withstanding the corrections and additions in the last sheet seen references to articles that are not to be met with; we have seen others defective, owing, perhaps, to the wrong spelling of a word as in the instance of guiac, which is put for guaiacum, and a similar error somewhere appears by the omission of a letter in the word caoutehouc. These it may be said are but trifling mistakes, they are so, but they ought to be attended to in future editions of a work, which promi happiness, and the commands of a benevolent Creator necessarily lead us to consider it as such; yet he who follows it only as a means to an end, and who obeys God only for the sake of the rewards he has attached to obedience, would, in all probability, be continually wandering from the direct path, and seeking for happiness where it was not to be found. The road to duty is so plain, that the man who seeks it with an upright heart cannot greatly wander from it; but the road to happiness, (except where that confidence in the Supreme Being is formed, which supposes the pious affections to have become disinterested) would be found dark and intrises, with some corrections, to rank cate, full of thorns and dangers, and therefore not to be trodden without fear, and care, and perplexity-The happy man, therefore, is not he whose happiness is his only care; but he who with perfect resignation leaves the care of his happiness to his Maker, while he pursues with ardour the road of his duty. This gives an elevation to his mind which is real happiness; instead of care, and fear, and anxiety, and disappointment, it brings peace and joy. It gives a relish to every good we enjoy; it smoothes the brow of distress, calms the perturbed mind, and makes the pillow of suffering and of death the rest of happiness." The law articles are given under the various heads as they occur in the alphabet: they are drawn up with judgment, and modern cases are perpetually referred to as authorities for the doctrines advanced. If our limits would allow of it we should be glad to transcribe the article liberty which contains much valuable legal matter with references to a variety of other articles in which all are more or less interested. We feel we have already exceeded the bounds allowed to a work, which, notwithstanding its merits, will be regarded, in general, as a compilation. It is, however, a compilation of no ordinary kind, and its execution is highly creditable to all the gentlemen concerned. Nevertheless it is not without its defects; we have, not among the standard books in our language. We could indeed enumerate a vast number of separate articles of great value, among these is a history of the Bank of England; an account of the docks; a neat article on the long contested doctrine of necessity; another containing much information on silk; besides many minor articles on the a very neat system of chronology, bissextile, calendar, &c.: nor can we wholly omit those belonging to as the distillery, brewing, hat-makcommerce and the manual trades, ing, cutlery, &c. The articles tactics and sporting will be read with interest by those who pursue, for fame or for pleasure, either their fellow creatures in war, or the beasts of the field, or the birds of the air, by way of pastime. In the We wish to notice another circumstance which is perhaps peculiar to the British Encyclopedia, neither in the plates nor in the letter press is there any thing to offend against delicacy. large works of this kind every thing must occur, but these are chieny resorted to by scientific persons: in a work intended for general purposes, and which will be the companion of all ages and of both sexes, there demands that kind of caution which we are pleased to find the editors have used in compiling the work before us. ART. II. A Course of Lectures on Natural Philosophy, and the Mechanical Arts. By THOMAS YOUNG, M. D. &c. 2 vols. 410. AT an early stage of the royal institution we were one morning introduced into the lecture room, where every thing had been prepared for that day's entertainment, and company was expected in a short time to assemble to hear the scientific author of the volumes before us. A diagram in one place caught our attention it was a circle with the sagitta and chord intended to explain the nature of the centripetal forces in circles, as it is given in the second section of the Principia. We could not but applaud the capacities and the zeal of the audience, and at the same time admired the assiduity of the lecturer, who could so soon introduce a subject, to which, in our academical studies, we had been led after no little arduous labour. We had waded through Euclid and Algebra before we were permitted to enter the great volume, and even then it was thought right to explain to us many of the easier parts of natural philosophy before we were thought capable of understanding the fundamental doctrine of the great master. How happy, we said to ourselves, are the young philosophers in London. Instead of the solitary hours of a 'college room, and the dry lectures of a tutor, a spacious theatre is open to them, and in the midst of the loves and the graces they drink deep of the Pierian stream, at one moment discussing the squares of the distances and the cubes of the periodical times, at the next investigating the radius of curvature of a lady's eyebrow. Cruel fate severed us from this theatre of delight, and science; we were obliged to go on the beaten road without any of these allurements in our path, but the scientific world is at last gratified by the publication of the very lectures which excited so much our admiration, and we may judge of the great progress that is likely to be made in science, ANN. REV. VOL. VII. by the new mode of destroying every obstacle in our way, and rapidly carrying us through all the discoveries of ancient and modern times. The work is contained in two very thick volumes in quarto, and it is needless to attempt to give a detail of their contents: suffice it that every subject in the mathematics or natural philosophy comes in one way or the other. Not every part has been improved by the lec turer. Several improvements are mentioned in the preface; such as in the theory of waves, the circulation of the blood, the propagation of sound, the vibrations of musical chords, the curvature of images formed by lenses and mirrors, the phenomena of Halos and Parhelia, the theory of the tides, of the cohesion and capillary action of liquids. These are improvements of the higher kind, which however have been no obstruction to a due degree of attention to lesser objects, on which the writer shall speak for himself. "Besides these improvements, if I may be allowed to give them that name, there are others, perhaps of less impor tance, which may still be interesting to those who are particularly engaged in chanical practice, to which they relate. those departments of science, or of medivision of mechanics, properly so called, Among these may be ranked, in the a simple demonstration of the law of the force by which a body revolves in an ellipsis; another of the properties of cy cloidal pendulums; an examination of the mechanism of animal motions; a comparison of the measures and weights of different countries; and a convenient estimate of the effect of human labour, with respect to architecture; a simple method of drawing the outline of a coJun; an investigation of the best forms which affords the greatest space for for arches; a determination of the curve turning; considerations on the strueture of the joints employed in carpentry, and on the firmness of wedges; and an easy mode of forming a kirb Tool for Xx the purposes of machinery of different kinds; an arrangement of bars for obtaining rectilinear motion; an inquiry into the most eligible proportions of wheels and pinions; remarks on the friction of wheel work, and of balances; a mode of finding the form of a tooth for impelling a pallet without friction; a chronometer for measuring minute por tions of time; a clock scapement; a calculation of the effect of temperature on steel springs; an easy determination of the best line of draught for a carriage; an investigation of the resistance to be overcome by a wheel or roller; and an estimation of the ultimate pressure produced by a blow." "In the hydraulic an optical part may be enumerated an overflowing lamp; a simplification of the rules for finding the velocity of running water; remarks on the application of force to hydraulic machines; a mode of letting out air from water pipes; an analysis of the human voice; and some arrange. ments for solar microscopes, and for other optical instruments of a similar na ture. "In the astronomical and physical division of the work, will be found a general rule for determining the correction on account of aberration; a comparison of observations on the figure of the earth; a table of the order of electrical excitation; a chart of the variation of the compass, and of the trade winds; formulae for finding the heat of summer and winter; remarks on the theory of the winds; and a comparative table of all the mechanical properties of a variety of natural bodies." How far the public will agree with this writer time will determine, but in the following paragraph there will be but one opinion among his readers. which access may be obtained to all the widely scattered treasures of science; and which will enable those, who are desirous of extending their researches in any particular department, to obtain expeditiously all the information that books can afford them." "The arrangement of the whole work is probably different in many res pects from any other that has yet been adopted; the extent of the subjects, which have been admitted, rendered it necessary to preserve a very strict attention to a very methodical and uniform system; and it it presumed that this arrangement will be considered as in itself of some value, especially in a work callculated to serve as a key, by means of The arrangement is perfectly novel, on its value different apprehen sions will be entertained. The first six lectures explain to us the nature of motion, forces, pressure and the collision of bodies. In the third lecture we plunge into the doctrine of accelerating forces, and at the end of the fourth were difficulties might have startled us complete masters of them; divers indeed in the way, but we found that there was no time for reflection, and on we went congratulating ourselves at the end of the ninth lecture, that perpetual motion was impossible. Here fortunately for us was an end of motion, for the tenth lecture gave a lucky turn to our ideas: we were introduced to drawing, writing, and measuring, had an explanation of pen, ink and pencils, crayons, body colours and encaustic paintings, polygraphs, pantographs and log lines, cum multis aliis. We learned that the best pencils are made of English black lead or plumbago, and that Italian black chalk is better than the French; that paper must not be too smooth for crayons, and that in water colours a size is used, made of isinglass with a little sugar candy. Much more useful information is communicated, and a very good receipt is given for making ink, concluding with a sagacious remark, that if the ink-stand is too open, a little cotton is useful for preserving the ink. An equally entertaining lecture follows on modelling, perspective, engraving, and printing, in which the nature of orthographical and stereographical projection is discussed in a trice, and the lecturer had not time to introduce the globular projection so usefully employed by Arrowsmith pas We now come to statics, and sive strength, and friction, which employ two lectures: architecture and carpentry follow in one: machinery gives us a lecture, and then we come to twisting, spinning, ropemaking, &c. Time-keepers afford a lecture, which none but watchmakers, and not many of them we fear, can understand. Let the reader of the next lecture go to the custom-house quay, or he will make nothing out of it on raising weights, and he must visit half the shops in London to make out the next. All mechanical arts and trades having been thus brought before him, the reader will naturally be glad to have the will naturally be glad to have the history of them, which is given in the 20th lecture, and concludes the first part on the science of mechanics, of which, if he is not a complete master, it must be his own fault, since the lecturer has brought under his view all the forms belonging to them, and he has nothing to do but to take up an encyclopædia, and in the course of a few months he will have some ideas of the subject. In the same manner the science of hydrostatics and hydronamics in all its branches is treated, and many things are very ingeniously stated. We doubt much however whether the audience went away very much edified by the solution of the rising of a stone from the water in the common play of making ducks and drakes; but as it is no bad specimen of the mode of lecturing, we shall insert it. "It is not easy to explain, in a manner perfectly satisfactory, the reflection of a cannon ball, or of a stone, which strikes the surface of the sea, or of a piece of water, in an oblique direction. We may however assign some causes which appear to be materially concerned in this effect. In the first place the surface of the water, acting at first for some time on the lower part of the ball, produces, by its friction, a degree of rotatory motion, by means of which the ball, as it proceeds, acts upon the mass of wa ter which is heaped up before it, and is obliged by a similar friction to roll upwards, so that it mounts again to a much greater height than it could possibly have attained by the mere hydrostatic pressure of the water at a depth so inconsiderable. But a more powerful tinual succession of new surfaces which cause than this appears to be the conbe supposed to react on the ball, so as are to be depressed, and which may to produce the same effect, as a more intense pressure would have done, if it had continued stationary; and the mutual action of the water and the ball may be compared to the impulse of an oblique stream, moving with the velocity of the ball, which would impel it much more powerfully than the simple hydrostatic pressure at a much greater depth. It happens in this case, as in many others, that the effects which appear to be the most familiar to us, do not by any means admit the clearest simplest explanation." the nature of sound is treated, In this part entitled hydronamics, which of course leads to musical instruments, and among them the human throat holds deservedly a speak or sing without the least atdistinguished rank. Many of us tention to the process, by which tertaining a purpose. In the clear we accomplish so useful, or so enmanner in which it is explained in these lectures, no doubt can remain on the subject, as will be seen by reading the following passage. cipally on the vibrations of the mem"The human voice depends prinbranes of the glottis, excited by a current of air, which they alternately intercept and suffer to pass; the sounds being also modified in the r subsequent progress through the mouth. Perhaps the interception of the air by these membranes is only partial; or it may be more or less completely intercepted in sounds of different kinds: the operation of the organs concerned is not indeed perfectly understood, but from a knowledge of their structure we may judge in some measure of the manner in which they are employed. The trachea, or windpipe, conveys the air from the chest, which serves for bellows: hence it enters the larynx, which is principally composed of five elastic cartilages. The lowest of these is the cricoid cartilage, a strong ting, which forms the basis of the rest to this are fixed, before, the thyreoid car. tilage, and behind, the two arytaenoid cartilages, composing together the cavity of the glottis, over which the epiglottis inclines backwards, as it ascends from its origin at the uper part of the thyreoid cartilage. Within the glottis are extended its ligaments, contiguous to each other before, where they are inserted into the thyreoid cartilage, but ca pable of diverging considerably behind whenever the arytaenoid cartilages separate. These ligaments, as they vary their tension, in consequence of the motions of the ary taenoid cartilages, are sus ceptible of vibrations of various frequency, and as they vibrate, produce a continuous sound. Properly speaking, there are two ligaments on each side; but it is not fully understood how they operate; probably one pair only performs the vibration, and the other assists, by means of the little cavity interposed, in enabling the air to act readily on them, and in communicating the vibrations again to the air." In this part are included also optics. We see the propriety of sound entering into this division, but should have hesitated on the pretensions of light, till we considered the definition of a ray, which is an infinitely narrow portion of a stream of light, the pencil being a smail detached stream." This being the case, this subject is a portion only of the doctrine of fluids or hydronamics. The third part treats of physics, in which we have, in eight lectures, the whole of physical and practical astronomy, with its history. The next lecture, which is the forty-ninth lecture, enters upon the investigation of the essential properties of matter, a subject which in general is the first examined by the philcsophers, who have written upon these Sobjects We wore pleased how ever in this lecture to find that the author had spoken with some hesitation on the subject of the divisibility of matter; for assuredly the proofs hitherto given are by no means decisive. They prove only that a line is divisible ad infinitum, but how far this extends to the elements of matter itself, is beyond our powers to determine. We cannot however conceive a stop to the division; for, if we take any piece of matter, and halve it, dividing each half continually into halves, we know that, when the common coarse methods have been tried, skilful mechanics will divide for us, till the particle shall be very minute, and when he has come to the end of these divisions, there remains a particle capable of being halved, if greater powers were applied. If we suppose a succession of superior powers to be applied, still there remains at last a substance, which we cannot conceive to be incapable of being divided into two equal parts, and thus we are under the necessity of confessing an ignorance, which not all the lectures in the world will have the least tendency to remove. Heat, electricity, magnetism, vegetation, and animal life, conclude this part, and the volume, which contains the substance of sixty lectures. The second volume, nearly of equal size with the first, is divided into three parts, the first containing mathematical elements of natural philosophy, the second a catalogue of mathematical books, the third, miscellaneous papers, chiefly those that have been inserted in the philosophical transactions. The first part begins with definitions, and we were much amused by the fifth. A negative quantity is of an opposite nature to a positive one, with respect to addition or subtraction, the condition of its determination be ing such, that it must be subtracted where a positive quantity would be added, and the reverse. Negatie |