They have refused him that favour. John has refused me that favour. I have found my treasures. Has the post3 arrived1? We have found the spoons. Hast-thou travelled through Spain? Have-ye refused them that favour? Have you (vmd.) not eaten bread? I have eaten much bread. I have kept (cumplido) my word. They have fulfilled their word. Has the judges arrived1? Have you (vms.) found1 my lamps? Hast thou eaten much honey? Have you2 (vmd.) travelled' through the United States? Till then ye-had spoken Spanish. Till then we-had not terminated our business (plur.). They-had already1 eaten3 when we arrived. Hadst-thou not already lived1 in London? Till then they had lived in peace. When I-had found the treasure, I wrote letters to my friends. When thou-hadst dined, thy father arrived. When we-had spoken, our sisters wept. I-shall travel through Spain. We-shall-travel through FRENCH READING S.-No. XXXIV. EUDOXIE. SECTION IV. Les informations sur le général furent faciles à prendre. Quand M. Offenheim fut tout à fait en règle de ce côté, il appela Eudoxie et lui révéla le grand secret.2-Si vous ne vous sentez pas d'éloignement pour le général, mon enfant,3 c'est une chose faite. -Ah! Monsieur....mon bon oncle, mon père. C'est tout ce que puts, articuler Eudoxie. .... Puis, après un moment de silence, elle ajouta: Mais tant de gloire et de bonheur ne vaut pas la douEngland. He-will find a treasure. I-shall-eat bread. They- ceur de rester près de vous; je ne puis rompre cette will-eat apples. Thou-wilt-read those books. We-shall-habitude de mon cœur.... il m'est impossible de vous fulfil our words. They-will-write letters. My male-servant quitter, même pour une félicité dont je sens tout le will-carry the letters to the post. I-shall-have dined at two o'clock. They-will-have arrived at three o'clock. The post prix. will-have-arrived at two o'clock. 6 11 -Mon enfant, reprit le vieillard, votre piété filiale et Weep-ye with those who weep. Eat-ye this bread. Fulfil- ingénieuse, a instruit ceux qui m'entourent, de tous les ye your promises (palabras). Drink-ye water. Live-ye in soins que demande ma pauvre existence. Vous avez de peace with all men. Speak-thou loud (alto). Weep thou bons élèves ici, je vous assure, je m'en contenterai fort with those who weep. Eat thou with me. Eat thou with bien. Et d'ailleurs, si je voulais ce mariage, si je vous Peter. Fulfil thy duties. Let John speak loud. Let Mary | l'ordonnais9.. read my letters. Let the ladies read those books. Let men fulfil their duties. Read (vmd.) this letter. Speak Spanish Oui....et ne vous facheze pas. -Je vous désobéirais, mon père 10 répliqua Eudoxie. (let your-worship speak Spanish). Eat (vmd.) some apples fut près de mourir, elle nous fit jurer, à ma sœur et à moi, Quand ma bonne tante and pears. Read (vms.) that letter. Do not speak of this. Do not read this book. Do not drink (sing.) wine. Weep-ye de ne pas vous quitter.12 Ce serment, qui était d'avance en nous léguant nos dots, de ne nous marier qu'à la condition not. Answer-ye me. Write-ye to them. Write-thou to us. It-is possible that thou-mayest-find a treasure. It-is possible écrit dans mon cœur fut bien vite sur mes lèvres.13 Vous ne that they-may-read those books. It-is probable that they-voudriez pas me rendre parjure et malheureuse. may not fulfil their duties. It-is probable that she may not -Eh bien reprit encore M. Offenheim, vous answer him. O-that ye-may-find repose! marierez et vous ne me quitterez pas.14 Je vous suivrai en France, dans votre ménage Qu'avez vous à dire maintenant? If I should-find books, I would-read them. If Mary should-weep, John would-weep. O-that they would not drink wine! O-that he would not weep! O-that men would-fulfil their duties! It-was (era) necessary that Mary should not speak loud (alto). Is-it possible that they have not found a treasure? It-is possible that he-may not have arrived. O-that I had not (might not have) spoken! It-was (era) strange that theyshould not have found those books. If John had not (should not have) spoken, Mary would not have wept. If Peter3 should-arrive to-morrow,1 I-will-write to-thee. If they (shall) find a treasure to-morrow, they-will-write to-us. If James has not (say, shall not have) arrived to-morrow at three o'clock, we will write him a letter. Permit me to-read that book. Will you (vmd.) permit me to read that letter? It-was necessary to-speak to-them. John pretends not to-have spoken. They-were (estaban) eating and drinking. Having found a book, I am reading it. Remark. In order to become thoroughly familiar with the conjugation of the regular verbs, the student should write and re-write all the persons of the various moods and tenses (as before directed), until he finds himself able to write them without referring to the model verbs. He must be careful to remember the changes in orthography sometimes required. .... Vous The following verbs, together with those already given in the vocabulary of this lesson, will serve as examples for prac-6. tice : 7. Querépondit l'excellent vieil- 8. Que dit-il à l'égard des élèves 9. Que dit-il du mariage? 10. Quelle fut la réponse de la jeune fille? 11. Que dit-elle de sa tante? 14. Que répondit l'oncle? 16. Que fit alors Eudoxie? 18. Que fit enfin Thécla? NOTES AND REFERENCES.- --a. prendre, make.-b. en règle, satisfied-c. from pouvoir; L. part ii., p. 98.-d. ne vaut pas, is not equal to; from valoir; L. part ii., p. 108.-e. L. S. 39, R. 4 -f. spirituel, witty.-g. from accroître; L. part ii., p. 76. LE VAISSEAU EN PE'RIL. UN vaisseau tourmenté par de longs ouragans, Ne reconnaissait plus la voix du capitaine.3 Tous veulent commander; nul ne veut obéir ;5 De ce désordre innocentes victimes, Ce malheur éteint-il la rage des partis? Non, non; de leur ruine, ils s'accusent l'un l'autre ;14 La dispute redouble; on n'entend que ces cris: -C'est ta faute.-Non, c'est la vôtre.15 -C'est vous.-C'est toi qui nous perdis. --C'est la faute de tous, répond le capitaine, Dont la voix, libre enfin, domine les clameurs. C'est votre vanité qui fit tous vos malheurs.17 De vos divisions vous subissez la peine. Un dernier craquement retentit à ces mots ;18 Le pont' s'était ouvert sous la vague en furie, Un dernier cri s'élève, et l'abîme des flots Se referme en grondant sur la nef engloutie.19 Je ne sais point sous quels climats Ni sous quel nom naviguait ce navire;20 Mais, vous qui me lisez,s vous pourriez me le dire Et, si vous m'en croyez, vous ne l'oublierez pas.21 VIENNET. Que devint le navire pendant le désordre? 13. Qu'est-ce qui répond aux mugissements des vagues et de la tempête? 14. Cet accident éteignit-il la rage de l'équipage? 15. Que se dit l'équipage? 16. Que répondit alors le capitaine? 17. Que dit-il de la vanité de ses gens? 18. Qu'arriva-t-il à ces mots? 19. Que devint le malheureux vaisseau ? 20. Que dit le poète en conclusion? 21. Quel avis donne-t-il a ses lecteurs? NOTES AND REFERENCES.--a. la discorde en son sein, internal discord.-b. avis, opinion.-c. mettra bientôt d'accord et vain queurs et vaincus, will soon reconcile conquerors and conquered, -d. from éteindre; L. part ii., p. 90.--e. L. S. 80, R. 2.--f. pout, deck.-g. from lire; L. part ii., p. 94. ANSWERS TO CORRESPONDENTS. W. BUTTS: A knowledge of English grammar is highly desirable, if not absolutely necessary, before studying phonetic short-hand, or, indeed, any. thing else. W. C. INGLIS: The Lessons in Chemistry are closed. JEUNE HOMME: There is no separate rule for ascertaining the interest of a sum of money by decimals, beyond reducing the rate per cent. to a decimal and multiplying the principal by it. Thus to find the interest of £12 for one year at 5 per cent., inultiply £42 by 05 (which is equal to 5 100' or 5 per cent.), and the product £2-10, or £2 28., is the interest required. If the principal contains shillings, pence, and farthings, or the time months and days, reduce them to the form of a decimal, and work according to the rules already given in the lessons. HAMLET: Apply to Messrs. Horne, Thornthwaite and Co., Newgate street. WILLIAM TALBOT: Liddell and Scott's School Greek Lexicon is the best for your purpose. G. Z. M. will find commercial terms explained in Cassell's French Dic tionary. We are obliged to him for his suggestion, but cannot promise to adopt it. W. R. T.: We have repeatedly expressed our regret at the impossibility of treating upon the subject of Hebrew. J. J. BROWNE: Read Voltaire's History of Charles XII., which may be obtained in a cheap form for about a shilling or fifteen-pence. LITERARY NOTICES. COMPLETION OF CASSELL'S LATIN DICTIONARY. CASSELL'S LATIN DICTIONARY. In Two Parts:-1. Latin and English. 2. English and Latin. By J. R. Part I.-LATIN-ENGLISH, price 48., in paper covers; 5s, cloth. CASSELL'S GERMAN PRONOUNCING DICTIONARY. In Two Parts:-1. German and English; 2. English and German. Ia one large handsome Octavo Volume, price 93. cloth. The German-English Division, price 5. in paper covers, or 53. 6d. neat cloth; the EnglishGerman Division, 3s. 6d. paper covers, or strongly bound in cloth, is. CASSELL'S LESSONS IN GERMAN. Parts I. and II.-Price 2s. each in paper covers, or 2s. 6d. in cloth. Two Parts bound together, price 4s. 6d. CASSELL'S ECLECTIC GERMAN READER: containing choice Selections from the best German Authors, in Prose and Verse. Price 2. paper covers, or 2s. 6d. cloth. CASSELL'S LESSONS IN GERMAN PRONUNCIATION: consisting of easy Extracts from German Writers. Price is. paper covers, or 1s. 6d. cloth. A Key to the above Lessons is now ready. Now ready, price 9s. 6d. strongly bound. CASSELL'S FRENCH AND ENGLISH DICTIONARY: Landais, etc.; from the English Dictionaries of Ogilvie, Johnson, Webster, Composed from the French Dictionaries of the French Academy, Bescherelle, 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, manufac ture, commerce, law, politics, etc., as well as familiar conversation-which are indispensable to a knowledge of language, but yet are rarely, if ever, to the two languages-the constructions of verbs, the force of prepositions, and be found properly translated in any Dictionary. The idiomatic usages of the changes of meaning caused by different combinations of words-are limits. The meanings are also classified and arranged in such a manner t more coplously and carefully illustrated than elsewhere within the same 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, orbs. neat cloth; the English-French Division, price is. paper covers, or strongly bound. ON PHYSICS, OR NATURAL PHILOSOPHY. No. LXVIII. (Continued from page 635.) ELECTRO-MAGNETISM. WHIE the investigations mentioned in our last lesson were going on in America, Professor Moll, of Utrecht, made some experiments with one of Mr. Sturgeon's electro-magnets, which he procured from Mr. Watkins of London, the object of which was, to try the mechanical effect of using powerful single batteries. With a battery presenting a zinc surface of 11 square feet, the magnet lifted 75 pounds; but a battery of 17 feet, and also one of very great size, gave no increase of magnetic power. He then sought to produce greater effects by using a horseshoe 12 inches high and 2 inches in diameter, which lifted 154 pounds with the same battery. But that he had no idea of the effect of increasing the number of spires of the magnetising helix, is evident from the fact that he wound the latter magnet with only 44 turns of uncovered wire, while the number of similar spires on the smaller magnets was 83, or nearly twice as many. Professor Moll, however, particularly observed the instantaneous destruction and reproduction of magnetism, which takes place when the current is reversed, by changing the netic induction, Professor Henry was enabled to make soft iron magnets of wonderful power. One, in the cabinet of Yale College, weighing 59 pounds (exclusive of the copper wire round it), was formed of a bar of iron 3 inches square and 30 inches long. It was wound with 26 strands of copper bell-wire covered with cotton-thread, and 31 feet long. About 18 inches of the ends were left projecting, so that only 28 feet actually surrounded the iron; the aggregate length of the coils was, therefore, 728 feet. Each strand was wound on a little less than an inch; in the middle of the horse-shoe the wire formed three thicknesses, and on the ends, or near the poles, it was wound so as to form six thicknesses. This magnet supported 2,063 pounds, or nearly a ton, with a battery exposing a zinc surface of nearly five square feet. The effect of a larger battery was not then tried. Another, and the largest of these magnets, constructed by Professor Henry, is in the cabinet of the College of New Jersey, and the following is his description of it :-It is formed of a bar of rounded iron, nearly four inches in diameter, weighing about 100 pounds, and surrounded with 30 strands of copper bell-wire, each about 40 feet long. With a calorimeter on Dr. Hare's plan, consisting of 22 plates of zinc, each 9 inches by 12, alternating with plates of copper of the same size, it supports 3,500 pounds, or more than a ton and a half. After the connection with the battery is broken, this magnet supports a thousand pounds for several minutes; and from year to year the lifter adheres with a force which is overcome only by a weight of several hundred pounds. When connection of each end of the helix from one pole of the battery to the other. This prompt action of the magnet is essential to the usefulness of the electro-magnetic telegraph, and on that account the same fact has since been investigated by other philosophers. the lifter, however, is detached, nearly all the magnetism disappears. It is evident that, by increasing the size of the iron bar, the number of the coils, and the power of the battery, the magnetic power may be almost indefinitely extended. As the claims of Professor Moll have been asserted to the That a force of such great intensity may be applied to the prejudice of Professor Henry's, it may here be remarked, that production of mechanical effects, is an idea which would the former employed one of Mr. Sturgeon's magnets, pur- naturally arise in any mind; and that Professor Henry should, chased of Mr. Watkins, and only thought of increasing the therefore, have been the first to attempt such an application, size of the horse-shoe, when he failed to obtain any greater is almost a consequence of his previous researches. In an development of magnetism by using much larger and more American periodical for 1831, he described a machine for propowerful batteries. Professor Henry, on the contrary, ducing a reciprocating motion "by a power never before thoroughly investigated the effects of varying the quantity applied in mechanics-by magnetic attraction and repulsion." and intensity of the battery-current, the size and form of Of which he remarks: "Not much importance, however, is the horse-shoe, the number of spires of the helix, and the attached to the invention, since the article, in its present state, resistance of the conducting-wires. The experiments of Pro- can only be considered a philosophical toy; although, in the fessor Moll were very incomplete; and though they were pub-progress of discovery and invention, it is not impossible that lished shortly before the researches of Professor Henry, yet the same principle, or some modification of it on a more the latter had discovered in 1828, and exhibited to the Albany extended scale, may hereafter be applied to some useful Institute in 1829 (two years previously), the fact that the cur- purpose.' rent of a small galvanic element passed through a wire covered with silk, and wound 400 times round a horse-shoe of soft iron, rendered it more powerfully magnetic than a similar horseshoe wrapped loosely with a few turus of an uncovered wire, and excited by a battery of 28 plates of copper and zinc, each eight inches square. Having fully investigated the phenomena of electro-mag VOL. V. The next person who contrived a modification of the abovedescribed electro-magnetic machine, was Professor Ritchie, of the London University, who published an account of it, in 1833, in the "Transactions of the Royal Society." In 1834, Mr. Davenport, an ingenious blacksmith of the American State of Vermont, having seen a powerful electromagnet, contrived a machine upon the same principle, which 146 was exhibited in the principal cities of the United States, but res.. ei in no useful or valuable application, though an Att was made to drive a prin ing-press with it. port, K. The current of a Bunsen battery, with ten or éleven couples, enters at A, passes along to a cylinder, H, and thence to the bobbins, M, whence it goes along the wire g to 5, descends along the wire i, again reaches the cylinder a, and goes out at B. The two soft iron cylinders, s and a, which apertures, to allow the luminous rays to pass through. Lastly, at 6 and a are two Nicol prisms, the former serving as polariser, the latter as analyser. The latter is made to revolve at the centre of a graduated circle, P. Or in re recent attempts to apply this power, we may menti : one made on the Edinburgh and Glasgow Railway, by Mr. Davidson, who constructed an electro-magnetic locomo-form the axes of the bobbins, are pierced with cylindrical ve, 16 feet long, 6 feet broad, and weighing 5 tons; and another, by Professor Jacobi, of St. Petersburg, at the expense of the Russian government. That of Mr. Davidson failed to propel the engine alone more rapidly than 4 miles an hour; but Professor Jacobi propelled a boat 28 feet by 7 feet, drawing 2 feet of water, at the rate of three miles an hour against the stream, with a party of about a dozen persons on cart. It is evidently possible, when we possess a source of mechanical power, to accumulate it, either by employing one very large engine, or a number of smaller ones. The question Whether electro-magnetic forces can be rendered practically asefal, depends not, therefore, so much upon the amount of power required, as upon considerations of economy. Water and fuel are found everywhere in nature in the greatest abundance, while zinc and acids are manufactured articles of Comparatively high cost. An engine which consumes such substances in large quantity cannot, therefore, be employed with profit in competition with steam. And this conclusion, based upon theoretical reasons, is fully confirmed by experiDents with such machines. It should also be borne in mind, in estimating the effective These two prisms being arranged in such a manner that their principal sections may be perpendicular to each other, the prism a completely extinguishes the light passed through the prism b. If you then put a piece of flint or glass with parallel surfaces at e on the axis of the two bobbins, the light is still extinguished as long as the current does not pass; but directly the communications are established, the light reap pears, but coloured, and if the analyser a is turned to the right or the left, according to the direction of the current, the light exhibits the various colours of the spectrum, as is the case with plates of quartz cut perpendicularly to the axis. M. E. Be querel has shown that a great number of solid and liquid substances are thus capable of deflecting the plane of polarisation under the influence of powerful magnets. Mr. Faraday considers that, in these experiments, the rotation of the plane of polarisation is owing to an action of the magnets upon the luminous rays. Messrs. Birt and E. Becquerel think the phenomenon is owing to an action of the magnets upon the Fig. 458. www sb.re, that the armature or lifter of a ayout your aer connection with the battery is T pete ferful Electro-magnets-Professor Faraday, *that* powerful electro-magnet exercises he with everal transparent substances, that if 4 thigh them in the direction of the line , ine plane of polarisation is deflected to #is, whading to the direction of the mag• Perdana Faraday is represented in fig. maly powerful electro-magnets, town slides, o and o', which are vaste of hight heat each other by sliding on a sup transparent bodies brought under their influence-an hypothesis generally admitted. Effects of Diamagnetism produced by powerful Electro-Magnets. -Professor Faraday's apparatus serves also to exhibit other very remarkable effects of powerful magnets. We will describe a few experiments which require soft iron armatures, s and of various forms (figs. 456, 457, 458) to be screwed on to the bobbins. 1. M. Bancalari first observed that on placing the flame of s candle between the two magnets, it is repelled, fig. 456. Professor Faraday having found that oxygen, which is magnetic at an ordinary temperature, becomes diamagnetic at the temperature of flame, the repulsion thus exhibited may be explained by the mere repulsion to which the air is subjected; an explanation analogous to that given of the repulsion of flame by electrical machines. 2. If a small cube of red copper be hung between two magnets by a twisted silk thread, fig. 457, and be allowed to revolve rapidly by untwisting itself, it will stop directly the current passes through the bobbins, and remain fixed in its position. If instead of a cube a small rectangular bar is substituted, it will come into a position at right angles with the axis of the bobbins, or in a line with it, according as is made of a diamagnetic substance, as bismuth and antimony or a magnetic substance, as iron, nickel, or cobalt. Professor Faraday, who first observed these phenomena, attributes them to currents of induction which are developed in bodies by the influence of magnets. 3. M. Plücker, having placed a solution of chloride of in a watch-glass, fig. 458, observed that, according to the distance of the bobbins, the solution formed one or two swell ings, as represented at A and B. The curvature of the Squid in this case evidently depends upon the magnetic setion of the bobbins combined with that of gravity. LESSONS IN GEOLOGY.-No. LX. BY Those W. JENKYN; D.D.; F.G.S., F.R.G.S., ETC. ON THE CLASSIFICATION OF ROCKS. SECTION XI. (continued.) ON THE COAL MEASURES. III. GEOLOGICAL PHENOMENA OF THE COAL You have already been told that the carboniferous strata or coal-bearing rocks consist of sandstones; clays, containing iron, and hence called iron-stone; a slaty clay called shale; beds of grit, limestone, and coal seams. The number of these beds varies in different coal-fields, but the thickness of the entire series is almost invariably very great. In Durham and Northumberland the coal strata altogether form a mass of more than four thousand féet in depth, i. e. about three-quarters of a mile in thickness. This deposit consists of the following number of beds: 32 Beds of coal seams with their corresponding shales. 62 Beds of sandstone. 17 Beds of limestone towards the bottom. The enumeration of the strata may be different in the coalfields of Staffordshire, of South Wales, etc., but this specimen of the lithological structure and geological order of the series, is sufficient to indicate that the various beds must have been formed under different geological influences and agencies, which I will endeavour to explain. I. THE VEGETABLE ORIGIN OF COAL. The vegetable origin of coal is now almost universally admitted by all scientific geologists. The problem of its origin was rendered difficult by the fact that the vegetable matter, by bituminous fermentation and by the chemical and mechanical processes which converted it into a mineral, caused the original structure of the plants to be obliterated. Yet the evidences of its vegetable origin are not lost. 1. The experiments of Dr. Mc Culloch enabled him to trace successfully the gradual passage of vegetable matter from peat, brown coal, lignite and jet, to pitchy coal, anthracite, graphite, and plumbago or black-lead. 2. Professor Göppert, to demonstrate the vegetable origin of the impressions of leaves found in iron-stone, placed a common fern leaf in a lump of clay, which, after being dried, he exposed to red heat. When he broke this mass open, the inside presented an exact resemblance of fossil plants in iron-stone. By frequent experiments he found that, according to the degree of heat in which such clay was placed, the plant became brown, or shining black: or the plant became entirely lost, in which case only the impression remained. The disappear ance of the plant had caused the whole of the surrounding clay to be stained black-a fact which indicates that the black colour of the coal shales is derived from the carbon of the plants. 3. The microscope has satisfactorily revealed in chips or slices of coal, duly prepared, traces of the fibrous tissue and woody structure of the plants. In the same manner traces of the spiral vessels and the cells of plants are found in the white ashes after the coal has been burnt. Sometimes the mineral coal appears to be entirely composed of very small leaves, bruised and decayed, but all matted together. second class have thought that groves and forests were swept away by floods and inufidations, and were thus drifted out to the ocean, where they were engulphed and became decomposed; while a third class think that the coal plants have grown and have been imbedded on the spot where the coal seams are now found. It is possible that coal may have been formed under each of these three circumstances, and that in some places each of these causes may have been in operation in producing a coal seam. Some of the coal deposits in Yorkshire have every appearance of having been formed at the bottom of fresh-water lakes, as the associated beds have fresh-water shells. Seams in the coal field to the south and west of Shrewsbury, seem formed in the bed of a river or estuary. Other seams were no doubt formed at the bottom of the ocean, for the associated grits and limestones contain marine shells. On these theories, Sir RODERICK MURCHISON makes the following remarks in his "SILURIA," p. 279: "The supposition of many and successive subsidences of vast Swampy jungles beneath the level of the waters, best explains how the different vegetable masses became covered by beds of sand and mud, so as to form the sandstone and shales of such coal fields. But this theory of oscillation, or of the subsidence én massé of ancient marshes, and their re-elevation, with occasional sand-drifts, though good in such examples as those of the South Wales and Newcastle coal fields in England, ás also of the large coal fields in British North America, can have little application to those other seams of coat, which are interstratified with beds containing mariné shells, the animals of which, such as Producti and Spirifers; must have lived in comparatively deep sea-water. In such examples, and nearly all the older coal-beds come into the category, we may, on the contrary, endeavour to explain the facts by the supposition, that the ancient streams, like the present Mississippt and other large rivers, which flowed through groves or low lands and mud banks, transported great quantities of trees, leaves and roots entangled in earth, and deposited them at the bottom of adjacent estuaries, or that they were carried en masse into the broad, open sea." Notwithstanding this high authority for the formation of coal on the theory of plants, groves, and forests being drifted by rivers into estuaries, lakes, or seas, the structure of the coal itself supplies us with many arguments to prove that the coal grew and decayed upon the spot. seams are the decomposed remains of plants and trees that All these arguments subvert the theory of its having been drifted, and show that nothing but the accidental results of the inundation by which the instances in which plants and trees have been drifted, are the submersion of the forest was effected. 1. THE UNIFORM THICKNESS OF EACH SEAM OF COAL.-A seam of coal is of equal thickness, and without any inequality throughout the whole of its extent, for many miles wide and some scores of miles long. Over such areas, some of them hundreds of square miles, no stream, flood, or inundation would have formed a deposit of equal thickness everywhere. The only exceptions are the cases in which they thin out. 2. THE PRESERVATION OF THE COAL PLANTS.-The coal plants are found in the most perfect state of preservation, with their soft leaves, the delicate texture of ferns, and the sharp angles of stems, all well defined. These plants were once soft, and a little rolling would have crushed and disintegrated them; and yet all the lines, streaks, dottings and flutings of the Sigillaria, etc., are preserved in all their delicate textures. The fruits also of some of the coal plants are found in clusters and heaps. If these plants had been drifted, their structure would have currents. been destroyed, and their fruits would have been dispersed by 3. THE CHEMICAL ELEMENTS OF COAL.-Coal consists of carbon combined with the gases hydrogen, oxygen, and nitrogen. These three gases are very volatile, and easily escape. If successive masses of vegetable matter were drifted and deposited by floods or tides, such an agency, by allowing the gases to escape during decomposition, would be inadequate to produce coal; for without the gases being detained, there would be no coal. II. THE DEPOSITION OF THE COAL SEAMS. Though all naturalists admit the vegetable origin of coal, the manner in which that vegetable matter was deposited is a question of considerable dispute among geologists. From the various circumstances in which the coal fields are found, some geologists have thought that the present coal seams were at 4. THE PURITY OF THE COAE.-With the exception of the first mere peat bogs, and that their different layers were pro-chemical production called Iron Pyrites, every seam of coal is duced by successive subsidence and elevation of the land. A an unmixed mineral-without a pebble, without gravel, with |