per, moderation, and good manners." But his liberal mind did not permit him, on seeing the manuscript, and knowing the worth of its author, to yield to his hasty anticipations. Writing personally to Reid, he said, " By Dr Blair's means I have been favoured with the perusal of your performance, which I have read with great pleasure and attention. It is certainly very rare, that a piece so deeply philosophical, is wrote with so much spirit, and affords so much entertainment to the reader, though I must still regret the disadvantages under which I read it, as I never had the whole performance at once before me, and could not be able fully to compare one part with another. To this reason chiefly I attribute some obscurities, which, in spite of your short analysis or abstract, still seem to hang over your system. For I must do you the justice to own, that, when I enter into your ideas, no man appears to express himself with greater perspicuity than you do; a talent which, above all others, is requisite in that species of literature which you have cultivated. There are some objec tions, which I would willingly propose, to the chapter Of Sight, did I not suspect that they proceed from my not sufficiently understanding it; and I am the more confirmed in this suspicion, as Dr Black tells me that the former objections I had made, had been derived chiefly from that cause. I shall, therefore, forbear till the whole can be before me, and shall not at present propose any farther difficulties to your reasonings. I shall only say, that if you have been able to clear up these abstruse and important subjects, instead of being mortified, I shall be so vain as to pretend to a share of the praise; and shall think that my errors, by having at least some coherence, had led you to make a more strict review of my principles, which were the common ones, and to perceive their futility."

It may be as well here to pass over the intervening events of Dr Reid's life, and give a brief sketch of the principles of his philosophy, as developed in his other works, to which, as Mr Stewart has properly remarked, the Inquiry into the Human Mind forms an introduction. In 1785, he published his "Essays on the Intellectual Powers of Man," and in 1788, those on the "Active Powers." These two have been generally republished together, under the well known title, "Essays on the Powers of the Human Mind ;" a work which has gradually gained ground in the estimation of intelligent thinkers, and is now used as a text book by many eminent teachers of philosophy. When it is said that Dr Reid's philosophy is entirely, or intended to be entirely synthetical, and that it adopts no theory, except as an induction from experiment, it will readily be understood, that a view of its general principles and tendency cannot be given; but it is not on this account very difficult to describe the method by which he reasoned, and came to the different conclusions he has adopted. Reid has generally received, and probably with justice, the praise of having been the first to extend, by a general system, the process of reasoning from experiment, so strongly recommended by Bacon in natural science, to the operations of the mind. In this he was, to a certain extent, anticipated by Hume, who, especially in his arguments on cause and effect, and his essay on miracles, proceeded on analyses of our experience: but the two philosophers followed a different method; the sceptic using his experience to show the futility of any systems of philosophy which had been raised; while Reid made use of them to redeem, as it were, mental science, by eschewing these systems, and founding one of his own on that experience which he saw had enabled the sceptic to demolish the systems, destitute of such a support. But to accomplish his purpose and this is what distinguishes his philosophy from all other systemsReid found it necessary to set bounds to his inquiries, which other philosophers had passed. He abstained from that speculation concerning the nature and

essence of the mind itself, which, as followed by others, had formed the most convenient object of demolition to the sceptic, and limited himself to observations on the operations of the mind, as he saw them performed before him. Instead, therefore, of appealing to any theories of his own (which he knew would require to be founded on vague speculation, and independently of observation,) on the essence of the mind, when he tried the truth of his observations, he appealed to what he called "common sense," or that sense, however acquired, which prompts us to believe one thing, and disbelieve another. Hence it might be said, in common language, that, instead of making his inquiries by means of subtle and metaphysical reasonings, he stated his views, trusting that his readers would believe him from their common sense, and, if they did not choose to do so, knowing that the greater part of the world was on his side, despite of any fine-spun objections which might be produced by the sophist. The following, perhaps, more than most other passages in his works, bears a marked stamp of his method of reasoning: "Perhaps Des Cartes meant not to assume his own existence in this enthymeme, but the existence of thought, and to infer from that the existence of a mind, or subject of thought. But why did he not prove the existence of his thought? Consciousness, it may be said, vouches that. But who is voucher of the consciousness? Can any man prove that his consciousness may not deceive him? No man can: nor can we give a better reason for trusting to it, than that every man, while his mind is sound, is determined, by the constitution of his nature, to give implicit belief to it, and to laugh at, or to pity, the man who doubts its testimony. And is not every man in his wits as determined to take his existence upon trust, as his consciousness ?" It is easier to find objections to, than to erect a system of metaphysical philosophy; and that of Reid affords ample room for controversy. Admitting that the only ground on which we can ever place metaphysical truths is, the general belief of men of sound mind, it must still, in every instance, be a very questionable matter, whether these men of sound mind have come to the right conclusion, and whether it may not be possible, by a little more investigation and argument, even though conducted by a sceptical philosopher, to show reasons for coming to a different conclusion, and to establish it upon the very same grounds, viz., the general belief of men of sound mind. When Galileo discovered that nature abhorred a vacuum, and was afterwards obliged to admit that this abhorrence did not extend above thirty-three feet, many men of sound mind probably felt themselves" determined, by the constitution of their nature, to give implicit belief" to both positions, until one discovered the effect of atmospheric pressure, and got men of common sense to admit that nature had no greater horror at a vacuum than at a plenum. It became a necessary consequence of this method of reasoning, that Reid's first, or instinctive principles, were less simple and more numerous than those of other philosophers; and his opponents accused him of having by that means perplexed and complicated the science of mind. In simplifying this science, there are two evils to be avoided; a propensity to refine every thing into first principles, unsupported by reason; and the lesser vice of producing confusion, by not extending speculation so far towards the establishment of first principles, as there may be good reason for proceeding. It was probably in his anxiety to avoid the former, that Reid incurred not unjust censure for sometimes embracing the latter alternative. The "Principle of Credulity," and the "Principle of Veracity," are certainly objectionable. Reid has had many warm followers, and many who have looked on his philosophy with great contempt. Those who conceive that all systems of mental philosophy are merely useful for the exercise they give the mind, 4 Inquiry, (1819,) 28.

and the undoubted truths which they occasionally lay open, will perhaps make the fairest appreciation of his merit, and by such it may perhaps be allowed, that the broad method he followed, has enabled him to lay before the world a greater number of interesting circumstances connected with moral science, than most other philosophers have been enabled to display. Before leaving the subject of his works, it may be mentioned, that he composed, as a portion of lord Kames' Sketches of the History of Man, "A brief Account of Aristotle's Logic;" the chief defect of this production is, its professed brevity. It is very clear and distinct, and leads one to regret, that so accurately thinking and unprejudiced a writer, had not enriched the world with a more extensive view of the Aristotelian and other systems.

In 1763, while he was, it may be presumed, preparing his Inquiry for the press, a knowledge of what was expected to come from his pen, and his general fame, prompted the university of Glasgow to invite him to fill the chair of natural philosophy there. In this office, professor Stewart remarks, that "his researches concerning the human mind, and the principles of morals, which had occupied but an inconsiderable space in the wide circle of science, allotted to him by his former office, were extended and methodized in a course, which employed five hours every week, during six months of the year. The example of his illustrious predecessor, and the prevailing topics of conversation around him, occasionally turned his thoughts to commercial politics, and produced some ingenious essays on different questions connected with trade, which were communicated to a private society of his academical friends. His early passion for the mathematical sciences was revived by the conversation of Simson, Moor, and the Wilsons; and at the age of fifty-five, he attended the lectures of Black with a juvenile curiosity and enthusiasm." Dr Reid's constant desire for the acquisition of facts on which to raise his deductions, kept him continually awake to all new discoveries; and he spent many, even of the latter days of his long life, in observing the truths which were developed by this illustrious chemist. The biographer, after observing that the greater part of the course of lectures delivered by Dr Reid at Glasgow, is to be found in his published works, proceeds: "Beside his speculations on the intellectual and active powers of man, and a system of practical ethics, his course comprehended some general views with respect to natural jurisprudence, and the fundamental principles of poli tics. A few lectures on rhetoric, which were read at a separate hour, to a more advanced class of students, formed a voluntary addition to the appropriate functions of his office, to which, it is probable, he was prompted rather by a wish to supply what was then a deficiency in the established course of education, than by any predilection for a branch of study so foreign to his ordinary pursuits." It may be right to quote, from the same authority, those observations as to his method of teaching, which none but an ear-witness can make. "In his elocution and mode of instruction, there was nothing peculiarly attrac tive. He seldom, if ever, indulged himself in the warmth of extempore discourse; nor was his manner of reading calculated to increase the effect of what he had committed to memory. Such, however, was the simplicity and perspicuity of his style; such the gravity and authority of his character; and such the general interest of his young hearers in the doctrines which he taught, that by the numerous audiences to which his instructions were addressed, he was heard uniformly with the most silent and respectful attention. On this subject, I speak from personal knowledge, having had the good fortune, during a considerable part of winter 1772, to be one of his pupils." In 1781, Dr Reid retired from the duties of his professorship; and while his labour and assiduity had earned for him a full right to enjoy his old age in literary retirement, his mental faculties

remained unimpaired. After this period, he communicated some essays to the Philosophical Society. The most important were: "An Examination of Priestley's Opinions concerning Matter and Mind;" "Observations on the Utopia of Sir Thomas More ;" and " Physiological Reflections on Muscular Motion." By this time Reid had suffered considerable domestic affliction; four of his children had died after reaching the age of maturity, leaving one daughter married to Patrick Carmichael, M. D. After his retirement, his wife died. In a letter to professor Stewart, he thus affectingly describes his situation after that event: "By the loss of my bosom friend, with whom I lived fifty-two years, I am brought into a kind of new world, at a time of life when old habits are not easily forgot, or new ones acquired. But every world is God's world, and I am thankful for the comforts he has left me. Mrs Carmichael has now the care of two old deaf men, and does everything in her power to please them; and both are very sensible of her goodness. I have more health than at my time of life I had any reason to expect. I walk about; entertain myself with reading what I soon forget; can converse with one person, if he articulates distinctly, and is within ten inches of my left ear; and go to church, without hearing one word of what is said. You know I never had any pretensions to vivacity, but I am still free from languor and ennui." In the summer of 1796, he spent a few weeks in Edinburgh, and his biographer, who was then his almost constant companion, mentions, that, with the exception of his memory, his mental faculties appeared almost unimpaired, while his physical powers were progressively sinking. On his return to Glasgow, apparently in his usual health and spirits, a violent disorder attacked him about the end of September; and, after repeated strokes of palsy, he died on the 7th October following. The affectionate biographer, in drawing a character of this eminent and excellent man, may be said to sum up the particulars of it in the words with which he commences. "Its most prominent features were-intrepid and inflexible rectitude;-a pure and devoted attachment to truth;—and an entire command (acquired by the unwearied exertions of a long life) over all his passions."

RENNIE, JOHN, a celebrated civil engineer, was the youngest son of a respectable farmer at Phantassie, in East Lothian, where he was born, June 7, 1761. Before he had attained his sixth year, he had the misfortune to lose his father; his education, nevertheless, was carried on at the parish school (Prestonkirk) by his surviving relatives. The peculiar talents of young Rennie seem to have been called forth and fostered by his proximity to the workshop of the celebrated mechanic, Andrew Meikle, the inventor or improver of the thrashing-machine. He frequently visited that scene of mechanism, to admire the complicated processes which he saw going forward, and amuse himself with the tools of the workmen. In time, he began to imitate at home the models of machinery which he saw there; and at the early age of ten he had made the model of a wind-mill, a steam-engine, and a pile-engine, the last of which is said to have exhibited much practical dexterity.

At twelve, Rennie left school, and entered into the employment of Andrew Meikle, with whom he continued two years. He then spent two years at Dunbar, for the purpose of improving his general education. So early as 1777, when only sixteen years of age, his Dunbar master considered him fit to superintend the school in his absence, and, on being removed to the academy at Perth, recommended Rennie as his successor. This, however, was not the occupation which the young mechanician desired, and he renewed his former labours in the workshop of Andrew Meikle, employing his leisure hours in modelling and drawing machinery. Before reaching the age of eighteen, he had erected two or three corn-mills in his native parish; but the first work which

he undertook on his own account was the rebuilding of the flour-mills at Invergowrie, near Dundee.

Views of an ambitious kind gradually opened to him, and, by zealously prosecuting his professional labours in summer, he was enabled to spend the winter in Edinburgh, where he attended the lectures of professor Robison on natural philosophy, and those of Dr Black on chemistry. Having thus fitted himself in some measure for the profession of an engineer, he proceeded to Soho, with a recommendation from Robison to Messrs Bolton and Watt. On the way, he examined the aqueduct bridge at Lancaster, the docks at Liverpool, and the interesting works on the Bridgewater canal. At Soho, he was immediately taken into employntent, and it was not long ere Mr Watt discov ered the extraordinary talents of his young assistant. In the erection of the Albion mills in London, which was completed in 1789, Mr Rennie was intrusted by his employers with the construction of the mill-work and machinery, which were admitted to be of superior excellence. These mills consisted of two engines, each of fifty horse power, and twenty pairs of millstones, of which twelve or more pairs, with the requisite machinery, were constantly kept at work. In place of wooden wheels, so subject to frequent derangement, wheels of cast-iron, with the teeth truly formed and finished, and properly proportioned to the work, were here employed; the other machinery, which used to be made of wood, was made of cast-iron in improved forms. This splendid establishment, which Mr Watt acknowledges to have formed the commencement of the modern improved system of mill-work, was destroyed in 1791, by wilful fire, being obnoxious to popular prejudices, under the mistaken supposition of its being a monopoly. The mechanism, however, established Mr Rennie's fame, and he soon after began to obtain extensive employment on his own account.

The earlier years of his professional life were chiefly spent in mill-work; and his merits in this line may be briefly stated. One striking improvement was in the bridge-tree. It was formerly customary to place the vertical axis of the running mill-stone in the middle of the bridge-tree, which was supported only at its two extremities. The effect of this was that the bridge-tree yielded to the variations of pressure arising from the greater or less quantity of grain admitted between the mill-stones, which was conceived to be an useful effect. Mr Rennie, however, made the bridge-tree perfectly immovable, and thus freed the machinery from that irregular play which sooner or later proves fatal to every kind of mechanism. Another improvement by Mr Rennie has been adverted to in the above account of the Albion mills; but the principal one was in the comparative advantage which he took of the water power. economized the power of water as to give an increase of energy, by its specific gravity, to the natural fall of streams, and to make his mills equal to fourfold the produce of those, which, before his time, depended solely on the impetus of the current.

He so

Mr Rennie was gradually attracted from the profession of a mechanician to that of an engineer. In the course of a few years after his first coming into public notice, he was employed in a considerable number of bridges and other public works, all of which he executed in a manner which proved his extraordinary genius. His principal bridges are those of Kelso, Leeds, Musselburgh, Newton-Stewart, Boston, and New Galloway. The first, which was erected between 1799 and 1803, has been greatly admired for its elegance, and its happy adaptation to the beautiful scenery in its neighbourhood. It consists of a level road-way, resting on five elliptical arches, each of which has a span of seventy-three feet, and a rise of twenty-one. The bridge of Musselburgh is on a smaller scale, but equally perfect in its construction. A remarkable testi