Pudiera, podría, pudiese, French at present. The HISTORICAL EDUCATOR is completed, and may be had either in separate numbers or in two volumes. A French Testament may be obtained for about a shilling at almost any second-hand book-shop. There is a small one published "au frais de la Société pour l'impression de la Bible en langue anglaise et en langues étrangères," which may be got second-hand for a shilling. A new one, of a different edition, may be had of Bagster, in Paternoster-row, for about half-a-crown. J. B. The Italian Lessons will be published in a separate form. We are glad they meet our correspondent's approbation. JOHN COULES may find what he wants in our French Readings. NEKWAPIL (Kingston): Foster's Mercantile Arithmetic, published by Law, in Fleet-street, is very good. F. VINER: Decimal fractions differ from other fractions only in always having some power of 10 (that is, 1 followed by a number of 0's) for their denominator. They do not necessarily relate to inches, feet or yards, any more than other fractions or whole numbers. 3 means, and 01 means roo Surely there is no difficulty in understanding this. Though it may be hard to divide an inch into a hundred, a thousand, etc., equal parts, it is just as hard to comprehend distinctly thousands, hundreds of thousands, and millions of inches or anything else. A square inch is a surface one inch long and one inch broad. There is no such thing as a circle inch. The solidity, not the area, of a cylinder is found by multiplying the area of its circular base or section into its height. J. A. D. We quite hoped to introduce the subject you speak of, but fear it is now too late. Pudieras, podrías, pudieses, Pudiera, podría, pudiese, Pudiere, Pudieres, Pudiere, LITERARY NOTICES. COMPLETION OF CASSELL'S LATIN DICTIONARY. Now ready, price 9s. 6d., handsomely bound in cloth, CASSELL'S LATIN DICTIONARY. Pudiéramos, podríamos, pudiése In Two Parts:-1. Latin and English. 2. English and Latin. By J. R. mos, Pudiérais, podríais, pudiéseis, Pudieran, podrían, pudiesen, First Future. Pudiéremos, Pudiéreis, Pudieren, CORRESPONDENCE. THE SABBATH. 'Twas He who in His power and might did call To roll in space, until its crust be storm'd That man might quench his thirst for things divine, And gaze by faith into futurity. O, Sacred Day! around our hearts entwine A virtuous hope for all thy peaceful charms; A hope to cheer and help us on our way, Through fears, distresses, and this world's alarms; A foretaste of that everlasting love, And prove earth's pleasures vain and useless toys. AMICUS. ANSWERS TO CORRESPONDENTS. VOTRE ECOLIER: Your letter in French has given us much satisfaction. It does you great credit, notwithstanding one or two slight blemishes, which are scarcely worth mentioning amid so many excellencies. Though fully aware of the superior character of our Lessons in French, we should hardly have thought it possible for any one to have acquired from them so much knowledge of the idiom of the language as you exhibit, nor would they have been equally productive in everybody's hands. The happy result is as much owing to yourself as to them, and we heartily congratulate you upon it. It is not our intention to publish any additional works in BBARD, D.D., and C. BEARD, B.A. Part I.-LATIN-ENGLISH, price 4s., in paper covers; 5s. cloth. Part II.-ENGLISH-LATIN, price 4s., in paper covers; 5s. cloth. CASSELL'S LATIN GRAMMAR. By Professors E. A. ANDREWS and S. STODDARD. Revised and Corrected. Price 3s. 6d. in cloth boards. CASSELL'S SHILLING EDITION OF FIRST LESSONS IN LATIN. By Professors E. A. ANDREWS and S. STODDARD. Revised and Corrected. Price Is. paper covers, or 1s. 6d. neat cloth. CASSELL'S LESSONS IN LATIN.-Price 2s. 6d. paper covers, or 3s. neat cloth. A KEY TO CASSELL'S LESSONS IN LATIN. Containing Translations of all the Exercises. Price 1s. paper covers, or 1s. 6d. cloth. CASSELL'S CLASSICAL LIBRARY.-The First Volume of this Work, price 1s. d. cloth, consists of a LATIN READER, adapted to "Cassell's First Lessons in Latin."-Volume II. comprises LATIN EXERCISES, price 2s. neat cloth.-Volume 111. contains THE ACTS OF THE APOSTLES in the Original Greek, with copious Notes and a Lexicon, price 2s. 6d. neat cloth. Now ready, price 9s. 6d. strongly bound, CASSELL'S FRENCH AND ENGLISH DICTIONARY: Composed from the French Dictionaries of the French Academy, Bescherelle, Landais, etc.; from the English Dictionaries of Ogilvie, Johnson, Webster, etc.; and from the Technological and Scientific Dictionaries of both Languages. By Professor DE LOLME and HENRY BRIDGEMAN, Esq. The following are the distinctive features which render this Work superior to any of the same class now extant. It has been compiled with unusual care from the very best authorities. It contains correct renderings of all the most modern words and phrases-including those of science, art, manufacture, commerce, law, politics, etc., as well as tamiliar conversation -which are indispensable to a knowledge of language, but yet are rarely, if ever, to be found properly translated in any Dictionary. The idiomatic usages of the two languages-the constructions of verbs, the force of prepositions, and the changes of meaning caused by different combinations of words-are more copiously and carefully illustrated than elsewhere within the same limits. The meanings are also classified and arranged in such a manner as to prevent the possibility of mistake. To crown all, the Work is as moderate in price as it is comprehensive in aim, accurate in detail, and superior in arrangement.-The French-English Division, price 4s. paper covers, or 5s. neat cloth; the English-French Division, price 48. paper covers, or 5 strongly bound. A SERIES OF LESSONS IN FRENCH, on an entirely Novel and Simple Plan. Reprinted in a revised form from "The Working Man's Friend." Price 6d., by post 7d. Above 30,000 copies of this work have been sold. CASSELL'S GERMAN PRONOUNCING DICTIONARY, In Two Parts:-1. German and English; 2. English and German. In one large handsome Octavo Volume, price 93. cloth. The German-Englan German Division, 3s. 6d. paper cavers, or strongly bound in cloth, 4s The imperative is inserted merely to exhibit the form, there being, in Division, price 5s. in paper covers, or 5s. 6d. neat cloth; the Englishfact, no imperative of poder in use ON PHYSICS, OR NATURAL PHILOSOPHY. No. LXX. (Continued from page 668.) DYNAMICAL ELECTRICITY. PHENOMENA OF INDUCTION. Effects of Tension produced by Currents of Induction.-M. Ruhmkorff has lately constructed some very powerful bobbins, by means of which not only violent shocks may be produced by currents of induction, but also luminous effects very strongly resembling those of electrical machines of strong tension. This apparatus consists of a strong bobbin B (fig. 465), placed vertically upon a thick plate of glass, which isolates it. The bobbin, which is about six inches high, is formed of two wires-one thick, about one-twelfth of an inch in diameter, and making three hundred turns; the other fine, being only about-an eightieth of an inch in diameter, and rolled round the former ten thousand times. These wires are not only covered with silk, but each coil is isolated from the next by a layer of gum-lac varnish. It is the thick wire which is the inductor. The current which passes through it is simply that of a Bunsen battery. The positive pole of the battery being in connexion with the wire PH, the current passes through the conductor c to a cylinder G; thence it descends by a metallic part g, and reaches a copper plate F, which conducts Fig. 465. duced in the thin wire. Now this latter being completely isolated, the induced current acquires so great a tension that it is capable of producing very intense luminous effects. For this purpose, the two ends of the fine wire, qy and px, which come out from beneath the glass plate, are connected with the two rods attached to a globe M, such as has been already described under the title of the electrical egg, and is employed to observe the luminous effects of an electrical machine in a vacuum. Having produced a vacuum in the globe, a beautiful luminous trail is produced from one end to the other, apparently unbroken, and of the same intensity as is obtained with a powerful electrical machine, the plate of which is turned rapidly. It is the positive pole of the induced current which exhibits most brightness. Its light is red, while that of the negative pole is feeble and of a violet colour, and extends throughout the whole length of the negative rod, a phenomenon which does not take place at the positive pole. Messrs. Masson and Breguet made the first experiment to show that a bobbin of induction is capable of producing the physiological effects of the Leyden jar; but it was M. Ruhmkorff who first, having completely isolated the induced current by means of the above bobbin, was enabled to obtain from it electricity of any tension, and to produce effects of light such as have just been described. Stratification of Electric Light.-In studying the electric light obtained from M. Ruhmkorff's bobbin of induction, M. Quet has lately observed, that if we do not produce a Fig. 466. it to one of the extremities v of the thick wire of the bobbin. The other end of the wire terminating at i, in one of the copper supports of the glass plate, the current, on leaving the bobbin, proceeds to a second plate c, whence it ascends in an iron column A. There the current reaches an oscillating hammer a (fig. 466), which is sometimes in contact with a conductor n, and sometimes separated from it. When contact takes place, the current proceeds along the conductors n and E (fig. 465), as shown by the arrows, ascends into the cylinder G, and thence returns to the battery along the conductor d and the wire Q. vacuum in the globe м (fig. 466), till after having introduced into it essence of turpentine, spirits of wine, etc., the appearance of the light is completely altered. It then appears under the form of a series of zones, alternately bright and dark, forming a sort of pile of electric light between the two poles (fig. 467). In this experiment, it follows, from the discontinuity of the current of induction, that the light is not continuous, but consists of a series of discharges nearer to each other, in proportion as the hammer a (fig. 466) oscillates more rapidly. The luminous zones then appear affected with a rapid doublerevolving and undulatory motion. M. Quet considers this motion as an optical illusion, because, if the hammer be made to oscillate slowly with the hand, the zones appear very dis With regard to the motion of the hammer a backwards and forwards, that is produced by a soft iron cylinder ro, placed in the axis of the bobbin. When the current of the battery passes along the thick wire of the bobbin, this iron is mag-tinct and fixed; but the phenomenon is then too instantaneous netised, and draws up the hammer a-which is also iron from below. The current then being interrupted, since it connot pass through the part n, the cylinder or loses its magnetic properties, and the hammer a falls down again. At this moment the current recommences, the hammer a is again raised, and so on continually. As the current of the battery passes thus interruptedly along the thick wire of the bobbin, at each interruption a current of induction, successively direct and inverse, is pro VOL. V. to allow the undulations to be perceived, if there are any. The light of the positive pole is, as we have said, generally red, and that of the negative pole violet; but the colour varies with the vapour or gas which is in the globe. M. Despretz has lately observed that the phenomena established by Messrs. Ruhmkorff and Quet with a discontinuous current may be produced with an ordinary continuous current, but with this important difference, that the continuous current requires a great number of Bungen couples, while the 148 discontinuous current of M. Ruhmkorff's bobbin requires only one. It is a remarkable fact, established by experiment, that the intensity of the effects of this bobbin increases very little when the number of Bunsen couples is increased, Fig. 467. The theory of the phenomena of the stratification of electric light in vapours, and the colouring of the poles, is not yet ascertained satisfactorily. Characters of Currents of Induction. - From the various experiments upon currents of induction to which we have called the reader's attention, we see that, in spite of their instantaneous duration, they possess all the properties of ordinary voltaic currents. Like them, they produce violent physiological, luminous, calorific, and chemical effects, and themselves give rise to fresh induced currents. Lastly, they deflect the needle of galvanometers and magnetise steel bars, when they are passed along a copper wire wound round these bars in the form of a helix (fig. 452). The shock of induced currents is much more intense than that of hydro-electric currents. The latter, indeed, do not give any shock except with a large number of couples, while a single Bunsen couple, with the bobbin, above described (figs. 456 and 461), produces induced currents, the shock of which is insupportable and even dangerous when prolonged. The shock is entirely owing to the direct current, that is to say, to that which is produced when the current in the inducing wire is interrupted. The intensity of the shock of induced currents renders their effects like that of electricity in a state of tension. However, as they always act upon the galvanometer, it is probable that in the wires subjected to induction, there is electricity both in a state of tension and in a dynamical state. The direct and inverse induced currents have been compared together in three points of view: the violence of the shock, the magnitude of the deflection in the galvanometer, and the magnetising action upon steel bars. Thus examined, these currents exhibit very different results. They appear nearly equal in respect of the deflection of the galvanometer, while the shock of the direct current being very violent, that of the inverse current is almost imperceptible. There is the same difference with regard to the magnetising power. The direct current magnetises powerfully, but the inverse current does not magnetise at all. PRACTICAL APPLICATIONS OF THE GALVANIC Electric Telegraphs.-We now come to a subject in which all are interested, and with which all are in some degree familiar, though comparatively few understand it thoroughly. Of all the scientific marvels wrought in this remarkable century, there is none more astounding than the electric telegraph, which enables us to convey communications to persons hundreds of miles off with all the rapidity of the lightning flash, whether they be in the same country or separated from us by miles of ocean waves. This achievement eclipses all the wonders accomplished by the application of steam, and is in itself sufficient to render the present century for ever memorable in the annals of our race. Electric telegraphs, we need scarcely say, are apparatus which serve for the transmission of messages to great distances, by means of voltaic currents along metallic wires. Even last century, philosophers had entertained the idea of corresponding at great distances by means of the effects produced by the electricity of electrical machines, and propagated along conducting wires. In 1814, Sommering invented a telegraph based upon the decomposition of water by the battery, which he employed as a means of indicating signals. In 1820, at a time when the electro-magnet was not known, Ampère, guided by Ersted's experiment, proposed to correspond by means of magnetised needles, above which a current was directed, employing as many needles and as many wires as there are letters in the alphabet. In 1837, M. Steinheil, at Munich, and Professor Wheatstone, in London, constructed telegraphs with several wires, each acting upon a magnetised needle, the source of the current being a Clarke's electro-magnetic apparatus, or a hydro-electrical battery. But the telegraph could not be made simple enough, till Professor Wheatstone, in 1840, introduced the use of electro-magnets. Without altering the principle of the electric telegraph, its form has been much changed; but all the forms may be referred to three classes-the dial telegraph, the signal telegraph, and the writing telegraph. We proceed to give some account of each of these varieties. The Dial Telegraph.-There are several sorts of dial tele graphs. That which is represented in figs. 468 and 469 was constructed by M. Froment, and our drawings were made in June, 1850. M. Froment's telegraph is the same in principle as those employed on railways. Like them, it consists of two distinct apparatus, one called the manipulator, for transmitting signals, and the other the receiver, for receiving signals. The former is connected with a carbon pile or battery a, and the two apparatus are connected together by means of two metallic wires, either iron or copper, the former of which goes from the starting-point to the distant station, and the latter from the distant station to the point of departure. Lastly, each apparatus is furnished with a dial containing twenty-four letters, and a needle moveable upon the dial. It is the experimenter's hand which moves the needle at the point of departure, but it is the electricity which turns that at the distant station. The following is the course of the current in the two apparatus and the effects which it produces. From the battery it proceeds along a copper wire A (fig. 468) to a piece of brass N in contact with a metallic wheel R, passes into a second piece M, and then into the wire o, which joins the other station. There the current goes into the bobbin of an electro-magnet b, concealed in fig. 469, but represented in profile in fig. 470, Fig. 470. T mits it to a ratchet-wheel a, the axis of which carries the indi- From what has been stated, it is easy to understand how correspondence is carried on from one place to another at a distance. Suppose, for example, the first apparatus (fig. 465) to be in London, and the second (fig. 469) at Birmingham, and the communication between the two stations being established by means of wires, we wish to transmit from London to Birmingham the word signal. The needles of the two apparatus being both at the interval between A and Z, the person who sends the despatch moves forward the needle r to the letter S, where it stops for a very short time; the needle of the apparatus at Birmingham, faithfully following the movements of the needle in London, stops at the same letter, and then the person who receives the despatch marks this letter. He who is in London, continuing to turn the needle always in the same direction, stops the needle at the letter I, and the other needle instantly stops at the same letter. Proceeding in the same manner for the letters G NA L, the whole word is soon transmitted to Birmingham. To call the attention of the person to whom we are about to make a communication, a bell is fitted up at the distant station, and is connected with the current whenever the correspondence is suspended. A trigger, moved by the electromagnet, rings this bell directly the current passes, and thus gives a signal that a message is about to be communicated. Further, each station ought to be provided with the two apparatus above described (figs. 468 and 469), otherwise it will be impossible to return an answer. We have supposed that the current which goes from London to Birmingham returns in the same way from Birmingham to London. But this second wire is useless. Experience has shown that, if the positive pole in London is connected with the apparatus, and the negative pole with the earth, it is sufficient for the conducting wire which goes to Birmingham to be there connected with the earth. It is generaly believed that the circuit is then closed by the earth through which the current returns from Birmingham to London. This hypothesis has been severely criticised by some philosophers, particularly by the Abbé Moigno, in his treatise on the electric telegraph. And indeed it is difficult to conceive that, on its arrival at Birmingham, the current, which by its nature tends to disperse in all directions, should choose precisely that which takes it back to the battery whence it started. M. Moigno considers that the earth, acting in this case as a reservoir, absorbs at the two ends of the wires the electricity which the battery transmits, and the consequence is, that there is the game continuous current in the wire as if the two ends touched each other. which shows the hinder part of the apparatus. This electromagnet is fixed horizontally at one of its extremities, and by the other it attracts a soft iron armature a, which forms part of a bent lever moveable about its point of support o, while a coiled spring tends to move the lever in the contrary direction. When the current passes, the electro-magnet attracts the lever a c, which, by means of a rod i, acts upon a second lever d fixed to a horizontal axis, which is itself attached to a fork F. When the current is interrupted, the spring draws back the L'objet de la science est de connaître la vérité; son occupation, de lever a c, and with it all the parts of the apparatus depending la rechercher; son caractère, de l'aimer: les moyens de l'acquérir sont The result of this is a motion backwards and de renoncer aux passions, de fuir la dissipation et l'oisiveté.-J. J upon it. forwards, which is communicated to the fork P, which trans-Rousseau. BIOGRAPHY.-No. XXI. GOLDSMITH. BY J. R. BEARD, D.D. OLIVER GOLDSMITH is one of the few pets of literature. Having failings and faults neither few nor small, he is always regarded with interest, and spoken of with pity rather than blame. If this charity resulted from gratitude for the instruction and pleasure conveyed in his writings, we should regard it as a sort of allowable offset paid by gratitude. But we fear the sentiment is allied to a toleration of the kind of errors of which Goldsmith was guilty, and which made the plague of his existence. Improvidence and moral infirmity are defects of character too serious to be glossed over even by qualities as amiable as the better points in Goldsmith's life. Perhaps the existence of such goodness ought to make the moral censor the more rigid, because it is great excellence which those evil habits tarnish or almost destroy. Nor is it possible to think of the numerous and severe penalties which Goldsmith's faults inflicted on him without combining detestation of the sin with commiseration for the sinned. Amiable Goldsmith always was; but for his want of forethought and moral fortitude, he would have been pre-eminently good and great. Goldsmith, distinguished alike in prose and poetry, was born on the 10th of November, 1728, in the county of Longford, Ireland, of whose sons, in their want of thrift and their superabundance of buoyancy, he is no unfit representative. His father, a clergyman, desirous that his son should follow his own profession, sent him to the university of Dublin, a relative bearing the cost (1745). A life of trouble began with bickerings. Goldsmith fell out with his tutor, to whom he was reconciled by his brother. With a wandering disposition, he bethought him of emigrating to America, but, destined to miss all his days, he missed his passage. He had no resource but to return to the parental roof. Theology having been abandoned, he thence proceeded to Edinburgh in order to study medicine. For the same purpose he repaired to the university of Leyden. The way back was not easy, for his money was all spent. However he had a flute, and he could play thereon. With this resource he passed through Flanders, France and Germany into Switzerland, where he wrote a part of his poem, "The Traveller." In Geneva he had the good fortune to be made tutor to a young Englishman. Leaving his pupil at Marseilles, he turned his steps to Padua, in whose university he graduated as doctor of medicine. In the year 1756 he returned to England, and under the pressure of want took an ushership in a school at Peckham, and then became a druggist's assistant. At length, encouraged by a college friend, he offered his services as a physician in London. Without practice and without money, he connected himself with "The Monthly Review," and so began a literary career out of which he was to gather an uncertain subsistence and an andying renown. He began his new mode of life with his Enquiry into the Present State of Taste and Literature in Europe" (1759), a wide subject for a young man, and a difficult one for an unpractised pen. Among other less considerable compositions, he published in "The Public Ledger" his Chinese letters, under the title of "The Citizen of the World" (1762). About the same time he finished "The Traveller" (1765), which was followed by the "Letters on English History" (1765), and his delightful "Vicar of Wakefield," (1766). The next year appeared his first theatrical piece, "The Goodnatured Man." Then came that sweet poem, "The Deserted Village" (1770), as full of bad philosophy as it is of good sentiment. Very readable compilations, entitled, "A History of England" (1772), a "Roman History," a "History of Greece," and a "History of the Earth and Animated Nature" (1774), were prepared for the booksellers. Meanwhile he had put forth (1773) his second and still popular play, "She stoops to conquer" (alas! poor Noll stooped but did not conquer; how different the result, had he resolved to conquer without stooping!) These productions were a heavy tax on a frame never very robust. Yet more serious labours were in contemplation. He was engaged with the plan of a general Dictionary of Art and Science, when he was relieved from his load by the hand of death (4th of April, 1774). The prize among his prose writings at least belongs to the "Vicar of Wakefield," a tale which, notwithstanding what critics have said, has become a favourite with the civilised world. Washington Irving, who published an edition of Goldsmith's "Miscellaneous Works," has written a charming sketch of his life. The rich materials accumulated by Prior in his "Life of Oliver Goldsmith" (1837), have been wrought into an admirable biography by Forster, in "The Life and Adventures of Oliver Goldsmith" (1848). Of neither the man nor the author can extracts give any adequate ideas. Yet we can only ask attention to what ensues. THE VILLAGE INN. Near yonder thorn that lifts its head on high, The parlour splendours of that festive place; No more the farmer's news, the barber's tale, Yes! let the rich deride, the proud disdain, Ye friends to truth, ye statesmen who survey |