe Gouvon, in whose service he afterwards was, at Turin, treated him rather as a secretary than a footman, and read Latin with him, he was found to be very ill grounded, and wholly unable to construe Virgil. He acknowledges, indeed, that he never was tolerably acquainted with the language, though he repeatedly attempted to gain it. His statement to this effect, twelve years after he had translated the first L 146 ROUSSEAU. book of Tacitus' s i History,' and translated it exceed- ingly well, in most passages correctly, in some with great felicity, is one of the exaggerations in which he indulges both of his merits and his defects. But he learnt whatever he knew comparatively late. Nothing could possibly be worse than the education of a man who made it a principle through life to cry down learning, not because he never possessed it, but because he found it was hurtful to the character and incon- sistent with sound wisdom and true virtue. After quitting the school at Boissy, he was appren- ticed to an engraver, who seems to have treated him harshly. But his conduct was already bad. He had a habit of lying on all occasions, whether moved by fear to conceal some misconduct, or incited by some appetite he wished to gratify, or actuated by some other equally sordid motive. A strong disposition to thieving was likewise among his propensities, and this continued to abide by him long after he grew up, and even when he lived in society he never could entirely shake it off. His temperament, too, was vehement, and his timidity and shyness equally strong. The indulgences into which he was thus seduced, he has himself described ; but to embellish such subjects, or even to veil them so as to hide their disgusting aspect, would require the magic of that diction in which he has clothed his own story, and of which he never seems to have been a master in any of his other writings. After serving through half his apprenticeship, he was surprised one Sunday evening in an excursion with his companions, out of the town, by the shutting of the gates ; and there wanted no more to make him elope. He went ROUSSEAU. 147 to the parsonage of a Savoyard cure (rector) at Carouges, two leagues from Geneva, who received him hospitably in the hopes of converting him, and gave him letters of introduction* to Madame de Warens, a Swiss lady, who having left her husband, had become a Catholic, and lived on a pension from the devout King of Sardinia. She received him kindly, and sent him to Turin, where he was entertained at the semi- nary of Catechists, established for converting heretics. In this religious establishment he found manners of the most dissolute and even abominable kind ; he was feebly reasoned with by the brethren on the errors of his belief; he does not seem in reality to have been convinced ; but a provision in the Church had been placed before his eyes as the probable reward of his apostacy, and he embraced publicly the Catholic religion. It was, however, soon discovered by the officers of the Inquisition that he was not sufficiently orthodox in his faith, for he would not avow his belief that his mother had been numbered among the damned. He was, therefore, turned out of the seminary, with a present of twenty francs from the sum collected at the exhibition of his abjuration. After living obscurely in Turin in a lodgings-house for common people at half a sous a night, he now en- tered as a footman the service of the Countess de Ver- cellis, and wore livery with the rest of the servants. In the course of a few months this lady died, and the servants were of course dismissed. It was found that * The common accounts say that the Bishop of Annecy gave him this introduction. It was M. de Pontverre, Romish cure, in Savoy. L 2 148 ROUSSEAU. a ribbon had been stolen ; all were interrogated, and Rousseau, in whose possession it was found, and who was in fact the thief, had the wickedness to charge it upon an innocent girl ; he persisted in averring that she had stolen it to give him, there having been some little love-making between them. The ruin of this poor girl was the consequence, and he describes the bitter agonies of remorse which he ever after endured in reflecting upon the crime thus committed. He endeavours to explain it in a refined, absurd, and false manner, by saying that his love for Marian caused it all, because he had stolen it to give her, and this put it into his head to think of accusing her of the same intention. But the truth is, that his cowardice, the parent of lies, caused it all. He never would have dared charge a man with the offence. He thought he could escape exposure and perhaps punishment (though he affects to say he dreaded not that) by laying the blame on an innocent young girl who had shown a liking for him which he returned. He also tries to represent himself as only a child then,* and, writing in 1766 or 1767, speaks of forty years having elapsed. But this is not true. He came to Annecy in 1728, sixteen years old, having left Geneva in July or August, and after several months' residence in Turin and the seminary, and three in the Countess's house, he must have been seven- teen when she died, instead of fourteen or fifteen, which his calculation of forty years would make him. He expressly says that he had attained the age of sixteen before he ran away from his master, and he was born * " La faute d'un enfant." — (Conf., part i. liv. 2.) KOUSSEAU. 149 on the 28th of June. Indeed, if he remained in his next place less than a year, as he was uncertain when he left it, he must have been eighteen when he com- mitted the offence. Nothing therefore like an excuse, or extenuation from his youth, can be urged on this head. He was now to prove himself as foolish as he had been found wicked. Received as footman in the great family of Solar, an accident showed him to be superior in reading to the other servants, and one of the house, the Abbe de Gouvon, a man of great accomplishments and of a kindly disposition, made him a sort of secre- tary, taking much pains also with his education ; so that, though he could not master Latin, he became a good Italian scholar. Suddenly the fancy seized him of quarrelling with the good people, and returning on foot to Geneva with a good-for-nothing young rake from that town, named Bacler, whose acquaintance he had made, and whose low buffoonery he could not refrain from re- lishing, and even envying, as he uniformly did whatever qualities he observed to attract the admiration of the multitude. He showed the utmost insolence and in- gratitude to the Solars, and was all but kicked out of their palace, where he had been cherished as a child of the family, and had been offered the sure means of mak- ing his fortune. A plaything, which in his extreme ignorance he calls fontame the brated in A churchyards, and that »o- every action in life might bear marks of this" dreadful situation, the people were prohibited forbid the use of meat, as in lent or tke- times of the highest penance, were debarrd from all pleasures and entertainments, and were forbid even to salute each other, or so much as to shave their beards and give any decent attention to their carryd the symptoms person and apparel. Every circumstance bore the marks of immediate the deepest distress, and of the most dreadfa apprehensions of divine vengeance and indignation." * Illegible. 252 HUME. HENRY III. " I reckon not among the violations of the great charter arbitrary some practices A Exertions of Prerogative, which Henry's without producing any discontents necessities oblig'd him to practice, and which A were uniformly continued practiced by all his successors till the last century. As the par- that -flQmctinws- in a manner somewhat liament often refusd him supplies, and A often in a very, rude and indecent-flftftfmep, he obliged his opulent subjects, parti- cularly the citizens of London, to grant him loans of money : want of economy and it is natural to imagine, that the same •rtcccasities- which reduced him to the necessity of borrowing him from obliged him to borrow, would prevent -b«t being very regular He demanded benevolences, or pretended voluntary their contributions from his nobility & prelates. in 4ke payment of his — dob to A He was the first King of England since the Conquest who could be fairly said to also lye under the restraint of law : and he was A the first who practicd the dispensing power, and employed the famous Patents clause oinon obstante in his grants and char tors. The Princes notwithstanding the great power of the monarchs, both of the Saxon & Norman line own country of Wales ^ still preserved authority in their mountains ; and had often -bad been constraind to pay tribute tho' they sontinuod to do- homage to the crown of England, in subordination or even in peace they were with difficulty retaind in subjection, and almost throughout 4ft- every reign since the conquest had infested the English inroads frontiers with petty incursions and sudden -inourciono, which -dooopvod to be mentioned merited to have place seldom merited to have placo in a general history." " The behaviour , of John show'd him not unworthy of •generous courteous never this A treatment. His present abject fortune * made him never forget a moment that he was a King. More sensible Edward's to hio the Princco generosity than to his own calamities, he HTIME. 253 confess'd, that, notwithstanding his Defeat and Captivity, his Honour was still unimpair'd : and that, if he yielded the victory, it was at least gain'd by a Prince of such consummate Valour and Humanity." EDWARD III. " The prisoners were everywhere treated with Humanity and were soon after dismissd on paying moderate Ransoms to the Persons into whose hands they had fallen. The extent of their fortunes was consider 'd, and no more was exacted of them, that* what woud still leave them sufficient to enable them for the future, to take the field in a manner suitable to their quality rank & station- Yet so numerous and ouch a were the noble Prisoners, that these Ransoms woro ouffioiont to onri Field join'd to the spoils of the Battle were sufficient to enrich the Princes army : and as they had sufferd very little in the joy & exultation action, their triumph was complete." DIALOGUES ON NATURAL RELIGION. " Now Cleanthes said Philo, with an air of Alacrity & Triumph — Mark the consequence. First By this Method of claim Reasoning, you renounce all Pretensions- to Infinity in any of the attributes of the Deity. For as the Cause ought only to be proportion'd to the Effect, and the Effect so far as it falls under you wiH , upon your supposition our cognisance : what Pretensions youll oay have we to ascribe Attribute You will still resist that, by that Epithet, to the Divine Being ? A -By^ removing him so hypothesis • by th give into the most arbitrary -cupporitione & at the same time weaken much from all similarity to human creatures, we * deetroy all Proofs of his Existence. Sic. 254 HUME. " This Theory, I own, replyd Cleanthes, has never before occurd to me, tho* a pretty natural one; and 1 cannot readily deliver- any epinioji abcut it upon so short an exami- deliver any opinion wilh regard to it nation & reflection * . You are very scrupulous indeed, said Were examine Philo : -aftd woio I to start objections aad difficulties- to- any system of yours, I should not have acted with half that in starting objections & difficulties to it caution and reserve A . However, if any thing occur to you, will youtt- oblige us by proposing it. between " I allow of your comparison betwixt the Stoics & Sceptics, may -as justj replyd Philo. But you -must observe, at the same time, that the mind cannot in Stoicism, support the highest Flights of Philosophy, yet even when it sinks lower, it still retains somewhat of its former Disposition; & the The Stoics -the Stoics- •4mr-Thc Stoic his- will his effects of ite^ ^Reasoning A appear in ^4&- conduct in common thro' his Life, and ^ the whole Tenor of -its- actions. The Antient that of A schools, particularly that of A Zeno, produced examples of Virtue & Constancy which seem astonishing to present times." It is necessary to correct a very gross misstatement into which some idle or ill-intentioned person has betrayed an in- genious and learned critic respecting the papers of Mr. Hume still remaining and in Edinburgh. " Those who have exa- mined the Hume papers, which we know only from report, speak highly of their interest, but add that they furnish pain- ful disclosures concerning the opinions then prevailing among the clergy of the northern metropolis ; distinguished ministers of the Gospel encouraging the scoffs of their familiar friend, the author of the ' Essay on Miracles,' and echoing the blas- phemies of their associate the author of the ' Essay on Sui- cide.' ' These Edinburgh clergymen are then called " be- HUME. 255 trayers of their Lord," and much more is added of a like kind.* Now this heavy charge against some of the most pious and most virtuous men who ever adorned any church, Dr. Robert- son, Dr. Blair, Dr. Jardine, Dr. Drysdale, and others, seemed eminently unlikely to be well founded. I have caused minute search to be made ; and on fully examining all that collection, the result is to give the most unqualified and peremptory contradiction to this scandalous report. It is in- conceivable how such a rumour should have arisen in any quarter. A severe, and we may well be permitted to add, a singularly absurd observation of Archbishop Magee is cited in the same criticism.f His Grace describes Hume's heterodox writings as " standing memorials of a heart as wicked and a head as weak as ever pretended to the character of philosopher and moralist." Now I have no right to complain of the Most Reverend Prelate for forming so low an estimate of Mr. Hume's under- standing, and entertaining so bad an opinion of his heart ; an estimate and an opinion not confined by his Grace to one class of his writings, though undeserved by any. Yet it does appear somewhat strange that merely because one of the most able men that ever lived, and one of the most virtuous, unhappily entertained religious opinions very different from those of the Archbishop, therefore he must be proclaimed both a dunce and a knave. It may also be permitted us to wish that the disciples of the religion in which " the greatest of these things is charity," and in which erring mortals are forbidden fe to judge lest they be judged," should emulate the candour and the charity of unbelievers ; for assuredly if Mr. Hume had lived to read the Archbishop's work on the f Atonement,' though he might not have been converted by it, he would freely have confessed the great talents and the unspotted virtue of its author. Quarterly Review, vol. Ixxiii. p. 556. f Id., p. 552. ( 256 ROBERTSON. JOINED in friendship and in fame with the great man whose life and writings we have been contem- plating, and, equally with him, founder of the repu- tation of our country for excellence in historical com- position, was William Robertson, also a native of Scotland. His father, a learned, pious, and eloquent divine, was settled for several years as minister of the Scotch church in London Wall, but had returned to Scotland before his marriage with Miss Pitcairn of Dreghorn, in the county of Edinburgh, and was settled at Borthwick, in the same county, at the time of the historian's birth, on the 19th of September, 17*21. I have been curious to ascertain the kind of genius which distinguished his father beside his talent for drawing, of which I possess a specimen showing some skill,* and by the kindness of a kinsman I have had the great * It is a miniature in Indian ink of James, Earl of Seafield, one of the forfeited Lords, to whom he was believed to be distantly re- lated. A tradition prevailed in the family that they descended from John Knox. The historian professed himself quite unac- quainted with the reasons of this rumour which connected him with " the rustic Apostle," whose character and conduct he has described most faithfully and strikingly. 258 ROBERTSON. of his placid temper, and the cheerfulness of his kindly disposition, I have heard him spoken of in terms of the warmest enthusiasm by such of his children as were old enough at the time of his decease to recollect him distinctly. The idea of again meeting him in another state was ever present to my grandmother's mind, (who was his eldest daughter,) and especially when stricken with any illness. It was with her a common source of argument for a future state, as proved by the light of nature, and in her pious mind a confirmation of the truth of Christianity, that, believ- ing in the Divine goodness, she could not conceive the extinction of so much angelical purity as adorned her parent, and so fine an understanding as he pos- sessed. Their mother was a woman of great ability and force of character ; but like many of that cast, women especially, she was more stern, and even severe, than amiable ; and this contrast, unfavourable to the one, redounded to the augmented love of the other. It cannot be doubted that the son's character derived a strong tincture from both parents, but that while he was mild and gentle in his temper, and of an engaging demeanour, his firmness and decision, nay, his inclina- tion towards the Stoical system of morals, and even to a certain degree of Stoical feeling too, was derived from his mother. The death of these two excellent persons was singu- larly melancholy, and served to impress on the minds of their family a mournful recollection of their virtues. Mr. Robertson had been removed to the Old Grey Friars Church of Edinburgh in 1733 ; and ten years after- wards, both he and his wife, seized with putrid fever, ROBEKTSON. 259 died within a few days of one another, leaving eight children, six daughters and two sons, of whom Wil- liam was the elder. He had been educated first at the school of Dalkeith, under a very able teacher of the name of Leslie, a gentleman at that time of the great- est eminence in his profession. On his father's removal to Edinburgh, he was taken thither and placed at the University, though only twelve years old. His dili- gence in study was unremitting, and he pursued his education at the different classes for eight years with indefatigable zeal. He had laid down for himself a strict plan of reading ; and of the notes which he took there remain a number of books, beginning when he was only fourteen, all bearing the sentence as a motto which so characterised his love of learning, indi- cating that he delighted in it abstractedly, and for its own sake, without regarding the uses to which it might be turned — " Vita sine litteris mors" I give this gloss upon the motto or text advisedly. His whole life was spent in study. I well remember his constant habit of quitting the drawing-room both after dinner and again after tea, and remaining shut up in his library. The period of time when I saw this was after the * History of America' had been published, and before Major Ren- nell's map and memoir appeared, which he tells us first suggested the ' Disquisition on Ancient India.' Consequently, for above ten years he was in the course of constant study, engaged in extending his inform- ation, examining and revolving the facts of history, contemplating ethical and theological truths, amus- ing his fancy with the strains of Greek and Roman poetry, or warming it at the fire of ancient eloquence s2 260 ROBERTSON. so congenial to his mind, at once argumentative and rhetorical ; and all this study produced not one written line, though thus unremittingly carried on. The same may be said of the ten years he passed in constant study from 1743, the beginning of his residence in a small parish, of very little clerical duty, to 1752, when we know from his letter to Lord Hailes he began his first work. But, indeed, the composition of his three great works, spread over a period of nearly thirty years, clearly evinces that during this long time his studies must have been much more subservient to his own grati- fication than to the preparation of his writings, which never could have required one half that number of years for their completion. Translations from the classics, and especially from the Greek, of which he was a perfect master, formed a considerable part of his labour. He considered this exercise as well calculated to give an accurate know- ledge of our own language, by obliging us to weigh the shades of difference between words or phrases, and to find the expression, whether by the selection of the terms or the turning of the idiom, which is required for a given meaning ; whereas, when composing origi- nally, the idea may be varied in order to suit the dic- tion which most easily presents itself, of which the influence produced manifestly by rhymes, in moulding tbe sense as well as suggesting it, affords a striking and familiar example.* His translations, however, were not wholly confined to their purpose of teaching composi- * I may mention that both he and his son, the Judge, prescribed this exercise to me, and, among others, made me translate all the * History ' of Florus. EOBEKTSON. 261 tion ; he appears to have at the same time indus- triously completed the work of rendering some ancient treatises, which peculiarly interested him. He had even prepared for the press a translation of Antoninus's ' Me- ditations,'* having thus early felt a strong leaning towards the Stoical philosophy. The appearance of a very poor translation at Glasgow prevented the execu- tion of this design, but the work remains : I have it now in my possession, and shall give one or two pas- sages in the Appendix. In elocution he acquired faci- lity and correctness by attending a society which met weekly to debate literary and philosophical questions. This society gave rise many years later to another, which was frequented by the men who in after life proved the most distinguished of their countrymen : Hume, Smith (neither of whom ever took part in de- bate), Wedderburn (afterwards Chancellor), Fergu- son, Home (Lord Kames), were of the number. But his thirst of knowledge was not confined to these its more easy and more inviting walks. He had deeply studied some branches of the severer sciences. It is not, therefore, without good cause that he speaks of mathematical subjects (in his preface to the work on India) as having been embraced in his course of study, though not having been carried so far as a discussion of the Brahminical astronomy might require. In 1741, according to the constitution of the Scotch Church, he was licensed by the Presbytery of Edin- burgh to preach ; orders being only conferred upon a * Marc. Aurel. : Twv etc ICLVTOV. 262 ROBERTSON. presentation to a living or Kirk. Two years after, he was appointed minister of Gladsmuir, a country parish in East Lothian ; and this event happened fortunately on the eve of the irreparable loss sustained by the family in the death of both their parents, which left his brother and his sisters wholly without provision. He immediately took the care of them upon himself, and would form no connexion in marriage until he had seen them placed in situations of independence. He thus remained single for eight years, during which his eldest and favourite sister superintended his family. In her sound judgment he always placed the greatest con- fidence ; for he knew that to great beauty she added a calm and a firm temper, inherited from their mother, but with greater sweetness of disposition. An instance of her fortitude and presence of mind was sometimes mentioned by him, though never alluded to by herself, that a swarm of bees having settled on her head and shoulders while sitting in the garden, she remained motionless until they took wing, thus saving her life, which was in imminent jeopardy. She was married in 1750, and the year after he married his cousin, Miss Nesbit. While at Gladsmuir, where he remained fifteen years, his life was passed in constant study, and in the duties of his sacred profession. He rose very early, and devoted the whole morning to his books. Later in the day he had ample time for visiting the sick and the poor generally ; and he gave great attention to the important duty of examining and catechising the young people under his care. But nothing can be more absurd than the statement in some of the lives which ROBERTSON. 263 have been published, as if his whole time after break- fast was devoted to these duties. It would have been utterly impossible to find subjects for his visits in that small country parish, not containing two hundred families. It is remarkable that, with all the love of study which formed so striking a feature of his character, nay, with the contemplative disposition which histhirst of knowledge for its own sake plainly indicates, he should have joined an extraordinary fitness for the less speculative pursuits of active life, and a manifest willingness to bear a part in them. The rebellion of 1745 afforded an occasion on which he conceived that the dangers surrounding civil and religious liberty called for the exertions of all good citizens in its defence. On the news of the rebels marching towards Edinburgh he quitted his parsonage (manse) and joined the volunteers of the capital. How far they marched is not known ; but that they must have proceeded towards the Highlands, and for some time remained under arms, is certain from this, that he always men- tioned the effect of the first coal fire on his head after he had been for some time accustomed to burn peat only. When Edinburgh was surrendered he joined a small body of persons from the city, who offered their services at Haddington to the Commander-in-Chief. Soon after his marriage he was returned as a member to the General Assembly, and again his capacity and his inclination for active life appeared. He devoted himself assiduously to the business of that body ; and, having a very strong and clear opinion in favour of lay patronage, the great question which divided the Church 264 ROBERTSON. of Scotland in that day, as, in truth, it again does in our own, he assumed the lead of its advocates. At first they formed a small minority of the Assembly ; but, by degrees, reason enforced by eloquence had its course, and he gained ultimately a complete victory over his adversaries. The persecution of John Home, by the fanatical party, for writing the moral and innocent and even pious tragedy of f Douglas/ gave another occasion to show Dr. Robertson's liberal and rational sentiments. Such of the clergy as had attended the theatre to witness the representation were involved in the same bigoted outcry. Home himself bent to the storm, and resigned his living ; Robertson's judicious but spirited defence saved the rest from more than a rebuke to • some, and a few weeks' suspension to others. He man- fully explained why he had never attended himself, say- ing, that it was only owing to the promise already men- tioned ; but he avowed that he saw no harm in the at- tendance of his brethren whom no such promise bound. He was now looked up to as the acknowledged leader of the moderate party ; and, as they soon after became the ruling body in the Church, he must be considered as the leading minister of that venerable body during all the time he continued in the Assembly. Of the lustre with which his talents now shone forth all men are agreed in giving the same account. I have frequently conversed with those who could well re- member his conduct as a great party chief, and their uniform observation was upon the manifest capacity which he displayed for affairs. " That he was not in his right place when only a clerical leader or a literary ROBERTSON. 265 man, but was plainly designed by nature, as well as formed by study, for a great practical statesman and orator," is the remark which seems to have struck all who observed his course. His eloquence was bold and masculine ; his diction, which flowed with perfect ease, resembled that of his writings, but of course became suited to the exigencies of extemporaneous speech. He had the happy faculty of conveying an argument in a statement, and would more than half answer his adversary by describing his propositions and his reason- ings. He showed the greatest presence of mind in debate ; and, as nothing could ruffle the calmness of his temper, it was quite impossible to find him getting into a difficulty, or to take him at a disadvantage. He knew precisely the proper time of coming forward to debate, and the time when, repairing other men's errors, supplying their deficiencies, and repelling the adverse assaults, he could make sure of most advantageously influencing the result of the conflict, to which he ever steadily looked, and not to display. If his habitual command of temper averted anger and made him loved, his undeviating dignity both of demeanour and of con- duct secured him respect. The purity of his blameless life, and the rigid decorum of his manners, made all personal attacks upon him hopeless ; and, in the management of party concerns, he was so far above any thing like manoeuvre or stratagem, that he achieved the triumph so rare, and for a party chief so hard to win, of making his influence seem always to rest on reason and principle, and his success in carrying his measures to arise from their wisdom, and not from his own power. They relate one instance of his being thrown some- 266 ROBERTSON. what off his guard, and showing a feeling of great displeasure, if not of anger, in a severe remark upon a young member. But the provocation was wholly out of the ordinary course of things,, and it might well have excused, nay, called for, a much more unsparing visitation than his remark, which really poured oil into the wound it made. Mr. Cullen, afterwards Lord Cullen, was celebrated for his unrivalled talent of mimicry, and Dr. Robertson, who was one of his favourite subjects, had left the Assembly to dine, meaning to return. As the aisle of the old church, consecrated to the Assembly meetings, was at that late hour extremely dark, the artist took his opportunity of rising in the Principal's place and delivering a short speech in his character, an evolution which he accom- plished without detection. The true chief returned soon after ; and, at the proper time for his interposition, rose to address the house. The venerable Assembly was convulsed with laughter, for he seemed to be repeating what he had said before, so happy had the imitation been. He was astonished and vexed when some one explained the mystery — opened as it were the dark passage where Mr. Cullen had been acting. He said he saw how it was, and hoped that a gentleman who could well speak in his own person would at length begin to act the character which properly belonged to him.* That great additional weight accrued to him as ruler * A somewhat similar scene occurred in the House of Commons on the publication of Mr. Tickell's celebrated jeu d'esprit, ( Anti- cipation.' It only appeared on the morning of the day when the session opened, and some of the speakers who had not read it verified it, to the no small amusement of those who had. ROBERTSON. 267 of the Church, from the lustre of his literary fame, cannot be doubted ; and that the circumstance of his connexion with the University always securing him a seat in the Assembly, while others went out in rotation, tended greatly to consolidate his influence, is equally clear. But these accidents, as they are with respect to the General Assembly, would have availed him little, had not his intrinsic qualities as a great practical statesman secured his power. He may be said to have directed the ecclesiastical affairs of Scotland for more than a quarter of a century with unexampled success, and without any compromise of his own opinions, or modification of his views of church policy ; and he quitted the scene of his brilliant career while in the full vigour of his faculties, and the untarnished lustre of his fame. At the latter end of George II.'s reign, that Prince, or his advisers, deemed it expedient to make a proposal, having for its object the elevation of this eminent person to a high rank in the English Church. The particulars are not known ; but Mr. Stewart, who probably had some intimation of them, says that the offer was met with f< a rejection, in terms which effectually prevented a repetition of the attempt." Probably he considered it as, in substance, an insult to his character for sincerity as well as independence ; for though no man was less tainted by narrow-minded bigotry, and none probably could regard less than he did the differences, rather political than religious, which separate the two churches as matters of con- science, he yet had declared his aversion to Episcopacy on grounds not to be shaken, at any rate not to be shaken by a proposal accompanied with temporal 268 ROBERTSON. advantage, and he would have deemed his entertaining it for an instant a corrupt sacrifice of his principles to the gratification of his ambition. While the conflict was raging in the Church Courts on Patronage, he had given to the world his first pub- lished works — his historical articles j contributed to a periodical work established by Smith, Wedderburn (afterwards Chancellor), Jardine, Blair, Russell, and others, under the name, since become more famous, of the Edinburgh Review, and a sermon preached before the Society for promoting Christian Knowledge, in January 1755. The Review contained many able and learned papers, and reached a second number, when its con- ductors were obliged to give it up, in consequence of the fanatical outcry raised against a most justly severe criticism upon a wretched production of theolo- gical bigotry and intolerance which had just disgraced the extreme party in the Church.* The subject of the sermon is one peculiarly suited to his habits of inquiry — the situation of the world at the time of our Saviour's appearance as connected with the success of his mission. The merits of this piece, as a sermon, are very great ; and it is admirable, as an historical composition, in that department which Voltaire first extended to all the records of past times. It was * This criticism was from the elegant pen of Dr. Jardine, one of the most pious ministers of the Church, and a very intimate friend of the Principal. The papers of the latter appear to have been chiefly written on subjects which he had occasion to consider as incidental to his historical researches, and he does not seem to have put forth his strength in their composition. They are slight as compared with Adam Smith's review of Johnson's Dictionary, and his excellent letter to the editors on the General State of Literature, recommending an en- largement of their plan, which was confined to Scottish publications. ROBERTSON. 269 written and published before the appearance of the * Essai sur les Moeurs ;' though, as has been already said,* detached portions of that work had appeared in a Paris periodical work. As a preacher he was most successful. His lan- guage, of course, was pure, his composition graceful, his reasoning cogent, his manner impressive. He spoke according to the custom of the Scottish Church, hav- ing only notes to assist his memory. His notions of usefulness, and his wish to avoid the fanaticism of the High Church party (what with us would be called the Low Church, or Evangelical), led him generally to prefer moral to theological or Gospel subjects. Yet he mingled also three themes essential to the duties of a Christian pastor. He loved to dwell on the goodness of the Deity, as shown forth not only in the monu- ments of creation, but the work of love in the redemp- tion of mankind. He delighted to expatiate on the fate of man in a future state of being, and to contrast the darkness of the views which the wisest of the heathen had, with the perfect light of the new dispensation. He oftentimes would expound the Scriptures, taking, as is the usage of the Kirk, a portion of some chapter for the subject of what is called lecture as contradis- tinguished from sermon ; and in these discourses, the richness of his learning, the remarkable clearness of his explanation, the felicity of his illustration, shone forth, as well as the cogency and elegance of his practical application to our duties in life, the end and aim of all his teaching. I have heard him repeatedly, occupying as he did from 1759 to his death the pulpit of the Old * Life of Voltaire. 270 ROBERTSON. Grey Friars, where his father had been minister before him. But one sermon, though I was very young at the time, I never can forget. The occasion was the celebra- tion (5th November, 1T88) of the centenary of the Revo- lution, and his sister, considering that to have heard such a man discourse on such a subject was a thing to be remembered by any one through life ever after, took me to hear him. It was of singular and striking inte- rest, for the extreme earnestness, the youthful fervour with which it was delivered. But it was in some pas- sages upon a revolution which he expected and saw approaching, if not begun, as well as upon the one which was long past, and almost faded from the memory in the more absorbing interest of present affairs, I well remember his referring to the events now going on on the Continent, as the forerunners of far greater ones which he saw casting their shadows before. He certainly had no apprehensions of mischief, but he was full of hope for the future, and his exult- ation was boundless in contemplating the deliverance of " so many millions of so great a nation from the fetters of arbitrary government." His sister and I often afterwards reflected on this extraordinary dis- course with wonder, and I feel almost certain of some such expressions as these having been used, and of his foretelling that our neighbours would one day have to celebrate such an event as had now called us together. We dined with him the same day on leaving the church, for it was the afternoon service that he had performed. His eldest son, afterwards Lord Robert- son, was of the company ; and when the Principal expressed his satisfaction at having had his presence at church (a thing by no means of weekly occurrence), ROBERTSON. 27 1 the answer was, "Aye, sir, if you'll always give us such sermons, you may make it worth our while." " Ah," answered he, "you would like it, as the boys say," referring to a vulgar school taunt. I have again and again asked my learned kinsman to show me the ser- mon, which he admitted he possessed among his father's papers, fairly written out. His answer was that he wished to avoid giving it publicity, because, in the violence of the times, the author of it would be set down for a Jacobin, how innocent soever he was at the day of its being preached. Those times have hap- pily long since passed away. I cannot believe that any one has ventured to destroy this remarkable produc- tion, though hitherto it has not been found.* — I return to the course of his life. From 1752 to 1758 he had been diligently occu- pied with the ' History of Scotland ;' in 1759 it ap- peared. The success of this admirable work was as immediate and as universal as it was deserved. The whole edition, though of two quarto volumes, was ex- hausted in less than a month. There was but one voice in every part of the country, and among all ranks and descriptions of men, both upon its pure and beautiful composition, its interesting narrative, and its anxious and conscientious accuracy. A murmur was heard from the Jacobite party, who in Scotland * My kinsman, executor of Lord Robertson, has at length, after many a fruitless search, succeeded in finding the sermon, and it now lies before me, written in his own hand. I can see the places where he added remarks made on the inspiration of the moment, particularly the one above cited, of which I am the more certain from the subsequent conversations of his sister, who heard it with me. 272 ROBERTSON. were more wild and -romantic, and more unreasoning, than in the southern parts of the island. Not satis- fied with the far less harsh view of Mary's conduct which he had taken compared with Hume's, partial as Hume was to the Stuarts, it was the fashion of this little set of enthusiasts to say that he had " cut her with a razor dipped in oil." It was no little conces- sion to have acquitted her of all part in Babington's conspiracy, to have left her share in Darnley's murder hanging in doubt, to have pronounced a decisive judg- ment against Elizabeth, for her whole conduct both towards the Scots and their Queen. These silly per- sons would not be appeased unless, in the face of all her own conduct and her own words, she was ac- quitted of the outrage on common decency of wed- ding her husband's murderer, and screening his accom- plices from punishment. But the clamour, though it produced a book or two in support of this most des- perate cause, spread very little even in Scotland ; and the national vanity was inexpressibly gratified by this great triumph in the most important and most popu- lar of all the walks of polite learning. The delight of his friends was of course still more lively. Aware of his merits, as they always had been, and somewhat impatient of the length of time which he had suffered his known capacity to remain barren, now that they saw the abundant fruits crowning his works, they exulted as if they gathered in the rich harvest in common, and confessed that the postponement had not stunted the growth, but, like a fallow, made it more plenteous and more rich. In truth, the discipline of so many years' study to which he had subjected him- self, the long delay which he had interposed, though ROBERTSON. 273 all the while thoroughly versed in all the arts of com- position, had the salutary effect of making his first work as mature as his latest production. This is per- haps a singular instance of one who had from his early youth been studying diction, who had been constantly writing, and had for long years been almost as expert as he ever became, withholding himself from employing the faculty which he had acquired, except to render himself still more dexterous in its use, and continuing four and twenty years ere he appeared before the world, nay, eighteen years before he even began to write the work which should lay the foundation of his fame. He was eight and thirty when he published it. But then it is another singularity as great, that considerable doubt remains if any of his subsequent works surpassed this first pro- duction. Among his exulting friends, David Hume deserves to be singled out for the heartiness of his disinterested joy. Far from not bearing a brother near the throne, he entirely rejoiced in his rival's success, and even in the uniting of all testimonies to his merits, so strongly contrasted with the universal clamour for some years raised against his own 'History/ and the niggard praise which, even after five years, that work received. Among other kind acts, he encouraged some literary men at Paris to translate the new * His- tory ;' and he thus jocosely touches upon the loss of his undivided superiority as an historian : "I warn you, however, this is the last time I shall ever speak the least good of it. A plague take you ! Here I sat T 274 ROBERTSON. near the historical summit of Parnassus, immediately under Dr. Smollett,* and you have the impudence to squeeze yourself past me, and place yourself directly un- der his feet ! Do you imagine that this can be agree^ able to me ? and must not I be guilty of great simpli- city to contribute by my endeavours to your thrusting me out of my place both at Paris and in London ? But I give you warning that you will find the matter somewhat difficult, at least in the former city. A friend of mine who is there1, writes home to his father the strangest accounts of that kind, which my modesty will not allow me to repeat, but which it allowed me very deliciously to swallow." Just before the ' History ' was published, the author visited London for the first time ; and his merit hav- ing been made known to some persons of eminence and of good taste, who had been allowed to peruse por- tions, at least, of the proof sheets, his reception was of a distinguished kind. I have now before me some letters of his to his bosom friend^ and steady coadjutor in ecclesiastical politics, Dr> Jardine, and it is pleasing to mark the natural expression of his satisfaction with his visit. The first letter which I shall give begins with a good deal of narrative upon the success of John tiorne's f Agis/ At that time the violence* and folly of the fctiiatical party made the subject of this elegant and amiable writer's dramas doubly interesting to his friends. The tragedy, so successful at first, chiefly be- * He of course had the lowest opinion of this writer's parts as an historian. ROBERTSON. 2?5 cause of its predecessor, ' Douglas,'* having succeeded through merit, and partly because of high patronage, is a very middling performance, and, like all Mr. Home's plays, except ' Douglas/ has long since sunk into deserved oblivion. Dr. Robertson's amiable zeal for his friend, and his exultation at the success of his piece, is very striking in this letter. " MY DEAR SIR, " Thursday, March 16th. " When I wrote you the history of ' Agis,' I certainly foresaw some of the purposes for which it would serve, and that you would naturally employ it for an use of mortification to the wicked, as well as of comfort to the pious. I could not, however,, have any presage either of the absurdity of the players, or of the malice and credulity of Home's enemies, which rendered my account doubly seasonable. I now put it in your power to mortify them with still fuller accounts of the triumphs of ( Agis.' Never were there more crowded houses than during the whole run of the play. The Prince of Wales was present no less than three different nights, one of which a benefit night. Such honourable distinction was never formerly bestowed upon any new piece. The snarlers and small critics are somewhat enraged at this, and every one against Lord Bute ; though I can assure you, the frequency of the Prince's attendance was his own proper motion, and pro- ceeded from his admiration of ' Agis/ But what is still more honourable for Home, since the ninth night, ' Agis' has been acted twice, and both times the house was more crowded (if possible), and the applause louder than ever. There has ap- * « Douglas' was the second in date of composition, though the first performed. Garrick had rejected it peremptorily; and it was brought out with great success at Edinburgh. Garrick had also rejected all Home's other pieces ; until Lord Bute and other persons of distinction patronised the poet, when the manager, following his ignoble nature, suddenly became the zealous and forward patron of all he wrote, and joined those noble supporters in forcing the very poor tragedy of ' Agis' on the public. T 2 276 ROBERTSON, peared a critic on ' Agis,' one Heiierden. I am persuaded Home has hired him, and given him a crown to write such execrable stuff. Every body laughs at it ; and, in the wicked language of this town, it is called a d d tame piece of non- sense. Wedderburn makes all the progress we could wish : even the door-keeper of the House of Peers tells me that ' he is a d d clever fellow, and speaks devilish good English.' This very morning he was retained in a Plantation cause before the Privy Council, which is a thing altogether extra- ordinary for so young a man. You cannot imagine what odd fellows his rivals are, and how far and how fast he is likely to go. " I can't say so much about my own progress. I unluckily have but one copy of my ' History/ otherwise I might advance with more rapidity. I have been with Horace Walpole, a son of Sir Robert's, a very clever man, and of great leading among the literary people of fashion. We had much conversation about Mary. He is one of the greatest critics I ever met with, as to the facts in the period. Our notions jumped perfectly. Part of my papers are in his hands ; the Duke of Argyle has another ; Scott, who was preceptor to the Prince of Wales, a third ; and Lord E-oyston a fourth. I have got from this last a vast collection of original papers ; many of them are curious. I am advised by several people to transcribe as many as will swell the book to a guinea price. The taste of this town is such, that such an addition will be esteemed very meritorious ; and though it cost me little but having an amanuensis, it will add to the price in proportion to the increase of bulk. You see I begin to learn the craft of authorship. I have hitherto industriously avoided meeting with booksellers, but shall soon begin my operations with them. I have had a great offer from Hamilton and Balfour, which you'll probably have heard of. I can scarcely believe that even the effrontery of W r's roguery could have seriously set his face to such a scheme as that you mention. I scarce think it necessary, upon such a surmise, to write to Lord Milton ; but I shall drop a line to Mrs. Wedderburn or Miss Hepburn, in order to prevent any such foolish measure being heard with patience. I have not yet seen either Dr. Chandler or the Lions. All the ROBERTSON. 277 other scenes you recommend to me I have seen. I have heard the Bishops of Salisbury and Oxford. There was some elegance, a spice of drollery, and not a little buffoonery in the sermon of the latter ; and his audience admired and laughed, and were edified. Blair is but a ninny of an orator ; he makes his hearers serious, and sets them a- crying; but here they go to heaven, laughing as they go. You cannot imagine what strange characters I have met with, which I cannot now take off. I am a sort of domestic with Dr. Campbell, the best of all the authors I have seen.* I am often with Tucker of Bristol. I dined and drank claret with Douglas, the murderer of Bower." — " There were nine other persons in company (at another dinner), all of them retainers to the author or bookseller ; and I will draw you such a picture of that night, that you shall say the seeing of it alone was worth my coming to London. I wrote Bruce a long letter about news some days ago : you would probably meet with him and hear its contents. The Hanoverians are still making progress, as you will read more at large in the ' Chronicle.' The only thing which engrosses the talk of politicians is the flight of Bonneville. He was the officer who dissuaded the landing at Rochefort, and who, before the court-martial, gave evidence directly opposite to Clerk's. He went over to Holland ; was seen often at d'Affry's, the French Ambassador's : he told him, ' Sir, I do possess some merit ; I saved one town to France, and three generals to England.' His evidence acquitted Mordant, &c. From Holland he went over to France. You may believe Pitf and Colonel Clerk, &c., enjoy this adventure, which is indeed a remarkable one. Last day I was in the House of Commons, of which I am made free by " Unfortunately the MS. breaks off just as he was about to describe the debate. * The able author of the fine historical pieces in the edition 1740 of Harris's 'Voyages.' Dr. R. always used to mention his Presbyterian horror of the " profane expletives " which he found formed a part of all English colloquial discourse in those days. f Sic. 278 ROBERTSON. The following letter gives a further account of the historian's progress in preparing for the publica- tion of his work. It is written to the same friend, Dr. Jardine : — " MY DEAR JOHN, " London, 20th April, 1759. 44 1 write this in the British Coffee-House,* in the middle £f a company playing at cards and drinking claret. After this preamble, you are not to expect either a very long or a very distinct epistle. As to your letter, I postponed writing an answer to it, in expectation of hearing some account of the transactions of the Haddington Presbytery ; but as that has not come to hand, I must proceed to write without it. I am as much interested as you can possibly be in preventing the intended elevation of Turnstill to the Moderator's chair. But how could it possibly enter into the head of such a politician as you are, and one who has seen London too, that there was any method of engaging our laymen here to take part in a ques- tion about which they (laymen) are totally indifferent ? At the same time, I am earnest in giving opposition, and I think it may be made with great probability of success ; but I should be apt to imagine that neither Dick nor Hamilton are the proper candidates. You know neither of them stand well with Lord Milton ^f and if either you or I should give o*rr interest or solicit for them, you know what a handle might be made of it. If Morrison, or some such grave, inoffensive, ecclesiastical personage could be set up, I join you with all my vigour. You must make the choice as well as you can. Why may you not stand yourself ? At any rate, fix upon some feasible man. Write a few letters, and endeavour to raise the jealousy of the brethren against a perpetual moderator, and I don't doubt of our defeating the Doctor. If we can dis- comfit him by our own strength, this will render him incon- siderable : all other methods of doing so would be ineffectual. * Much frequented then, as it still is, by Scotchmen. The gentle- woman who at that time kept it was sister to Bishop Douglas, and a person of excellent manners and abilities. | Then a kind of minister for Scotland, being Lord Bute's uncle. ROBERTSON 279 " I Jjaye now brought my .offers to a conclusion with An.- drew Millar. After viewing the town, and considering the irresistible power of a combination of booksellers, I have agreed to sell him the property for £600. This, you see, is the sum I originally fixed upon as #he full price of my work, and is more than was ever given for any book except David Hume's. You canno(t imagine how much it has astonished all the London authors, nor how much Andrew Millar was astonished at the encomiums of my book whicji he got from people of rank. I have got some of the best puffers of England .on my .side. Mr. Doddington, Horace Walpole, Lady Hervey, and the Speaker are my sworn friends ; and you will wonder, even in this great place, how I have got Mary Queen of Scots to be a subject of conversation. Every body here approves of the bargain I have made with Millar, and I am fully satisfied of the prudence of my own conduct ; but of this I shall have full leisure to talk with you spon. The exploits which Carlyle and I have performed among the Dis- senters are beyond belief. Poor Dr. Chandler is humbled to the dust, and he feels it as much as other quack doctors feel their mortification. "This day I signed my contract with Andrew Millar, and am, according to your advice, to be a Doctor of Divinity within .six months, so that I shall take place immediately after Dr. Blair, as he taketh place immedi- ately after Dr. Turnstill. What great things have I to say ,of Mr. Pit,* who yesterday brought all the Tories to approve of continental measures as the only thing for the good of old England ! Yesterday I dined with Mr. Garrick, in spite of John Jjlyndmanf and -the Presbytery of Dalkeith. tTo.- morrow I go :to Portsmouth, to wa.it on Admiral 1^ awke and see the Royal George. How much have T to tell yo,u ! I ever am yours, " WM. R." 'The rank of the ' History of Scotland ' stands very high indeed among the most eminent of historical compositions. The philosophical spirit which per- <* Sic. $ A leader a^ong the fanatical party in ,the Kirk. 280 ROBERTSON. vades it, the enlarged views of polity in which it abounds, the sober and rational, but bold speculations with which it is variegated, and the constant references to authorities which accompany it, place it above the works of antiquity, deficient in all these particulars, altogether wanting in some of them. The skilful and striking delineations of individual character which are mingled with the narrative, but never overlaying it, and the reference to the histories of other countries which is introduced wherever it became necessary or in- structive, forms another high merit of the work. But it is as a history, and a history of Scotland, that its execution must mainly be regarded, and in this it is truly a great performance. It is difficult to admire sufficiently the graphic power which the historian displays in bringing before us the rude and stormy period he has chosen to describe — the strange mixture of simple barbaric manners in some classes with arti- ficial refinement in others — of poverty in the country with splendour at court, and among the chiefs — of great crimes with striking virtues — the morality of unprincipled and ferocious men with the vehement religious opinions of fanatics — the spectacle of a nation hardly half-civilized, barely emerging from a rude state, conducted by rulers, and disputed by factious leaders, with all the refinements and corruption of statesmen bred in the Italian courts. In the great staple of all historical excellence, the narrative, it has certainly never been surpassed. There is nothing obscure or vague, nothing affected or epigrammatic, nor is any sacrifice made of the sense to the phrase ; the diction is simple and pure, and soberly, if at all, adorned ; but ROBERTSON. 281 it is also striking ; the things described are presented in the clearest light, and with the most vivid, natural, and unambitious colouring, without exaggeration, ap- parently without effort ; like the figures of Raphael, which, for this reason, never captivate us so much on the first view as after we have repeatedly gazed upon them with still increasing wonder. The even flow of the story, the last perfection and the most difficult which the nar- rative art attains, is likewise complete. If not overlaid with ornament, nor disfigured by declamation, nor studded with points and other feats of speech, so neither is it broken by abrupt transitions and unseemly pauses, but holds its clear, simple, majestic course unin- terrupted and untroubled. The story of Livy does not more differ from that of Tacitus in all these essen- tials than the simple but striking narration of the Scotch historian from the tinsel, the epigram, the word-catching of Gibbon. For examples to illustrate the high merits of this narrative, we need not have recourse to a curious selec- tion of remarkable scenes or events, because the texture of the ' History ' in the ordinary portions of its fabric where the mere common annals are related, would be sufficient. There may, however, be no harm in not- ing the singular effect of the story when Rizzio's murder is related, or Gowrie's conspiracy, or Mary's execution. The artistlike selection of particulars is to be marked in all these cases ; as in the first, Ruthven's figure clad in armour, and ghastly pale from his late illness ; in the second, the trembling of the mysterious armed man with a dagger near him, and a sword in the small study whither the Earl had led the King, 282 ftOBERTS.ON. closing the doors behind them, and up a staircase ; in the third, the Queen's majestic air and noble dress, the pomander chain of iier Agnus Dei round her neck, the beads at her girdle, the crucifix of ivory in her hand. By all these skilful selections we are made to see, as it were, the things represented to us, and the pen of the great historian produces the affect of the great artist's pencil, while its pictures are not subject to the destroy* ing influence of time.* There seems considerable reason to lament that a» intimate acquaintance with the great scenes and cele- brated characters of history, in all ages, should have made the historian too familiar with the crimes on a great scale of importance, and therefore of wickedness, perpetrated by persons in exalted stations, so that he suppresses in recounting or in citing them the feelings of severe reprobation to which ,a more pure morality, a more strict justice, would certainly have given ven,t. It is painful to see him fall into the vulgar and perni- cious delusion which secures for the worst enemies of their species the ;praise .and the increase of worldly greatness. It is equally painful to see the worst crimes, even of a more ordinary description, passed over in silence when they sully .the illustrious culprit. JLet us * Hume, as well as Robertson, has given this scene of Mary's death ; the latter with by far greater effect. But it is singular that he should have left out 'her noble remonstrance with the commis- sioners when refused fthe assistance of hervf»rf aisrfao ,e Y 2 BLACK. THE physical sciences have few more illustrious names to boast than that of Joseph Black. With all the habits and the disciplined faculties of a true philoso- pher, with the temper as well as the capacity of a sage, he possessed that happy union of strong but disciplined imagination, powers of close undivided attention, and ample resources of reasoning, which forms original genius in scientific pursuits ; and, as all these qualities may be combined in an individual without his happening to signalise his investigations of nature by any discovery, we must add that his life was crowned with the good fortune of opening to mankind new paths in which both himself and his followers successfully trod, enlarging to an incalculable extent the bounds of human knowledge. The modesty of his nature making him averse to publish his specu- lations, and the genuine devotion to the investigation of truth, for its own sake, rendering him most open in his communications with all who were engaged in the same pursuits, his incontestable claim to be regarded as the founder of modern chemistry has been oftentimes overlooked ; and, while some have endeavoured more or less obscurely to mingle themselves with his dis- coveries, others have thought it becoming to post-date «n //////// ea^dfet ' fa, • / & /' ,f C // -.'//•/<• / ' •//////x7 BLACK. 327 to the press, often while their speculations are crude, and their inquiries not finished. Nor could the reason often urged in defence of this find much favour with one who seemed never to regard the being anticipated by his fellow-labourers as any very serious evil, so the progress of science was secured. Except two papers, one in the 'London Philosophical Transactions' for 1775 on the freezing of boiled water ; the other, in the second volume of the ' Edinburgh Transactions,' on the Iceland hot springs ; he never published any work after that of which we are now to speak, in 1755, and which, but for the accidental occasion that gave rise to it, would possibly, like his other original speculations, never have been given by himself to the press. Upon taking his degree at Edinburgh College he wrote and published a Latin Thesis, after the manner of that as well as the foreign universities. The subject was 'Magnesia, and the Acid produced by Food in the Stomach' (De Acldo e Cibis orto ; et de Magnesia), and it contained the outline of his discoveries already made. Having sent some copies of this Thesis to his father at Bordeaux, one was given to Montesquieu, who at once saw the vast importance of the truths which it unfolded. He called a few days after and said to Mr. Black, " I rejoice with you, my very good friend : your son will be the honour of your name and of your family." But though the discoveries were sketched distinctly enough in this writing, they were only given at large the following year in his celebrated work, 'Experiments on Magnesia, Quicklime, and other Alkaline Substances,' incontestably the most 328 BLACK. beautiful example of strict inductive investigation since the ' Optics' of Sir Isaac Newton. His fervent ad- miration of that masterly work was indicated by his giving it to Professor Robison, then a student, and desiring him to " make it the model of all his studies," recommending him at the same time a careful study of the mathematics. It appears that this important inquiry concerning the alkaline earths, the results of which were destined to change the face of chemical science, was suggested by the attempts then making to find a solvent for the stone. I distinctly recollect Dr. Black, in his lectures, prefacing the admirable and most interesting account which he gave of his dis- coveries, with the statement that the hopes of finding a solvent which should not, like the caustic alkalie,s, destroy the substance of the bladder in melting the stone, first led him to this investigation. Professor Robison has given a note from his memorandum-book indicating that he had at first fallen into the notion of alkalies, when treated with quicklime, deriving from it their caustic quality ; the common belief (which gave rise to the term caustic) being that lime obtained from the fire the quality of growing extremely hot, even to ignition when united with water. But expe- riment soon corrected this idea ; for, having exposed the caustic or quicklime to the air till it became mild, he says, " Nothing escapes (meaning no fire or heat) ; the cup rises considerably by absorbing air." Another observation on the comparative loss of weight sustained by chalk when calcined (in the fire), and when dis- solved in an acid, is followed by the account of a medical case, which the Professor knew to have BLACK. 329 occurred in 1752. A third note follows, and proves him to have now become possessed of the true theory of causticity, namely, the expulsion of air, and of mildness, namely, its absorption. The discovery was therefore made as early as 1752 — it was published generally in 1754 — it was given in its fullest details in 1755. At this time M. Lavoisier was a boy at school — nine years old when the discovery was made — eleven when it was published — twelve when it was as fully given to the world as its author ever delivered it. No pos- sibility therefore existed of that great man finding out when he composed his great work that it was a discovery of his own, as he did not scruple to describe oxygen, though Dr. Priestley had first communicated it to him in the year 1774 ; or that Black and he dis- covered it about the same time, as he was in the habit of stating with respect to other gases, with a con- venient degree of ambiguity just sufficient for self- defence, should he be charged with unfair appropriation. Who that reflects on the noble part which this great philosopher acted, both in his life and in his death, can avoid lamenting that he did not rest satisfied with the fame really his due, of applying the discoveries of others, in which he had no kind of share, to the investigation of scientific truths, as entirely the result of his extraordinary faculty of generalization, and genius for philosophical research, as those discoveries, the mate- rials of his induction, were the undivided property of others ! The capital discovery of Black, thus early made, and to any share in which no one has ever pretended, was that the causticity, as it was formerly termed upon a 330 BLACK. false theory, of the alkalis and alkaline earths, was owing to the loss of a substance with which they had been combined, and that their reunion with this sub- stance again rendered them mild. But the nature of this substance was likewise ascertained by him, and its detection forms by far the most important part of the discovery, for it laid the foundation of chemical science. He found that it was a permanently elastic fluid, like air in some of its mechanical qualities, those of being transparent or invisible, and incondensable, but differ- ing entirely from the air of our atmosphere in its chemical properties. It was separated from alkaline substances by heat, and by the application of acids, which, having a stronger elective affinity for them, caused it to be precipitated, or to escape in the aeriform state ; it was heavier than common air, and it gave a slight acidulous flavour to water on being absorbed by it; hence the inference that it was an acid itself. A short time afterwards (in 1757) he discovered that this peculiar air is the same with that produced by the fermentation of vegetable substances. This he ascertained by the simple experiment of partially emptying in a brewer's vat, where the fermenting process was going on, the contents of a phial filled with lime-water. On shaking the liquid that remained with the air that had entered, he found it become turbid, from the lime having entered into union with the air, and become chalk. The same day he discovered by an experiment, equally simple and equally decisive, that the air which comes from burning charcoal is of the same kind. He fixed a piece of charcoal in the broad end of a bellows nozzle, unscrewed ; and putting that in the fire, he inserted BLACK. 331 the other end in a vessel filled with lime-water. The air that was driven through the liquid again pre- cipitated the lime in the form of chalk. Finally, he ascertained by breathing through a syphon filled with lime-water, and finding the lime again precipitated, that animals, by breathing, evolve air of this description. The great step was now made, therefore, that the air of the atmosphere is not the only permanently elastic body, but that others exist, having perfectly different qualities from the atmospheric air, and capa- ble of losing their elasticity by entering into chemi- cal union with solid or with liquid substances, from which being afterwards separated, they regain the elastic or aeriform state. He gave to this body the name of fixed air, to denote only that it was found fixed in bodies, as well as elastic and separate. He used the term " air" only to denote its mechanical re- semblance to the atmospheric air, and not at all to imply that it was of the same nature. No one ever could confound the two substances together ; and ac- cordingly M. Morveau, in explaining some years after- wards the reluctance of chemists to adopt the new theory of causticity, gives as their excuse, that although this doctrine " admirably tallies with all the pheno- mena, yet it ascribes to fixed air properties which really make it a new body or existence" ("forment reellement un nouvel elre").* In order to estimate the importance of this dis- covery, and at the same time to show how entirely it * Supplement to the * Encyclopedic,' vol. ii. p. 274, published in 1777. 332 BLACK. altered the whole face of chemical science, and how completely the doctrine was original, we must now examine the state of knowledge which philosophers had previously attained upon the subject. It has often been remarked that no great discovery was ever made at once, except perhaps that of logarithms ; all have been preceded by steps which conducted the dis- coverer's predecessors nearly, though not quite, to the same point. Some may possibly think that Black's dis- covery of fixed air affords no second exception to this rule ; for it is said that Van Helmont, who flourished at the end of the sixteenth and beginning of the seven- teenth century, had observed its evolution during fer- mentation, and given it the name of gas iifoestre, spirit from wood, remarking that it caused the phenomena of the Grotto del Cane, near Naples. But though he as well as others had observed an aeriform substance to be evolved in fermentation and in effervescence, there is no reason for affirming that they considered it as differing from atmospheric air, except by having absorbed, or become mixed with, certain impurities. Accordingly, a century later than Van Helmont, Hales, who made more experiments on air than any other of the old chemists, adopts the commonly received opinion that all elastic fluids were only different combinations of the atmospheric air with various exhalations or impurities ;* and this was the universal belief upon the subject, both of philosophers and of the vulgar. * It may safely be affirmed that Van Helmont's observation, which lay for a century and a half barren, threw no light of any value upon the subject. No one questions Newton's title to the discovery of the different refrangibility of light, and the true theory BLACK. 333 It is now fit that we see in what manner the subject was treated by scientific men at the period immediately preceding Black's discoveries. The article ' Air' in the French 'Encyclopedic' was published in 1751, and written by D'Alembert himself. It is, as might be expected, able, clear, elaborate. He assumes the sub- stance of the atmosphere to be alone entitled to the name of air, and to be the foundation of all other per- manently elastic bodies : " L'air elementaire, ou 1'air proprement dit," he says. He describes it as " homo- gene," and terms it " 1'ingredient fondamental de tout 1'air de 1'atmosphere, et qui lui donne son nom." Other substances or exhalations mix with it, he says, but these he terms " passageres," passing vapours, and not permanent : the air alone (that is, the atmo- spheric air) he calls "permanent," or permanently elastic (vol. i. p. 225). So little attention had the ob- servation of Van Helmont respecting the Grotto del of the rainbow; yet at the beginning of the 17th century, Antonio de Dominis, Archbishop of Spalatro, had really made an ingenious and well-grounded experiment on the similarity of the rainbow colours with those formed by the sun's rays refracted twice and reflected once in a globe filled with water. The doctrine of universal gravitation was known to both Kepler and Galileo ; and Boulland (Astronomia Philolaica, lib. i., 1645) distinctly stated his belief or conjecture that it acted inversely as the squares of the distances. The famous proposition of equal areas in equal times was known to Kepler. The nearest approach to the Fluxional Calculus had been made by Harriott and Roberval and Fermat ; and to take but one other ex- ample, the electrical explosion of the Leyden jar, discovered in 1747, obtained the name of the coup-foudroyant, and was by Abbe Nollet conjectured to be identical with lightning, Franklin's celebrated experiment being only made in 1752. 334 BLACK. Cane excited, that we find a conjecture hazarded in the article * Grotte' (vol. vii. p. 968), which appeared in 1756, — " peut-etre respirent ils (les chiens), au lieu d'air, des vapeurs minerales;" but this was some time after Black's discovery had taught us to distinguish such permanently elastic vapours from atmospheric air. In the article ' Fermentation' (vol. vL p. 523) we find Van Helmont's doctrines of the connexion between fermentation and digestion treated with ridicule, and those who adopted them jocularly called the " fermen- tateurs." A few years later, however, the face of things changed. In the ' Supplement,' published in 1776, we find an article on ' Fixed Air,' and a reference to Dr. Black's discovery ; but nothing can be more indistinct than the author, M. Morveau's, ideas respecting it; for he leaves us in doubt whether it be the atmospheric air or a separate substance, and yet he states that the phenomena of fermentation and putrefaction are ex- plained by the evolution or absorption of this air, and that mineral waters derive from its presence their fla- vour. An abstract of M. Venel's book had in 1765, under the head of ' Mineral Waters,' given this explana- tion ; but instead of representing the air combined with the water as a different substance, he calls it " veritable air et meme tres pure." We have, however, seen that, in the following year (1777), M. Morveau's ideas were perfectly distinct on the subject ; for he treats it as a new substance, wholly different from atmospheric air. The slowness with which Black's doctrine made its way in France may be presumed from Morveau's re- mark on causticity, already cited, and also from this, BLACK. 335 that the article on 'Magnesia,' published in 1765, dog- matically asserts Black to be in error when he de- scribes Epsom salts as yielding that earth, " because," says the author, "those salts are purely Seidlitian," " entierement Seidlitiens" (vol. x. p. 858). In fact, Ep- som salts, magnesia, limestone, and sea- water are the great sources from which all magnesia is obtained. The first of these substances is in truth only a com- bination of magnesia with sulphuric acid. The other discoveries to which Black's led were as slowly disseminated as his own. Oxygen gas had been discovered, in August, 1774, by Priestley, and soon after by Scheele without any knowledge of Priestley's previous discovery ; yet in 1777 Morveau, who wrote the chemical articles in the ' Supplement/ never mentions that discovery, nor the almost equally important dis- covery of Scheele, chlorine, made in 1774, nor that of azote, discovered by Rutherford in 1772, nor hydro- gen gas, the properties of which had been fully inves- tigated by Cavendish as early as 1766. Lavoisier's important doctrine, well entitled to be called a dis- covery, of the true nature of combustion, had likewise been published in 1774 in his ' Opuscules/ yet Mor- veau doggedly adheres to his own absurd theory of the air only being necessary to maintain those oscilla- tions in which he holds combustion to consist; and finding that the increase of weight is always the result of calcination as well as combustion, he satisfies him- self with making a gratuitous addition to the hypo- thesis of phlogiston, and supposes that this imaginary substance is endowed with positive levity ; nor does he allude to the experiments of Lavoisier on gases, on 336 BLACK. combustion, and on oxidation, further than to say that he had for a considerable time been engaged in these inquiries. It was not indeed till 1 787 that he became a convert to the sound and rational doctrine, and abandoned the fanciful hypothesis, simple and inge- nious though it be, of Stahl. Berthollet, the earliest convert, had come over to the truth two years be- fore. Thus, discoveries had been made which laid the foundation of a new science, and on which the atten- tion of all philosophers was bent ; yet the greatest scientific work of the age made no more mention of them than if Black, Cavendish, Priestley, and Scheele had not been. The conjecture may be allowed to us, that if any of these great things had been done in France, M. Morveau would not have been suffered to preserve the same unbroken silence respecting them, even if his invincible prejudices in favour of the doc- trine of phlogiston had disposed him to a course so unworthy of a philosopher. The detail into which I have entered, sufficiently proves that the discovery of fixed air laid at once the foundation of the great events in the chemical world to which reference has just been made, because the step was of incalculable importance by which we are led to the fact that atmospheric air is only one of a class of permanently elastic fluids. When D'Alem- bert wrote the article ' Air/ in 1751, he gave the doc- trine then universally received, that all the other kinds of air were only impure atmospheric air, and that this fluid alone was permanently elastic, all other vapours being only, like steam, temporarily aeriform. Once the truth was made known that there are other gases BLACK. 337 in nature, only careful observation was required to find them out. Inflammable air was the next which became the subject of examination, because, though it had long been known, before Black's discovery it had been supposed only to be common air mixed with unc- tuous particles. His discovery at once showed that it was, like fixed air, a separate aeriform fluid, wholly distinct from the air of the atmosphere. The other gases were discovered somewhat later. But it is a very great mistake to suppose that none of these were known to Black, or that he supposed fixed air to be the only gas different from the atmospheric. The nature of hydrogen gas was perfectly known to him, and both its qualities of being inflammable and of being so much lighter than atmospheric air ; for as early as 1766 he invented the air balloon, showing a party of his friends the ascent of a bladder filled with inflammable air. Mr. Cavendish only more precisely ascertained its specific gravity, and showed what Black could not have been ignorant of, that it is the same, from what- ever substance it is obtained. But great as was the discovery of fixed air, and important as were its consequences, the world was indebted to its illustrious author for another scarcely less remarkable, both from being so unexpected, and from producing such lasting effects upon physical science. About the year 1763 he meditated closely upon the fact, that on the melting of ice more heat seems to disappear than the thermometer indicates, and also that on the condensation of steam an unexpected pro- portion of heat becomes perceptible. An observation of Fahrenheit, on the cooling of water below the tem- z 338 BLACK. perature of ice until it is disturbed, when it gives out heat and freezes at once, appears also to have attracted his careful consideration. He contrived a set of simple but decisive experiments to investigate the cause of these appearances, and was led to the discovery of latent heat, or the absorption of heat upon bodies passing from the solid to the fluid state, and from the fluid to the aeriform, the heat having no effect on surrounding bodies, and being therefore insensible to the hand or to the thermometer, and only by its absorption maintaining the body in the state which it has assumed, and which it retains until, the absorbed heat being given out, and becoming again sensible, the state of the body is changed back again from fluid to solid, from aeriform to fluid. He never published any account of this discovery, but he explained it fully in his Lectures, both at Glasgow and Edinburgh, and he referred to it in the paper already mentioned, which was printed in the ' Philosophical Transactions ' for 1775. Well, then, may we marvel that no mention whatever of latent heat is made in the celebrated ' Ency- clop6die,' which owed its chemical contributions to no less a writer and experimentalist than Morveau. The doctrine of latent heat, however, was immediately applied by all philosophers to the production of the different airs which were successively discovered. They were found to owe their permanently elastic state to the heat absorbed in their production from solid or fluid substances, and to regain their fluid or solid state by combining either together or with those sub- stances, and in the act of union giving out in a sensible form the heat which, while absorbed and BLACK. 339 latent, had kept them in the state of elastic and in- visible fluids.* The third great discovery of Black was that which has since been called the doctrine of specific heat, but which he called the capacity of bodies for heat. Dif- ferent bodies contain different quantities of heat in the same bulk or weight ; and different quantities of heat are required to raise different bodies to the same sen- sible temperature. Thus, by Black's experiment, it was found that a pound of gold being heated to 150°, and added to a pound of water at 50°, the temperature of both became not 100°, the mean between the two, but 55°, the gold losing 95°, and the water gaining 5°, because the capacity of water for heat is nineteen times that of gold. So twice as much heat is required to raise water to any given point of sensible heat as to raise mercury, the volumes of the two fluids compared being equal. The true doctrine of combustion, calcination of metals, and respiration of animals, which Lavoisier deduced from the experiments of Priestley and Scheele upon oxygen gas, and of Cavendish on hydrogen gas, and which has changed the whole aspect of chemical science, was founded mainly upon the doctrines of latent and specific heat. It was thus the singular felicity of Black to have furnished both the pillars upon which modern chemistry reposes, and to have * It is by no means impossible that one day we may be able to reduce the phenomenon of light within the theory of latent heat. It may be that this body when absorbed, that is, fixed in substances, gives out heat ; as, while passing through diaphanous substances and remaining unfixed, its heat is not sensible. z 2 340 BLACK. furnished them so long before any one attempted to erect the superstructure, that no doubt could by any possibility arise respecting the source of our increased knowledge, the quarter to which our gratitude should be directed. Fixed air was discovered in 1752, and fully explained to the world in 1754 and 1755. Latent heat was yearly, from 1763, explained to nu- merous classes of students, before whom the experi- ments that prove it were performed by the author's own hands. Cavendish made his experiments on in- flammable air in 1766 ; Priestley began his in 1768, first publishing in 1 77*2 ; and he discovered oxygen in 1774, in which year the nature of combustion was first explained by Lavoisier, a boy at school when fixed air was discovered, and having made no experiments nor written any one line upon chemical subjects for seven years after latent heat was discovered. But we shall form a more striking idea to ourselves of the revolution which Black thus effected in che- mistry, if we attend a little to the state of that science in general before he began his labours, We have already seen the low condition of the knowledge then possessed respecting aeriform fluids ; the general con- dition of the science was in the same proportion humble. The celebrated ' Preliminary Discourse' to the ' En- cyclopedic' makes hardly any mention of chemistry among the sciences; and in the ' Arbre Encyclopedique,' on which the authors (D'Alembert and Diderot) plume themselves much, we find it not very distinctly repre- sented, or in very good company. It is termed the science of interior and occult qualities of bodies, its BLACK. 341 objects being to imitate and rival nature, by decom- posing, reviving, and transferring substances. It is represented as holding among the sciences the place which poetry occupies among other branches of litera- ture. Its fruits are said to be alchemy, metallurgy, natural magic, and chemistry properly so called, which is stated to consist of pyrotechny and dyeing. Strange to tell, pharmacy is not given as one of its fruits, being referred wholly to the branch of medical science. But the state of chemistry is better understood by the article itself in the ' Encyclopedic/ the elaborate work of M. Venel of Montpelier, well known for his researches concerning mineral springs, and author of most of the chemical articles in the original work, as M. Morveau was of those in the 'Supplement/ and whose mistakes on the subject of magnesia, aris- ing from prejudice, have already been mentioned. This article begins with lamenting the low condition of his favourite science : " Elle est peu cultivee parmi nous. Cette science n'est que tres mediocrement r6pandue, meme parmi les savans, malgre la pretention a 1'uni- versalite des connaissances qui font aujourd'hui le gout dominant. Les chimistes forment un peuple distinct, tres-peu nombreux, ayant sa langue, ses mysteres, ses loix, et vivent presque isoles au milieu d'un grand peuple peu curieux de sa connaissance, n'entendant presque rien de son industrie." He then goes on to show that this " incuriosite, soit reelle, soit simulee," is yet extremely unphilosophical, inasmuch as it leads to a rash condemnation ; and that those who know any subject superficially may possibly be deceived in their 342 BLACK. own judgment upon it, "the consequence of which has been," he adds, " that owing to the prejudices enter- tained against the nature and reach of the science, it becomes a matter of no small difficulty or slight con- troversy to say clearly and precisely what chemistry is. Some make no distinction between the chemist and the quack who seeks after the philosopher's stone ( souffleur ) ; others think any one a chemist who has a still for preparing perfumes or colours. Many con- sider the compounding of drugs as containing the whole of the art. Even men of science know scarcely any thing about the chemists." — " What natural phi- losopher," he asks, " so much as ever names Becker or Stahl? Whereas those who, having other scientific illustrations, as John Bernouilli and Boerhaave, have written chemical works, or rather works on chemical subjects, are very differently thought of; so that the for- mer's work on ' Fermentation,' and the latter's on 'Fire,' are known, cited, and praised, while the far greater views of Stahl on the same subjects only exist for a few chemists." He then goes on to cite other proofs of the low estimate formed of the science, and even the pre- vailing impression of chemists being mere workmen ; and concludes, that " the revolution which should raise chemistry to the rank it merits, and place it on a level with natural philosophy, can only be accomplished by a great, an enthusiastic, and a bold genius." While waiting for the advent of this new Paracelsus, he says, it must be his task to present chemistry in a light which may show it worthy the notice of philosophers, and capable of becoming something in their hands. If we go back to an earlier period, we shall find BLACK. 343 that Lord Bacon, although he quite clearly perceived that chemistry might one day be advanced to the rank of a science (De Dig. et Aug. iii.), yet always treats the chemistry of his day as merely empirical (Nov. Org. s. Ixiv. Ixxiii.*). But I have preferred taking the account of chemical science from the ' Encyclopedic/ first, because it gives, if not the opinion or the testi- mony of the learned body at large who prepared that work, yet certainly an opinion and a testimony which had the sanction of its more eminent members ; and, secondly, because its date is at the eve of the great revolution in natural science of which we are speaking. * " Itaque tails philosophia (in paucorum experimentorum ar- gutiis et obscuritate fundata) illis qui in hujusmodi experimentis quotidie versantur atque ex ipsis phantasmatis contaminarunt, pro- babilis videtur, et quasi certa ; cseteris incredibilis et vana, cujus exemplar notabile est in chemicis eorumque dogmatibus," It must be added that beside the injustice here done to Van Hel- mont, he goes on to rank Gilbert in the same empirical class, as he elsewhere does — a most incorrect view of Gilbert's induction, the most perfect by far of any before Lord Bacon's age, and, though mixed with some hypothetical reasoning, hardly in strictness ex- celled by any philosopher of after times. I cannot come so near the remarkable sixty-fifth section of the * Novum Organum' without digressing so far from my subject as to cite the prophetic warning given to some zealots without knowledge of our own times against the "apotheosis errorum," the " pestis intellectus, si vanis accedat veneratio." " Huic autem vanitati (adds the pious and truly Chris* tian sage) nonnulli ex modernis summa levitate ita indulsenmt ut in primo capitulo Geneseos et in libro Job et aliis scripturae locis phi- losophiam naturalem fundari conati sunt ; inter mortua quserentes viva ;" a folly the more to be deprecated, he says, because " ex divinarum et humanarum malesana admistione non solum educitur philosophia phantastica, sed etiam religio hseretica." His practical conclusion, therefore, is to render unto faith the things alone which are faith's : " Admodum salutare, si mente sobria, fidei tantum dentur quse fidei sunt." 344 BLACK. The last passage which has been cited from that work strikingly illustrates the low ebb at which chemical science then was. — It is certain that after the discoveries of Black had opened vast and new views of nature, both as regards the operations of heat, the most powerful and universal of all agents, and as regards the constitution of elastic fluids, the most unknown of the four elements, no natural philo- sopher would have had the hardihood to doubt if che- mistry was an important branch of his science, and no chemist would have performed the superfluous task of vindicating its claim to the title. We have now gone through the whole of this in- teresting subject, rather occupied in contemplating the foundations of a new science than in tracing the exten- sion of the boundaries which confine an old one. The universal operation of heat, and the agency which it exerts by its absorption and its evolution on the struc- ture of all bodies, renders the discovery of its nature and action in these respects, next to that of gravitation, the most important step which has been made in the progress of physical science. The new field opened to philosophical inquiry by the discovery of the gaseous bodies is only second to the former step in the import- ance of its consequences. It is as objects of pure science, the mere contemplation of scientific truth, that we have been considering these great discoveries ; yet they have amply contributed also to the advance- ment of the arts. The illustrious improver of the steam engine was too young to have joined in the experiments on fixed air ; but in the course of those by which latent heat was discovered, he had a constant and confidential BLACK. 345 intercourse with Black, one of his earliest patrons ; and although it is as certain that he did not owe to that philosopher's suggestions any of the steps by which his inventions were compassed, as it is that he had him- self no share in Black's great discovery, it cannot be doubted that the knowledge thus acquired of the true nature of heat, of steam, of evaporation, and of con- densation, contributed most essentially to his mighty improvements. As for the gases, it would be difficult to name the branch of art which has not in some manner and to some extent gained by their discovery. So that the great man whose history we are contem- plating, had the satisfaction of seeing the triumphs of his youth bear fruit in every direction, exalting the power and increasing the comforts of mankind as well as extending the bounds of their knowledge and enlarg- ing the range of their industry. He was but twenty- four years old when he made his first discovery, and thirty-four when his second was added. He lived to nearly fourscore. It remains to consider him as a teacher ; and cer- tainly nothing could be more admirable than the manner in which for forty years he performed this use- ful and dignified office. His style of lecturing was as nearly perfect as can well be conceived ; for it had all the simplicity which is so entirely suited to scientific discourse, while it partook largely of the elegance which characterized all he said or did. The publica- tion of his lectures has conveyed an accurate idea of the purely analytical order in which he deemed it best to handle the subject with a view to instruction, consider- ing this as most likely to draw and to fix the learner's 346 BLACK. attention, to impress his memory, and to show him both the connexion of the theory with the facts, and the steps by which the principles were originally ascer- tained. The scheme of the lectures may thence be ap- prehended— the execution imperfectly ; for the diction was evidently, in many instances, extemporaneous, the notes before the teacher furnishing him with little more than the substance, especially of those portions which were connected with experiments. But still less can the reader rise from the perusal to any con- ception of the manner. Nothing could be more suited to the occasion ; it was perfect philosophical calmness ; there was no effort ; it was an easy and a graceful conversation. The voice was low, but per- fectly distinct and audible through the whole of a large hall crowded in every part with mutely attentive lis- teners ; it was never forced at all any more than were the motions of the hands, but it was anything rather than monotonous. Perfect elegance as well as repose was the phrase by which every hearer and spectator naturally, and as if by common consent, described the whole de- livery. The accidental circumstance of the great teacher's aspect, I hope I may be pardoned for stopping to note, while endeavouring to convey the idea of a phi- losophic discoverer. His features were singularly grace- ful, full of intelligence, but calm as suited his manner and his speech. His high forehead and sharp temples were slightly covered, when I knew him, with hair of a snow-white hue, and his mouth gave a kindly as well as most intelligent expression to his whole features. In one department of his lecture he exceeded any I have ever known, the neatness and unvarying success with BLACK. 347 which all the manipulations of his experiments were performed. His correct eye and steady hand contri- buted to the one ; his admirable precautions, foreseeing and providing for every emergency, secured the other. I have seen him pour boiling water or boiling acid from a vessel that had no spout into a tube, holding it at such a distance as made the stream's diameter small, and so vertical that not a drop was spilt. While he poured he would mention this adaptation of the height to the diameter as a necessary condition of success. I have seen him mix two substances in a receiver into which a gas, as chlorine, had been introduced, the effect of the combustion being perhaps to produce a com- pound inflammable in its nascent state, and the mixture being effected by drawing some string or wire working through the receiver's sides in an air-tight socket. The long table on which the different processes had been carried on was as clean at the end of the lecture as it had been before the apparatus was planted upon it. Not a drop of liquid, not a grain of dust remained. The reader who has known the pleasures of science will forgive me if at the distance of half a century I love to linger over these recollections, and to dwell on the delight which I well remember thrilled me as we heard this illustrious sage detail, after the manner I have feebly attempted to pourtray, the steps by which he made his discoveries, illustrating them with anecdotes sometimes recalled to his mind by the passages of the moment, and giving their de- monstration by performing before us the many expe- riments which had revealed to him first the most important secrets of nature. Next to the delight of 348 BLACK. having actually stood by him when his victory was gained, we found the exquisite gratification of hear- ing him simply, most gracefully, in the most calm spirit of philosophy, with the most perfect modesty, recount his difficulties, and how they were overcome ; open to us the steps by which he had successfully ad- vanced from one part to another of his brilliant course ; go over the same ground, as it were, in our presence which he had for the first time trod so many long years before ; hold up perhaps the very instruments he had then used, and act over again the same part before our eyes which had laid the deep and broad foundations of his imperishable renown. Not a little of this extreme interest certainly belonged to the accident that he had so long survived the period of his success — that we knew there sat in our presence the man now in his old age reposing under the laurels won in his early youth. But take it altogether, the effect was such as cannot well be conceived. I have heard the greatest under- standings of the age giving forth their efforts in its most eloquent tongues — have heard the commanding periods of Pitt's majestic oratory — the vehemence of Fox's burning declamation — have followed the close- compacted chain of Grant's pure reasoning — been carried away by the mingled fancy, epigram, and argumentation of Plunket ; but I should without hesitation prefer, for mere intellectual gratification (though aware how much of it is derived from asso- ciation), to be once more allowed the privilege which I in those days enjoyed of being present while the first philosopher of his age was the historian of his own discoveries, and be an eye-witness of those experiments BLACK. 349 by which he had formerly made them, once more per- formed with his own hands. The qualities which distinguished him as an inquirer and as a teacher followed him into all the ordinary affairs of life. He was a person whose opinions on every subject were marked by calmness and sagacity, wholly free from both passion and prejudice, while affectation was only known to him from the comedies he might have read. His temper in all the circumstances of life was unruffled. This was perceived in his lectures when he had occasion to mention any narrow prejudice or any unworthy proceeding of other philosophers. One ex- ception there certainly was, possibly the only one in his life ; he seemed to have felt hurt at the objections urged by a German chemist called Meyer to his doctrine of causticity, which that person explained by supposing an acid, called by him acidum pingue, to be the cause of alkaline mildness. The unsparing severity of the lecture in which Black exposed the ig- norance and dogmatism of this foolish reasoner cannot well be forgotten by his hearers, who both wondered that so ill-matched an antagonist should have succeeded where so many crosses had failed in discomposing the sage, and observed how well fitted he was, should occasion be offered, for a kind of exertion exceedingly different from all the efforts that at other times he was wont to make. The soundness of his judgment on all matters, whether of literature or of a more brdinary description, was described by Adam Smith, who said, he " had less nonsense in his head than any man living." The elegance of his taste, which has been observed upon as 350 BLACK. shown in his lectures, was also seen in the efforts of his pencil, which Professor Robison compares to that of Woollett. The neatness of his manipulations was not confined to his experiments when investigating or when lecturing. I have heard one who happened to see him at his toilette describe the operations as per- formed with exquisite neatness by a number of contrivances happily adapted to the saving of trouble and avoiding uneasiness. His perfect equanimity has been adverted to, and it did not proceed from coldness of disposition, for he was affectionately attached to his friends. Having no family of his own, he may be said to have fallen into those precise and regular habits which sometimes raise in happier individuals a smile, I stop not to inquire whether of envy or contempt, for the single state. It was sometimes said, too, that his habits were penurious. That the expenses of one who had no love of pleasure and no fancy for ostentation to gratify, must have been moderate, is certain ; but he lived in the style and manner suited te one possessing an ample income. The ground of the charge was, I believe, that he was said to have a scale by him when he received the fees of his students. I can answer for the truth of this statement, for I well remember the small brass instrument ; but I also recollect that he said it became necessary from the quantity of light gold which he used at first to receive unsuspected from one class, particularly, of his pupils. There was certainly no reason why he should pay a sum of forty or fifty pounds yearly out of his income on this account. Both Professor Ferguson and Professor Robison have positively denied the charge of avarice, and have given BLACK. 351 ample testimony even to his generous nature. While he lived at Glasgow he lost three-fourths of his fortune by the failure of a house in which it was invested ; and though he had foreseen the catastrophe for two years, he neither attempted to withdraw his funds, nor altered in any respect his kind demeanour towards the head of the firm, whom he knew. At Edinburgh he more than once incurred great risks to help friends in business. The gradual decay of his strength brought about the extinction of life without pain and without any discom- posure. Professor Robison told me that he was sure nothing could be more agreeable to his illustrious friend's wishes than this end, as nothing was more likely to vex and annoy him than the unavoidable ac- companiments of a protracted illness and a sick-bed. He often indeed expressed a wish that he might be spared this suffering, and that wish was fully gratified. It seemed, said the Professor, as if he waited calmly until the last stroke of his pulse should be given. It is cer- tain that he passed from this life so quietly as not to spill a cup of milk and water (a customary dinner with him) which he at the moment was holding in his hand, and which rested on his knee. His attendants saw him in this posture, and left the room supposing him still alive. On returning soon after they saw him exactly sitting as before, and found that he had expired. ( 352 ) WATT. THE intimacy of Mr. Watt with Dr. Black from his earliest years has been already mentioned. When the latter was a Professor at the University of Glasgow, Watt, then a young man, was employed as mathe- matical instrument maker to the Natural Philosophy class, and was in daily communication with the Pro- fessor while his experiments on heat, evaporation, and condensation were carried on. I well remember him afterwards, in his lectures at Edinburgh, mentioning that his young coadjutor employed himself at the same time in researches upon the nature of steam ; and it is certain that his subsequent inventions were greatly aided by the discoveries of Black respecting heat. To the inquiries out of which these inventions arose, he appears to have been led by the accident of having a model of an engine to repair for the Professor of Natural Philosophy. But, before examining the foundations upon which his great and well-earned fame rests, it is fit that we should first consider the state in which he found the engine, which he almost created anew. This is following the same course which has been pursued with respect to the discoveries of Dr. Black. The power of steam is far too generally perceived in the ordinary affairs of life to have wholly escaped the WATT, WATT. 355 clearly described in his book appears to me to have no foundation. The inference arising from the descrip- tion seems to remove that doubt ; but we have external evidence more precise and satisfactory still.* The travels in England of the Grand Duke of Tuscany, Cosmo de' Medicis, were written by his Secretary, Magalotti, a man of some scientific eminence ; and a translation into English was published in 1821. The visit to London took place in the year 1 669 ; and it appears that the Grand Duke "went to see, at Vaux- hall, an engine or hydraulic machine invented by the Marquis of Worcester," and the account which he gives of it tallies with Lord Worcester's description of his " stupendous water-commanding engine." The account of Lord Worcester is far from being clear and distinct, and nothing appears to have resulted from his suggestions. In 1690, Papin, an eminent and able French engineer, settled in London, and author of the digester which goes under his name, pub- lished a work in which he showed that he had made two most important steps in the use of steam. Caus and Worcester had applied the force directly to the body which it was intended to move ; and it was evident that, while that was a condition of its use, very limited bounds must confine the operation. But Papin, observing the use of the piston in a com- mon sucking-pump, applied this to the steam machine, making it work in the cylinder, and be the medium of * See also the Marchioness of Worcester's correspondence with her Confessor, communicated by the Beaufort family to Mr. Par- tington for his edition of the < Century/ 2 A 2 356 WATT. communicating motion to other apparatus. Next, he applied steam directly as the agent, to raise the piston ; and making a vacuum by the condensation of the steam, he thus caused the atmosphere to press down the piston. Guericke, the inventor of the air-pump, had half a century earlier used the vacuum, made by his machine in the same manner, as a mechanical power, by the help of a piston and rod ;* and he invented the valve, without which the vacuum could not be produced. The application of the same principle and of the same contrivance to steam was Papin's ; and its importance,, and his merit, are not diminished by considering the source from which he borrowed it.f Indeed the action of the air in the sucking-pump is another form of the same experiment. It must be added that to Papin also we owe the im- portant invention of the safety-valve, although he did not apply it to the steam engine. He introduced it as a part of his digester, but suggesting that it was appli- cable to the steam engine. It is, however, certain that the most rude and cum- brous part of the former invention was continued by Papin. The fire was applied to the water, and when it had filled the cylinder with steam, the condensation was only effected by withdrawing or extinguishing the fire. Savery about the year 1 698 made considerable * See the distinct figure in his plate xiv., p. 109, of * Experi- menta nova Magdeburgica de Vacuo Spatio/ Amstelodami, 1672. | Acta Eruditorum, 1688. The paper has an excellent and clear figure. Nothing can be more groundless than Mr. Stuart's statement that Baptista Porta had anticipated Papin in this impor- tant step. The passage refers only to the rise of water in a vacuum. See * I tre Libri dei Spiritali,' 1606. WATT. 357 improvements on the apparatus ; and though he did not use the vacuum as Papin had done, but only as it is used in the sucking-pump, he yet produced it by apply- ing cold water to the outside of the cylinder. The machines made by him were so manageable that they were brought into use for raising water in many country houses. D'Alesme exhibited a machine before 1705 (as appears by the c Histoire de 1' Academic des Sciences' for that year, p. 1 37), in which water was made to spout to a great height by the force of steam alone. It is extremely doubtful if Papin ever erected any steam engine, either upon his own or upon any other principle. It is certain that he did not adhere to the two great propositions which he had brought forward, the operating by a piston, and the operating by the pressure of the atmosphere ; he recurred to the old plan of making the steam act directly upon the weight to be raised. In 1711 Newcomen, an iron-master of Dartmouth, and Galley, or Cawley, a glazier of the same town, constructed an engine upon Papin's principle of a piston and a condensing process, using, however, Savery's mode of creating a vacuum by cold affusion, for which they were led by an accident to substitute the method of throwing a jet or stream of cold water into the cylinder. This important improvement saved, in a considerable degree, the waste of heat occasioned by Savery's method of condensing. Their engine could be applied with advantage to raise water from mines, which Savery's was wholly incapable of effect- ing, its power being limited to that of the sucking- pump. Newcomen's engine, as it is generally called, made no use at all of the direct force of steam ; it 358 WAIT. worked entirely by means of the vacuum ; and hence it is sometimes and justly termed the atmospheric engine, as its moving force is the pressure of the atmosphere. Desaguliers, who has given the best description of Newcomen and Cawley's engine, about the year 1717 or 1718 made several of those engines, in which he executed Papin's suggestion of using the safety- valve. In the same year Beighton perfected the me- chanism whereby the engine itself shut and opened the valves, by which the supply of steam to the cylinder and of water to the boiler is regulated ; and Smeaton subsequently made some other mechanical improve- ments. With these exceptions the steam engine con- tinued exactly in the same state from the time of New- comen to that of Watt, above half a century later. We have thus seen how very slowly this great invention was brought to the state in which Mr. Watt found it, and how considerable a number of persons con- tributed each a small share to its progress. Let us enu- merate these steps : they are at least six in number. S. de Caus made steam act to raise water ; Worcester per- formed this operation in a more regular and mechanical manner ; Papin used the condensation of steam, and through that the atmospheric pressure, as well as the direct expansive force, and he worked the engine by a piston ; Savery condensed by refrigeration instead of the mere absence of fire, but did not use the atmosphere ; Newcomen used the jet for condensing and the atmo- sphere for pressure, but did not use the direct force of steam ; Desaguliers introduced the safety-valve ; Beigh- ton and Smeaton improved the mechanism ; D'Alesme needs not be mentioned, as we are not informed what WATT. 359 plan he executed, but he certainly made no step himself. If the direct force of steam, as well as atmospheric pressure, had been both employed, with the jet of cold water, the safety-valve, and the contrivance for regu- lating the supply-valves, a far better engine than any ever known before the time of Watt would have been produced, and yet nothing whatever would have been added to the former inventions ; they would only have been combined together. The result of the whole is, that one of the greatest theoretical steps was made by Papin, who was, during a long period, little commemo- rated; and that Savery and Newcomen, who have been by many called the inventors, were the first of all the inge- nious and useful persons whose successive improvements we have now recorded, to apply the steam-engine to practical purposes. France has thus produced the man who, next to Watt, must be regarded as the author of the steam-engine : of all Watt's predecessors, Papin stands incontestably at the head ; but it is almost cer- tain that he never actually constructed an engine. Though the engine of Savery was of considerable use in pumping to a small height, and indeed has not entirely gone out of use even in our own times, and though Newcomen's was still more extensively useful from being applicable to mines, not only had no means ever been found of using the steam power for any other purpose than drawing up water, but even in that operation it was exceedingly imperfect and very expensive, insomuch that a water power was often preferred to it, and even a horse power in many cases afforded equal advantages. The great consumption of fuel which it required was its cardinal defect; the 360 WATT. other imperfection was its loss of all direct benefit from the expansive force of the steam itself. That element was only used in creating a vacuum, and an air-pump might have done as much had it been worked by water or by horses. It was, in the strictest sense of the word, an air and not a steam engine. When Mr. Watt was directed to repair the working model for the Professor at Glasgow, he of course exa- mined it attentively. He was at that time, 1763, in his twenty-eighth year, having been born in 1736 at Greenock, where his father was a magistrate, and had learnt the business of a mathematical instrument maker. He had been prevented by delicate health from benefiting much by school instruction ; but he had by himself studied both geometry and mechanics, hav- ing from his childhood shown a marked taste for those pursuits, in which his grandfather and uncle, teachers of the mathematics, had been engaged. It is related of him that a friend of his father's one day found the child stretched on the floor drawing with chalk nume- rous lines that intersected each other. He advised the sending the young idler, as he supposed him, to school, but the father said, " Perhaps you are mistaken ; exa- mine first what he is about." They found he was try- ing, at six years old, to solve a problem in geometry. So his natural turn for mechanics was not long in showing itself; and his father indulging it by putting tools in his hands, he soon constructed a small elec- trical machine, beside making many childish toys. He occasionally visited his mother's relations at Glasgow, but never attended any lectures there, or elsewhere. The ardour of his active mind was su- WATT. 361 perior to all the restraints which the weakness of his bodily frame could impose. He devoured every kind of learning. Not content with chemistry and natural philosophy, he studied anatomy, and was one day found carrying home for dissection the head of a child that had died of some hidden dis- order. His conversation, too, was so rich, so animated, that we find, from the relation of Mrs. Campbell, a female cousin of his, the complaints made by a lady with whom he resided. She spoke of the sleepless nights which he made her pass by engaging her in some discus- sion or some detail of facts, or some description of phe- nomena, till the night was far advanced towards morn- ing, and she found it impossible to tear herself away from his talk, or to sleep after he had thus excited her. In 1755 he placed himself with Mr. Morgan, mathematical and nautical instrument maker, of Cornhill, and resided with him somewhat less than a year, during which he was chiefly employed in the preparation and adjustment of sextants, compasses, and other nautical instruments. But the same fee- ble health which had interrupted his studies at Glasgow again oppressed him ; he was obliged to leave London, and return to Glasgow. On his arrival there he had the intention of setting up as an instrument maker, but the Glasgow Body of Arts and Trades, one of the sub-corporations in the muni- cipal corporation of that city, opposed him as not free of their craft or guild, and therefore not entitled to exercise his calling within the limits of the charter. Attempts were made to obtain their leave for a very small workshop, on the humblest scale, but this was 362 WAIT. peremptorily refused. The University therefore came to his assistance, granted him a room in their own building, and gave him the appointment of their mathematical instrument maker. There remain small instruments then made by him in this workshop, and executed entirely with his own hands ; they are of exquisite workmanship. The earliest of his steam- engine drawings are likewise preserved, and those competent judges who have examined them, particularly M. Arago, describe them as " truly remarkable for the neatness, the strength, and the accuracy of their outline." His manual dexterity and skill, therefore, is clear, and he had good cause to plume himself as he always did upon it, estimating the same quality in others at its just value. In the course of a very few years, beside renewing his intimacy with Mr. Robison, afterwards Professor there and at Edinburgh, he became intimately acquainted with the most eminent of the Glasgow Professors, Adam Smith, Robert Simson, Robert Dick, and above all, Dr. Black. Of these all but Mr. Dick have left the deep im- press of their great names upon the scientific history of their age ; and he was always described by both Mr. Watt and Professor Robison as a person of most admira- ble capacity and great attainments, treating natural philosophy, too, with singular ability and success, nor prevented from acquiring a more extensive and lasting reputation by anything save his premature death. While thus occupied and thus befriended by men of great names, his own reputation increased daily as a successful cultivator of natural science. His work- WATT. 363 shop became the resort of all zealous students and enlightened inquirers into physical science, and was particularly resorted to by the pupils of the University. Professor Robison tells us that though regarding himself as a proficient in the mixed mathematics and in experimental philosophy, he was somewhat mortified at finding Watt so greatly his superior in the same favourite departments of study. In truth, it was the ordinary practice to consult him as the oracle upon any difficulty coming in the way of either students or in- quirers. His fixed resolution to be deterred by no difficulties was constantly apparent, and one example is given by the Professor. The solution of a problem which occupied Watt and his friends, seemed to require the perusal of JLeupold's Theatre of Machines, and as it was written in German, he at once learnt that language in order to consult the book. Another instance of his indomitable perseverance against great difficulties apparently irremovable, though not insuper- able, may be added. He had no ear at all for music : not only was he through life wholly insensible to its charms, but he could never distinguish one note from another; yet he undertook the construction of an organ ; and the instrument which he made not only had every mechanical merit from the most ingenious contrivances for conducting and regulating the blasts and the move- ments of the machine, but produced the most admirable harmonic results, so as to delight the best performers. He overcame the difficulties which lay in his way, partly by the phenomenon of the beats of imperfect consonances, a theory then little understood, and only contained in a work at once very profound and very 364 WATT. obscure, Smith's ' Harmonics/ This treatise, of which only the first and less perfect edition was then pub- lished, must have been read and understood by the young engineer. While employed by Dr. Roebuck at his Works, he made a guitar for his daughter, after- wards Mrs. Stuart, which she still possesses, and relates the sum given for it to have been five guineas. It only remains to add that all the reading and all the speculations of Watt were strictly confined to hours which did not interfere with his profession or his trade of an instrument maker. The whole of the day was devoted to his business, only subject to the interruption of the discussions raised by those who frequented his workshop in search of assistance and information. It was late in the evening, or rather in the night, that he prose- cuted with zeal and close attention his philosophical studies; for his principle through life was steadily kept in view, and uniformly acted on, never to let anything whatever interfere with business, the transaction of which he regarded as a primary duty to be performed, and entitled, as such, to take precedence of all other pursuits. There chanced to be among the apparatus of the Natural Philosophy class a model of Newcomen's steam-engine, which, from some defect in the construc- tion, never could be got to work well ; and Mr. Watt was desired to examine and report to the Professor, Mr. Anderson, successor of Dr. Dick, and better known afterwards as having founded by his will the class in which Dr. Birkbeck taught the working men, and thus gave rise to Mechanics' Institutes. The construc- tion of this working model was found to be exceedingly WATT. 365 imperfect, but Mr. Watt soon remedied all its defects. As far as the kind of engine could answer its purpose, the apparatus was found to perform its functions satis- factorily, being annually exhibited to the class with great success. He had, however, been taught by his examination of the model what were the defects of the machine itself, and which no care in repairing or ad- justing that model could remove. He found first of all that the boiler was much too small in proportion to the column of water which the steam had to raise, and yet it was larger than the boiler used in practice. The cylinder was on the scale of two inches diameter, the height being half a foot. The vacuum being imper- fect from the size of the boiler, he diminished the length of the piston rod. He found that the brass of which the cylinder was made carried off a great deal of heat, and that too large a surface was exposed to the steam. These observations set him upon making a variety of experiments upon steam, and upon the mode of applying it both directly and to produce a vacuum. He had, in the year 1759, while a fellow-student with Mr. Robison, received from that gentleman a sugges- tion of the application of steam to wheel-carriages, as he tells us in 1803, long before steam travelling was dreamt of.* They had together made experiments on Papin's digester, in order to ascertain the expansive force of steam ; but these speculations had for several years * Mr. Murdock, in 1784, made a working model of a steam- carriage, which moved about the room. It was constructed upon the principle set forth in Mr. Watt's specification of 1769, Art. iv., and this is the very method used at the present day. 366 WATT. been given up. In 1760 and the two following years Watt had been in familiar intercourse with Professor Black, had witnessed his experiments on heat, and had learnt from him the true cause of evaporation and condensation. When, therefore, he began to experi- ment upon the mechanical application of steam, its expansion, and its condensation, he enjoyed that ines- timable advantage of thoroughly knowing the princi- ples on which its changes and its action depended. His own experiments now put him in possession of the causes which determine the rapidity of evaporation, the proportion which it bears to the surface exposed to the fire, the effects of pressure upon the boiling-point, and the quantity of fuel required to convert a given quantity of water into steam — circumstances which had hitherto been only vaguely and generally examined, but which he now reduced to mathematical precision. The first discovery which he made upon the atmo- spheric engine and its waste of fuel, was that the in- jection of cold water which condenses the steam also cools the cylinder to a degree which requires a great expenditure of fuel again to give it the necessary heat for keeping the steam expanded to fill it. He found that three-fourths of the fuel employed were thus con- sumed ; in other words, that if the cylinder could be kept at the temperature which it has before the jet is thrown in, one-fourth of the fuel would suffice for the operation. The next defect of the process was scarcely less im- portant. The water injected, coming in contact with the steam, was itself heated ; the evolution of the latent heat, which Black's discovery showed Watt WATT. 367 necessarily took place on its condensation, had the effect, together with the absorption of the steam's sensible heat, of converting a portion of the injected water itself into steam. Hence the vacuum was very far from perfect ; and the resistance which the piston thus met with in its descent was found to be equal to one- fourth part of the atmospheric pressure, that is to say, the working power of the machine was diminished one-fourth. From the distinct view thus obtained of the evil arose the suggestion of the remedy. The whole mis- chief proceeded from the condensation being performed in the cylinder, where the steam was thrown and the piston worked. It occurred to Watt, that if the con- densation could be performed in a separate vessel, com- municating with the cylinder, the latter could be kept hot while the former was cooled, and the vapour aris- ing from the injected water could also be prevented from impairing the vacuum. The communication could easily be effected by a tube, and the water could be pumped out. This is the first and the grand inven- tion by which he at once saved three-fourths of the fuel, and increased the power one-fourth, thus making every pound of coal consumed produce five times the force formerly obtained from it. But this was not all. He found it expedient to remove the air from the upper part of the cylinder, as it tended to diminish the heat. In effecting this he was, secondly, led to open a com- munication with the boiler, and introduce steam above the piston while it descended, thus making the upper chamber of the cylinder air-tight. The steam thus acted in aiding the descent of the piston, instead 368 WATT. of that descent being accomplished merely by the atmospheric pressure. Thirdly — the counterpoise at the pump-rod was done away, as a mere loss of power, and the piston was now forced up- wards by the steam entering to fill the cylinder. These two great additional improvements only required a communication to be opened by tubes with the con- denser as well as the boiler, and they gave to the machinery its right to be called a steam-engine ; for it now worked more by steam than by air. The upper chamber was kept air-tight by making the piston-rod work in a socket of tow saturated with grease, called the stuffing-box, which also diminished greatly the friction of the rod. If Mr. Watt's invention had gone no further than this, we may perceive that it not only increased the power of the fuel fivefold directly, but obtained from the steam as much additional force as could be derived, the limit being only the strength of the materials, within which limit the safety-valve of Papin always enabled the engineer to keep his power. But the three particulars which have been described were not the whole of this great engineer's improvements upon the mechanism of his predecessors. The smooth working of the engine, especially if it be applied to other and finer operations than those of the miner, depends essentially on the accurate position of the piston rod, with whatever velocity moving, and against whatever weight contending. Its motion must be steadily maintained in the same vertical straight line, or in the same horizontal line, or in the same straight line whatever be its direction, without WATT. 369 shaking or inclining so as to press at all against the sides of the cylinder — any such lateral pressure occa- sioning a loss of time, a jolting motion, a general de- rangement of the machinery. The motion of the rod and the piston must be perfectly equable, continuous, and smooth : it must work, as the engineers sometimes say, sweetly, at every instant, in order that the engine may well perform its functions. The contrivance for producing this motion of the rod so that it shall be always in one line, parallel to some supposed line whether vertical, as in a mine, or horizontal, or in any other direction, is thence called the " Parallel Motion" and it is one of Mr. Watt's most exquisite discoveries, and one to which scientific principle has the most con- duced. If a circle or other curve has its curvature gra- dually changed, until from being concave to its axis it becomes convex, it will pass through every possible position or variation (whence the great refinement upon fluxions, the calculus of variations, probably derived its name, if not its origin), and at one point it will be a straight line, or will coincide with a straight line. So if a curve have two branches, one concave to the axis, the other convex, as a cubic para- bola for example, the point at which its concavity ends and its convexity begins, is called for that reason a point of contrary flexure. The contrivance of the parallel motion consists in making the contrary circu- lar motions of arms which bear on the rod always keep to the point of contrary flexure and thus give a recti- linear motion to the rod, the tendencies to disturb it correcting each other. It was long ago shown by Sir Isaac Newton, in the ' Principia,' that if a circle moves 2 B 370 WATT. upon another of twice its diameter, each point describes a straight line. This is precisely the principle of the parallel motion. Three beams are made to revolve round different centres, two of these being moveable in the arm of the engine, and one fixed without it. These three are connected together and with the piston-rods of the cylinder and the pumps, which their revolu- tions cause to describe accurately straight lines. $-. A fifth invention is the Floaty which, placed on the surface of the water in the boiler, descends until the water is so low as to require a supply ; it then opens a valve which lets in the quantity wanted ; for, as soon as it rises to a certain height, the valve is shut by the float. The most refined contrivance of the whole may now be mentioned, in the sixth and last place, the adaptation of the Governor, previously used in wind and water mills. It is evident that the velocity of the working may be increased beyond what is required or con- venient without the safety-valve giving any indi- cation of the excess, and also that the warning given by this valve does little more than point out the risk without providing the remedy or preventive. The governor is a far more subtle invention. Two balls are fixed to the end of arms which are connected with the engine by a moveable socket ; this can play up and down a vertical rod revolving by a band on the axis or spindle of the fly-wheel, and it revolves, there- fore, with the velocity of that spindle. The arms are perfectly moveable on their centres, which are fixed in the socket and on opposite sides of it. Their centrifu- gal force, therefore, makes them diverge, more or less, in proportion as the rotatory motion of the spindle and WATT. 37 1 consequently the velocity of the engine increases; their divergence pushes the collar up the spindle, its axis, and as it rises, it closes, by means of cranks, a valve called the " throttle-valve," in the pipe which conveys the steam from the boiler to the cylinder, and this lessens the supply of steam : the motion of the engine is thus reduced, the centrifugal force is abated, the balls approach the spindle again, the collar de- scends, the throttle- valve is gradually opened, and the supply of steam again slowly increased, but never be- yond the quantity required, because as soon as that is exceeded, the increase of centrifugal force causes the balls to diverge, the collars to rise, and the valve to close. Thus the engine itself provides for its con- tinuing in the state of perfect adjustment required. As long as its motion continues uniform, the balls revolve at the mean distance from their axis without either receding or approaching, and the supply of steam con- tinues the same. As soon as the motion becomes ex- cessive, they diverge, and the supply of steam is dimi- nished ; as soon as the motion becomes defective, they converge, and the supply of steam is increased. But further, the baHs themselves, by their increased motion, absorb part of the force, independent of their action on the throttle^valve, and so contribute to the adjustment* The sagacious inventor soon satisfied himself that he had almost created a new engine of incalculable power, universal application, and inestimable value. But he had not the funds either to try his invention upon an adequate scale so as to bring it into use, or to secure his property in it by obtaining a patent. After some repulses, he happily met with Dr. Roebuck, a 2B 2 372 WATT. man of profound scientific knowledge, and of daring spirit as a speculator. He had just founded the Carron Iron Works, not far from Glasgow, and was lessee, under the Hamilton family, of the Kinneil Coal Works. He was the grandfather of the present Member for Bath, who, descended from him on the one side, and from the Tickells* on the other, may be said to unite in himself rare claims to hereditary dis- tinction ; but who is probably destined to exalt the name of his family still higher by his own virtues. Dr. Roebuck, like too many ingenious men, founded these Carron and Kinneil Works for the benefit of others ; and though he agreed to Mr. Watt's terms of receiving two thirds of the profit, he was obliged by pecuniary embarrassments to retire from the partner- ship after a patent had been obtained in 1769, and an engine of an eighteen-inch cylinder had been erected at Kinneil. The success of this amply proved the solidity of the invention, but the inventor was obliged, for some years, to abandon the pursuit, and to labour in his profession of what is now termed a civil engineer ; but the extensive operations of which Scotland soon became the scene, gave a much more ample scope to his talents. He was actively engaged in the surveys, and afterwards in the works, for connecting by a canal the Monkland coal-mines with Glasgow. He was afterwards employed in preparing the canal since completed by Mr. Rennie, across the Isthmus of . * His maternal grandfather was the author of l Anticipation,' and grandson of Addison's friend, the poet. WATT. 373 Crinan ; in the difficult and laborious investigations for the improvement of the harbours of Ayr, Greenock, and Glasgow; in improving the navigation of the Forth and the Clyde ; in the Campbelton Canal, and in the surveys and plans preliminary to the Grand Caledonian Canal; beside several bridges of great importance, as those of Hamilton and Rutherglen. At Dr. Roebuck's Mr. Watt had early received much kindness, and many valuable lessons in chemical science. He was here, too, introduced to Dr. Black. The various works which have been mentioned occu- pied his whole time from the disappointment experienced in 1769 respecting the steam engine, of which during that long interval he never despaired, to the year 1774, when he acceded to the proposal of Mr. Boulton, of Soho, near Birmingham, that he should be taken in Dr. Roebuck's place as partner in the patent, and in 1775 he settled there in this new business. An extension of the patent for twenty-five years from this time was obtained from Parliament, in consequence of the national importance which all men saw belonged to the invention ; and the partners constructed many engines upon the terms of receiving one third of the fuel saved by the improvements. It is a convenient mode of illustrating the effect of the invention in saving fuel, to observe what were the gains of the partners under this stipulation. On one mine, that of Chasewater, in Cornwall, the proprietors com- pounded for 2400/. a year, instead of paying the third of the fuel saved. That saving then must very con- siderably have exceeded 7200/. a year. But there seemed some difficulty in carrying bargains of this kind 374 WAIT. into effect ; and the genius of Watt, fertile in resources, immediately invented a small clock, called the counter, to be moved by the engine, and which accurately re- corded every stroke it made. Payment being in propor- tion to the number of strokes, the clock was enclosed in a box under a double lock, and thus the working could be easily and securely ascertained.* The first consequence of this grand invention, and the great saving of fuel it occasioned, was the renewed working of mines which had become unprofitable under the old plan. The next was the opening mines which Newcomen's engine could not drain at all. The steam-power, too, was no longer confined to draining mines. Various contrivances, for which Watt took out no less than four patents between 1781 and 1785, enabled him to communicate a rota- tory motion from the piston, so that the engine could now work any machinery whatever ; could spin cotton, cut iron and brass, stamp cloth, grind corn, print books, coin money, in short, could perform on any scale any kind of work in which human labour was either inefficient or expensive ; and while it was seen in one place pouring out rivers from the bowels of the earth with the arms of a giant, or cleaving rocks of granite formation, or clipping huge bars of stubborn iron into ribands, it was elsewhere to be found * Such an engine could not be made and used secretly, and thus piracy was prevented. It is far otherwise with small pieces of mechanism, and still more difficult would be the protection of patent rights in mere methods, though to these the protection of the law should be extended. WATT. 375 weaving or spinning like a quiet and industrious fe- male, or turning a small lathe, or forming the fine wheels of a watch, or drawing out a thread too fine for sight ; when the machine, instead of sawing the air aloft, and making the ground tremble around it, was placed quietly on a table like a candlestick or an inkstand. The latest use of the power, and the most important, is steam travelling by land and water. Watt himself early perceived this application of his engine ; and in 1785 he took out a patent for moving carriages by steam, but he does not appear to have practically used his method. The attempts had been numerous, and from very early times, to propel vessels by steam. There seems reason to think that the paddle-wheel, the only addition to the steam-engine required for navigation, was known in ancient Egypt : it certainly was known to the Romans. In the middle of the sixteenth century a Spanish engineer exhibited a steam-vessel to Charles V. The Marquis of Wor- cester appears to have turned his attention to the subject from some parts of the work already cited, and so superciliously condemned by Hume ; and Jonathan Hulls, in 1736, took out a patent for a kind of steam- tug. Various similar attempts were afterwards made, but with no success, and it was not until the steam- engine had been improved and had become generally used for all other purposes that it was applied to those of locomotion. It is truly painful to reflect, that among the rewards which this great public benefactor was destined to reap for his invaluable services, was the lot of having to pass many years of his life in the unenviable situa- 376 WATT. tion of a party to suits at law and in equity, so numerous as might well have worn out the patience of any one but him, whose unwearied perseverance had already toiled successfully against unnumbered difficulties of another kind. Such was, at that time, the patent law of this country ; such, in some degree, it still is, though much improved. Inventive genius is placed between two dangers, and it can hardly escape the one without falling into the other. — If the invention is such that it requires some new demand to be created, or some novel taste to be introduced, before it can be much used, the period of the monopoly expires before any gain can be reaped. This is the more likely to happen if it comes in competition with things already made, and of which, at some expense, a considerable stock has been prepared, because a formidable interest is combined against the use of that new method which must displace the old, and render valueless this col- lected stock. I remember sitting on the trial of a patent for a new and admirable pianoforte ; the only witness to its excellence being a sculptor of distinction who had once made such instruments, but had no longer any interest in crying down the invention : none of the trade could be trusted to give their opinion upon oath ; all were, of course, in a combination against that improvement, which, if adopted, would render unsaleable their pianofortes already made, — If, on the other hand, the superiority of the invention is quite manifest, if the demand for it already exists, if no combination can prevent its coming into general use — for example, the making a new instrument for perform- ing a known and necessary operation, or a new substance WATT. 377 for supplying a general want already existing — then the inventor has to prepare himself for encountering piracy in all its forms; capitalists, who would be ashamed to violate the law in their own persons, en- couraging men of no substance to infringe the patent, and omitting to pay the patentee's costs when these tools are defeated. My learned and ingenious kins- man, Dr. Forsyth, the inventor of the percussion lock, passed the fourteen years of his patent right in courts of justice, and in every instance prevailed ; but he found the pirates pennyless, the costs were to be paid, and he never gained one shilling by an invention which is, I believe, more universally used all over Europe than any other, except, perhaps, Argand's lamp. That jnvention was defeated in court, in con- sequence of the imperfect state of the law in those days, and of the absurd leaning of the Judges against all patentees ; their Lordships displaying the utmost ingenuity in discovering flaws, and calling into action all the resources of legal astuteness in grinding, as they went on, new law for the defeat of the inventor. Of this, one instance only needs be given. If a speci- fication contained ten good matters or processes, and by oversight one was either not original, or did not answer the description given in any other respect,* the courts held the patent wholly void, and not merely void for the erroneously described part, upon the subtle and senseless ground that the Crown had been deceived in the grant. * Turner v. Winter, 6 T. R. ; Rex v. Fuller, 3 B. and A. My Acts of 1835 and 1840 have in great part remedied these sad defects in the law ; others still remain. 378 WATT. Mr. Watt had to struggle against this state of the law as well as against the shameless frauds, the conspiracies of dishonest, unprincipled men. During seven years and upwards he was condemned to lead the life of litigation ; during seven years his genius was withdrawn from his own pursuits to become what he, no doubt, had, unfortunately for society, full time to make himself, an accomplished and learned lawyer; and it was not till five and thirty years after his invention had been made, that he was finally freed by a decision of the Court of King's Bench, in 1799, from a durance which lasted all the term of his patent, after all interest in the subject had expired by efflux of time. It was proved before a committee of the House of Commons in 1834, that had his statutory term in the patent only been secured to him, he would have been a great loser by the in- vention; and that for some years after the Act of Parliament had extended the time, he still was out of pocket: consequently it follows, that had he never taken a patent at all, but trusted entirely to the pre- ference which his being the inventor would have given him in the market, as a maker of steam-ap- paratus, that is, had he taken only this indirect benefit instead of the direct gains of the monopoly, he would have been better off in a pecuniary point of view than he was by means of the grant of the patent and its Parliamentary extension. The Act which I introduced in 1835, grounded mainly upon that evidence, has removed some of the greatest defects in the law ; and it has enabled, when coupled with the subsequent Act of last Session, an inventor to obtain, WATT. 379 at a very inconsiderable cost, an extension for any additional period, not exceeding the duration of the original patent.* The expenses of obtaining patents, and especially the grievous burden of having to take out one for each of the three kingdoms, are the principal parts of the grievance which remain to be redressed. Notwithstanding the serious drawbacks upon his gains which Watt thus experienced, he was, on the whole, successful in respect of profit, realizing an ample fortune, but which all men wished had been greater, and which, under a more just law, would have been thrice as great. We have been contemplating the great achievement of Watt, but it would be a mistake to suppose that the steam-engine is the only monument of his scientific ' genius or his inventive skill. He was the author of the machine in general use for copying letters ; of the method extensively used for heating buildings and hot-houses by steam ; and of an ingenious mechanism for multiplying copies of busts and other sculptures ; but he was also, without any doubt, the person who first discovered the composition of water. At this * The course which a patentee ought to pursue if there be no opposition to his claim of extension, is to employ no solicitor and no counsel, but to appear in person before the Judicial Com- mittee, as ray gallant and truly ingenious friend Lord Dundonald (better known as Lord Cochrane) lately did. Their Lordships will always favour such a course, the rather as they thus obtain the advantage of hearing the explanations required from the person best able to give them. In opposed cases professional aid is requisite. 380 WATT. most important truth he arrived by a profound ex- amination of all the experiments which had been made by Warltire, by Macquer, and especially by Priest- ley, upon the combustion of hydrogen and oxygen gases, then called inflammable, and vital or dephlo- gisticated airs. No former reasoner had come even near the true theory of the phenomena observed in those experiments. All had assumed that water was a simple or elementary body ; that it was contained in the airs burnt together, and was precipitated by their explosion. He, on the contrary, showed that it was formed by the union of the two gases, and their parting with the latent heat which had held them in the elastic or gaseous state, but which being with- drawn by their union, left them in a state of liquid or aqueous fluidity. As early as 1782, his attention had been closely directed to the experiments in which air is produced from water, and especially to those upon the com- bustion of inflammable air. In December of that year he had matured his theory, for we find him then an- nouncing to De Luc his discovery, that " one element must be dismissed from the list ;" water being, ac- cording to his doctrine (stated more explicitly to Dr. Black, April 1783,) " composed of dephlogisticated and inflammable airs deprived of a portion of their latent heat." To his whole correspondence with that great philosopher, with Smeaton, with Priestley, De Luc, and others, I have had access, and no trace is to be found in it that either he or they had even entertained the least suspicion of the same thing having before occurred WATT. 381 to any one else.* It is to be noted, too, that in 1784 Mr. Cavendish, after his celebrated experiment, had not attained by any means so clear a notion of the true doctrine as Mr. Watt explains in those previous letters, f I examined minutely the whole of this subject eight years ago, at the request of my dis- tinguished colleague M. Arago, then engaged in preparing his < Eloge' of Mr. Watt, who had also been our fellow-member of the Institute. The reader will find my statement of the evidence annexed to this account. But I cannot easily suppose that M. Arago ever intended, and I know that I never myself intended, to insinuate in the slightest degree a suspicion of Mr. Cavendish's having borrowed from Mr. Watt. He had, in all probability, been led to the same conclusion by his own researches, ignorant of Mr. Watt's speculations, a little earlier in point of time, just as Priestley when claiming, and justly claiming, the important discovery of oxygen (called by him, in accordance with the doctrine of Stahl, " dephlogisticated air"), never denied that Scheele also made the same discovery, calling it " empyreal air," without being aware of another having preceded him. Priestley, of course, treated the dis- creditable proceedings of Lavoisier in respect to this gas very differently, and so must all impartial men. It must on no account be supposed that Watt cannot be considered as having discovered the composition of water, merely because he made no new experiments of particular moment, like Cavendish, to ascertain that * Letters to Gilbert Hamilton of Glasgow, Fry of Bristol, Smeaton, De Luc — all dated March and April, 1783. f See Life of Cavendish for further particulars and explanations. 382 WATT. capital point. No one refuses to Newton the discovery of gravitation as the controlling and directing power of the solar system ; and yet he made not one of those observations upon which his theory rests ; nay, he threw it aside for sixteen years when the erroneous notion of a degree being only sixty miles appeared by its consequences to disprove his proposition, and instead of making any further experiments himself, waited until Picard's more accurate measurement became known to him accidentally in 1682, and enabled him to demonstrate his doctrine. In like manner, Lavoi- sier, who discovered no gas, and made no original experiments of the least value in pneumatic chemistry, is universally admitted to have discovered the true theory of combustion and calcination, by reasoning on the facts which others had ascertained. Watt's happy inference from the facts discovered by Warltire and Priestley was just as much entitled, and for the same reasons, to be regarded as the discovery of the composition of water. The latter years of Mr. Watt's useful and honour- able life were passed in the bosom of his family and the society of his friends, although he ever gave the due attention to the extensive concerns of the house in which he was the principal partner. He had been married as early as 1764 to Miss Miller, his cousin, and had by her a daughter who predeceased him, leaving children, and a son, James, who still survives, inherit- ing the scientific tastes, the extensive knowledge, the masculine understanding, and the scrupulous integrity of his father. With the late Mr. Robinson Boulton and Mr. Gregory Watt, he was admitted into the part- WATT. 383 nership, the concerns of which he extended, and, for the last quarter of a century, almost exclusively conducted. By his second wife, Miss Macgregor, whom he married in 1776, he had one son, Gregory, who unfortunately died in October, 1804, at the age of twenty- seven, after giving an earnest of brilliant ta- lents and accomplishments. This loss was, no doubt, a severe blow to his family, and the father shared fully in their sorrow. But he bore it like a man : and I feel great satisfaction in correcting an error into which my illustrious friend and colleague M. Arago has fallen through misinformation, when he represents Mr. Watt's spirit as so entirely broken by the misfortune that he " preserved an almost total silence during the latter years of his life." The fact is, that he survived his son's death between fourteen and fifteen years, and never was more cheerful or enjoyed the pleasures of society more heartily than during this period. I can speak on the point with absolute certainty, for my own acquaintance with him commenced after my friend Gregory's decease. A few months after that event, he calmly and with his wonted acuteness discussed with me the composition of an epitaph to be inscribed on his son's tomb. That autumn and winter he was a constant attendant at our Friday club, and in all our private circles, and was the life of them all. He has, moreover, left under his hand an account of the effect which the recent loss had produced upon his spirits, and a flat contradiction to the notion that it had de- pressed them. " I perhaps," he observes, "have said too much to you and Mr. Campbell on the state of my mind : I therefore think it necessary to say that I am 384 WATT. not low-spirited, and were you here you would find me as cheerful in the company of my friends as usual ; my feelings for the loss pf poor Gregory are not passion, but a deep regret that such was his and my lot." He then expresses his pious resignation to the will of " the Disposer of events." It is true, he adds that he had lost one stimulus to exertion, and with it his relish for his usual avocations, but he looks to time for a remedy, and adds, " meanwhile, I do not neglect the means of amusement which are within my power." This letter was written in January 1805, only a few weeks after the loss of his son. In another letter written in April to the same gentleman, his cousin, Mr. Muirheadj great uncle of the able and learned translator of M. Arago's ' Eloge,' after expressing his confident hopes that Gregory had changed this mortal state for a far happier existence, he says, as if anxious to avoid all suspicion of his giving way to excessive sorrow, " You are not to conceive that we give way to grief : on the contrary, you will find us as cheerful as we ought to be, and as much disposed to enjoy the friends we have left as ever. But we should approach to brutes if we had no regrets." In this letter he quotes the beautiful lines of Catullus, " Nunc it per iter tenebricosum," &c. To this evidence at the period of his son's death let me add the testimony of Lord Jeffrey, who knew him well, and who brings down the account to the latest years of his life. " His health, which was deli- cate from his youth upwards, seemed to become firmer as he advanced in years ; and he possessed, up almost to the last moments of his existence, not only the full command of his extraordinary intellect, but all the WATT. 385 alacrity of spirit and the social gaiety which had illu- mined his happiest days. His friends in this part of the country (Edinburgh) never saw him more full of intellectual vigour and colloquial animation, never more delightful or more instructive, than in his last visit in autumn 1817." It was after this period that he invented the machine for copying sculpture. He distributed among his friends some specimens of its performances, jocularly calling them " the productions of a young artist just entering into his eighty-third year." In the summer of .the following year, 1819, 1 saw him for the last time, and did not observe any change in his conversation or in his manner ; but I understand that he suffered some inconvenience through the summer ; though, until a few weeks before his death, he was not seriously indisposed. He soon became aware of the event which was approaching, and he seemed only anxious to impress upon his sorrowing family the circumstances cal- culated to minister consolation under the change which must soon take place. He expressed his sincere gratitude to Divine Providence for the blessings which he had been permitted to enjoy, for his length of days, his exemption from the infirmities of age, the calm and cheerful evening of his life passed after the useful labours of its day had closed. He died on the 25th of August, 1819, in his eighty-fourth year. His remains lie buried in Handsworth church, near his residence of Heathfield, and a statue, the work of Chantrey, is there erected to his memory by his son ; and the same filial piety has presented a statue to the College of Glas- gow, in grateful recollection of early patronage. But a truly noble monument is raised to him in West- 2 c 386 WATT. minster Abbey, by the genius of Chantrey, at the expense of the Sovereign and of many Peers and distinguished Commoners, who held a meeting in honour of this illustrious man and great public bene- factor. The Ministers of the Crown, and the chiefs of the opposition in either House of Parliament, the most eminent men of science, the most distinguished cultivators of the arts, assembled with this view, and the account of their proceedings was made public in an authentic form. The Prime Minister, Lord Liver- pool, presided ; and it was none of the least remarkable passages of that day, that his successor, the present Premier, was anxious to declare the obligation under which he lay to the genius of him they were comme- morating, the fortunes of his family being reared by manufacturing industry, founded upon the happy inventions of Arkwright and Watt. It has ever been reckoned by me one of the chief honours of my life, that I was called upon to pen the inscription upon the noble monument thus nobly reared. The chisel of Chantrey, whose greatest work this certainly is, has admirably presented the features of the countenance at /once deeply meditative and calmly placid, but betokening power rather than delicacy and refinement. The civilized world is filled with im- perishable records of his genius, and the grateful recollection of the whole species embalms his memory. But for this, the author of the epitaph might well feel how inadequately his feeble pen had performed its office in attempting to pourtray such excellence : how much more inadequately when its lines are traced in most disadvantageous contrast with the signal success of the sculptor ! He who has ever made the attempt to write WATT. 387 with a chisel in our language, little lapidary as it cer- tainly is, will comprehend the extraordinary difficulties of the task, and will show mercy to the failure : — NOT TO PERPETUATE A NAME WHICH MUST ENDURE WHILE THE PEACEFUL ARTS FLOURISH BUT TO SHEW THAT MANKIND HAVE LEARNED TO HONOUR THOSE WHO BEST DESERVE THEIR GRATITUDE THE KING HIS MINISTERS AND MANY OF THE NOBLES AND COMMONERS OF THE REALM RAISED THIS MONUMENT TO JAMES WATT WHO DIRECTING THE FORCE OF AN ORIGINAL GENIUS EARLY EXERCISED IN PHILOSOPHIC RESEARCH TO THE IMPROVEMENT OF THE STEAM ENGINE ENLARGED THE RESOURCES OF HIS COUNTRY INCREASED THE POWER OF MAN AND ROSE TO AN EMINENT PLACE AMONG THE MOST ILLUSTRIOUS FOLLOWERS OF SCIENCE AND THE REAL BENEFACTORS OF THE WORLD BORN AT GREENOCK MDCCXXXVI DIED AT HEATHFIELD IN STAFFORDSHIRE MDCCCXIX. We have been considering this eminent person as yet only in his public capacity, as a benefactor of mankind by his fertile genius and indomitable perse- verance ; and the best portraiture of his intellectual character was to be found in the description of his attainments. It is, however, proper to survey him also in private life. He was unexceptionable in all its relations ; and as his activity was unmeasured, and his taste anything rather than fastidious, he both was master of every variety of knowledge, and was tolerant of discussion on subjects of very subordinate importance compared with those on which he most excelled. Not 2c2 388 WATT. only all the sciences from the mathematics and astro- nomy, down to botany, received his diligent attention, but he was tolerably read in the lighter kinds of literature, delighting in poetry and other works of fiction, full of the stores of ancient literature, and readily giving himself up to the critical disquisitions of commentators, and to discussions on the fancies of etymology. His manners were most attractive from their perfect nature and simplicity. His conversation was rich in the measure which such stores and such easy taste might lead us to expect, and it astonished all listeners with its admirable precision, with the extra- ordinary memory it displayed, with the distinctness it seemed to have, as if his mind had separate niches for keeping each particular, and with its complete rejection of all worthless and superfluous matter, as if the same mind had some fine machine for acting like a fan, casting off the chaff and the husk. But it had besides a peculiar charm from the pleasure he took in convey- ing information where he was peculiarly able to give it, and in joining with entire candour whatever discussion happened to arise. Even upon matters on which he was entitled to pronounce with absolute authority, he never laid down the law, but spoke like any other partaker of the conversation. You might ob- serve him, however, with his pencil in his hand, ready to prove what might require explanation, and he was an adventurous disputant who would not rather see his in- tellect play in illustrations than descend with demon- strative force. He was ever in pursuit of truth or the gratification of a rational curiosity, and this attempered as well as guided his talk. If he seemed occasionally to be moved beyond the interest thus excited, it was when WATT. 389 he perceived any thing uncandid or unfair, or, above all, indirect and dishonest. The attempts of one man to appropriate another's inventive merit were the things that most roused his indignation ; for, regarding dis- covery and invention as the most precious of all property, he could not bear the sight of its violation, and would stop minutely and curiously to ascertain the relative shares of different individuals, when any doubt was raised upon the distribution. His conversation was withal spirited and lively — it was easy and concise, and without the least of a lecturing formality. His voice was deep and low, and if somewhat monotonous, it yet seemed in harmony with the weight and the beauty of his discourse, through which however there also ran a current of a lighter kind ; for he was mirth- ful, temperately jocular, nor could anything to more advantage set off the living anecdotes of men and things, with which the graver texture of his talk was interwoven, than his sly and quiet humour, both of mind and of look, in recounting them. No one who had the happiness of knowing him, no member, more especially, of the club in Edinburgh which he frequented as often as he visited that capital, can ever forget the zest which his society derived from the mixture of such various matters as those to which I have referred ; and one of its most distinguished founders * has justly * Lord Jeffrey. The club was called from the day, Friday, on which it met at supper, after the business of the week was over, and the half-holiday of Saturday only lightly hanging over the heads of the lawyers, who chiefly composed it. Mr. Watt was an honorary member. He had for his colleagues no less distinguished men than Professor Playfair, Sir Walter Scott, Lord Corehouse, Mr. Homer, Mr. Elmsley, Sir W. Drummond, and several who still survive and fill exalted places in the State. 390 WATT. said, that in no other person was there ever observed so " fine an expression of reposing strength and unin- terrupted self-possession as marked his whole manner." APPENDIX. HISTORICAL NOTE ON THE DISCOVERY OF THE THEORY OF THE COMPOSITION OF WATER. THERE can be no doubt whatever, that the experiment of Mr. Warltire, related in Dr. Priestley's fifth volume,* gave rise to this inquiry, at least in England; Mr. Cavendish expressly * Mr. Warltire's letter is dated Birmingham, 18th April, 1781, and was published by Dr. Priestley in the Appendix to the seventh volume of his c Experiments and Observations relating to various branches of Natural Philosophy ; with a continuation of the Ob- servations on Air,' — forming, in fact, the fifth volume of his l Ex- periments and Observations on different kinds of Air ;' printed at Birmingham in 1781. Mr. Warltire's first experiments were made in a copper ball or flask, which held three wine pints, the weight 14 ounces ; and his ob- ject was to determine " whether heat is heavy or not." After stating his mode of mixing the airs, and of adjusting the balance, he says, he "always accurately balanced the flask of common air, then found the difference of weight after the inflammable air was introduced, that he might be certain he had confined the proper proportion of each. The electric spark having passed through them, the flask became hot, and was cooled by exposing it to the common air of the room 1 it was then hung up again to the balance, and a loss of weight was always found, but not constantly the same ; upon an average it was two grains." He goes on to say, u I have fired air in glass vessels since I saw you (Dr. Priestley) venture to do it, and I have observed, as you did, that, though the glass was clean and dry before, yet, after firing the air, it became dewy, and was lined with a sooty substance." It WATT. 391 refers to it, as having set him upon making his experiments. — (Phil. Trans. 1784, p. 126.) The experiment of Mr. Warltire consisted in firing, by electricity, a mixture of inflammable and common air in a close vessel, and two things were said to be observed : first, a sensible loss of weight ; second, a dewy deposit on the sides of the vessel. Mr. Watt, in a note to p. 332 of his paper, Phil. Trans. 1784, inadvertently states, that the dewy deposit was first observed by Mr. Cavendish; but Mr. Cavendish himself, p. 127, expressly states Mr. Warltire to have observed it, and cites Dr. Priestley's fifth volume. Mr. Cavendish himself could find no loss of weight, and he says that Dr. Priestley had also tried the experiment, and found none.* But Mr. Cavendish found there was always a dewy deposit, without any sooty matter. The result of many trials was, that common air and inflammable air being burnt together, in the proportion of 1000 measures of the former to 4'23 of the latter, " about one-fifth of the common air, and nearly all the inflammable air, lose their elasticity, and are condensed into the dew which lines the glass." He examined the dew, and found it to be pure water. He therefore concludes, that " almost all the inflammable air, and about one-sixth of the common air, are turned into pure water." Mr. Cavendish then burned, in the same way, dephlogisti- cated and inflammable airs (oxygen and hydrogen gases), and the deposit was always more or less acidulous, accord- ingly as the air burnt with the inflammable air was more or less phlogisticated. The acid was found to be nitrous. Mr. Cavendish states, that " almost the whole of the inflammable and dephlogisticated air is converted into pure water;" and, again, that ' ' if these airs could be obtained perfectly pure, the It seems evident that neither Mr. Warltire nor Dr. Priestley attributed the dew to anything else than a mechanical deposit of the moisture suspended in common air. — [NOTE BY MB. JAMES WATT.] * Mr. Cavendish's note, p. 127, would seem to imply this; but I have not found in any of Dr. Priestley's papers that he has said so. —[NOTE BY MR. JAMES WATT.] 392 WAIT. whole would be condensed." And he accounts for common air and inflammable air, when burnt together, not producing acid, by supposing that the heat produced is not sufficient. He then says that these experiments, with the exception of what relates to the acid, were made in the summer of 1781, and mentioned to Dr. Priestley ; and adds, that " a friend of his (Mr. Cavendish's), last summer (that is, 1783), gave some account of them to M. Lavoisier, as well as of the conclu- sion drawn from them, that dephlogisticated air is only water deprived of its phlogiston ; but, at that time, so far was M. Lavoisier from thinking any such opinion warranted, that till he was prevailed upon to repeat the experiment himself, he found some difficulty in believing that nearly the whole of the two airs could be converted into water." The friend is known to have been Dr., afterwards Sir Charles Blagden ; and it is a remarkable circumstance, that this passage of Mr. Cavendish's paper appears not to have been in it when ori- ginally presented to the Royal Society ; for the paper is appa- rently in Mr. Cavendish's hand, and the paragraph, p. 134, 135, is not found in it, but is added to it, and directed to be inserted in that place. It is, moreover, not in Mr. Cavendish's hand, but in Sir Charles Blagden's ; and, indeed, the latter must have given him the information as to M. Lavoisier, with whom it is not said that Mr. Cavendish had any corre- spondence. The paper itself was read 15th January, 1784. The volume was published about six months afterwards. M. Lavoisier's memoir (in the Mem. de TAcademie des Sciences for 1781) had been read partly in November and December 1783, and additions were afterwards made to it. It was published in 1784. It contained M. Lavoisier's account of his experiments in June 1783, at which, he says, Sir Charles Blagden was present ; and it states that he told M. Lavoisier of Mr. Cavendish having " already burnt inflamma- ble air in close vessels, and obtained a very sensible quantity of water." But he, M. Lavoisier, says nothing of Sir Charles Blagden having also mentioned Mr. Cavendish's conclusion from the experiment. He expressly states, that the weight of the water was equal to that of the two airs burnt, unless the heat and light which escape are ponderable, which he hold WATT. 393 them not to be. His account, therefore, is not reconcilable with Sir Charles Blagden's, and the latter was most probably written as a contradiction of it, after Mr. Cavendish's paper had been read, and when the Memoires of the Academic were received in this country. These Memoires were published in 1784, and could not, certainly, have arrived when Mr. Cavendish's paper was written, nor when it was read to the Royal Society. But it is further to be remarked, that this passage of Mr. Cavendish's paper in Sir Charles Blagden's handwriting, only mentions the experiments having been communicated to Dr. Priestley; they were made, says the passage, in 1781, and communicated to Dr. Priestley ; it is not said when, nor is it said that " the conclusions drawn from them," and which Sir Charles Blagden says he communicated to M. Lavoisier in summer 1783, were ever communicated to Dr. Priestley; and Dr. Priestley, in his paper (referred to in Mr. Cavendish's), which was read June 1783, and written before April of that year, says nothing of Mr. Cavendish's theory, though he mentions his experiment. Several propositions then are proved by this statement. First, That Mr. Cavendish, in his paper, read 1 5th January, 1784, relates te capital experiment of burning oxygen and hydrogen gases in a close vessel, and finding pure water to be the produce of the combustion. Secondly, That, in the same paper, he drew from this expe- riment the conclusion that the two gases were converted or turned into water. Thirdly, That Sir Charles Blagden inserted in the same paper, with Mr. Cavendish's consent, a statement that the experiment had first been made by Mr. Cavendish in summer 1781, and mentioned to Dr. Priestley, though it is not said when, nor is it said that any conclusion was mentioned to Dr. Priestley, nor is it said at what time Mr. Cavendish first drew that conclusion. A most material omission. Fourthly, That in that addition made to the paper by Sir Charles Blagden, he conclusion of Mr. Cavendish is stated to be, that oxygen gas is water deprived of phlogiston; this addition having been made after M. Lavoisier's memoir arrived in England. 394 WATT. It may further be observed, that in another addition to the paper, which is also in Sir C. Blagden's handwriting, and which was certainly made after M. Lavoisier's memoir had arrived, Mr. Cavendish for the first time distinctly states, as upon M. Lavoisier's hypothesis, that water consisted of hydrogen united to oxygen gas. There is no substantial difference, perhaps, between this and the conclusion stated to have been drawn by Mr. Cavendish himself, that oxygen gas is water deprived of phlogiston, supposing phlogiston to be synonymous with hy- drogen ; but the former proposition is certainly the more dis- tinct and unequivocal of the two : and it is to be observed that Mr. Cavendish, in the original part of the paper, i. e. the part read January 1784, before the arrival of Lavoisier's, considers it more just to hold inflammable air to be phlogisticated water than pure phlogiston (p. 140). We are now to see what Mr. Watt did ; and the dates here become very material. It appears that he wrote a letter to Dr. Priestley on 26th April, 1783, in which he reasons on the experiment of burning the two gases in a close vessel, and draws the conclusion, " that water is composed of dephlogisti- cated air and phlogiston, deprived of part of their latent heat."* The letter was received by Dr. Priestley and de- livered to Sir Joseph Banks, with a request that it might be read to the Royal Society ; but Mr. Watt afterwards desired this to be delayed, in order that he might examine some new experiments of Dr. Priestley, so that it was not read until the 22d April, 1784. In the interval between the delivery of * It may with certainty be concluded from Mr. "Watt's private and unpublished letters, of which the copies taken by his copying- machine, then recently invented, are preserved, that his theory of the composition of water was already formed in December 1782, and probably much earlier. Dr. Priestley, in his paper of 21st April, 1783, p. 416, states, that Mr. Watt, prior to his (the Doctor's) ex- periments, had entertained the idea of the possibility of the conver- sion of water or steam into permanent air. And Mr. Watt himself, in his paper, Phil. Trans., p. 335, asserts, that for many years he had entertained the opinion that air was a modification of water, and he enters at some length into the facts and reasoning upon which that deduction was founded. — [NOTE BY MR. JAMES WATT.] WATT. 395 this letter to Dr. Priestley, and the reading of it, Mr. Watt had addressed another letter to M. de Luc, dated 26th No- vember, 1783,* with many further observations and reasonings, but almost the whole of the original letter is preserved in this, and is distinguished by inverted commas. One of the passages thus marked is that which has the important conclusion above mentioned ; and that letter is stated, in the subsequent one, to have been communicated to several members of the Royal Society at the time of its reaching Dr. Priestley, viz. April, 1783. In Mr. Cavendish's paper as at first read, no allusion is to be found to Mr. Watt's theory ; but in an addition made in Sir C. Blagden's own hand, after Mr. Watt's paper had been * The letter was addressed to M. J. A. de Luc, the well-known Genevese philosopher, then a Fellow of the Royal Society, and Reader to Queen Charlotte. He was the friend of Mr. Watt, who did not then belong to the Society. M. de Luc, following the motions of the Court, was not always in London, and seldom at- tended the meetings of the Royal Society. He was not present when Mr. Cavendish's paper of 15th January, 1784, was read ; but, hearing of it from Dr. Blagden, he obtained a loan of it from Mr. Cavendish, and writes to Mr. Watt on the 1st March following, to apprise him of it, adding that he has perused it, and ^promising an analysis. In the postscript he states, " In short, they expound and prove your system, word for word, and say nothing of you." The promised analysis is given in another letter of the 4th of the same month. Mr. Watt replies on the 6th, with all the feelings which a conviction he had been ill-treated was calculated to inspire, and makes use of those vivid expressions which M. Arago has quoted ; he states his intention of being in London in the ensuing week, and his opinion, that the reading of his letter to the Royal Society will be the proper step to be taken. He accordingly went there, waited upon the President of the Royal Society, Sir Joseph Banks, was re- ceived with all the courtesy and just feeling which distinguished that most honourable man ; and it was settled that both the letter to Dr. Priestley of 26th April, 1783, and that to M. de Luc of 26th November, 1783, should be successively read. The former was done on the 22d, and the latter on the 29th April, 1784.— [NOTE; BY MK. JAMES WATT.] 396 WATT. read, there is a reference to that theory (Phil. Trans. 1784, p. 140), and Mr. Cavendish's reasons are given for not en- cumbering his theory with that part of Mr. Watt's which regards the evolution of latent heat. It is thus left somewhat doubtful, whether Mr. Cavendish had ever seen the letter of April 1783, or whether he had seen only the paper (of 26th November, 1783) of which that letter formed a part, and which was read 29th April, 1784. That the first letter was for some time (two months, as appears from the papers of Mr. Watt) in the hands of Sir Joseph Banks and other members of the Society, during the preceding spring, is certain, from the statements in the note to p. 330 ; and that Sir Charles Blagden, the Secretary, should not have seen it, seems impossible ; for Sir Joseph Banks must have delivered it to him at the time when it was intended to be read at one of the Society's meetings (Phil. Trans., p. 330, Note), and, as the letter itself remains among the Society's Records, in the same volume with the paper into which the greater part of it was introduced, it must have been in the custody of Sir C. Blagden. It is equally difficult to suppose, that the person who wrote the remarkable passage already referred to, re- specting Mr. Cavendish's conclusions having been communi- cated to M. Lavoisier in the summer of 1783 (that is, in June), should not have mentioned to Mr. Cavendish that Mr. Watt had drawn the same conclusion in the spring of 1783 (that is, in April at the latest). For the conclusions are identical, with the single difference, that Mr. Cavendish calls dephlogisticated air, water deprived of its phlogiston, and Mr. Watt says that water is composed of dephlogisticated air and phlogiston. We may remark, there is the same uncertainty or vague- ness introduced into Mr. Watt's theory, which we before ob- served in Mr. Cavendish's, by the use of the term Phlogiston, without exactly defining it. Mr. Cavendish leaves it uncer- tain, whether or not he meant by phlogiston simply inflamma- ble air, and he inclines rather to call inflammable air, water united to phlogiston. Mr. Watt says expressly, even in his later paper (of November 1783), and in a passage not to be found in the letter of April 1783, that he thinks that inflam- WATT. 397 mable air contains a small quantity of water, and much elementary heat. It must be admitted that such expressions as these on the part of both of those great men, betoken a certain hesitation respecting the theory of the composition of water. If they had ever formed to themselves the idea, that water is a compound of the two gases deprived of their latent heat, — that is, of the two gases, — with the same distinctive- ness which marks M. Lavoisier's statement of the theory, such obscurity and uncertainty would have been avoided. Several further propositions may now be stated, as the re- sult of the facts regarding Mr. Watt. First, That there is no evidence of any person having re- duced the theory of composition to writing, in a shape which now remains, so early as Mr. Watt. Secondly, That he states the theory, both in April and No- vember 1783, in language somewhat more distinctly referring to composition than Mr. Cavendish does in 1 784, and that his reference to the evolution of latent heat renders it more dis- tinct than Mr. Cavendish's. Thirdly, That there is no proof, nor even any assertion, of Mr. Cavendish's theory (what Sir C. Blagden calls his con- clusion) having been communicated to Dr. Priestley before Mr. Watt stated his theory in 1 783, still less of Mr. Watt having heard of it, while his whole letter shows that he never had been aware of it, either from Dr. Priestley, or from any other quarter. Fourthly, That Mr. Watt's theory was well known among the members of the Society, some months before Mr. Caven- dish's statement appears to have been reduced into writing, and eight months before it was presented to the Society. We may, indeed, go further, and affirm, as another deduction from the facts and dates, that as far as the evidence goes, there is proof of Mr. Watt having first drawn the conclusion, at least that no proof exists of any one having drawn it so early as he is proved to have done. Lastly, That a reluctance to give up the doctrine of phlo- giston, a kind of timidity on the score of that long-established and deeply rooted opinion, prevented both Mr. Watt and Mr. Cavendish from doing full justice to their own theory; while 398 WATT. M. Lavoisier, who had- entirely shaken off these trammels,, first presented the new doctrine in its entire perfection and consistency. All three may have made the important step nearly at the same time, and unknown to each other ; the step, namely, of concluding from the experiment, that the two gases entered into combination, and that water was the result ; for this, with more or less of distinctness, is the inference which all three drew. But there is the statement of Sir Charles Blagden, to show that M. Lavoisier had heard of Mr. Cavendish's drawing this inference before his (M. Lavoisier's) capital experiment was made ; and it appears that M. Lavoisier, after Sir C. Blagden's statement had been embodied in Mr. Cavendish's paper and made public, never gave any contradiction to it in any of his subsequent memoirs which are to be found in the Me- moires de 1' Academic, though his own account of that ex- periment, and of what then passed, is inconsistent with Sir Charles Blagden's statement. But there is not any assertion at all, even from Sir C. Blag- den, zealous for Mr. Cavendish's priority as he was, that Mr. Watt had ever heard of Mr. Cavendish's theory before he formed his own. Whether or not Mr. Cavendish had heard of Mr. Watt's theory previous to drawing his conclusions, appears more doubtful. The supposition that he had so heard, rests on the improbability of his (Sir Charles Blagden's) and many others knowing what Mr. Watt had done, and not communicat- ing it to Mr. Cavendish, and on the omission of any assertion in Mr. Cavendish's paper, even in the part written by Sir C. Blagden with the view of claiming priority as against M. Lavoisier, that Mr. Cavendish had drawn his conclusion before April ] 783, although in one of the additions to that paper reference is made to Mr. Watt's theory. As great obscurity hangs over the material question at what time Mr. Cavendish first drew the conclusion from his experi- ment, it may be as well to examine what that great man's habit was in communicating his discoveries to the Royal Society. WATT. 399 A Committee of the Royal Society, with Mr. Gilpin the clerk, made a series of experiments on the formation of nitrous acid, under Mr. Cavendish's direction, and to satisfy those who had doubted his theory of its composition, first given accidentally in the paper of January 1784, and afterwards more fully in another paper, June 1785. Those experiments occupied from the 6th December, 1787, to 19th March, 1788, and Mr. Cavendish's paper upon them was read 17th April, 1788. It was, therefore, written and printed within a month of the experiments being concluded. Mr. Kirwan answered Mr. Cavendish's paper (of 15th January, 1784) on water, in one which was read 5th February, 1 784, and Mr. Cavendish replied in a paper read 4th March, 1784. Mr. Cavendish's experiments on the density of the earth were made from the 5th August, 1797, to the 27th May, 1798. The paper upon that subject was read 27th June, 1798. The account of the eudiometer was communicated at apparently a greater interval ; at least the only time men- tioned in the account of the experiments is the latter half of 1781, and the paper was read January 1783. It is, however, probable, from the nature of the subject, that he made further trials during the year 1782. That Mr. Watt formed his theory during the few months or weeks immediately preceding April 1783, seems probable.* It is certain that he considered the theory as his own, and makes no reference to any previous communication from any one upon the subject, nor of having ever heard of Mr. Cavendish drawing the same conclusion. The improbability must also be admitted to be extreme, of Sir Charles Blagden ever having heard of Mr. Cavendish's theory prior to the date of Mr. Watt's letter, and not mention- ing that circumstance in the insertion which he made in Mr. Cavendish's paper. * That the idea existed in his mind previously, is proved by his declarations to Dr. Priestley, cited by the latter ; by his own asser- tions, p. 335 of his paper ; and by the existing copies of his letters in December 1782.— [NOTE BY MR. JAMES WATT.] 400 WATT. It deserves to be farther mentioned, that Mr. Watt left the correction of the press, and every, thing relating to the publishing of his paper, to Sir Charles Blagden. A letter remains from him to that effect, written to Sir Charles Blag- den, and Mr. Watt never saw the paper until it was printed. Since M. Arago's learned Eloge was published, with this paper as an Appendix, the Rev. W. Vernon Harcourt has entered into controversy with us both, or, I should rather say, with M. Arago, for he has kindly spared me ; and while I ex- press my obligations for this courtesy of my reverend, learned, and valued friend, I must express my unqualified admiration of his boldness in singling out for his antagonist my illustrious colleague, rather than the far weaker combatant against whom he might so much more safely have done battle. Whatever might have been his fate had he taken the more prudent course, I must fairly say (even without waiting until my fellow champion seal our adversary's doom), that I have seldom seen any two parties more unequally matched, or any disputation in which the victory was so complete. The attack on M. Arago might have passed well enough at a popular meeting at Bir- mingham, before which it was spoken ; but as a scientific inquirer, it would be a flattery running the risk of seeming ironical to weigh the reverend author against the most eminent philo- sopher of the day, although upon a question of evidence (which this really is, as well as a scientific discussion) I might be content to succumb before him. As a strange notion, how- ever, seems to pervade this paper, that everything depends on the character of Mr. Cavendish, it may be as well to repeat the disclaimer already very distinctly made of all intention to cast the slightest doubt upon that great man's perfect good faith in the whole affair ; I never having supposed that he borrowed from Mr. Watt, though M. Arago, Professor Robison,* and Sir H. Davy, as well as myself, have always * Encyc. Brit., vol. xviii., p. 808. This able and learned article enters at length into the proofs of Mr. Watt's claims, and it was published in 1797, thirteen years before Mr. Cavendish's death. WATT. 401 been convinced that Mr. Watt had, unknown to him, antici- pated his great discovery. It is also said by Mr. Harcourt that the late Dr. Henry having examined Mr. Watt's manu- scripts decided against his priority. I have Dr. H/s letter before me of June, 1820, stating most clearly, most fully, and most directly, the reverse, and deciding in Mr. Watt's favour. I must add, having read the full publication with fac-similes, Mr. Harcourt has now clearly proved one thing, and it is really of some importance. He has made it appear that in all Mr. Cavendish's diaries and notes of his experiments, not an intimation occurs of the composition of water having been in- ferred by him from those experiments earlier than Mr. Watt's paper of spring, 1783. 2 D ( 402 ) PRIESTLEY. MENTION has already been more than once made of Dr. Priestley ; and certainly history would imperfectly perform its office of recording the progress of natural knowledge should it pass over his important discoveries without the large share of attention and of praise which they are well entitled to claim. In turning, however, to recount the events of his life, we make a somewhat painful transition from contemplating in its perfection the philosophic character, to follow the course of one who united in his own person the part of the experi- mental inquirer after physical truth with that of the angry polemic and the fiery politician, leading some- times the life of a sage, though never perhaps free from rooted and perverted prejudice — sometimes that of a zealot against received creeds and established in- stitutions, and in consequence of his intemperance, alternately the exciter and the victim of persecution. Nevertheless, the services which he rendered in the former and better capacity, ought to be held in grate- ful remembrance by the cultivators of physical science. Nor are we to suppose that even in his polemical ca- pacity he was not in pursuit of truth. He may have had a tendency to oppose established opinions ; a disposition which led him, as he says himself, at the xich lie in pursuit of truth. He nn Knarai-ed />>• ff. Jlell / '/' / ••> PRIESTLEY. 405 ation as his scanty and rambling education had laid. That education, however, far from redounding to his discredit, very greatly enhances the merit of the man. He presents one of the memorable examples of know- ledge pursued, science cultivated, and even its bounds extended, by those whose circumstances made their ex- ertions a continued struggle against difficulties which only virtue and genius like theirs could have overcome. He went to study for some years at the dissenting academy founded by Mr. Coward, at Daventry, and since transferred to London, where it is in a kind of union, mutually beneficial, with the University Col- lege. Mr. Ashworth had succeeded the learned and pious Dr. Doddridge as its principal teacher, and under him Priestley remained till 1755. During the three years that he studied here, he and his intimate friends used to make a point of reading, daily, ten pages of Greek, and every week one Greek play, a practice which they continued after they left the school, corre- sponding with each other on the subject of their studies. On quitting Daventry, having taken orders, he was appointed minister of a congregation at Needham Mar- ket, in Suffolk. He had been brought up by his father and aunt in the strictest Calvinistic principles, most of which he very soon from conviction abandoned ; and so early did his spirit of free inquiry show itself, that having before he left his aunt's house desired to be admitted as a communicant at the chapel which she attended, he was rejected by the minister on his prepa- ratory examination, in consequence of doubts expressed respecting original sin, and eternal damnation as its punishment. He describes the deep distress into which 106 PRIESTLEY. he was thrown by feeling that he was unable to ex- perience due contrition and repentance for Adam's fault ; and the rigid divine who tested the state of his mind on this point, withheld the sacred ordinances in consequence. At Needham his salary did not exceed thirty pounds, indeed it seldom amounted to so much, and he could only subsist by the aid which certain dis- senting charities afforded to augment this poor stipend. His predecessor, Dr. Doddridge, had never received above thirty-five pounds a-year, and his board then (1723) only cost him ten pounds. Priestley's opinions proved distasteful to the congregation, who probably regarded the eternity of hell- torments as a peculiar pri- vilege rudely invaded by him ; and he removed in 1758 to Nantwich, in Cheshire, where he obtained some thirty pupils, beside a few young ladies and a private tutorship in an attorney's family. This increased his income, and enabled him, by means of the strictest frugality, to purchase a scanty apparatus ; for he had now added a little natural philosophy to his favourite theological studies, the fruit of which had been already two works, one of them against the atonement. I say a little natural philosophy ; for he confesses that when nine years later he began to write his ' History of Electricity/ he was but imperfectly acquainted with the subject. It is a careless and superficial work, hastily written, as is his ' History of Vision ;' and the original experiments afforded no new information of any value. In 1761 he removed to Warrington Academy, in which he succeeded Dr. Aikin as tutor in the belles lettres. On settling at Warrington he married the daughter of Mr. Wilkinson, a respectable iron master in Wales. PRIESTLEY. 407 She was an amiable woman, and endowed with great strength of mind, which was destined afterwards to be severely tried. By her he had several children, one of whom survived them both. He appears to have chiefly devoted himself to theo- logical studies, and hence the great disproportion which his Hebrew and Greek learning bears to his other ac- quirements. Metaphysical speculations, next to these, engaged his attention ; and the influence produced in his mind, and even his conduct, by Dr. Hartley's cele- brated work ('Observations on Man'), has been re- corded by himself. " I hardly know," he says, " whether it more enlightens the understanding or improves the heart." He says he also had studied com- position, and mainly by the help of writing poetry, of no merit, but according to him the best means of learning to write good prose. That his taste, however, was some- what deficient in this respect we may fairly affirm, when we find him pronouncing, many years after, a decided opinion that Belsham's 'History' is written in a better style than Robertson's or Hume's.* The universality of his attempts may be judged from his delivering at Warrington a course of lectures on ana- tomy. He sought relaxation from music, and learnt to play on the flute. He strongly recommends this to students, especially, he says with some naivete, such as have no fine ear, " for they will be the less annoyed by bad music." As early as during his education at Daventry he had written a work which, however, was not published till twenty years later ; it was the ' Institutes of * Mem. and Cor. 1796, vol. i. part ii. p. 358. 408 PRIESTLEY. Natural and Revealed Religion/ But having once begun to publish in 1761, his appeals to the press were incessant, and on almost every subject. A ' Theory of Language,' books on 'Oratory and Criticism/ on ' History and General Policy,' on the ' Constitution and Laws of England,' on * Education,' a 'Chart of Bio- graphy,' a ' Chart of History ;' these and others were all written while he resided at Warrington, from 1761 to 1769. How well he was qualified to write on oratory and on English law, we may easily conjecture, from the circumstance that he could never have heard any speaking save in the pulpits of meeting-houses, and in all probability had never seen a cause tried ; but even if he had been present at debates and trials, it is difficult to imagine anything more adventurous than the tutor of an academy, afflicted with an incurable stutter, and who devoted his time to teaching and to theology, pro- mulgating rules of eloquence and of jurisprudence to the senators and lawyers of his country. That we may come without interruption to his really useful studies, it may be well here- to take notice of his other contro- versial writings. In consequence of a disagreement with the Warrington trustees in 1767 he removed to Leeds, where he became minister of the Mill-Hill chapel, and wrote many controversial books and pamphlets In after times he wrote 'Letters to a Philosophical Institution ;' ' An Answer to Gibbon ;' ' Disquisitions on Matter and Spirit ;' ' Corruptions of Christianity ;' f Early Opinions on Christ ;' ' Familiar Letters to the Inhabitants of Birmingham;' 'Two Different Histo- ries of the Christian Church ;' ' On Education ;' < Com- parison of Heathen and Christian Philosophy ;' ' Doc- PRIESTLEY. 409 trine of Necessity ;' ' On the Roman Catholic Claims ;' ' On the French Revolution ;' ' On the American War ;' beside twenty volumes of tracts in favour of the Dissenters and their rights. His general works fill twenty-five volumes,* of which only five or six are on scientific subjects : his publications being in all one hundred and forty-one (in one year ten), of which only seventeen are on scientific matters. He is one of the most voluminous writers of any age or country, and probably he is of all voluminous writers the one who has the fewest readers. This arises from the circum- stance that, though his political opinions are shared by many, the bulk of his works are theological and metaphysical, but especially theological ; and his re- ligious opinions were confined to an extremely small class of persons. Indeed it may be questioned if he was not in several respects the only person who held his peculiar faith upon all points. It happened, fortunately, that when he went to* reside at Leeds in care of the Mill-Hill Chapel, his house immediately adjoined a common brewery, and this led him to make experiments upon the fixed air copiously produced during the process of ferment- ation. It must be observed, that long before this time the great step had been made by Black, of ascertaining that there are other permanently elastic fluids than our atmosphere, and which have properties wholly different from it. Cavendish, too, had very recently subjected both fixed and inflammable airs (carbonic acid and * Edited by the affectionate care of an able and worthy man, Mr. Towell Rutt. 410 PRIESTLEY. hydrogen gases) to accurate experiments, showing their relative specific gravities, and proving that they were of the same nature from what bodies soever they were obtained. The probability was, that other gaseous fluids existed in nature as well as those two and common air. The experimenter had, therefore, thenceforth, his attention directed to meeting with these : and an examination of all the products of mixture and of heat, by precipitation or evaporation, was now the natural course of experimental inquiry. At first, Priestley only tried in what way fixed air could be most easily combined with water; he pub- lished in 1772 a pamphlet upon the means of effecting this union, and the condensing process which he employed is used to this day. He soon after gave to the Royal Society his observations on different kinds of air, which ascertained the important fact, that at- mospheric air, after having been corrupted by the re- spiration of animals or by the burning of inflammable bodies, is restored to salubrity by the vegetation of plants ; and that if the air is exposed to a mixture of sulphur and iron filings, as in one of Hales's experi- ments, its bulk is diminished between a fourth and a fifth, and the residue is both lighter than common air and unfit to support life. This residue he called 4 Phlogistic air;' afterwards it was called 'Azotic' or 6 Nitrogen gas ;' and Dr. Rutherford, of Edinburgh, as well as Priestley, though unknown to each other, discovered it about the same time. For these experi- ments the Copley Medal was, in 1773, justly awarded to him by the Royal Society. The following year was destined to be the period PRIESTLEY. 411 of a discovery most important for science, and truly glorious for its author. Having exposed red-lead, or minium, in a close vessel to the sun's rays concentrated by a burning-glass, he found that an aeriform body, permanently elastic, was evolved, and that this air had the peculiar property of increasing exceedingly the intensity of flame. This gas he called ' dephlogisticated air/ upon the principle that the matter of heat and light, the phlogiston of Stahl, being abstracted from it by the return of the calx to its metallic state, which phlogiston was supposed by that theory to effect, the air had great avidity for phlogiston, and seized it from the inflammable bodies it came in contact with. This most important discovery, which he thus con- nected with an erroneous theory, was made on the 1st of August, 1774. He afterwards discovered that its absorption by the lungs in the process of respiration gives its red colour to arterial blood, as it was proved to act through the substance of thin bladder ; and he found that when plants grow in close vessels, and restore the purity of the air in which a candle has burnt or an animal breathed, they do so by evolving this pure air. The new nomenclature gave it the name of ' oxygen gas/ from the belief then generally entertained that it was the acidifying principle. Later experiments have proved that there is at least one great exception to this in chlorine, formerly called 'oxy- genated muriatic acid ;' but now found to be wholly without oxygen, and yet to have all the properties of an acid. But, indeed, water itself, and the atmo- spheric air, having neither of them the nature of acids, are both contrary to the theory ; and the fixed alkalis 412 PRIESTLEY. are found to owe their alkaline state and lose their metallic, like other oxides, by uniting with oxygen. Priestley is the undoubted discoverer of oxygen. He was the first who communicated a knowledge of it to Lavoisier, at Paris, soon after he had made the dis- covery ; nor can anything be more disingenuous than that celebrated person's afterwards affirming that he, Priestley, and Scheele, had all discovered it " about the same time." He never discovered it until Priestley discovered it to him. Bergmann's suppressing in his book all knowledge of the experiments of Black and Cavendish, the former published twenty and the latter eight years before, was bad enough, but not equal to Lavoisier's positive assertion contrary to what must have been his positive knowledge. This great discovery was far from being the last of its justly celebrated author. He discovered the gases of muriatic, of sulphuric, and of fluoric acids, ammonial gas, and nitrous oxide gas. He also dis- covered the combination which nitrous gas forms suddenly with oxygen ; diminishing the volume of both in proportion to that combination ; and he thus invented the method of eudiometry, or the ascertain- ment of the relative purity of different kinds of atmo- spheric air. It must not be forgotten, in considering the great merits of Priestley as an experimentalist, that he had almost to create the apparatus by which his processes were to be performed. He, for the most part, had to construct his instruments with his own hands, or if he employed others, he had to make unskilful work- men form them under his own immediate direction. PRIESTLEY. 413 His apparatus, however, and his contrivances for col- lecting, keeping, transferring gaseous bodies, and for exposing substances to their action, were simple and effectual, and they continue to be still used by chemical philosophers without any material improvement. It was fortunate in this respect that he began his pneu- matic inquiries with seeking for the means of im- pregnating water with carbonic acid ; this inquiry naturally turned his attention to the contrivance of apparatus and generally of manipulations, serviceable in the examination of bodies whose invisible form and elastic state renders inapplicable to them the machi- nery of the old laboratory, calculated only for solids and liquids. The pertinacity with which Priestley clung to the phlogistic theory is marvellous. It might have been expected, that the fact of a combustion leaving the residue, whether of two gases, or of a gas and an in- flammable body, exactly equal in weight to the sum of the weights of the bodies burnt and which had disap- peared in the process, would have been accepted as a proof that these two bodies had entered into an union, giving out the latent heat which had previously held the gaseous body or bodies in a state of aeriform fluidity. It might, in like manner, have been ex- pected, that when a metal, by absorbing oxygen gas, becomes calcined, and gains in weight precisely the weight of the gas which has disappeared, the calcination should be ascribed to the gas, and that the reproduction of the gas by heat, or by its abstraction by electric affinity for some other body, should be allowed to restore the metallic state by simply severing that 414 . PRIESTLEY. union of the gas and the metal which had changed it. But nothing could overcome Priestley's repugnance to give up phlogiston : he adhered to it while he lived ; he never would believe that water was formed of the two gaseous bodies whose combustion and disappear- ance leaves a weight of liquid equal to their joint weights ; he always imagined that water was held in suspense by these gases and precipitated on their disappearing. He never would believe that metals owe their malleability and lustre to any cause other than phlogiston, or lose their properties except by combining with oxygen, which takes the phlogiston from them. He never would believe that combustion is anything but the phlogiston leaving the inflammable body and joining the oxygen ; or that when an acid is formed by the burning, that acid contains the oxygen and the combustible base. That his obstinate unbelief was perfectly disinterested no one can doubt. The discoverer of oxygen, and of the true cause of re- spiration, had, of all men, the strongest interest in assenting to a theory which was wholly founded upon his own discovery, and which made him the imme- diate, as Black was the more remote, author of modern chemical science — made him the philosopher who had raised the superstructure upon the foundation which his predecessor had laid. The merit of Dr. Priestley, as a cultivator of science, was the activity with which he made experiments — the watchful attention with which he observed every phenomenon, following the minutest circumstances of each process— the versatility with which he prosecuted each new idea that arose from his trials — his diligence PRIESTLEY. 415 in recording all the particulars, as if well aware how much depends in every branch of inductive philosophy upon allowing no fact to escape, when we are con- fessedly in search of light, and can never tell how any given fact may bear on the unknown conclusion to which our analytical process is leading^ us. As a reasoner his powers were far less considerable. He possessed not the sound judgment, the large circum- spection, which enables men to weigh the relative value of either reasons or facts. He was cautious enough and drew little from his imagination in feigning hypotheses, if it be not the reasons which he invented from time to time for the purpose of sustaining the desperate fortunes of the phlogistic theory, and making the facts bend to it as they successively arose with a force capable of shivering it in pieces. But he was also deficient in the happy sagacity which pierces through apparent dissimilarity, and ranges things apparently unlike under the same class — he had not that chas- tened imagination which can see beyond the fact present to the senses — in a word, he was much greater as a collector of new facts than a reasoner upon them — and his inductive capacity was inferior to his power of ex- perimenting and of contriving the means of observation. Perhaps his want of general scientific acquirements, and his confined knowledge of chemistry, itself contri- buted to the activity and the boldness with which he performed novel experiments, while the same defect impaired his capacity as an inductive philosopher. It is extremely probable that the strict attention to prin- ciple, the methodical systematic spirit which prevailed over the inquiries of Black and of Cavendish — the 416 PRIESTLEY. scientific views which directed the contrivance of all their processes, never leading them to make any trial without some definite object in view, prevented them from performing many experiments, — from stooping, as it were, to try things which Priestley did not disdain to try from his more empirical turn of mind — what Mr. Watt, in a letter, calls "his random haphazarding." In 1779, when Captain Cook was preparing to sail upon his second voyage, Mr. Banks, who took a great interest in it from having been engaged in the first, invited Dr. Priestley to accompany the Captain as as- tronomer to the expedition. Advantageous terms were proposed, including a provision for his family. He entertained the proposal, and then agreed to it ; but objections were taken by the clerical members of the Board of Longitude, not to his ignorance of astronomy and of natural history, but to his Socinian principles in religion, which one might have supposed could exer- cise but a limited influence upon his observations of the stars and of plants. I know not if the same scientific authorities objected, on like grounds, in the council of the Royal Society, to receiving papers upon his chemical discoveries. It is certain that a like in- fluence prevented Professor Playfair from afterwards proceeding to India, where he had designed to prosecute his inquiries into the science of the Hindoos. Such passages stamp the history of a great nation with indelible infamy in the eyes of the whole world. In 1773, when his fame had been established by his first discoveries, and the Royal Society had crowned his paper with their medal, Priestley accepted an invita- tion from Lord Shelburne, afterwards first Marquis of PRIESTLEY. 417 Lansdowne, to fill the place of librarian and philoso- phic companion, with a salary of 250/., reducible to 150/. for life should he quit the employment. An additional allowance of 40/. a-y ear was given by this truly munificent patron for the expense of apparatus and experiments ; homes were provided for his family in the neighbourhood both of Lord Shelburne's town and country residence ; nor can anything be easily conceived more truly gratifying to a man of right feelings, and of a noble ambition, than the reflection must have been, that the discovery of oxygen was made under his roof, and with the funds which his disin- terested liberality had provided for his philosophic guest. With whatever difference of sentiments states- men may at any time view Lansdowne House, the lovers of science to the latest ages will gaze with veneration on that magnificent pile, careless of its architectural beauties, but grateful for the light which its illustrious founder caused to beam from thence over the whole range of natural knowledge ; and after the structure shall have yielded to the fate of all human works, the ground on which it once stood, consecrated to far other recollections than those of conquest or of power, will be visited by the pilgrim of philosophy with a deeper fervour than any that fills the bosom near the forum or the capitol of ancient Rome. In 1780 Priestley settled at Birmingham, where he was chosen minister of the principal Dissenting con- gregation. He had left Lansdowne House without any difference to interrupt the friendship of its inmates ; and some years afterwards an offer to return, made on the death of Lord Lansdowne's friends, Dunning and 2 E 418 PRIESTLEY. Lee, was declined.* A subscription among his friends furnished the means of prosecuting his experimental researches ; and he declined an offer to obtain for him a pension from the Government. A shade is cast upon this passage of his history by the circumstance of the pecuniary aid which he thus received being only in a small part rendered necessary for his experimental pur- suits. Mr. Parker, the eminent optician, furnished him for nothing all the instruments made by him, as did Mr. Wedgwood all his earthenware utensils. Yet we find in his correspondence a painful thankfulness expressed, in any thing rather than the language of a philosopher, to Mrs. Rayner and Mr. Lee, for " seasonable benefactions." The "apology" which he evidently feels required for this kind of dependence is not at all confined to the " ex- pense of his philosophical and theological studies ;" he refers also to the education of his children, and to the expenses of housekeeping occasioned by his reputation. f It is not invidious to observe that, be a man's celebrity ever so great, he is not bound to incur any expenses in keeping hospitality, if these, " exceeding twice his own income" (and that, with the pension of Lord Lans- downe, not an inconsiderable one), can only be met by the large " benefactions" of his friends. He names fifteen \vjxo gave him by subscription a yearly allow- ance, all the while he chose to decline an offer made to * This offer, and Lord Lansdowne's frank declaration that he never had any fault to find with his guest, entitles us to state that no quarrel, nor anything like it, had occurred. Nevertheless Priest- ley's offer to visit his Lordship when he occasionally came to London was politely declined. Political reasons apparently caused this refusal. f Memoirs, vol. i., part i., page 217. PRIESTLEY. 419 procure a pension from the Government, " wishing to preserve himself independent of every thing connected with the Court." We must on this be content to remark, that different men entertain different notions of independence. Settled at Birmingham, he continued, however, his controversial writings, and engaged eagerly in conflict with Gibbon upon his celebrated chapters respecting the Early History of Christianity, and with Bishop Horsley upon the Socinian doctrines. In the latter controversy the Episcopal and the Sectarian tempe- rature, both high, were not very unequal ; but in the former the minister of the Gospel had all the heat to himself — at least in the layman it was latent, if it existed at all. He was desirous of drawing his adversary into a controversy, and, failing in this, lost his temper, and had the vulgar recourse to calling names and imputing motives. Mr. Gibbon may have shown some superciliousness in his treatment of this angry polemic ; but he certainly had a good right to marvel at the intolerance of one whose heterodoxy was so universal as to " condemn by circumscribing the inspiration of the Evangelists, and to condemn the reli- gion of every Christian nation as a fable less innocent, riot less absurd, than Mahomet's journey to the third heaven." Haw fortunate it was that Priestley lived in an age when the use of actual fire is withheld from theological disputants, as a mode of argumentation, must appear from the wonder he expresses' at David Hume's monument having been so long suffered to offend the pious eyes of the Edinburgh people— an ex- pression which might seem to convey a hint that he 2 E 2 420 PRIESTLEY. would have taken care to avoid, after lie had himself felt the weight of the popular hand when called in to settle theological disputes. Having taken, as was his wont, an active but not a very temperate part in the controversy to which the French Revolution gave rise, and having published a ' Reply' to Mr. Burke's famous pamphlet, he was early in 1791 made a citizen of the French Republic. An ironical and somewhat bitter pamphlet against the high church party still further excited the feelings of the people against him ; and a dinner being given on the 14th of July to celebrate the anniversary of the attack upon the Bastille, the mob attacked the tavern where the party were assembled. Dr. Priestley was not present, but his chapel and house were immediately after assailed. His library, manuscripts, and apparatus were destroyed ; his person and his family escaped. The compensation which he ob% tained, by an action against the hundred, fell short, according to his own account, by 2000/. of his loss. As, however, an ample subscription was made for him, and as his brother-in-law generously gave him 10,000/., with an annuity of 2001. for life, he could not be other than a large gainer by the execrable violence of which he had been the victim ; and as he never allowed any of his writings to remain unpublished for even the shortest time after they were finished, it is not likely that any loss of an irreparable kind was incurred by the burning of his papers. He found, however, that he could no longer reside with comfort in the scene of such outrageous proceedings, and among a community which had so shamefully countenanced PRIESTLEY. 421 them. He removed to London, and succeeded his friend, Dr. Price, as Principal of the Hackney Academy. Late in the month of September, 1792, he was elected by the department of the Orne a member of the National Convention, about to assemble after the subversion of the French monarchy. This singular honour bestowed on him, as well for his philosophical fame as for his political services and the persecutions to which they had exposed him, he re- spectfully declined, giving as his reason that he was not familiar with the French language, and had not devoted his time sufficiently to legislative duties. But this moderation disarmed not his enemies — he was pur- sued by the intolerant spirit of the times. He found himself shunned by his former associates in science. Even the Royal Society did not afford an exception to this persecuting loyalty* or a shelter from its effects ; and in the spring of 1794 he withdrew to America. Here he again suffered considerable disappointment. His religion was too much for those who had ceased to care for sacred things, and far too scanty for those who still were Christians, while his republican opinions were exceedingly distasteful because they were tinged with a decided admiration of France. He continued, however, to inhabit the country, and to prosecute his studies, chiefly theological. He received contributions regularly from his benefactors in England, Mrs. Rayner and the Duke of Grafton ; but these, though acknow- ledged by him in the same unpleasant style as eleemo- synary (" very acceptable benevolences"), were for the most part on a different footing from the English CIUBRAR1 422 'PRIESTLEY. charities ; they appear generally to have been required for the propagation of their Unitarian opinions, to which the parties were all so zealously attached. He settled at Northumberland, in an uncleared dis- trict, where he purchased three hundred acres of land ; and his youngest son, Henry, then a very fine young man of eighteen, devoted himself to the clearing and culti- vating this woodland spot, working with his labourers and sharing their toils. The father himself partook of this labour for two or three hours daily. On Sun- days he frequently preached, and w}ien he visited Philadelphia he always did so. He devoted the rest of his time to his works, particularly his 'Church History ;' and he wrote answers to Paine and Volney. He was much obstructed in his philosophical pursuits by the want of proper accommodation for his apparatus, and he only wrote three traets on chemical subjects during the ten years of his residence in America ; two of which were merely arguments on phlogiston, and the third alone had any experiments, written eight years before his death. At the end of 1795 he suffered a heavy affliction in the death of his son Henry, after a few days' illness ; and in ten months more he also lost his wife. These blows, though he felt their weight, did not at all crush him; his resignation was exemplary; and his steady, enthusiastic faith in Revelation gave him a cer- tain hope of meeting before many years should elapse with those whom he had lost. Indeed, his letters clearly show that he regarded the sundering of these ties far less attentively than their restoration. A few PRIESTLEY. 423 days after his son's death he writes to his most inti- mate friend and constant correspondent, Theophilus Lindsay, recounting the particulars of his loss, and he adds that he is composing three discourses on Revela tion against modern unbelievers. The letter next year announcing his wife's death, begins with saying to the same friend how much he stands in need of his sym- pathy, and goes on to add, " This day I bury my wife ; she died on Saturday after an illness of a fortnight." He adds some remarks on his literary occupations, and concludes with mentioning a plan he has of travelling to distract his mind.* No one who reads his letters and memoirs by himself can doubt that this stoical firmness is not the result of a callous disposition, but the signal triumph of a heartfelt belief in the promises of Religion over the weakness of our nature. It is, indeed, quite manifest that Religion was as much an active principle in him as in any one who ever lived. Not only is it always uppermost in his thoughts, but he even regards temporal concerns of a public nature always in connexion with the Divine superintendence, and even with the prophecies of Scripture. His letters are full of references to those prophecies as bearing on passing events, and he plainly says that since his removal to America he should care little for European events but for their connexion with the Old Testament. He also looked far an actual and material second coming of Christ upon earth. It is not true to affirm that he was little of a poli- * Mem., vol. i. part ii. p. 328, 354. 424 PRIESTLEY. tician, though in declining the seat in the National Convention he says* his studies had been little directed towards legislation compared with theology and philo- sophy; and denies in a letter to William Smith that he ever taught or even mentioned politics to his pupils, as he had been charged with doing, among the innu- merable falsehoods of which he was the subject. Nor is the circumstance of his not attending political meet- ings at all decisive of his being little of a political agi- tator, because his incurable stutter prevented him from taking a part in such proceedings. But he wrote in 1774, at Franklin's request, an address to the people on the American disputes, previous to the general election. He answered Mr. Burke's * Reflections on the French Revolution.' He mixed in the question of the Catholic claims ; and he published in all no less than eleven political works, almost every one upon the topics of the day. It is equally true, however, that theological controversy occupied him far more con- stantly and engaged his mind far more deeply than political matters ; that he was regularly a theologian and incidentally a partisan. , , . The cast of his political opinions was originally little more tending to democracy than those of Whigs usually are who have read and discussed more than they have reflected and seen. He used, indeed, to say that in politics he was a Trinitarian, though a Unitarian in religion. It must, however, be confessed that he went very much further in the same direction after the French Revolution had set fire to the four * Mem., vol. i. part ii. p. 190—198. PRIESTLEY. 425 quarters of the political world, and his admiration of republican principles might be measured by his zeal for the innovators of France, with the success of whose arms he deemed the safety of freedom to be bound up. When we read his answer to the offer of a seat in 1792, and reflect that it was penned about three weeks after the horrible massacres of September, the worst of the atrocities which disfigured the Revolution, it moves our wonder to find a Christian minister accompanying his acknowledgment of the, honour proposed, that of being enrolled among the authors of the tragedy so recently enacted, with no protest against the bloody course then pursuing, no exception to the unquali- fied admiration expressed of the youthful republic. In America we find his leanings are all against the Federal party, and his censures of the great Chief of the Union little concealed. He felt for the demo- cratic party, the French alliance, the enemies of Eng- lish partialities, and he regarded Washington as un- grateful because he would not, from a recollection of the services of France twenty years before to American independence, consent to make America dependent upon France. The indifferent reception which he met with in society was probably owing to this party vio- lence full as much as to the dislike of his Unitarian opinions. But it must be added, that his temper was so mild, and his manners so gentle, as to disarm his most prejudiced adversaries whensoever they came into his society. Many instances of this are given in his correspondence, of which one may be cited. Pie hap- pened to visit a friend whose wife received him in her husband's absence, but feared to name him before a Cal- 426 PRIESTLEY. vinistic divine present. By accident his name was men? tioned, and the lady then introduced him. But he of the Genevan school drew back, saying, " Dr. Joseph Priestley ?" and then added in the American tongue, " I cannot be cordial." Whereupon the Doctor, with his usual placid demeanour, said that he and the lady might be allowed to converse until their host should return. By degrees the conversation became general ; the repudiator was won over by curiosity first, then by gratification; he remained till a late hour hanging upon Priestley's lips ; he took his departure at length, and told the host as he quitted the house, that never had he passed so delightful an evening, though he ad- mitted that he had begun it "by behaving like a fool and a brute." One such anecdote (and there are many current) is of more force to describe its subject than a hundred laboured panegyrics^ After the loss of his wife and his younger and favourite son, he continued with unabated zeal to pursue his theological studies, and published several works, both controversial and historical, beside leaving some which have been given to the world since his decease. He endeavoured, too, as far as he could, to propagate the tenets of Unitarianism, and to collect and extend a congregation at Philadelphia attached to that doctrine. At one time, in the sum- mer of 1797, entertaining hopes of peace in Europe, he had resolved to visit France, where he might communicate personally with his English friends ; and he even thought of making a purchase in that country on which he might reside during a part of each year. So nearly did he contemplate this removal, that we PHIESTLEY. 427 find him desiring the answers to letters he was writing might be sent to the care of Messrs. Perregaux at Paris. The revolution of Fructidor, however (4th September, 1797), put an end to all prospects of peace, and the war soon raged in every quarter with re- doubled fury. He seems now to have derived his chief comfort from tracing the fancied resemblance between the events passing before him and the prophecies in Scripture ; though occasionally he felt much puzzled, and the book of Daniel, especially, appears to have given him trouble and perplexity. When the peace came at last, his health was too much broken to permit any plans to be executed such as he had four years before contemplated. In 1802 he became a confirmed invalid, suffer- ing from internal, and apparently organic, derange- ment. His illness was long and lingering, and he suffered great pain with perfect patience for two years. The prospect of death which he had before him did not relax his application to literary labour, his faculties remaining entire to the last. Neither did that awful certainty, ever present to his mind, afieet him with sorrow or dismay. The same unshaken belief in a future state, the same confident hope of immortal life which had supported him under his affliction for the death of others, cheered him while contemplating the approach of his own. In this happy frame of mind he gently expired on the 6th of February, 1804, in the seventy-second year of his age. His character is a matter of no doubt, and it is of a high order. That he was a most able, most indus- trious, most successful student of nature, is clear ; and 428 PRIESTLEY. that his name will for ever be held in grateful remem- brance by all who cultivate physical science, and placed among its most eminent masters, is unques- tionable. That he was a perfectly conscientious man in all the opinions which he embraced, and sincere in all he published respecting other subjects, appears equally beyond dispute. He was, also, upright and honourable in all his dealings, and justly beloved by his family and friends as a man spotless in all the relations of life. That he was governed in his public conduct by a temper too hot and irritable to be con- sistent either with his own dignity, or with an amiable deportment, may be freely admitted ; and his want of self-command, and want of judgment in the practical affairs of life, was manifest above all in his controversial history ; for he can be charged with no want of pru- dence in the management of his private concerns. His violence and irritability, too, seems equally to have been confined to his public life, for in private all have allowed him the praise of a mild and attractive demeanour; and we have just seen its great power in disarming the prejudices of his adversaries. ( 429 ) CAVENDISH. A GREATER contrast between two men of science, both eminent benefactors to the same branch of know- ledge, can hardly be imagined than Cavendish offers to Priestley. He was thoroughly educated in all branches of the Mathematics and Natural Philosophy ; he studied each systematically ; he lived retired from the world among his books and his instruments, never meddling with the affairs of active life ; he passed his whole time in storing his mind with the knowledge im- parted by former inquirers and in extending its bounds. Cultivating science for its own sake, he was slow to appear before the world as an author ; had reached the middle age of life before he gave any work to the press ; and though he reached the term of four- score, never published a hundred pages. His methods of investigation were nearly as opposite as this diversity might lead us to expect ; and in all the accidental circumstances of rank and wealth the same contrast is to be remarked. He was a duke's grandson ; he possessed a princely fortune ; his whole expenditure was on philosophical pursuits ; his whole existence was in his laboratory or his library. If such a life presents little variety and few incidents to the vulgar observer, it is a matter of most interesting con- templation to all who set its just value upon the cultivation of science, who reckon its successful pur- 430 CAVENDISH. suit as the greatest privilege, the brightest glory of our nature. Henry Cavendish was born at Nice, whither his mother's health had carried her, the 10th of October, 1731. He was the son of Lord Charles Cavendish, the last Duke of Devonshire's great uncle, by the daughter of Henry Grey, Duke of Kent. His family, aware of the talents which he early showed, were anxious that he should take the part in public life which men of his rank are wont to do, and were much displeased with his steady refusal to quit the studies which he loved. An uncle, disapproving of the course pursued towards him, made him his heir ; and so ample a fortune came into his possession that he left at his death a million and a quarter of money.* The Mathematics, and the various branches of Natural Philosophy, were the chief subjects of his study, and of all these sciences he was a consummate master. The discoveries of Black on carbonic acid and latent heat, appear to have drawn his attention to the cultivation of pneumatic chemistry ; and in 1766 he communicated to the Royal Society his experiments for ascertaining the properties of carbonic acid and hydrogen gas.f He carried his mathematical habits into the laboratory ; and not satisfied with showing the other qualities which make it clear that these two * M. Blot's article in the Biog-. Univ. makes him the son of the Duke of Devonshire, and states his yearly income at 300, OOO/. sterling, and yet gives the property he left at only 1,200,000/.— so that he must have spent 300,000/. a year, ^and also dissipated five millions. Such errors seem incredible. •f* Three papers containing experiments on factitious air. Phil. Trans., 1766, p. 141. CAVENDISH. 431 aeriform substances are each mi generis, and the same from whatever substances, by whatever pro- cesses, they are obtained ; nor satisfied with the mere fact that one of them is heavier, and the other much lighter, than atmospheric air,— he inquired into the precise numerical relation of their specific gravities with one another and with common air, and first showed an example of weighing permanently elastic fluids : unless, indeed, Torricelli may be said before him to have shown the relative weight of a column of air and a column of mercury : or the common pump to have long ago compared in this respect air with water. It is, however, sufficiently clear, that neither of these experiments gave the relative measure of one air with another : nor, indeed, could they be said to compare common air with either mercury or water, although they certainly showed the relative specific gravities of the two bodies, taking air for the middle term or common measure of their weights. The common accounts in chemical and in biogra- phical works are materially incorrect respecting the manner in which Mr. Cavendish was led to make his great experiment upon the composition of water in 1781 and the following years. It is said, that while making his experiments on air in 1765 and 1766, he had observed for the first time, that moisture is pro- duced by the combustion of inflammable air, and that this led him, sixteen or seventeen years later, "to com- plete the synthetical formula of water, and to find that the moisture that he had before observed was simple water."* Nothing can be more erroneous than * Penny Cyclopaedia^ vol. vi. p. 392. This and other similar 432 CAVENDISH. this whole statement. In Mr. Cavendish's paper, of 1766, upon fixed and inflammable airs, there is not one word said of the moisture formed by the com- bustion ; and respecting inflammable air, the experi- ments are confined entirely to its burning or exploding, to its specific gravity, and to its production. The paper of 1784 is, in fact, entitled ' Experiments upon Air,' and it commences with stating, not that those experiments were undertaken with any view to the water formed by burning inflammable air, but that they were made " with a view to find out the cause of the diminution which common air is well known to suffer by all the various ways in which it is phlogisticated, and to discover what becomes of the air thus lost or con- sumed ;" and the author adds, that besides " determining this fact, they also threw light on the constitution and means of production of dephlogisticated air." In- stead of referring to any former observation of his own either in 1766, or subsequently, on the moisture left by burning inflammable air, he expressly refers to Mr. Warltire's observation of this moisture, as related by Dr. Priestley : and both Mr. Warltire's observation and Dr. Priestley's publication were made in 1781. Upon this observation Mr. Cavendish proceeded to further experiments, with the view of ascertaining " what becomes of the air lost by phlogistication." accounts are plainly given by some persons who never read Mr. Cavendish's writings. But a still greater error occurs in them : they represent him as having first shown that fixed and inflammable airs are separate bodies from common air ; whereas Dr. Black, in his Lectures from 1755 downwards, showed this distinctly by his experi- ments, proving clearly that these gases have nothing in common with the atmospheric air (vol. ii., p. 87, 88). CAVENDISH. 433 For this purpose, he introduced a portion of hydrogen gas into a globe or balloon of glass, sufficiently strong to resist the expansive force of the combustion which had often been observed in mines, and also in experi- ments upon a smaller scale, to produce an explosion. He adapted to the globe two wires of metal, fixing them in air-tight sockets, and bringing their points within a short distance of each other in the inside of the globe ; so that, by an electrical machine, he could send the spark or the shock from the one point to the other, through the gases mixed together in the globe. He found that the whole of the hydrogen gas disappeared by the combustion thus occasioned, and a considerable portion also of the common air. Water was, as usual, found in small quantity, and an acid was also formed. He then weighed accurately the air of both kinds which he exposed to the stream of elec- tricity, and he afterwards weighed the liquid formed by the combustion ; he found that the two weights cor- responded with great accuracy. It was difficult to resist the inference that the union of the two airs had taken place ; and it might further have been inferred that the latent heat which held them in an elastic state had been given out, forming the flame which was produced ; and that water was formed by the union of the two airs, having, of course, less latent heat than was required to keep them in a gaseous state ; but Mr. Cavendish did not approve of this manner of stating the conclusion which Mr. Watt had adopted, because of. doubts which he had respect- ing the nature of heat.* The residue of the com- * Page 140. 2 F 434 CAVENDISH. bustion, however, was two -.fold: there was an aeriform body left in the glass vessel, as well as liquid in the bottom. This was much smaller in volume than the air which had filled the globe before the combustion, because the hydrogen gas and part of the common air had disappeared. This aeriform residue was also of a different nature from common air ; it was found to be the phlogistic air of Priestley ; the azotic air of Jlutherford : and the air consumed in burning t)je hydrogen gas must, therefore, be the vital air or oxygen gas of the atmosphere. By another ex- periment he more fully ascertained this : for, burning oxygen gas with hydrogen gas, nearly the whole aeriform contents of the globe disappeared, and water, equal in weight to the two gases taken together, remained as the produce of the combustion ; but still an apid was formed, unless in some cases, when very pure oxygen gas was used. Thus was effected the important discovery of the com- position of water, which Watt had inferred some time before from a careful examination of the similar facts collected by former experimentalists ; one of whom, Warltire, had even burned the gases in a close vessel, and by means of electricity. The conclusion arrived at by Mr. Cavendish from his capital experiment was, in }iis own words, that " dephlogisticated air is in reality nothing but dephlogisticated water, or water deprived of its phlogiston, or in other words, that water consists of dephlogisticated air united to phlogiston, and that inflammable air is either pure phlogiston, or else water united to phlogiston ;" and he then gives his reasons in favour of the second inference, namely, that inflammable air is water united to phlogiston ; but he repeatedly CAVENDISH. 435 dwells on the preference due to this inference over the conclusion that inflammable ah- is pure phlogiston * This statement of the theory is somewhat less distinct than Mr. Watt's, who considered water to be dephlo- gisticated air united to inflammable air or pure phlo- giston, and both deprived of their latent heat. But he, as well as Mr. Cavendish, expresses himself with some hesitation, and even, like him, in some passages 'enter- tains the idea of water as united in a small proportion with inflammable air. The theory, though nearly completed by those great chemists, was perhaps first stated with perfect certainty and distinctness by La- voisier, f In the combustion of hydrogen gas with common air, and even with impure oxygen gas, Cavendish had observed that the water was slightly tinged with acid, though not always when pure oxygen gas was used for the operation. He therefore devised an experiment which should ascertain the nature of this acid, and in what manner it was formed. He passed the electric spark through common air with- out any hydrogen gas being present ; the air was in a receiver over mercury, and the operation was of long continuance, on account of the slowness with which the combination is formed of the two gases whereof the atmosphere is Composed. He had not supposed that the hydrogen had any share in forming the acid : his theory being that water, rind not acid, is the produce of that gas's combustion. He naturally * Philosophical Transactions, 1784, p. 137, 140, t See Appendix to the Life of Watt. 2 F 2 436 CAVENDISH. suspected the acid to be the produce of some union between the azote and the oxygen of the atmosphere. He left the process in the hands of a committee of his scientific friends, fellow-members of the Royal Society ; and after some weeks of constantly passing the electric fluid through a limited portion of air, a small quan- tity of liquid was formed, which readily combined with a solution of potash in water sent up through the mercury. This union was found to be common nitre, having all the qualities of that well-known sub- stance. It detonated with charcoal ; it sparkled when paper impregnated with it was burnt; it gave out nitrous fumes when sulphuric acid was poured on it. There could, therefore, no doubt whatever now exist that nitrous acid is composed of the two airs deprived of latent heat, which form our atmosphere; that it is a true oxide of azote. The undivided merit of this important discovery has never been denied to Mr. Cavendish. Even Lavoisier could not intrude ; but his avidity to claim a share in all discoveries had been exerted respecting the composi- tion of water, which he asserts in his ' Elements of Chemistry' to have been discovered by himself and Mr. Cavendish about the same time. I have shown clearly in the Appendix to the Life of Mr. Watt, that the dis- covery had been previously communicated to the French philosopher ; but it is worth while to consider the ex- periment upon which he grounded his claim ; and that experiment, when examined, is found wholly insufficient to prove the position, even if it had been contrived and performed before the communication of Watt's and Cavendish's discovery. Of that discovery CAVENDISH. 437 it was plainly a corollary — by that discovery it was manifestly suggested. The former experiments, both those of Cavendish and those on which Watt reasoned, were all syn- thetical and decisive — that of Lavoisier was analytical and radically defective. It proved nothing conclusively : it was well enough after the experimentum crucis had demonstrated the proposition ; to that proposition it was a corollary — it was nothing like a critical experiment. He placed water in a retort exposed to heat ; the vapour of the retort, when the water boiled, was passed through a tube (a gun barrel with the breech-pin knocked out was generally used) ; the tube, if made of earthenware, had iron filings placed in its course ; it was placed in a fire ; its further extremity was connected with a receiver, in which cold water or mercury rose to fill it entirely. As the water slowly boiled there came through the tube, and into the glass receiver, a current of gas, which, upon examination, was found to be hy- drogen gas, while the iron filings were converted into calx or oxide. The weight of the gas produced, added to the weight acquired by the gun barrel or by the filings during the process, was found to be nearly equal to the weight lost by the water in the retort. Hence the inference was, that the lost portion of water had been decomposed into its two elements, the oxygen gas forming the calx of the iron and the hydrogen gas being received in the glass vessel. But the adversaries of the new doctrine had an answer to this inference far more formidable than any that they could urge against the conclusion drawn from the synthetical experiment. The analytical experiment was liable to all the uncertainty 438 CAVENDISH. of the process called the destructive distillation. The substances found might have been the product, anfl npt merely the educt of the process. It is knpwn that if coal or oleaginous bodies be distilled in close vessels there are obtained; gases and water and acids which never existed in the matters subjected to the action, of the fire. The component parts of these matters enter into new com- binations with one another under the action of heat, just as a.taljpw ca.ndlq or an oil lamp, gives lamp-black and water in burning, though no w#ter> but only: hydrogen, nor, ofcpurse any lamp-black;, exists an the tallow and the pil< So, in, Lavoisier's, experiment, the water might contain only oxygen and hydrogen, and the action of the hot iron might have separated them from each other, But it. was also quite ppssible that the iron gave out hydrogen, and that the hot water was partly kept in solution by this gas, partly combined with the iron, for oi> that supposition the combined weight of the calcined iron and the, hydrogen gas would be exactly equal, to the united, weight of the water evaporated, and of th$ iron before calcination. The previous discovery of Watt and Caven.dish is liable to no such ambiguity ; and it has the merit of also removing all ambiguity from the experiment of Lavoisier, which it manifestly, suggested. These great discoveries placed Cavendish in the highest rank of philosophers. No one doubted of nitrous acid ; that he was the undisputed discoverer of the composition of water, before Mr. Watt's: claim, is equally certain; nor, even r now, is . it necessary for the defenders of Watt's priority to deny that Cavendish made the great step without any previous knowledge CAVENDISH. 439 of Watt's reasoning, while all admit that his expe- rimentum crucis was of the greatest value in com- pleting the foundation on which Watt's happy infer- ence had been built. Lavoisier's attempt to intrude himself was wholly unsuccessful ; it had no effect whatever except to tarnish his reputation, already injured sufficiently by his similar attempt to share in the discovery of oxygen. All men held Cavendish's name as enrolled among the greatest discoverers of any age, and only lamented that he did not pursue his brilliant career with more activity, so as to augment still farther the debt of gratitude under which he had laid the scientific world. The reader, especially the French reader, must not suppose that any prejudice respecting Lavoisier has dictated the remarks occasionally made in the course of this work upon his pretensions as a discoverer. It is scarcely possible to estimate too highly the services which he rendered to chemical science by his labours. The truly philosophic spirit which guided his researches had not been found to prevail much before his time in the speculations of chemists. He had a most happy facility in reducing the knowledge of scattered and isolated facts to a system. His talent for generalization has not often been surpassed ; and it led him, together with his admirable freedom from preconceived preju- dice, and his resolute boldness of investigation in unfrequented paths, to make some of the most felicitous inductions, well deserving the title of discoveries, that have ever been made, although the materials of his inferences were obtained from the experiments and observations of his predecessors, and his own experi- 440 CAVENDISH. ments, except on the nature of the diamond, led to no material extension of our chemical knowledge. Stript of the plumes in which he sought to array himself, re- pulsed from the avenues by which he would fain have intruded himself among those whose experiments led at once to great discoveries, he is now, on all hands, allowed to have never made us acquainted with a single new gas, or a new substance of any kind, or, except as to carbon, with a single new combination of the old. He did not, like Black, discover carbonic acid or latent heat — he did not, like Priestley, discover oxygen — he did not, like Scheele, discover chlorine — he did not, like Davy, discover the alkaline metals — or like Cavendish, by direct experiment, show how water and nitrous acid are constituted — or, like Ber- thollet, explain of what ammonia consists. But it is equally confessed that, by sound and happy reasoning on the experiments of* others, he showed how the process of combustion and of calcination takes place, and to him and his individual researches we owe the important discovery that fixed air, however generated, whether by respiration or by combustion or by fermen- tation (its three great sources, as proved by Black), is the combination of oxygen and carbon. Nor is it any deroga- tion from his claims to the title of a discoverer of physical truths that his generalization pushed too far made him regard oxygen as necessary to all combustion and all acidification, whereas it has been found that heat and light are abundantly evolved both by the combustion of metals and sulphur in close vessels — by the combustion of hydrogen and azotic gas — and by the combination of metals with chlorine ; and also that chlorine, an acid CAVENDISH. 441 of the strongest kind, contains no oxygen at all, while the alkalis themselves are oxides. The doctrine of latent heat was happily applied by him to the union of gases with bodies, and if he had only followed that doctrine more closely he would have avoided the error into which he fell, and perceived that other gases as wel] as oxygen may support flame, and that all, on becoming liquid or solid, must part with heat. Against his error respecting the constitution of acids may justly be set the great merit of his conjecture, that the fixed alkalis are oxides of metals ; for this has been since proved, and the conjecture is a sufficient evidence that he did not doggedly adhere to his theory of the acidi- fying principle. It does not appear that Mr. Cavendish ever after 1785, when he discovered the nature of nitrous acid, prosecuted his chemical inquiries so as to make new discoveries ; but beside making numberless use- ful chemical experiments, about ten years later he engaged in some important experiments upon the force of attraction. It occurred to him that he could measure that force, and thereby ascertain the density of the earth by accurately observing the action of bodies suddenly exhibited in the neighbourhood of a horizontal lever nicely balanced, loaded with equal leaden balls of a small size at its two ends, and pro- tected from all aerial currents by being inclosed in a box. In that box a telescope and lamp were placed, that the motions of the lever might be carefully ob- served. On approaching the external leaden balls made use of, whose diameter was eight inches, to the small ones inclosed, and near the lever, it was found that a 442 CAVENDISH. horizontal oscillation took place. This was measured ; and the oscillation caused by the earth on a pendulum being known, as well as the relative specific gravities of lead and water, it was found, upon the medium of his observations, that the earth's density is to that of water as eleven to two, or five-and-a-half times greater. Di». Button, who repeated his calculations, made the result five three-tenths, or as fifty- three to ten. Maske- lyne's experiments at Schehallion made the proportion as five to one. Zach's experiment on a smaller hill near Marseilles did not give a result materially different. A paper on the civil year of the Hindus, connected, like Newton's chronological works, with astronomical researches, an account of a new eudiometer, and some papers on electricity, form the rest of this great philo- sopher's works ; and altogether they shrink into a very inconsiderable bulk compared with the voluminous works of inferior men. In this, as hr other respects, we trace his resemblance to Black. Indeed the admi- rable contrivance of their experiments— their circum- spect preparation of the ground by previous discussion of principles — the cautious following of facts, and yet the resolute adoption of legitimate consequences in their generalizations — the elegance of their processes, and the conciseness of their descriptions and remarks, with an unsparing rejection of everything superfluous — forms the characteristic of both those illustrious students of nature. While, as regards Cavendish's writings, it has been, and as regards Black's it might have been, justly said by one that every sentence will bear the microscope ; another writer, the most eminent of his successors, has, with equal truth, described his processes afc of so -finished a nature, CAVENDISH. 443 so perfected by the hand of a master, as to require no- correction ; and, though contrived in the infancy of the science, yet to remain unsurpassed, perhaps unequalled, for accuracy and beauty at the present day. The world, even the scientific world, dazzled by the brilliancy of those discoveries which we have described, is wont to regard Cavendish as a chemist merely. But it was not only in chemical science and in a few depart- ments of natural philosophy that this great man had thoroughly exercised himself ; he was profoundly versed in every branch of physics, and was a most complete and accomplished mathematician. I have had access to the manuscripts which he left behind him ; and it would be difficult to name any subject which had not engaged, his close attention : all had been made the subject not only of his study, but of his original investigations. The two papers on Electricity which he published in the £ Philosophical Transactions ' contain, the one of 1776, the first distinct statement of the difference be- tween animal and common electricity ; the other, in 1771, twenty-seven propositions upon the action of the electric fluid, treated mathematically. They are grounded upon the general hypothesis that the par- ticles of the fluid repel one another, and attract those of. other matter with . a force inversely as some lesser power than the cube of the distance ; and with this theory the experiments which he examines are found to tally perfectly. But his voluminous unpublished papers show how, constantly his life was devoted to experimental 'inquiries, and analytical or geometrical investigations. Beside ranging over the whole of che- mical science, they relate to various branches of optics, 444 CAVENDISH. of physical and of practical astronomy — of the theory of mathematical and astronomical instruments — of me- chanical and dynamical sciences, both theoretical and practical — of pure mathematics in all its branches, geo- metry, the integral and differential calculus, the doctrine of chances and annuities. He seems in his application of mathematics to physics to have disregarded elegance, and even simplicity, and to have chosen always the shortest and most certain path to his object. Accordingly this somewhat surprises the mathematical reader ; as 77 Ci 77 77 77 when we find him using (j~^ (or rather ^7-, for he always employs the Newtonian notation) for the sub- normal, having taken a? for some other quantity than the abscissa, and using three letters, as a, %, and «r, to denote segments of the same line, when perhaps a is the whole line, and a — a? is equal to z. But that he had the most familiar and masterly knowledge of the calculus is plain throughout all his investigations, as it is that his trust in its powers induced him to throw himself willingly and habitually upon them. In this respect he stands not only at the head of chemical philosophers, but alone among them, with perhaps one or two exceptions in the French school. In giving the history of his labours, and the cha- racter of his intellectual capacity, we have written the life of Cavendish. His personal history cannot be expected to have any striking interest ; yet they who have been dwelling on his scientific eminence will not be displeased to know somewhat of his ordinary life. He was of a most reserved disposition, and peculiarly shy habits. This led to some singularity of manner, CAVENDISH. 445 which was further increased by a hesitation or difficulty of speech, and a thin shrill voice. He entered diffi- dently into any conversation, and seemed to dislike being spoken to. He would often leave the place where he was addressed, and leave it abruptly, with a kind of cry or ejaculation, as if scared and disturbed. He lived in a house on Clapham Common, and his library, vast in extent, was at another place, because he made it accessible to all, and did not wish to be trou- bled by those who resorted to it. He allowed friends to take books from it, and he himself never took one without giving a receipt for it. On the death of his librarian he began the practice of himself attending one day in the week to give out and take in books. His large income was allowed to accumulate ; and when his bank- ers, after finding that a very considerable balance was always left in their hands, mentioned the circumstance, suggesting that it might be invested to some profit, he answered with much simplicity, that if the balance was an inconvenience to them he could go to another banker. Him self a man of no expense, his habits never varied, nor did his style of living at all suffer a change on suc- ceeding to his uncle's large fortune. His purse was ever accessible to the claims of charity, as well as to pro- posals for the promotion of scientific pursuits. Having formed a high opinion of Dr. (afterwards Sir Charles) Blagden's capacity for science, he settled a consider- able annuity on him, upon condition that he should give up his profession and devote himself to philosophy ; with the former portion of which condition the Doctor complied, devoting himself to the hopeless pursuit of a larger income in the person of Lavoisier's widow, who 446 CAVENDISH. preferred marrying Count RumforcL* Mr. Cavendish received no one at his residence ; he ordered his dinner daily by a note which he left at a certain hour on the hall table, where the housekeeper was to take it, for he held no communication with his female domestics, from his morbid shyness. It followed, as a matter of course, that his servants thought him strange, and his neigh- bours deemed him out of his mind. He hardly ever went into society. The only exceptions I am aware of are an occasional christening at Devonshire or Burling^- ton House, the meetings of the Royal Society, and Sir Joseph Banks' weekly conversaziones. At both the latter places I have met him, and recollect the shrill cry he uttered as he shuffled quickly from room to room, seeming to be annoyed if looked at, but sometimes approaching to hear what was passing among others. His face was intelligent and mild, though, from the nervous irritation which he seemed to feel, the expres- sion could hardly be called calm. It is not likely that he ever should have been induced to sit for his picture ; the result therefore of any such experiment is want- ing. His dress was of the oldest fashion, a greyish green coat and waistcoat, with flaps, a small cocked hat, and his hair dressed like a wig (which possibly it was) with a thick clubbed tail. His walk Was quick and uneasy ; of course he never appeared in London unless lying back in the corner of his carriage. He probably uttered fewer words in the course of his life than any man who ever lived to fourscore years, not at all excepting the monks of La Trappe. , , . - •» r , • li-t-: -. , i :_^ i_t_: * He left Sir Charles a legacy of 15,000/. \ which was generally understood to have fallen much short of his ample expectations. CAVENDISH. 447 Mr. Cavendish died on the 10th of March, 1810, after a short illness, probably the first as well as the last under which he ever suffered. His habit of curious observation continued to the end. He was desirous of marking the progress of disease, and the gradual ex- tinction of the vital powers. With this view, that he might not be disturbed he desired to be left alone. His servant returning sooner than he had wished was ordered again to leave the chamber of death, and when he came back a second time he found his master had expired. t 448 ) D A V Y. SIR HUMPHRY DAVY being now removed beyond the reach, of such feelings, as he ought always to have been above their influence, that may be said without offence of which he so disliked the mention : he had the honour of raising himself to the highest place among the chemical philosophers of the age ; emerging by his merit alone from an obscure condition. His father was a carver in wood at Penzance, in Corn- wall ; a man of some ingenuity in his craft. He pos- sessed a small landed property in the village of Varfell, near Penzance, and Davy was born there in 1778. He received the rudiments of his education at a school in Truro, but was very early apprenticed to an apo- thecary at Penzance, where, disliking the profession to which he had been destined, he occupied himself with chemical experiments, ingeniously contriving to make the utensils of the shop and the kitchen serve for ap- paratus ; and it is remembered of him that he fre- quently alarmed the household by his explosions. The result of his dislike to the shop was a disagree- ment with his master, and he went to another in the same place ; but here he continued in the same course. Pursuing a plan of study which he had laid down for , and he went to an< SOS. MTUMIPHRIY ///"<' ''/•/.)/•/.)/('// ^t — f'//f DAVY. 451 Oxide,' on the respiration of which he had made some very curious experiments. The singular circumstances which he thus ascertained, gave him considerable re- putation as an experimentalist, and he was soon after (1802) chosen first Assistant Lecturer in Chemistry, by the Royal Institution of London, and the year follow- ing, sole Chemical Professor. Nor must the boldness which he had shown in conducting his experiments be passed over. He had exposed himself to serious hazard in breathing some most deleterious gases, and both in his trials of gaseous mixtures, and in his galvanic pro- cesses, he had made many narrow escapes from the danger of violent explosions. It is a singular fact that, although his attention had never been confined to his favourite science, for he had studied literature, and especially poetry to the extent of writing tolerable verses, yet he was of so uncouth an exterior and manners, notwithstanding an exceedingly handsome and expressive countenance, that Count Rumford, a leading director of the Institution, on see- ing him for the first time, expressed no little disap- pointment, even regretting the part he had taken in promoting the engagement. But these feelings were of short duration. Davy was soon sufficiently human- ized, and even refined, to appear before a London and a fashionable audience of both sexes with great advan- tage, and his first course of lectures had unbounded and unparalleled success. This he owed, certainly, to the more superficial accomplishments of good and lively language, an agreeable delivery, and, above all, an ingenuous enthusiasm for his subject which in- formed and quickened his whole discourse. But the 452 DAVY. fame which he thus acquired would have been of limited extent and of short duration, had his reliance only been upon the fickle multitude whom such quali- ties can please. The first consequences of his success in the line of mere exhibition were unfavourable, and threatened to be fatal ; for he was led away by the plaudits of fashion, and must needs join in its frothy, feeble current. For a while he is remarked to have shown the incongruous combination of science and fashion, which form a most imperfect union, and pro- duce a compound of no valuable qualities, somewhat resembling the nitrous gas on which he experimented earlier in life, having an intoxicating effect on the party tasting it, and a ludicrous one on all beholders. They who have recorded this transformation, while they lament the substitution of anything for " the natural candour and warmth of feeling which had singularly won upon the acquaintance of his early life," add most justly that the weakness which they describe never " cooled his regard for his family and former friends." I can vouch for the change, which was merely superficial, being of very short duration ; and it is pleasing to add that, even while it lasted, there was none of that most offensive of all the effects pro- duced by such a transition state to be found in his con- versation ; he never for a moment appeared to be ashamed of his great vocation, nor to shun the fullest discussion of the subject on? which he was at home, in order to deal with topics to which he was of neces- sity a stranger. I am speaking, too, of his habits long before his great discoveries ; there would have been little ground for praise, any more than for wonder, DAVY. 453 that the discoverer of the alkaline metals should be willing to have the conversation roll upon che- mistry and galvanism ; but the time to which I have been referring was when his fame rested chiefly upon the success of his lectures to mixed companies in Albemarle Street, and to lovers of agriculture in Sackville Street, where the Board had chosen him their Chemical Professor. If his situation at the Royal Institution had exposed him to the risk which we have seen he escaped, it had put him in possession of invaluable helps to his pur- suits. He had now an ample command of books ; he had assistants under him ; above all, he had an un- limited power of collecting and of making apparatus ; his income was secure; and his time was at his own disposal. He failed not to avail himself diligently of these great advantages ; and although he lived a good deal in society, where he was always a welcome guest, his principal relaxations during the rest of his life con- sisted in shooting, and especially in fishing, of which he was from his earliest years passionately fond. The intercourse he had held with Southey and with Cole- ridge had given him not only his taste for poetry, but an extraordinary love of rural walks, in the peaceful solitude of which I have heard him say, answering the ordinary and obvious objections of those who are not smitten with the love of the " Angle," the gratifica- tions of that propensity very mainly consist. In 1801 he made his first important discovery, that by which he ascertained the true nature of galvanic action. That this was connected with electric or che- mical affinity had been generally suspected, though de- 454 DAVY. nied by Volta, the author of the pile, and indeed of the science which, like the continent of America, has borne the name of another than the discoverer. This had seemed probable from the presence being indispensable of a liquid capable of decomposing one or other of the metals, both supposed to be equally necessary to the production of the electric stream. Davy's experi- ments, which were numerous and admirably devised and most laboriously conducted, now showed that the presence of two metals was not required to provide the electricity. One metal, and one other substance separated from it, with a fluid acting upon either the metal or the substance ; or a metal separating two fluids, one of which acts upon it ; nay, one metal exposed to the same fluid, but acted upon differently on its diffe- rent sides or surfaces by the fluid's strength differing on the different sides ; or one and the same metal in different pieces plunged into the same fluid, at an interval of time — were all found to be combina- tions which gave the galvanic (or voltaic) shock, the same in kind, though varying in strength. In all these cases, and in every production of electricity by the voltaic process, the chemical action of a fluid upon the metallic substance was a necessary conco- mitant of the operation.* During the five following years Davy continued his experiments ; and in the autumn of 1806 he commu- nicated to the Royal Society hjs discovery of the con- nexion between the different ends of the electric circle * Subsequent experiments have shown that the effect may be pro- duced by other than metallic, or even carbonaceous bodies. DAVY. 455 and the different component parts of bodies submitted to the action of the fluid. Nothing could be more singular and unexpected than the laws which he now found to regulate this operation, nor anything which promised more clearly a rich harvest of new discoveries. The effect of the current, whether of common or gal- vanic electricity, in decomposing substances through which it passed, had been before known. Thus water had been resolved into its two elements by the passing of the fluid through wires whose points were opposite to each other at a small distance. Nicholson had first made this happy application of the voltaic pile ; but he and others had been much disturbed by finding other substances produced as well as oxygen and hy- drogen gases. This perplexing circumstance was care- fully investigated by Davy ; and he showed by a mas- terly course of experiments, that these substances owed their origin entirely to impurities in the water. When it was quite pure, they wholly disappeared. But he now proceeded farther, and found that when the electric current is thus passed, there is always a separation operated differently at the negative and at the positive part of the current. The oxygen of the water, for example, was accumulated round the positive wire ; its hydrogen round the negative. So when a neutral salt was subjected to the process, its acid was evolved round the positive ; its alkaline base round the negative wire. The same thing happened when a me- tallic oxide was operated upon ; its oxygen went to the positive, its metallic base to the negative side. The oxygen, or the acid with the oxygen, went to the for- mer ; the particles of the base were transferred to the 456 DAVY. latter, along with the hydrogen of the water in which the solution was made. But a still more extraordinary phenomenon was observed. If there was a liquid in- terposed between the two poles and the body to be de- composed, the acid, or the oxygen, was found to pass through that interposed liquid to the positive pole, the hydrogen and the matter of the base to the negative pole, and without acting upon the substance of the in- terposed liquid. Thus suppose a vegetable colour tinging the water in an intermediate cup, acid will pass through it without reddening it, and alkali with- out making it green. Nay, an acid will pass through an alkaline solution, or an alkali through an acid, without uniting in either case to form a neutral salt, unless the neutral compound is insoluble, for in that case it falls to the bottom. But muriatic acid will pass through a solution of potash, having been carried over from a solution of common sea salt by the electrical current, or soda will pass through muriatic acid in the same circumstances, without forming in the former case nitrate of potash, or in the latter nitrate of soda. It was also found that the exception in the case of in- soluble compounds arises from the mechanical effect of their insolubility, their falling to the bottom ; for if supported, as it were, on threads of any convenient substance passing through the intermediate liquid in the line of the electric current, the acid or alkali will pass through that liquid. Thus films of asbestos conduct- ing the electric stream, enabled magnesia or lime to pass ; and so were the particles of metal carried over when separated by the operation from nitrate of silver. DAVY. 457 It thus appeared certain that an indissoluble con- nexion exists between chemical and electric action, if indeed it was not even proved that chemical affinity and electricity are identical. The science of Electro- chemistry, at all events, now arose out of Davy's dis- coveries, and he is entitled to be regarded as its founder. It may easily be conceived that these important truths excited generally the anxious attention of philo- sophers. The French National Institute, greatly to their honour, though the war between the two coun- tries never raged more fiercely than now, and France never reached a higher pitch of military glory, crowned Davy with the first honour founded by Napoleon for scientific desert. But it was even more honourable to the philosopher, that great as his discoveries had been, expectation was high of the still more important results which must soon come from the discovery of so new a law of electrical and chemical action. I can well re- member that we used in discussing the subject to look forward with perfect confidence to the analysis of the bodies which had hitherto proved the most stubborn, and expected soon to find the fixed alkalis, and even the alkaline earths, shown to be oxides, as by some very imperfect experiments they had at one time been supposed to be proved, when it was ascertained that the metallic buttons found at the bottom of the crucible in which their reduction had been attempted by carbon- aceous or phosphoric re-agents, had come from the black lead in the pot. Nor must we omit to mention the truly candid and magnanimous proceeding of Davy, so worthy of a philosopher, in making public, with the fullest details, his proceedings, by which it was mani- 458 DAVY. • fest he intended still to persevere till he should make other discoveries. Any one possessed of a strong bat- tery, deeply reflecting on the paper of autumn 1806, and perceiving that the positive wire had such a strong attraction for oxygen as to take it from metallic oxides, reducing them to their reguline state, might well have bethought him of subjecting the alkalis to his machine ; and he would then have had the fame, though, in truth, Davy would have had the merit, of the grand discovery. That discovery was not long delayed. About a year after the former, that is in October 1807, after in vain endeavouring to decompose the alkalis when mixed with water, for he then only could decompose that fluid, he exposed them in the dry state ; that is, made liquid by fusion, without any other substance but heat to dissolve them — and, to his great delight, he found, as he had a right to expect, that the process of deoxi- dation proceeded by the positive wire attracting the oxygen, while globules of a metallic substance were found at the negative wire. The great attraction of this metal for oxygen made it impossible to keep it either in the air or in water. It burnt spontaneously in the air and became alkali — it decomposed water in like manner, and formed an alkaline solution. The two fixed alkalis both yielded in this process metallic bases ; but that of potash had alone the quality of combustion at the temperature of 150°, and it was, though a metal, lighter than water in the proportion of 97 to 100. When thrown into water in the air, it detonates and burns with violence, forming a solution of potash. The metal from soda is still lighter, being to water as 86 to 100 ; but it does not so easily unite with oxygen, DAVY. 459 though it decomposes water with a hissing noise, and makes with it a solution of soda. To these metals the discoverer gave the name of potassium and sodium. The glory of having now made the greatest discovery of the age was plainly Davy's ; and it was not the result of happy accident, but of laborious investigation, conducted with a skill and a patience equally admirable, and according to the strict rules of the soundest philo- sophy. He had indeed begun by discovering the laws of electrical action, and had thus formed the means of his new discovery, which was the fruit of the science he had founded, as Newton's tjieory of dynamics and of astronomy was the fruit of the calculus which he had so marvellously discovered when hardly arrived at man's estate. The wonder excited by the strange bodies with which philosophers were thus brought acquainted, was of course in part owing to their novel and singular properties, which formed no part of the discoverer's merits, yet might be reckoned as the perquisites of his genius. His praise would have been the same if in- stead of at once discovering the alkalis to be oxides, and the metal forming the base to be one lighter than water, or bees'-wax or box- wood, and the other to burn unheated in the open air, he had only shown those salts to be oxides of well-known metals. Yet, as his investigation had been crowned with the discovery of strange substances, metallic, and yet like no other metals, we justly admire the more, and the more thank him for his double service rendered to science. The long labour thus ending in so mighty a result, and the excitement naturally enough produced in an irritable habit, threw him into an illness of a most 460 DAVY. serious complexion. For many days he lay between life and death in a low nervous fever, and it was not till the following March that he could resume his inquiries into the composition of the alkaline earths. It is to the credit of chemists that no one deemed himself at liberty to interfere with him, as any one might now by only following his footsteps have done, and thus analysed these earthy bodies. He himself, early in the summer following his illness, had reduced lime, magnesia, strontites, and barytes. In these experiments he was greatly assisted by the ingenious contrivances which Gay-Lussac and Thenard had recently used for the reduction of the alkaline oxides. The metals thus discovered were not any wise light or fusible like potassium and sodium ; but they burnt with a bright light on being exposed to considerable degrees of heat, and they decomposed water ; and either by their com- bustion, or their exhibition to water, they reproduced the alkaline earths. A number of other experimental researches led Davy to new and curious observations on the constitu- tion and habits of different substances. But we need only mention the most important of these, for it was a discovery very unexpected both by himself and the chemical world at large. The acid hitherto called oxy- genated muriatic, or oxymuriatic, on account of its powerful acid qualities, had been always from thence supposed to contain an excess of oxygen, believed to be the acidifying principle. At last Gay-Lussac and Thenard, in 1809, concluded from some experimental researches, or rather they suspected, that it might be a simple and elementary substance ; but they on the whole still inclined to think it contained oxygen according to DAVY. 461 the old and received opinion. Davy now found, by a course of satisfactory experiments which have fixed the opinions of all philosophers on the subject, that the suspicion of those eminent men was well founded ; that the oxymuriatic acid is a simple substance, containing no oxygen; that it unites with oxygen to form an acid, which forms with alkalis the detonating salts hitherto called oxymuriates, as being supposed to contain oxymuriatic acid combined with alkaline bases ; and finally, that with hydrogen it forms the acid long and well known as the muriatic or marine. To the oxymuriatic acid he gave the name of chlorine from its green colour, and to common muriatic acid that of hydrochlorine. The union of chlorine and oxygen he calls chlorine acid, and its compounds, of course, chlorates. This is justly reckoned one of the most im- portant of Davy's many brilliant discoveries. It remains to make mention of the valuable present which this great philosopher offered to humanity — his safety-lamp. The dreadful ravages made on human life by the fire-damp explosions — that is, the burning of hydrogen gas in mines — had often attracted the notice of both the mine-owner and the philanthropist. Various inventions had been fallen upon to give light in those recesses of the earth with so low a degree of heat as should be insufficient to explode the gas. One of them was a series of flints playing by machinery against each other so as to give a dim light ; but this had very little success ; it was clumsy, and it was not ef- fectual so as to cause its use by miners. The ventilation of the galleries by furnaces and even by air-pumps was chiefly relied on as a preventive ; but gas would collect 462 DAVY. in spite of all preventives, and the destruction of a hundred or more lives was not an unusual calamity. Davy about the year 1815 turned his attention to the subject, and after fully ascertaining that carburetted hydrogen is the cause of the fire-damp, and finding in what proportions it must be mixed with air in order to explode (between six and fourteen times its bulk), he was surprised to observe, in the course of his experi- ments made for the purpose of ascertaining how the inflammation takes place, that the flames will not pass through tubes of a certain length or smallness of bore. He then found that if the length be diminished, and the bore also reduced, the flames will not pass ; and he fur- ther found that by multiplying the number of the tubes, their length may safely be diminished to hardly any- thing, provided their bore be proportionably lessened. Hence it appeared that gauze of wire, whose meshes were only one twenty-second of an inch diameter, stopped the flame, and prevented the explosion. The candle or lamp being wrapt in such gauze, and all access to the external air prevented except through the meshes, it is found that the lamp may be safely introduced into a gallery filled with fire-damp ; a feeble blue flame will take place inside the gauze, but no explosion, even if the wire be heated nearly red. The theory is, but it seems very questionable, that the conducting power of the wire carrying off the heat pre- vents a sufficient quantity reaching the explosive com- pound. Subsequent inquiries seem to prove that although in a still atmosphere of explosive gas the lamp is a perfect protection, yet it does not prevent a cur- rent of gas from penetrating to the flame and exploding. DAVY. 463 It is attempted to guard against this by interposing a tin shield or screen ; but a current very often in mining operations arises before any notice can be given. Had Davy's life and health been prolonged, he might have further improved his invention so as to meet this ob- jection. He certainly never was fully convinced of its force, as I know from having discussed the subject with him ; and no doubt the testimony of so great an engineer as the late Mr. Buddie, given before a Par- liamentary Committee to whom the examination of this important subject was referred, deserves great attention. He positively affirmed that " having seen 1000, and sometimes 1500 safety-lamps in daily use, and in all possible varieties of explosive mixtures, he had never known one solitary instance of an explosion." As for the lamentable accidents which continue to happen, we can scarcely doubt that they originate in the dreadful carelessness of their own and of other men's lives, which seems to be engendered in those who are habitually exposed to great danger. That they themselves are the first to suffer for it, can only suppress the outward expression of the feelings which recklessness like this is fitted to produce. It redounds to the credit of the north country mine- owners that in 1817 they invited the inventor of the Lamp to a public entertainment, and presented him with a service of plate of two thousand pounds value. It must be remembered that he had generously given to the public the whole benefit of his invention, and thus sacrificed the ample profit which a patent must have enabled him to acquire for himself. Davy had as early as 1806 been chosen a foreign associate of the French Institute. In 1812 he received 464 DAVY. from the Regent the honour of knighthood. About the same time he married Mrs. Apreece, a lady whose ample fortune was by far the least valuable part of her accomplishments — a person of great virtue, admirable talents, and extensive information. Of this marriage there has been no issue. In October, 1813, he published his ' Elements of Chemical Philosophy,' — a hasty and even somewhat crude work, but abounding, as what- ever he wrote was sure to abound, in important and ingenious observations. The following year appeared his 'Elements of Agricultural Chemistry,' of which the same general character may be given. In 1816 he was created a baronet. Napoleon had, during the war, given him permis- sion to visit the extinguished volcanoes in Dauvergne, and to pass through France towards Naples, Vesuvius being then in a state of eruption. His reception at Paris was very warm, but unfortunately he failed to retain the affection of his colleagues in the Institute. Their complaint against him for having interfered, as they termed it, with their recent discovery of iodine, on which, having obtained a specimen, he chose, naturally enough, to make experiments, appears incom- parably absurd. He had never complained of their in- terference, during his illness in 1807, with the process of deoxygenation by means of galvanic action ; on the contrary, he had availed himself thankfully of the lights shed by their ingenuity on his process, and had immediately after made new discoveries, at which they had failed to arrive. It may be more true that his manners were unpleasing ; and, as ever happens when a great man is also a shy one, he was charged with being supercilious and cold. They who knew him DAVY. 465 will at once acquit him of any such charge ; but he was painfully timid by nature when mixing with so- ciety ; and hence the mistake of our neighbours, who, though great critics in manner, are far from being infallible, and are exceedingly susceptible— fully as sus- ceptible as he was shy. Possibly they looked down upon him in consequence of a peculiarity which he no doubt had. He was fond of poetry, and an ardent ad- mirer of beauty in natural scenery. But of beauty in the arts he was nearly insensible. They used to say in Paris that on seeing the Louvre, he exclaimed that one of its statues was " a beautiful stalactite ;" and it is possible that this callousness, or this jest, which- ever it might be, excited the scorn or the humour of men not more sincere lovers of sculpture than himself, or more able judges of its merits, but better disposed to conceal their want of taste or want of skill. When Sir Joseph Banks terminated his long and respectable course in 1820, Davy was unanimously chosen to succeed him as President of the Royal So- ciety, and continued to fill that distinguished office un- til, his health having failed, he resigned it in 1 827, and was succeeded by his early patron Davies Giddy. To- wards the end of 1825 he had an apoplectic seizure, which, though slight (if any such attack can be so called), left a paralytic weakness behind, and he was ordered to go abroad in search of a milder and dryer climate. He returned home in the following autumn, not very ill, hut not much restored in strength, and unable to continue his scientific labours. The work on fly-fishing called ' Salmonia ' was the amusement of those hours in which, comparatively feeble, his mind 2 H 466 DAVY. • yet exerted what energy remained to it, on the favourite pursuit of his leisure. It contains both curious in- formation on natural history, and many passages of lively and even poetical description. The same may be said of many things in his latest work, * Last Days of a Philosopher/ which he wrote in the year after, when he again went to the continent in search of health. He wintered at Rome, and in May 1829, on his arrival at Geneva, after passing the day in excel- lent spirits, and dining heartily on fish, he had a fatal apoplectic attack in the night, and died early in the next morning, 29th May, without a struggle. There needs no further remark, no general charac- ter, to present a portrait of this eminent individual. Whoever has perused the history of his great exploits in science, with a due knowledge of the subject, has already discerned his place, highest among all the great discoverers of his time. Even he who has little acquaintance with the subjects of his labours may easily perceive how brilliant a reputation he must have en- joyed, and how justly; while he who can draw no such inference from the facts would fail to obtain any knowledge of Davy's excellence from all the panegyrics with which general description could encircle his name.* * It may not be impertinent to relate here a singular proof of the admiration in which his name was held by his countrymen, and how well it became known even among the common people. Re- tiring home one evening he observed an ordinary man showing the moon and a planet through a telescope placed upon the pavement. He went up and paid his pence for a look. But no such thing would they permit. " That's Sir Humphry," ran among the people ; and the exhibitor, returning his money, said, with an important air which exceedingly delighted him, that he could not think of taking any- thing from a brother philosopher. (-467) S I M S 0 N. THE wonderful progress that has been made in the pure mathematics since the application of algebra to geometry, begun by Vieta in the sixteenth, completed by Des Cartes in the seventeenth century, and espe- cially the still more marvellous extension of analytical science by Newton and his followers, since the inven- tion of the Calculus, has, for the last hundred years and more, cast into the shade the methods of investiga- tion which preceded those now in such general use, and so well adapted to afford facilities unknown while mathematicians only possessed a less perfect instrument of investigation. It is nevertheless to be observed that the older method possessed qualities of extra- ordinary value. It enabled us to investigate some kinds of propositions to which algebraic reasoning is little applicable ; it always had an elegance peculiarly its own ; it exhibited at each step the course which the reasoning followed, instead of concealing that course till the result came out ; it exercised the facul- ties more severely, because it was less mechanical than the operations of the analyst. That it afforded evi- dence of a higher character, more rigorous in its na- ture than that on which algebraic reasoning rests, 468 SIMSON. cannot with any correctness be affirmed; both are equally strict ; indeed if each be mathematical in its nature, and consist of a series of identical propositions arising one out of another, neither can be less perfect than the other, for of certainty there can be no de- grees. Nevertheless it must be a matter of regret — and here the great master and author of modern mathe- matics has joined in expressing it — that so much less attention is now paid to the Ancient Geometry than its beauty and clearness deserve ; and if he could justly make this complaint a century and a half ago, when the old method had but recently, and only in part, fallen into neglect and disuse, how much more are such regrets natural in our day, when the very name of the Ancient Analysis has almost ceased to be known, and the beauties of the Greek Geometry are entirely veiled from the mathematician's eyes ! It be- comes, for this reason, necessary that the life of Sim- son, the great restorer of that geometry, should be prefaced by some remarks upon the nature of the sci- ence, in order that, in giving an account of his works, we may say his discoveries, it may not appear that we are recording the services of a great man to some sci- ence different from the mathematical. The analysis of the Greek geometers was a method of investigation of peculiar elegance, and of no incon- siderable power. It consisted in supposing the thing as already done, the problem solved, or the truth of the theorem established ; and from thence it reasoned until something was found, some point reached, by pursuing steps each one of which led to the next, and by only assuming things which were already known SIMSON. 469 being ascertained by former discoveries. The thing thus found, the point reached, was the discovery of something which could by known methods be per- formed, or of something which, if not self-evident, was already by former discovery proved to be true ; and in the one case a construction was thus found by which the problem was solved, in the other a proof was ob- tained that the theorem was true, because in both cases the ultimate point had been reached by strictly legiti- mate reasoning, from the assumption that the problem had been solved, or the assumption that the theorem was true. Thus, if it were required from a given point in a straight line given by position, to draw a straight line which should be cut by a given circle in segments, whose rectangle was equal to that of the segments of the diameter perpendicular to the given line — the thing is supposed to be done ; and the equality of the rect- angles gives a proportion between the segments of the two lines, such that, joining the point supposed to be found, but not found, witfi the extremity of the dia- meter, the angle of that line with the line sought but not found, is shown by similar triangles to be a right angle, L e., the angle in a semicircle. Therefore the point through which the line must be drawn is the point at which the perpendicular cuts the given circle. Then, suppose the point given through which the line is to be drawn, if we find that the curve in which the other points are situate is a circle, we have a local theorem, affirming that, if lines be drawn through any point to a line perpendicular to the diameter, the rect- angle made by the segments of all the lines cutting the perpendicular is constant ; and this theorem would be 470 SIMSON. demonstrated by supposing the thing true, and thus reasoning till we find that the angle in a semicircle is a right angle, a known truth. Lastly, suppose we change the hypothesis, and leave out the position of the point as given, and inquire after the point in the given straight line from which a line being drawn through a point to be found in the circle, the seg- ments will contain a rectangle equal to the rect- angle under the perpendicular segments — we find that one point answers this condition, but also that the problem becomes indeterminate ; for every line drawn through that point to every point in the given straight line has segments, whose rectangle is equal to that under the segments of the perpendicular. The enun- ciation of this truth, of this possibility of finding such a point in the circle, is a Porism. The Greek geo- meters of the more modern school, or lower age, defined a Porism to be a proposition differing from a local theorem by a defect or defalcation in the hypothesis ; and accordingly we find that this ^porism is derived from the local theorem formerly given, by leaving out part of the hypothesis. But we shall afterwards have occa- sion to observe that this is an illogical and imperfect definition, riot coextensive with the thing defined ; the above proposition, however, answers every definition of a Porism. The demonstration of the theorem or of the construc- tion obtained by investigation in this manner of pro- ceeding, is called synthesis, or composition, in opposi- tion to the analysis, or the process of investigation ; and it is frequently said that Plato imported the whole system in the visits which he made, like Thales of Miletus and Pythagoras, to study under the Egyptian SIMSON. 471 geometers, and afterwards to converse with Theodorus at Cyrene, and the Pythagorean School in Italy. But it can hardly be supposed that all the preceding geo- meters had worked their problems and theorems at random ; that Thales and Pythagoras with their dis- ciples, a century and a half before Plato, and Hip- pocrates, half a century before his time, had no knowledge of the analytical method, and pursued no systematic plan in their researches, devoted as their age was to geometrical studies. Plato may have im- proved and further systematized the method, as he was no doubt deeply impressed with the paramount im- portance of geometry, and even inscribed upon the gates of the Lyceum a prohibition against any one entering who was ignorant of it. The same spirit of exaggera- tion which ascribes to him the analytical method, has also given rise to the notion that he was the discoverer of the Conic Sections ; a notion which is without any truth and without the least probability. Of the works written by the Greek geometers some have come down to us ; some of the most valuable, as the ' Elements' and ' Data' of Euclid, and the ' Conies' of Apollonius. Others are lost ; but, happily, Pappus, a mathematician of some merit, who flourished in the Alexandrian school about the end of the fourth cen- tury, has left a valuable account of the geometrical writings of the elder Greeks. His work is of a mis- cellaneous nature, as its name, 'Mathematical Col- lections,' implies ; and excepting a few passages, it has never been published in the original Greek. Com- mandini, of Urbino, made a translation of the whole six books then discovered; the first has never been 472 SIMSON. found, but half the second being in the Savilian library at Oxford, was translated by Wallis a century later. Commandini's translation, with his learned commen- tary, was not printed before his death, but the Duke of Urbino (Francesco Maria) caused it to be published in 1588, at Pisa, and a second edition was published at Venice the next year : a fact most honourable to that learned and accomplished age, when we recollect how many years Newton's immortal work was pub- lished before it reached a second edition, and that in the seventeenth and eighteenth centuries. The two first books of Pappus appear to have been purely arithmetical, so that their loss is little to be lamented. The eighth is on mechanics, and the other five are geometrical. The most interesting portion is the seventh ; the introduction of which, addressed to his son as a guide of his geometrical studies, contains a full enumeration of the works written by the Greek geometers, and an account of the particular subjects which each treated, in some instances giving a summary of the propositions themselves with more or less ob- scurity, but always with great brevity. Among them was a work which excited great interest, and for a long time baffled the conjectures of mathematicians, Euclid's three books of ' Porisms :' of these we shall afterwards have occasion to speak more fully. His 'Loci ad Superficiem,' apparently treating of curves of double curvature, is another, the loss of which was greatly lamented, the more because Pappus has given no account of its contents. This he had done in the case of the ' Loci Plani' of Apollonius. Euclid's four books on conic sections are also lost: but of Apol- SIMSON. 473 lonius's eight books on the same subject, the most important of the whole series, the * Elements* excepted, four were preserved, and three more were discovered in the seventeenth century. His Inclinations, his Tactions or Tangencies, his sections of Space and of Ratio, and his Determinate section, however curious, are of less importance ; all of them are lost. For many years Commandini's publication of the * Collections' and his commentary did not lead to any attempt at restoring the lost works from the general account given by Pappus. Albert Girard, in 1634, informs us in a note to an edition of Stevinus, that he had restored Euclid's * Porisms/ a thing eminently unlikely, as he never published any part of his resto- ration, and it was not found after his decease. In 1637, Fermat restored the ' Loci Plani' of Apollonius, but in a manner so little according to the ancient analysis, that we cannot be said to approach by means of his labours the lost book on this subject. In 1615, De la Hire, a lover and a successful cultivator of the ancient method, published his Conic Sections, but synthetically treated ; he added afterwards other works on epicycloids and conchoids, treated on the analytical plan. L'Hopital, at the end of the seventeenth century, published an excellent treatise on Conies, but purely algebraical. At the beginning of the eighteenth cen- tury, Vivian i and Grandi applied themselves to the ancient geometry ; and the former gave a conjectural restoration (Divinatio) of Aristaeus's ' Loci Solidi,' the curves of the second or Conic order. But all these attempts were exceedingly unsuccessful, and the world was left in the dark, for the most part, on the 474 SIM60N. highly interesting subject of the Greek geometry. We shall presently see that both Fermat and Halley, its most successful students, had made but an incon- siderable progress in the most difficult branches. How entirely the academicians of France were either careless of those matters, or ignorant, or both, appears by the * Encyclopedic ; ' the mathematical department of which was under no less a geometrician than d'Alembert. The definition there given of ana- lysis makes it synonymous with algebra : and yet mention is made of the ancient writers on analysis, and of the introduction to the seventh book of Pappus, with only this remark, that those authors differ much from the modern analysts. But the article ' Arithmetic' (vol. i., p. 677) demonstrates this ignorance completely; and that Pappus's celebrated introduction had been referred to by one who never read it. We there find it said, that Plato is sup- posed to have invented the ancient analysis ; that Euclid, Apollonius, and others, including Pappus himself, studied it, but that we are quite ignorant of what it was : only that it is by some conceived to have resembled our algebra, as else Archimedes could never have made his great geometrical discoveries. It is, certainly, quite incredible that such a name as d'Alembert's should be found affixed to this statement, which the mere reading of any one page of Pappus's books must have shown to be wholly erroneous ; and our wonder is the greater, inasmuch as Simson's ad- mirable restoration of Apollonius's ' Loci Plani' had been published five years before the ' Encyclopedic ' appeared. SIMSON. 475 Again, in the ' Encyclopedic/ the word Analysis, as meaning the Greek method, and not algebra, is not even to be found. Nor do the words synthesis, or composition, inclinations, tactions or tangencies occur at all ; and though Porisms are mentioned, it is only to show the same ignorance of the subject : for that word is said to be synonymous with ' lemma,' because it is sometimes used by Pappus in the sense of subsidiary proposition. When Clairault wrote his inestimable work on curves of double curvature, he made no reference whatever to Euclid's ' Loci ad Superficiem,' much less did he handle the subject after the same manner ; he deals, indeed, with matters beyond the reach of the Greek geometry. Such was the state of this science when Robert Simson first applied to it his genius, equally vigorous and undaunted, with the taste which he had early imbibed for the beauty, the simplicity, and the close- ness of the ancient analysis. ROBERT SIMSON was born on the 14th October (O.S.), 1687, at Kirton Hill, in the parish of Wester Kilbride, in Ayrshire. His father, John Simson, was a mer- chant in Glasgow : his grandfather, Patrick, was mini- ster of Renfrew, and Dean of the Faculties in the Uni- versity of Glasgow. Having been deprived at the Re- storation, on being reinstated at the Revolution, he accompanied Principal Carstairs and a deputation as one of the Commissioners from the Kirk of Scotland to ad- dress the Sovereigns. Being a man of fine presence, it is related that the Queen and her maids of honour mistook him for the Principal, till the King set them 476 SIMSON. right by presenting Carstairs to them. The grandson, Robert, is said to have been the eldest of seventeen children; and the estate of Kirton Hill, which had been in the family for several generations, being incon- siderable, it was necessary for him, as well as his brothers, to be placed in some profession. The asser- tion is made in one account, written by a son of Professor Millar, and is likely to be correct, that he was intended for the medical profession, and being sent to Ley den studied under Boerhaave. He appears to have been at first intended for the Church, and to have changed his plan. Dr. Traill, however, says, that he was always intended for the Church, and that when the University of St. Andrew's in 1746 wished to confer on him a degree, they made him a Doctor of Medicine, because he had studied botany in his youth. Nothing can be more improbable than this story ; for to give him a degree they had only to make him Doctor of Laws, instead of taking a step which for ever threw discredit upon their medical honours. Mr. Millar must have heard the truth from his father and the other professors, who had the honour of knowing Dr. Simson personally, and never could have imagined or invented the circumstance of his studying under Boerhaave.* Of his early years we know little ; but that he was always extremely fond of reading is certain ; and he * The account which I have seen was in the late Earl of Buchan's possession, and was extended by matters collected when he himself studied at Glasgow. It seems by the mathematical appearance of it to have come from James Millar, himself one of the Professors. SIMSON. 477 must have had a considerable turn for mechanical pur- suits if the tradition in the neighbourhood of Kirton Hill be well founded, which ascribes to him the mak- ing, or at least designing and placing a dial of a curious form (which I have seen) on a neatly ornamented pe- destal in the garden of his father's house. At the usual early age of matriculation in Scotland, he was sent to the University of Glasgow, and he had there made con- siderable progress in his studies before the love of mathe- matical pursuits appeared to possess him. His atten- tion was directed to theology, to logic, to Oriental learning ; and in the latter he had made such progress, that a relation who taught the class having fallen ill, Simson easily supplied his place for part of a session, the Scottish academical year. It was while engaged in theological studies that the mathematics first seized hold of his mind. He used in after life to relate how, wearied with the controversies to which his clerical studies led him, he would refresh himself with philo- sophical reading; and not seldom finding himself there also tossed about by conflicting dogmas, he retired for peace and shelter to the certain science of necessary truth ; " and then," said he, " I always found myself refreshed with rest." It happened that no lecture or teaching of any kind was given by the professor who filled the mathematical chair, receiving its emoluments, and neglecting its duties, when Simson went to the University. But curiosity, a propensity ever strong in his nature through his whole life, made him wish to see what the science was, and he borrowed from a friend a copy of Euclid, the work which he was destined afterwards to give 478 . SIMSON. forth in a perfection that has made all other editions of that great classic be forgotten. Over the elements of the science he pored assiduously and alone, with only the aid of suggestions occasionally given by a student some years older than himself; and the study falling in with his genius and his taste, he soon made himself master of the first six books, comprising plain geometry, and the eleventh and twelfth, treating of solids, those at least which are bounded by planes or by circular arches. But he did not neglect the other branches of science taught at the College; and he also gave his attention to the literary parts of educa- tion, so well mastering the Latin and Greek languages as to become a learned and accurate scholar. It was in the mathematics, however, that he chiefly excelled ; and his accomplishments in that science becoming known to the professorial body (the Senatus Academi- cus), in whom is vested the patronage of the mathe- matical chair, and an early vacancy being foreseen, they offered him the succession in that event. Being then in his twenty-second year, he modestly declined to undertake so important a charge, but requested a year's delay, during which he might repair to London, and become more familiar with the science and its cul- tivators. We may hence perceive that there could then have been no one at all versed in the mathematics at Glasgow ; and the allowing so important a branch of science to remain for so many years untaught because the teacher who received the ample emoluments of the chair either could not or would not perform its duties, affords a sufficient commentary upon the great abuse likely to flow from vesting the patronage of a profes- SIMSON. 479 sorship in the colleagues of the teacher. I have known a professor's son appointed to the same chair, with few or no mathematical acquirements, because his father was much and justly respected among the mem- bers of the academical body. The same thing could not happen in Edinburgh, where the Crown or the magistrates have the patronage of all the professorships excepting one, and that is in the representative of the founder.* Simson repaired accordingly to London, where he be- came intimately acquainted, among others, with Jones the optician, with Henry Ditton of Christ's Hospital, under whose tuition he placed himself, with Carswell, above all, with Edmund Halley, then a captain in the Navy, afterwards so celebrated as Dr. Halley ; of whom he used to assert that " he had never known any other man of so acute and penetrating an under- standing, and of so pure a taste." From him he re- ceived much personal kindness, and what he had reason to value still more, the advice to prosecute his study of the Ancient Geometry, and attempt restoring its lost books. Halley made him a present of his copy of Pappus, with notes in his own hand. But though these accidental circumstances tended to direct his attention towards the scrupulous rigour as well as surpassing elegance of the Greek methods, it is a great mistake to suppose that he objected to the strictness of the modern analysis as inadequate. That he deemed its beauty inferior, and that he was right in so deem- ing, is certain ; but that he questioned the solidity of * Agriculture, in the Pulteney Family. 480 SIMSON. its foundations is wholly untrue. Not only did he always explain its principles to his pupils, though in a manner peculiar to himself, but he has left behind him a trea- tise demonstrating the fundamental laws of the cal- culus, and we now possess it in a printed form. Equally groundless is the notion that he questioned the sound- ness of the Newtonian Philosophy. He was not ena- bled to make Sir Isaac's acquaintance during his resi- dence in London ; but among those he lived with he constantly had seen him viewed with a peculiar ob- servance, and Halley in particular regarded him as hardly human, and his attainments in science as exalt- ing our species, while they ennobled himself, its rarest individual. Simson's copy of the ' Principia ' is fully noted in the margin with illustrations, showing that he entirely assented to the results of the investigations in the several propositions, and only wished to substi- tute certain steps in the demonstrations. Professor Robison has also related (Art. Simson, Encyc. Brit. xvii. 505) his constant remark, that the celebrated proposition in the ' Principia ' on inverse centripetal forces " was the most important ever delivered to man- kind in the mixed mathematics." While he remained in London the expected vacancy occurred in the chair at Glasgow, and he returned thither. The professors appear to have thought it right that their former neglect of duty should be com- pensated by a very superfluous show of more than need- ful attention to it on this occasion ; for they required Mr. Simson to give proof of his fitness to succeed the sinecure incumbent, by solving a geometrical problem, of which it is all but absolutely certain that they could SIMSON. 481 have no knowledge, unless the question was so simple as to afford no test of the candidate's capacity. He pro- duced, however, what they might better understand, testimonials from known mathematicians in London, a farther proof of there being no cultivators of the science then resident in the metropolis of Scottish manufactures. He was thus appointed professor in 1711, and im- mediately began the regular course of instruction, which he continued for half a century. He taught two classes five days a week for seven months every year. Though geometry was his own favourite study, he was a thorough algebraist also, and so well versed in mathematical science at large, that he gave lectures on its general history. With astronomy, and the other branches of the mixed mathematics, he was no less conversant ; and in various departments of physics he had made great progress. In botany he was parti- cularly expert; it formed his chosen amusement dur- ing the walks in which he relaxed from his severer studies. His curiosity led him into other paths of science. To logic, that of the schools, he had given so much attention, that of a tract, composed by him upon its principles, some portion remains among his papers ; it is said to possess great merit ; and doubtless this study was congenial to the one which he mainly pursued, nor could it fail to aid his strict and luminous method of both defining, demonstrating, and explain- ing the truths of geometry. Among his colleagues, after he had been professor a few years, were some of the most eminent men of that, or indeed of any age, Moore, professor of Greek, and author of the admirable and elegant ' Grammar ;' 2i 482 . SIMSON. Hutcheson, and Adam Smith, successively teachers of moral philosophy ; Cullen, the celebrated physician ; Black, the great founder of modern chemistry — all taught while Simson flourished ; Millar only became professor of law at the close of the brilliant period now referred to, and Robison succeeded Black in 1761, soon after Simson's resignation. But a teacher's influence is nothing in surrounding himself with illustrious colleagues: of great pupils he may more easily obtain a following. Of these, Dr. Simson had some whose names are still honoured among mathematicians. Williamson, afterwards his assistant in the class, a man of great promise, whose early death at the Factory of Lisbon, to which he was chaplain, alone prevented him from following with distinction his master's footsteps ; Scott, preceptor to George III. when Prince of Wales, afterwards a Com- missioner of Excise in London, perhaps the most accomplished of all amateur mathematicians who never gave their works to the world ; Traill, author of the excellent elementary treatise of algebra, of a very learned and exceedingly ill-written, indeed, hardly readable, life of his friend and teacher, but a man of great capacity for science, entirely extinguished, to- gether with his taste for its pursuits (as Professor Playfair used to lament), by the sinecure emoluments of the Irish Church ; but above all, Matthew Stewart, Simson's favourite pupil, and whose suggestions, and indeed contributions, he records in his works with appropriate eulogy, as he does on one occasion an in- genious theorem of Traill — these were among his scholars, and were, with Robison, the most dis- tinguished of their number. His method of lecturing SIMSON. 483 is, by both of the pupils who have written his history, Professor Robison and Dr. Traill, described as singu- larly attractive. His explanations were perfectly clear, and were delivered with great spirit, as well as with the pure taste which presided over all his mathe- matical processes. His elocution was distinct and natural, his whole manner at once easy and impres- sive. He did not confine his tuition to the chair, but encouraged his pupils to propound their difficulties in private, and was always accessible to their demands of assistance and advice, Hence the affectionate zeal with which they followed his teaching and ever cherished his memory. Successful, however, as he proved in the chair, his genius was bent to the diligent investigation of truth in the science of which he was so great a master. The ancient geometry, that of the Greeks of which I have spoken, early fixed his attention and occupied his mind by its extraordinary elegance, by the lucid clear- ness with which its investigations are conducted, by the exercise which it affords to the reasoning faculties, and above all, by the absolute rigour of its demon- strations. He never undervalued modern analysis ; it is a great mistake to represent him as either disliking its process, or insensible to its vast importance for the solution of questions which the Greek analysis is wholly incapable of reaching. But he considered it as only to be used in its proper sphere: and that sphere he held to exclude whatever of geometrical investigation can be, with convenience and elegance, carried on by purely geometrical methods. The appli- cation of algebra to geometry, it would be ridiculous 2 i 2 484 SIMSON. to suppose that either he or his celebrated pupil Stewart disliked or undervalued. That application forms the most valuable service which modern analysis has rendered to science. But they did object, and most reasonably and consistently, to the introduction of algebraic reasoning wherever the investigation could, though less easily, yet far more satisfactorily, be performed geometrically. They saw, too, that in many instances the algebraic solution leads to con- structions of the most complex, clumsy, unmanage- able kind, and therefore must be, in all these instances, reckoned more difficult, and even more prolix than the geometrical, from the former being confined to the expression of all the relations of space and position, by magnitudes, by quantity and number, (even after the arithmetic of sines had been introduced,) while the latter could avail itself of circles and angles directly. They would have equally objected to car- rying geometrical reasoning into the fields peculiarly appropriate to modern analysis ; and if one of them, Stewart, did endeavour to investigate by the ancient geometry physical problems supposed to be placed beyond its reach — as the sun's distance, in which he failed, and Kepler's problem, in which he marvel- lously succeeded, that of dividing the elliptical area in a given ratio by a straight line drawn from one focus — this is to be taken only as an homage to the undervalued potency of the Greek analysis, or at most, as a feat of geometrical force, and by no means as an indication of any wish to substitute so imperfect, however beautiful, an instrument, for the more powerful; ifccJugh more ordinary one of the calculus which " alone can work SIMSON. 485 great marvels." At the same time, and with all the necessary confession of the merits of the modern method, it is certain that those geometricians would have regarded the course taken by some of its votaries in more recent times as exceptionable, whether with a view to clearness or to good taste : a course to the full as objectionable as would be the banishing of alge- braical and substituting of geometrical symbols in the investigations of the higher geometry. La Place's great work, the ' Mecanique Celeste,' and La Grange's ' Meca- nique Analytique,' have treated of the whole science of dynamics and of physical astronomy, comprehending all the doctrine of trajectories, dealing with geome- trical ideas throughout, and ideas so purely geometrical that the algebraic symbols, as far as their works are concerned, have no possible meaning apart from lines, angles, surfaces ; and yet in their whole compass they have not one single diagram of any kind. Surely, v ~v we may ask if 4~v doc'+dy*, , a , / dy \ can pos- y sibly bear any other meaning than the tangent and the radius of curvature of a curve line : that is, a straight line touching a curve, and a circle whose curvature is that of another curve where they meet; any meaning, at least, which can make it material that they should ever be seen on the page of the analyst. These expressions are utterly without sense, except in reference to geometrical con- * Or (d ~d^d7d-y} \dxj ,{] 486 SIMSON. siderations ; for although x and y are so general that they express any numbers, any lines, nay, any ideas, any rewards or punishments, any thoughts of the mind, it is manifest that the square of the differential of a thought, or the differential of the differential of a reward or punishment, has no meaning ; and so of every thing else but of the very tangent or osculating circle's radius : consequently the generality of the symbols is wholly useless ; the particular case of two lines being the only thing to which the expressions can possibly be meant to apply. Why, then, all geometrical symbols should be so carefully avoided when we are really treating of geometrical examples and geometrical ideas, and of these alone, seems hard to understand. As the exclusive lovers of modern analysis have frequently and very erroneously suspected the ancients of possessing some such instrument, and concealing the use of it by giving their demonstrations synthe- tically after reaching their conclusions analytically, so some lovers of ancient analysis have supposed that Sir Isaac Newton obtained his solutions by algebraic investigations, and then covered them with a synthetic dress : among others, Dr. Simson leant to this opinion respecting the ' Prineipia.' He used to say that he knew this from Halley, by whose urgent advice Sir Isaac was induced to adopt the synthetic form of demonstration, after having discovered the truths ana- lytically. Machin is known to have held the same language ; he said that the ' Principia' was algebra in disguise. Assuredly, the probability of this is far greater than that of the ancients having possessed and kept secret the analytical process of modern times. In the preface to his < Loci Plani/ Dr. Simson fully refutes SIMSON. 487 this notion respecting the ancients: a notion which, among others, no less a writer than Wallis had strongly maintained.* Dr. Simson is by some supposed to have had at one time the intention of discussing at large the proper limits of the ancient and the modern analysis in the investigation of mathematical truths. This no doubt appears to be the meaning of a passage in his preface to the Conic Sections : "In quantum autem differat ana- lysis geometrica ab ea quse calculo instituitur algebraico, atque ubi hcec aut ilia ait umrpanda, alias disseren- dum" Professor Robison thought he had seen a por- tion of the work ; but he must have been mistaken ; for in answer to Mr. Scott's letter urging him to pub- lish this, and referring to the preface in the words just cited, he expressly says, that though this passage might well mislead, he never meant, except by " blundering in the expression, anything of the kind, had no paper, and never wrote anything about the matter :" and this was written in 1764, four years before his death, and eleven or twelve years after Professor Robison attended his class. Nothing can be more clear than that between 1764 and his death, in 1768, he never attempted any work of moment; much more any work such as the one in * Algebra Praef. " Hanc Graecos olim habuisse non est quod dubitemus ; sed studio celatam, nee temere propalaudam. Ejus effectus (utut clam celatse) satis conspicui apud Archimedem, Apollonium, aliosque." It is strange that any one of ordinary reflection should have overlooked the utter impossibility of all the geometricians in ancient times keeping the secret of an art which must, if it existed, have been universally known in the mathematical schools, and at a time when every man of the least learning or even of the most ordinary education was taught geometry. 488 SIMSON. question, which we thus have his own authority for say- ing he never had previously entertained any intention of composing. It is much to be lamented that he never did give such a work to the world. His thoughts had often been very profoundly directed to the subject; and no one was so well fitted to handle it with the learning and with the judgment which its execution required. That he did not undervalue algebra and the calculus to which it has given rise, appears from many circum- stances— among others, froni what has already been stated ; it appears also from this, that in many of his manuscripts there are found algebraical formulas for propositions which he had investigated geometrically. Maclaurin consulted him on the preparation of his admirable work, the ' Fluxions,' and received from him copious suggestions and assistance. Indeed, he adopted from him the celebrated demonstration of the fluxion (or differential) of a rectangle.* But Simson's whole mind, when left to its natural bent, was given to the beauties of the Greek geometry ; and he had not been many months settled in his academical situation when he began to follow the advice which Halley had given him, as both calculated, he said, to promote his own reputation, and to confer a lasting benefit upon the science cultivated by them both with an equal de- votion. It is even certain that the obscure and most difficult subject of Porisms very early occupied his thoughts, and was the field of his researches, though to the end of his life he never had made such progress in * Book i. ch. ii. prop. 3. SIMSON. 489 the investigation as satisfied himself. Before 1715, three years after he began his course of teaching, he was deeply engaged in this inquiry ; but he only re- garded it as one branch of the great and dark subject which Halley had recommended to his care. After he had completely examined, corrected, and published, with most important additions, the Conies of Apollo- nius, which happily remain entire, but which, as we have seen, had been most inelegantly and indeed alge- braically given by De la Hire, L'Hopital, and others, to restore the lost books was his great desire, and formed the grand achievement which he set before his eyes. We have already shown how scanty the light was by which his steps in this path must be guided. The introduction to the seventh book of Pappus contained the whole that had reached our times to let us know the contents of the lost works. Some of the sum- maries which that valuable discourse contains are suffi- ciently explicit, as those of the Loci Plani and the Determinate Section. Accordingly, former geometri- cians had succeeded in restoring the Loci Plani, or those propositions which treat of loci to the circle and rectilinear figures. They had, indeed, proceeded in a very unsatisfactory manner ; Schooten, a Dutch mathematician of great industry and no taste, had given purely algebraic solutions and demonstrations. Fermat, one of the greatest mathematicians of the seventeenth century, had proceeded more according to the geometrical rules of the ancients ; but he had kept to general solutions, and neither he nor Schooten had given the different cases, according as the data in each proposition were varied, so that their works were nearly 490 . SIMSON. useless in the solution of problems, the great purpose of Apollonius, as of all the authors of the TOTTO? avaXvopevov — the thirty-three ancient books. As for the analysis, it was given by neither, unless, indeed, Schooten's algebra is to be so termed : Fermat's de- monstrations were all synthetical. His treatise, though written as early as 1629, was only published among his collected works in 1670. Schooten's was published among his ' Exercitationes Mathematics' in 1657. Of the field thus left open Dr. Simson took possession, and he most successfully cultivated every corner of it. Nothing is left without the most full discus- sion ; all the cases of each proposition are thoroughly investigated. Many new truths of great importance are added to those which had been unfolded by the Greek philosopher. The whole is given with the per- fect precision and the pure elegance of the ancient analysis ; and the universal assent of the scientific world has even confessed that there is every reason to consider the restored work as greatly superior to the lost original. The history of this excellent treatise shows in a striking manner the cautious and modest nature of its author. He had completed it in 1738 ; but, unsatisfied with it, he kept it by him for eight years. He could not bring himself to think that he had given the " ipsissimee propositiones of Apollonius in the very order and spirit of the original work." He was then persuaded to let the book appear, and it was published in 1746. His former scruples and alarms recurred; he stopped the publication ; he bought up the copies that had been sold ; he kept them three years longer SIMSON. 491 by him ; and it was only in 1749 that the work really appeared. Thus had a geometrician complied with the rule prescribed by Horace for those whose writings have no standard by which to estimate their merits with exactness. In the meantime he had extended his researches into other parts of the subject. Among the rest he had restored and greatly extended the work on Determi- nate Section, or the various propositions respecting the properties of the squares and rectangles of seg- ments of lines passing through given points. There is no doubt that the prolixity, however elegant, with which the ancients treated this subject, is somewhat out of proportion to its importance ; and as it is pecu- liarly adapted to the algebraical method, presenting, indeed, little difficulty to the analyst, the loss of the Pergsean treatise is the less to be deplored, and its re- storation was the less to be desired. Apollonius had even thought it expedient to give a double set of solu- tions ;. one by straight lines, the other by semicircles. Dr. Simson's restoration is most full, certainly, and contains many and large additions of his own. It fills above three hundred quarto pages. His predecessors had been Snellius, whose attempt, published in 1608, was universally allowed to be a failure ; and Anderson, a professor of Aberdeen, whose work, in 1612, was much better, but confined to a small part only of the subject. About the time that Dr. Simson finally published the Loci Plani, he began his great labour of giving a correct and full edition of the Elements. The manner in which this has been accomplished by him is well 492 SIMSON. known. The utmost care was bestowed on the revi- sion of the text; no pains were spared in collating editions ; all commentaries were consulted ; and the elegance and perfect method of the original has been so admirably preserved, that no rival has ever yet risen up to dispute with Simson's Euclid the possession of the schools. The time bestowed on this useful work was no less than nine years. It only was published in 1758. To the second edition, in 1762, he added a similarly correct edition of the Data, comprising several very valuable original propositions of his own, of Mr. Stewart, and of Lord Stanhope, together with two excellent problems to illustrate the use of the Data in solutions. We thus find Dr. Simson employed in these various works which he successively gave to the world, elaborated with infinite care, and of which the fame and the use will remain as long as the mathematics are cultivated, some of them delighting students who pursue the science for the mere speculative love of contemplating abstract truths, and the gratification of following the rigorous proofs peculiar to that science ; some for the instruction of men in the elements, which are to form the foundation of their practical applications of geometry. But all the while his mind never could be wholly severed from the speculation which had in his earliest days riveted his attention by its curious and singular nature, and fired his youthful ambition by its difficulty, and vanquished all his predecessors in their efforts to master it. We have seen that as early as 17 15 at the latest, probably much earlier, the obscure subject of Porisms had engaged his thoughts ; and soon SIMSON. 493 after, his mind was so entirely absorbed by it that he could apply to no other investigation. The extreme imperfection of the text of Pappus, the dubious nature of his description, his rejection of the definition which appeared intelligible, his substituting nothing in its place except an account so general that it really con- veyed no precise information, the hiatus in the account he subjoins of Euclid's three books, so that even with the help of the lemmas related to these propositions of the lost work, no clear or steady light could be de- scried to guide the inquirer — for the first porism of the first book alone remained entire, the general porism being given wholly truncated (mancum et im- perfectum) — all seemed to present obstacles wholly insurmountable, and after various attempts for years he was fain to conclude with Halley that the mystery belonged to the number of those which can never be penetrated. He lost his rest in the anxiety of this inquiry ; sleep forsook his couch ; his appetite was gone ; his health was wholly shaken ; he was com- pelled to give over the pursuit ; he was " obliged," he says, " to resolve steadily that he never more should touch the subject, and as often as it came upon him he drove it away from his thoughts."* It happened, however, about the month of April, 172*2, that while walking on the banks of the Clyde with some friends, he had fallen behind the company ; and musing alone, the rejected topic found access to * " Firmiter animum induxi haec nunquam in posterum investi- gare. Unde quoties menti occurrebant, foties eas arcebam." — (Op. Rel. 320. Praef. ad Porisrnata.) 494 SIMSON. his thoughts. After some time a sudden light broke in upon him ; it seemed at length as if he could descry something of a path, slippery, tangled, interrupted, but still practicable, and leading at least in the direction towards the object of his research. He eagerly drew a figure on the stump of a neighbouring tree with a piece of chalk ; he felt assured that he had now the means of solving the great problem ; and although he afterwards tells us that he then had not a sufficiently clear notion of the subject (eo tempore Porismatum naturam non satis cornpertamhabebam),* yet he accom- plished enough to make him communicate a paper upon the discovery to the Royal Society, the first work he ever published (Phil. Trans, for 1723). He was wont in after life to show the spot on which the tree, long since decayed, had stood. If peradventure it had been preserved, the frequent lover of Greek geometry would have been seen making his pilgrimage to a spot consecrated by such touching recollections. The graphic pen of Montucla, which gave such interest to the story of the first observation of the transit of Venus by Horrox in Lancashire, and to the Torricellian experiment,t is alone wanting to clothe this passage in colours as vivid and as unfading. This great geometrician continued at all the inter- vals of his other labours intently to investigate the subject on which he thus first threw a steady light. His first care upon having made this discovery was to extend the particular propositions until he had obtained Op. Rel. 320. j Hist- de Math- vo1- *• SIMSON. 495 the general one. A note among his memoranda ap- pears to have been made, as was his custom, of the date at which he succeeded in any of his investiga- tions.*— "Hodie heec de porismatis inveni, R. S., 23 April 1722." Another note, 27th April, 1722, shows that he had then obtained the general proposition ; he afterwards communicated this to Maclaurin when he passed through Glasgow on his way to France ; and on his return he communicated to Dr. Simson with- out demonstration a proposition concerning conies derived from it, which led his friend to insert some important investigations in his Conic Sections. In 1723 the publication of his paper took place in the Philosophical Transactions ; it is extremely short, and does not appear to contain all that the author had communicated ; for we find this sentence inserted before the last portion of the paper : — " His adjecit clarissimus professor propositiones duas sequentes libri primi Porismatum Euclidis, a se quoque restitutas." The paper contains the first general proposition and its ten cases, and then the second with its cases. No general description or definition is given of Porisms ; and it is plain that his mind was not then finally made up on this obscure subject, although he had obtained a clear view of it generally. * In one there is this note upon the solution of a problem of tactions, — " Feb. 9, 1734 : — Post horam primam ante meridiem ;" and much later in life we find the same particularity in marking the time of discovery. His birthday was October 14, and having solved a problem on that day, 1764, he says — 14 Octobr. 1764. Deo Opt. Max. benigmssimo bervaton 14 Octobr. 1687. Laus et gloria. 77 496 SIMSON. At what time his knowledge of the whole became matured we are not informed ; but we know that his own nature was nice and difficult on the subject of his own works ; that he never was satisfied with what he had accomplished ; and he probably went on making constant additions and improvements to his work. Often urged to publish, he as constantly refused ; in- deed he would say that he had done nothing, or next to nothing, which was in a state to appear before the world ; and moreover, he very early began to appre- hend a decay of his faculties, from observing his recol- lection of recent things to fail, as is very usual with all men; for as early as 1751, we find him giving this as a reason for declining to undertake a work on Lord Stanhope's recommendation, when he was only in his sixty-fifth year. Thus, though he at first used to say he had nothing ready for publication, he afterwards addeo1, that he was too old to complete his work satis- factorily. In his earlier days he used occasionally to affect a kind of odd mystery on the subject, and when one of his pupils (Dr. Traill) submitted to him some propositions, which he regarded as porisms, Dr. Sim- son would neither admit nor deny that they were such, but said with some pleasantry, " They are propositions." One of them, however, he has given in his work as a porism, and with a complimentary reference to its ingenious and learned author. Thus his life wore away without completing this great work, at least without putting it in such a con- dition as satisfied himself. It was left among his MSS., and by the judicious munificence of a noble geometri- cian, the liberal friend of scientific men, as well as the SIMSON. 497 successful cultivator of science, Earl Stanhope,* it was, after his death, published, with his restoration of Apollonius' treatise De Sectione determinate,, a short paper on Logarithms, and another on the Method of Limits geometrically demonstrated, the whole forming a very handsome quarto volume ; of which the Porisms occupies nearly one-half, or 277 pages. This work is certainly the master-piece of its distin- guished author. The extreme difficulty of the subject was increased by the corruptions of the text that re- mains in the only passage of the Greek geometers which has reached us, the only few sentences in which any mention whatever is made of porisms. This passage is contained in the preface or introduction to the seventh book of Pappus, which we have already had occasion to cite. But this was by far the least of the difficul- ties which met the inquirer after the hidden treasure, the restorer of lost science, though Albert Girard thought or said, in 1635, that he had restore^ the Po- risms of Euclid. As we have seen, no trace of his labours is left ; and it seems extremely unlikely that he should have really performed such a feat and given no proofs of it. Halley, the most learned and able of Dr. Simson's predecessors, had tried the subject, and tried it in vain. He thus records his failure : — " Hac- tenus Porismatum descriptio nee mihi intellecta nee lectori profutura." These are his words, in a preface to a translation which he published of Pappus's seventh book, much superior in execution to that of Commanding But this eminent geometrician was * Grandfather of the present Earl. 2 K 498 SIMSON. much more honest than some, and much more safe and free from mistake than others who touched upon the subject which occupied all students of the ancient analysis. He was far from pretending, like Girardus, to have discovered that of which all were in quest. But neither did he blunder like Pemberton, whom we find, the very year of Simson's first publication, actually saying in his paper on the Rainbow — " For the greater brevity I shall deliver them (his propositions) in the form of porisms, as, in my opinion, the ancients called all propositions treated by analysis only" (Philo- sophical Transactions, 1723, p. 148); and, truth to say, his investigation is not very like ancient analysis either. The notion of D'Alembert, somewhat later, has been alluded to already ; he imagined porisms to be synonymous with lemma, misled by an equivocal use of the word in some passages of ancient authors, if indeed he had ever studied any of the writers on the Greek geometry, which, from what I have stated be- fore, seems exceedingly doubtful. But the most extra- ordinary, and indeed inexcusable ignorance of the sub- ject is to be seen in some who, long after Simson's paper had been published, were still in the dark ; and though that paper did not fully explain the matter, it yet ought to have prevented such errors as these fell into. Thus Castillon, in 1761, showed that he con- ceived porisms to be merely the constructions of Eu- clid's Data. If this were so, there might have been some truth in his boast of having solved all the Porisms of Euclid ; and he might have been able to perform his promise of soon publishing a restoration of those lost books. SIMSON. 499 It is remarkable enough that before Halley's at- tempts and their failure, candidly acknowledged by himself, Fermat had made a far nearer approach to a solution of the difficulty than any other of Simson's predecessors. That great geometrician, after fully admitting the difficulty of the subject, and asserting* that, in modern times, porisms were known hardly even by name, announces somewhat too confidently, if not somewhat vaingloriously, that the light had at length dawned upon him,f and that he should soon give a full restoration of the whole three lost books of Euclid. Now the light had but broke in by a small chink, as a mere faint glimmering, and this restora- tion was quite impossible, inasmuch as there remained no account of what those books contained, except- ing a very small portion obscurely mentioned in the preface of Pappus, and the lemmas given in the course of the seventh book, and given as subservient to the resolution of porismatic questions. Never- theless Fermat gave a demonstration of five propo- sitions, " in order," he says, " to show what a porism is, and to what purposes it is subservient." These propositions are, indeed, porisms, though their several enumerations are not given in the true porismatic form. Thus, in the most remarkable of them, the fifth, he gives the construction as part of the enuncia- * " Intentata ac velut disperata Porismatum Euclidaea doctrina. — Geometric! (aevi recentioris) nee vel de nomine eognovemnt, aut quod esset solummodo sunt suspicati." — (Var. Opera, p. 166.) f " Nobis in tenebris dudum csecutientibus, tandem se (Natura Porismatum) clara ad videndum obtulit, et pura per noctem luce refulsit."— (Epist. ib.) 2K 2 500 SIMSON. tion. So far, however, a considerable step was made ; but when he comes to show in what manner he dis- covered the nature of his porisms, and how he defines them, it is plain that he is entirely misled by the erroneous definition justly censured in the passage of Pappus already referred to. He tells us that his pro- positions answer the definition ; he adds that it reveals the whole nature of porisms ; he says that by no other account but the one contained in the definition, could we ever have arrived at a knowledge of the hidden value;* and he shows how, in his fifth proposition, the porism flows from a locus, or rather he confounds porisms with loci, saying porisms generally are loci, and so he treats his own fifth proposition as a locus, and yet the locus to a circle which he states as that from which his proposition flows has no connexion with it, according to Dr. Simson's just remark ('Opera Reliqua,' p. 345). That the definition on which he relies is truly imperfect, appears from this : there could be no algebraical porism, were every porism connected with a local theorem. But an abundant variety of geometrical porisms can be referred to, which have no possible connexion with loci. Thus, it has never been denied that most of the Propositions in the Higher Geometry, which I investigated in 1797, were porisms, yet many of them were wholly unconnected with loci ; as that affirming the possibility of describing an hyper- bola which should cut in a given ratio all the areas of the parabolas lying between given straight lines, f * Var. Op., p. 118. Phil. Trans., 1798, p. 111. SIMSON. 501 Here the locus has nothing to do with the solution, as if the proposition were a kind of a local theorem : it is only the line dividing the curvilineal areas, and it divides innumerable such areas. Professor Play fair, who had thoroughly investigated the whole subject, never in considering this proposition doubted for a moment its being most strictly a porism. Therefore, although Fermat must be allowed to have made a considerable step, he was unacquainted with the true nature of the porism ; and instead of making good his boast that he could restore the lost books, he never even attempted to restore the investi- gation of the first proposition, the only one that re- mains entire. A better proof can hardly be given of the difficulty of the whole subject.* Indeed it must be confessed that Pappus's account of it, our only source of knowledge, is exceedingly obscure, all but the panegyrics which, in a somewhat tanta- lizing manner, he pronounces upon it. " Collectio," says he, " curiosissima multarum rerum spectantium ad resolutionem difnciliorum et generaliorum problema- tum" (lib. vii., Proem). His definition already cited is, as he himself admits, very inaccurate ; because the * The respect due to the great name of Format, a venerable magistrate and most able geometrician, is not to be questioned. He was, indeed, one of the first mathematicians of the age in which he flourished, along with the Robervals, the Harriots, the Descartes. How near he approached the differential calculus is well known. His correspondence with Roberval, Gassendi, Pascal, and others, occupies ninety folio pages of his posthumous works, and contains many most ingenious, original, and profound observations on va- rious branches of science. 502 SIMSON. connexion with a locus is not necessary to the poris- matic nature, although it will very often exist, inas- much as each point in the curve having the same re- lation to certain lines, its description will, in most cases, furnish the solution of a problem, whence a porism may be deduced. Nor does Pappus, while ad- mitting the inaccuracy of the definition, give us one of his own. Perhaps we may accurately enough define a porism to be the enunciation of the possibility of finding that case in which a determinate problem be- comes indeterminate, and admits of an infinity of solutions, all of which are given by the statement of the case. For it appears essential to the nature of a porism that it should have some connexion with an indetermi- nate problem and its solution. I apprehend that the poristic case is always one in which the data become such that a transition is made from the determinate to the indeterminate, from the problem being capable of one or two solutions, to its being capable of an infinite number. Thus it would be no porism to affirm that an ellipse being given, two lines may be found at right angles to each other, cutting the curve, and being in a proportion to each other which may be found : the two lines are the perpendiculars at the centre, and are of course the two axes of the ellipse ; and though this enunciation is in the outward form of a porism, the proposition is no more a porism than any ordinary pro- blem ; as that a circle being given a point may be found from whence all the lines drawn to the circumference are equal, which is merely the finding of the centre. But suppose there be given the problem to inflect two SIMSON. 503 lines from two given points to the circumference of an ellipse, the sum of which lines shall be equal to a given line, the solution will give four lines, two on each side of the transverse axis. But in one case there will be innumerable lines which answer the conditions, namely, when the two points are in the axis, and so situated that the distance of each of them from the farthest ex- tremity of the axis is equal to the given line, the points being the foci of the ellipse. It is, then, a porism to affirm that an ellipse being given, two points may be found such that if from them be inflected lines to any point whatever of the curve, their sum shall be equal to a straight line which may be found ; and so of the Cassinian curve, in which the rectangle under the in- flected lines is given. In like manner if it be sought in the cubic hyperbola (y x*=x — a) to inflect from two given points in a given straight line, two lines to a point in the curve, so that the tangent to that point shall, with the two points and the ordinate, cut the given line in harmonical ratio ; this, which is only capable of one solution in ordinary cases, becomes capable of an infinite number when the two points are in the axis, one of them the curve's apex, and the other at the distance equal to the given line a from the apex ; for in that case every tangent that can be drawn, and every ordinate, cut the given line har- monically with the curve itself and the given point.* * This curve has many curious and elegant properties : for ex- ample— All the lines which can be drawn in every direction from any point out of the curve are cut harmonically by the tangent, the ordinate, and the lines joining the two given points. This 504 SIMSON. Dr. Simson's definition is such that it connects itself with an indeterminate case of some problem solved, but it is defective, in appearance rather than in reality, from seeming to confine itself to one class of porisms. This appearance arises from using the word "given" (data or datum) in two different senses, both as describing the hypothesis and as affirming the possibility of finding the construction so as to answer the conditions. This double use of the word, indeed, runs through the book, and though purely classical, is yet very inconvenient ; for it would be much more distinct to make one class of things those which are assuredly data, and the other, things which may be found. Nevertheless, as his definition makes all the innumerable things not given have the same relation to those which are given, this should seem to be a limitation of the definition not necessary to the poristic nature. Pappus's definition, or rather that which he says the ancients gave, and which is not exposed to the objection taken by him to the modern one, is really no definition at all ; it is only that a porism is something between a theorem and a problem, and in which, instead of anything being proposed to be done, or to be proved, something is proposed to be investigated. might be called the Harmonical Curve, did not another of the 12th order rather merit that name, which has its axis divided harmoni- cally by the tangent, the normal, the ordinate, and a given point in the axis. Its differential equation is 2 d y*+d x*=- — - — -' oc which is reducible, and its integral is an equation of the 12th order. There is another Harmonical Curve, also, a transcendental one, in which chords vibrate isochronously. SIMSON. 505 This is erroneous, and contrary to the rules of logic from its generality ; it is, as the lawyers say, void for uncertainty. The modern one objected to by Pappus is not uncertain ; it is quite accurate as far as it goes ; but it is too confined, and errs against the rules of logic by not being coextensive with the thing proposed to be defined. The difficulty of the subject has been sufficiently shown from the extreme conciseness and the many omissions, the almost studied obscurity, of the only account of it which remains, and to this must cer- tainly be added the corruption of the Greek text. The success which attended Dr. Sirnson's labours in restoring the lost work, as far as that was possible, and, at any rate, in giving a full elucidation of the nature of porisms, now, for the first time, disclosed to mathe- maticians, is, on account of those great difficulties by which his predecessors had been baffled, the more to be admired. But there is one thing yet more justly a matter of wonder, when we contrast his proceedings with theirs. The greater part of his life, a life ex- clusively devoted to mathematical study, had been passed in these researches. He had very early become possessed of the whole mystery, from other eyes so long concealed. He had obtained a number of the most curious solutions of problems connected with porisms, and was constantly adding to his store of porisms and of lemmas subservient to their investi- gation. For many years before his death, his work had attained, certainly the form, if not the size, in which we now possess it. Yet he never could so far satisfy himself with what has abundantly satisfied every one else, as to make it public, and he left it un- 506 SIMSON. published among his papers when he died. Nothing can be more unlike those who freely boasted of having discovered the secret, and promised to restore the whole of Euclid's lost books. It is as certain that the secret was never revealed to them as it is that neither they nor any man could restore the books. But how speedily would the Castillons, the Alberts, even the Fermats, have given their works to the world had they become possessed of such a treasure as Dr. Simson had found ! Yet though ready for the press, and with its preface composed, and its title given in minute particularity, he never could think that he had so far elaborated and finished it as to warrant him in finally resolving on its publication. There needs no panegyric of this most admirable performance. Its great merit is best estimated by the view which has been taken of the extraordinary difficulties overcome by it. The difficulty of some investigations — the singular beauty of the propositions, a beauty peculiar to the porism from the wonderfully general relations which it discloses — the simplicity of the combinations — the perfect elegance of the demon- strations— render this a treatise in which the lovers of geometrical science must ever find the purest delight. Beside the general discussions in the preface, and in a long and valuable scholium after the sixth propo- sition, and an example of algebraical porisms, Dr. Sim- son has given in all ninety-one propositions. Of these four are problems, ten are loci, forty-three are theorems, and the remaining thirty-four are porisms, including four suggested by Matthew Stewart, and the five of Fermat improved and generalized ; there are, besides, four lemmas and one porism suggested SIMSON. 507 by Dr. Traill, when studying under the Professor. There may thus be said to be in all ninety-eight pro- positions. The four lemmas are propositions ancillary to the author's own investigations ; for many of his theorems are the lemmas preserved by Pappus as an- cillary to the porisms of Euclid. In all these investigations the strictness of the Greek geometry is preserved almost to an excess ; and there cannot well be given a more remarkable illus- tration of its extreme rigour than the very outset of this great work presents. The porism is, that a point may be found in any given circle through which all the lines drawn cutting its circumference and meeting a given straight line shall have their segments within and without the circle in the same ratio. This, though a beautiful proposition, is one very easily demonstrated, and is, indeed, a corollary to some of those in the ' Elements.' But Dr. Simson prefixes a lemma : that the line drawn to the right angle of a triangle from the middle point of the hypotenuse, is equal to half that hypotenuse. Now this follows, if the segment containing the right angle be a semi- circle, and it might be thought that this should be assumed only as a manifest corollary from the pro- position, or as the plain converse of the proposition, that the angle in a semicircle is a right angle, but rather as identical with that proposition ; for if we say the semicircle is a right-angled segment, we also say that the right-angled segment is a semicircle. But then it might be supposed that two semicircles could stand on one base : or, which is the same thing, that two perpendiculars could be drawn from one 508 SIMSON. point to the same line ; and as these propositions had not been in the elements, (though the one follows from the definition of the circle, and the other from the theorem that the three angles of a triangle are equal to two right angles,) and as it might be supposed that two or more circles, like two or more ellipses, might be drawn on the same axis, therefore the lem- ma is demonstrated by a construction into which the centre does not enter. Again, in applying this lemma to the porism (the proportion of the segments given by similar triangles), a right angle is drawn at the point of the circumference, to which a line is drawn from the extremity of a perpendicular to the given line ; and this, though it proves that perpendicular to pass through the centre, unless two semicircles could stand on the same diameter, is not held sufficient ; but the analysis is continued by help of the lemma to show that the perpendicular to the given line passes through the centre of the given circle, and that therefore the point is found. It is probable that the author began his work with a simple case and gave it a peculiarly rigorous investigation in order to explain, as he im- mediately after does clearly in the scholium already referred to, the nature of the porism, and to illustrate the erroneous definitions of later times (veorepiKoi) of which Pappus complains as illogical. Of porisms, examples have been now given both in plain geometry, in solid, and in the higher : that is, in their connexion both with straight lines and circles, with conic sections, and with curves of the third and higher orders. Of an algebraical porism it is easy to give examples from problems becoming inde- SIMSON. 509 terminate ; but these propositions may likewise arise from a change in the conditions of determinate pro- blems. Thus, if we seek for a number, such that its multiple by the sum of two quantities shall be equal to its multiple by the difference of these quantities, together with twice its multiple by a third given quantity, we have the equation (a+ £) #=(« — &) oc+ 2c