In arranging his general plan, the Editor proposed to have but two preliminary Dissertations,-the first containing the History of Metaphysical, Ethical, and Political Philosophy,-and the second that of Mathe

and the valuable hydraulic researches of preliminary Dissertations,-to some of its the Chevalier de Buat on rivers and water-principal articles on science and literaworks, were here for the first time laid be- ture, and, in a more general manner, to fore the British public. But although Pro- the various subordinate departments of the fessor Robison used to speak to his pupils work. of these essays as merely compilations intended to diffuse knowledge, yet they possess a character of a much higher kind. The labours of others rose in value under his hands; his thorough knowledge of the subject gave every contribution an air of ori-matical and Physical Science. Professor ginality, and new views and ingenious suggestions never failed to enliven his details. Throughout these multifarious treatises we feel everywhere the steady serene influence of an ardent love of truth, the highest tone of scientific morality, and a deep sense of religion.

Stewart engaged to supply the former, and Professor Playfair the latter; but though each performed a large portion of his task, they were both carried off in the midst of their labours. Mr. Stewart had completed the History of Metaphysics, and Mr. Playfair had brought the History of the Mathematical and Physical Sciences down to the period of Newton and Leibnitz. Sir James Mackintosh undertook to complete the labours of his friend by a continuation, including the History of Ethical and Political Philosophy, but he too was summoned from his labours before he had commenced the political portion of his subject. Professor Leslie resumed the History of the Physical Sciences at the point where they had been left by his predecessor, and brought it down to the commencement of the present century; but though he was spared to finish his task, he did not live to see the completion of the work to which he had been so active a contributor.

In the year 1810 a fourth edition of the work was completed under the editorship of the late Dr. James Millar, and a fifth and a sixth edition, marked by no distinguishing peculiarities, successively appeared. From this state of lethargy, however, the Encyclopædia' was destined to assume the highest station among the analogous works of the day. The enterprising house of Constable and Co. projected a Supplement, which extended to six volumes. It was placed under the skilful management of Professor Napier. Many very distinguished authors, among whom are numbered the names of Arago and Biot, were engaged as contributors, and all the resources of the proprietors, both pecuniary and It is no wonder that the Dissertations commercial, were devoted to this favourite produced by these four extraordinary men undertaking. The first half volume (De- are regarded with peculiar pride in Scotcember, 1815) was enriched with a Pre-land. Few nations, indeed, can boast of liminary Dissertation on the History of such an intellectual group living at the Ethical Science,' by Mr. Dugald Stewart, and the Supplement was completed in April, 1824.

A few years afterwards the copyrights were purchased by the present proprietors, who immediately made preparations for the seventh edition of the Encyclopædia Britannica,' which we have now before us. Their object was to widen it in its compass, to amplify and improve it in its contents, and to raise it, in all respects, to a level with the modes of thinking and spirit of the age;' and we have no hesitation in saying that they have, to a very large extent, fulfilled this obligation, both in the number and value of the original treatises which it contains, in the careful revision and extension of former articles, and in the elaborate engravings, maps, and embellishments with which the work is illustrated and adorned.

In order to give our readers some idea of the nature and value of this immense collection, we shall call their attention to its

same time, and adorning the same society; and yet, with powers of mind not far from equality, how various were their gifts, and how diversified their genius! While Stewart derived his powers of mental analysis and combination from the study of his own mind, chastened by the early and severe discipline of geometry, and expanded by extensive knowledge of preceding researches,Mackintosh approached the same subject under a profound acquaintance with the world

with the penetrating acuteness derived from legal studies, and with all the generalisations which an active and political life is likely to supply to a naturally very acute understanding. In the Dissertation of the one a stately and persuasive eloquenceinfluenced, no doubt, but rendered more commanding, by the habit of extempore

*This dissertation has been published separately, with a very able Preface by Mr. WHEWELL.

him, while he must be allowed to have surpassed most, in that creative faculty-one of the highand is necessary for discovery, though not allest and rarest of Nature's gifts-which leads to sufficient of itself for the formation of safe con

lecturing-excites the enthusiasm, without | logical accuracy; but we doubt if any surpassed distracting the attention, of the reader ;while in the other the style is at once elegant, copious, and felicitous in its illustrations-pure in its metaphors-elevated by a high tone of moral feeling-and exhibit-clusions; or in that subtilty and reach of dising, in singular, yet harmonious combination, the chaste and severe language of philosophy, and the flexible and powerful periods of forensic eloquence.

cernment, which seizes the finest and least obvious qualities and relations of things, which elicits the hidden secrets of nature, and ministers to new and unexpected combinations of her But the contrast is much more striking powers. "Discoveries in science," says he, in one of his works, "are sometimes invidiously between the two philosophers who have re- referred to mere fortuitous incidents. But the corded the achievements of mathematical mixture of chance in this pursuit should not deand physical science. Familiar though tract from the real merit of the invention. Such they both were with the highest acquisitions occurrences would pass unheeded by the bulk of of geometry and analysis, yet how differ- men; and it is the eye of genius alone that can ently were those instruments of research seize every casual glimpse, and discern the chain directed and applied! In quest only of of consequences." With genius of this sort he truth, the mind of Playfair never deviated was richly gifted. Results overlooked by others were by him perceived with a quickness apfrom the accustomed and deep-worn chan- proaching to intuition. To use a poetical exnels by which it had been reached. Eager pression of his own, they seemed "to blaze on principally for fame, the scientific faculties his fancy." He possessed the inventive in a far of Leslie were counteracted by antagonist higher degree of perfection than the judging and forces. Under the restraining influence reasoning powers; and it thus sometimes hapof abstract truth, and the more powerful pened that his views and opinions were not only curb of the dread of error, the one seldom at variance with those of the majority of the learned, but inconsistent with one another. ventured into the regions of invention and Notwithstanding the contrary testimony, explidiscovery, while the other-with loose reins citly recorded, of the founders of the English and heedless pace-diverged from the beat- Experimental School, he denied all merit and en highway of knowledge, and struck into influence to the labours of the immortal delinethose devious paths where Nature often un- ator of the Inductive Logic. He freely derided veils her mysteries, and yields to the daring the supposed utility of Metaphysical Science, enterprise of Fancy what she refuses to the without perceiving that his own observations on Causation virtually contained the important admore deliberate approaches of Reason. mission, that physical is indebted to mental is in science as it is in war-the forlorn philosophy for the correct indication of its legitihope succeeds when the physical force of mate ends and boundaries. His writings are thousands has been exhausted. In the in- replete with bold and imaginative suppositions; tellectual campaign it is not often that the yet he laments the "ascendency which the pasgallantry of genius can be exercised simul- sion for hypothesis has obtained in the world.” taneously with the sapping and mining of His credulity in matters of ordinary life was, to mental labour, yet the philosophical charac-say the least of it, as conspicuous as his tendency ter can only attain its full and perfect stature when the powers of reason and the gifs of fancy are united in definite proportions.

It

As separate lives of all these authors, except Leslie, had been previously published, our readers will, we doubt not, be gratified with the following candid and well-written character of this eminent man by Professor Napier :

It would be impossible, we think, for any intelligent and well-constituted mind, thoroughly acquainted with the powers and attainments of Sir John Leslie, to view them without a strong feeling of admiration for his vigorous and inventive genius, and of respect for that extensive and varied knowledge, which his active curiosity, his excursive reading, and his happy memory, had enabled him to amass and digest. Some few of his contemporaries in the same walks of science may have excelled him in profundity of understanding, in philosophical caution, and ine

to scepticism in science. It has been profoundly remarked by Mr. Dugald Stewart that, “though the mathematician may be prevented, in his own pursuits, from going far astray, by the absurdities to which his errors lead him, he is seldom apt to be revolted by absurd conclusions he adds, "mathematicians have been led to acin other matters. . . . . Thus, even in physics," quiesce in conclusions which appear ludicrous to men of different habits." Something of this sort was observable in the mind of this distinguished mathematician. He was apt, too, to indulge in unwarrantable applications of mathe matical reasoning to subjects altogether foreign to the science: as when he finds an analogy between circulating decimals and the lengthened cycles of the seasons! But when the worst has been said, it must be allowed that genius has struck its captivating impress over all his works. Whether his bold speculations lead him to figure the earth as enclosing a stupendous concavity filled with light of overpowering splendour; or to predict the moon's arrival at an age when her "silvery beams" will become extinct; or to asribe the phenomena of radiated heat to aerial

pulsations, we at least perceive the workings blest company; and we have often known him of a decidedly original mind. This, however, pass an afternoon with mere boys, discoursing is not all. His theoretical notions may be thrown to them pleasantly upon all topics that presented aside or condemned, but his exquisite instru- themselves, just as if they had been his equals ments, and his experimental combinations, will in age and attainments. He was thus greatly ever attest the utility, no less than the origin-liked by many who knew nothing of his learnality of his labours, and continue to act as helps ing or science, except that he was famous for to farther discovery. We have already alluded both.'* to the extent and excursiveness of his reading. It is rare, indeed, to find a man of so much in- But it is time to leave the Preliminary vention, and who himself valued the inventive Dissertations, and their authors, and come above all the other powers, possessing so vast a to the body of the book. store of information. Nor was it in the field of science alone that its amplitude was conspicuIn almost all encyclopædias the matheous. It was so in regard to every subject that matical and physical articles have occupied books have touched upon. In Scottish history, a prominent place, and have generally been in particular, his knowledge was alike extensive regarded as the most valuable and imporand accurate: and he had, in acquiring it, gone tant. Sir James Mackintosh, indeed, has deep into sources of information-such as parish made a similar remark, and has, at the records, family papers, and criminal trials- same time, stated that in such works' those which ordinary scholars never think of exploring on literary, moral, and political subjects are The ingenious mathematician, the original in most danger of being less ably exethinker, the rich depository of every known fact in the progress of science, would have appeared cuted.' Although Sir James has not atto any one ignorant of his name and character, tempted to explain the cause of this difand who happened to hear him talk on this sub- ference, it is, we think, not difficult to disject, as a plodding antiquary, or, at best, as a cover it. Owing to the abstract, and therecurious and indefatigable reader of history, whom fore unpopular, nature of mathematical nature had blest with at least one strong faculty, and physical inquiries, philosophers have that of memory. His conversation showed no inducement to compose new treatises acnone of that straining after "thoughts that breathe, and words that burn," so conspiccommodated to the existing state of knowuous in his writings. In point of expression, it ledge, and if they were to compose them was simple, unaffected, and correct. Though no bookseller would risk their publication. he did not shine in mixed society, and was lat- Hence it follows that works of this kind terly unfitted, by a considerable degree of deaf- will continue to be sold as standard producness, for enjoying it, his conversation, when tions long after they have ceased to represeated with one or two, was highly entertaining. sent the science of which they treat-when It had no wit, little repartee, and no fine turns their information has become antiquated, of any kind; but it had a strongly original and racy cast, and was replete with striking remarks and their speculations exploded. The Optics' of Dr. Smith, for example, and the

and curious information.

'Viewing the whole of his character, moral History of Vision' by Dr. Priestley, and intellectual, it must be confessed that it pre- were the prevailing works when Professor sented some blemishes and defects. He had Robison enlarged the treatise on Optics, prejudices of which it would have been better and wrote the article Telescope for the third to be rid; he was not over-charitable in his views of human nature; he was not so ready, edition of the Encyclopædia Britannica. on all occasions, to do justice to kindred merit Hence it is rarely elswhere than in the enas was to be expected in so ardent a worshipper cyclopædias of the day that we can expect of genius; and his care of his fortune went new and original treatises containing all much beyond what is seemly in a philosopher. the recent discoveries which have been But his faults were far more than compensated by his many good qualities; by his constant equanimity, his cheerfulness, his simplicity of character almost infantile, his straightforwardness, his perfect freedom from affectation, and, above all, his unconquerable good nature. was, indeed, one of the most placable of human beings; and notwithstanding his general attention to his own interests, it is yet undeniable that he was a warm and good friend, and a relation on whose affectionate assistance a firm reliance ever could be placed. He was fond of society, and greatly preferred and prized that of the intelligent and refined; but no man ever was more easily pleased: no fastidiousness ever interfered with his enjoyment of the passing hour: he could be happy, and never failed to converse in his usual way, though in the hum

He

made in the exact sciences. The case is entirely different with works on popular subjects, such as chemistry, literature, history, biography, and political philosophy. A wider circle of readers creates an increased demand for productions of this kind, and hence new and superior editions speedily remunerate the labour of the author and the enterprise of the bookseller. Writers of acknowledged eminence in these departments of knowledge have already an interest in their own separate books, and consequently persons of inferior distinc

* Art. LESLIE, Sir John, vol. xiii., p. 251.

tion must be employed in supplying such | written a separate work, and, in those cases articles to our encyclopædias. in which such works do exist, they have seldom been brought down to the present day, or drawn up with that copious detail of recent discoveries which is of so much importance to the progress of science. It is often in articles contributed by eminent individuals who have made the subjects of them their particular study that we have our only chance of finding the inestimable treasures of contemporary discovery which fill the Transactions' of domestic and foreign societies, and those less elaborate notices of experimental researches, circulated by numberless periodical journals, which are the depositories of American as well as European science.

ings; and the arts of voltaic etching, gilding, and plating.

The art of multiplying works in metal was invented in 1831, nearly about the same time, by M. Jacobi of St. Petersburg and Mr. Spencer of Liverpool. It consists of depositing copper, gold, silver, and platinum, &c., from their solutions, upon metallic or conducting surfaces, the metal being precipitated by galvanism. If the surface is that of an intaglio, we obtain from it a perfect cameo, and vice versa. In 1840 Mr. Murray announced the important fact, that these metals could be all precipitated upon non-conducting substances, such as plaster of Paris, wax, wood, &c., by previously metallising their surface with black lead. In this way, every work formed by art, whether it be the finest carvings, or the finest sculptures, can be multiplied in copper, or the other metals already mentioned. The multiplication of engraved copper-plates is another of the triumphs of this new art; and engravers have found that plain copper-plates deposited from a solution of sulphate of copper upon another previously prepared copper surface, are far superior to those manufactured in the usual way.

The modern arts presented to us by electro-magnetism, the new science of Oersted and Ampère, are not less wonderful and valuable. The electro-magnetic telegraph of Professor Wheatstone, now in use upon the Blackwall and the Great Western railways, was the first of these achievements. The telegraph, with its accompanying alarums, goes into a case not larger than that of a small table cloth, and so simple are its assertions, that any child can both read and send the messages with scarcely a minute's instruction.

The

The electro-magnetic clock of Professor Wheatstone is another of those singular inventions, and one which, though it may be less useful, is certainly not less ingenious and surprising than his telegraph. object of the inventor was to enable a single clock to indicate exactly the same time in as many different places, distant from each other, as may be required. A standard clock in an observatory, for example, would thus keep in order another clock in each apartment, and that too with such accuracy that all of them, however numcrous, will beat dead seconds audibly, with as great precision as the standard astronomical timepiece with which they are connected. But, beside this, the subordinate timepieces thus regulated require none of the mechanism for maintaining or regulating the power. They consist simply of a face with its second, minute, and hour hands, and of a train of wheels which communicate motion from the action of the second-hand to that of the

The art of voltaic etching is singularly beautiful. A copper-plate prepared for ordinary etching, and all covered with wax, is connected with a suitable galvanic battery, and placed in a solution of sulphate of copper. A piece of copper (negative) of the same size as the copper-plate is then connected with the zinc. When the bat-hour-hand, in the same manner as an orditery is put in action, copper is reduced from the solution on the negative piece of copper, while copper is removed from the clear lines of the etching-plate to supply what is taken away from the solution. In this process no nitrous fumes annoy the artist, and no air-bubbles interfere with the precision of his work. The lines may be bitten to any depth, and are much sharper and clearer than when they are made with an acid. The art of gilding upon silver and brass, which we owe to M. Delarive of Geneva, is equally beautiful and important. The gold is deposited in coatings of any thickness from a weak nitro-muriatic solution of it, and the deleterious effects of mercury upon the artist are thus completely avoided.*

* Great progress is now making in this beautiful art. Mr. Spencer, of Liverpool, has, in 1841, taken a patent for making picture and other frames by the deposition of copper upon suitable moulds, and subsequently gilding, silvering, or platinising them. Mr. Parker, of Birmingham, has, likewise, in the same year, taken a patent for manufacturing articles |

nary clock train. Nor is this invention confined to observatories and large establishments. The great horologe of St. Paul's might, by a suitable network of wires, or even by the existing metallic pipes of the metropolis, be made to command and regulate all the other steeple-clocks in the city, and even every clock within the precincts of its metallic bounds. When railways and telegraphs extend from London to the remotest cities and villages, the sen

in gold and silver, such as vases, chandelier branches, &c., by depositing the metal upon proper models, which may be afterwards removed from the silver and gold articles, by displacement, heat, or solution; and Mr. Edward Palmer has secured by patent another invention equally important. He obtains printing surfaces by drawing or painting on silver or copper, or any other conducting surface, and then, by the electrotype, he produces copper or other metallic plates with sunken surfaces from which prints may be taken, or from engraved copper plates. Mr. Palmer calls this art Electro-tinting, and he proposes to employ it for printing china, pottery ware, music, maps, and portraits. See, Newton's London Journal and Repertory of Arts' for April, 1842, vol. xx., pp. 166, 171, 172.