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LE VAISSEAU EN PE'RIL.
NOTES AND REFERENCES.--a. la discorde en son sein, internal
discord.-6. avis, opinion.--c. mettra bientôt d'accord et rain: L'N vaisseau tourmenté par de longs ouragans,
queurs et vaincus, will soon reconcile conquerors and conquered. Contre les aquilons et les flots mugissants,
---d. from éteindre; L. part ii., p. 90.--. L. S. 80, R. 2.--. pont, Luttait sur une mer d'écueils environnée;'
deck.--g. from lire; L. part ii., p. 94.
Son équipage mutiné
ANSWERS TO CORRESPONDENTS.
W. BUTTS: A knowledge of English grammar is highly desirable, il not
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5 Au sud, au nord, au couchant, au levant,
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quired. If the principal contains shillings, pence, and farthings, or the Va tantôt en arrière et tantôt en avant.s
time months and days, reduce them to the form of a decimal, and work according to the rules already given in the lessons.
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netic induction, Professor Henry was enabled to make soft ON PHYSICS, OR NATURAL PHILOSOPHY.
iron magnets of wonderful power. One, in the cabinet of No. LXVIII.
Yale College, weighing 59} pounds (exclusive of the copper
wire round it), was formed of a bar of iron 3 inches square (Continued from page 635.)
and 30 inches long. It was wound with 26 strands of copper
bell-wire covered with cotton-thread, and 31 feet long. About ELECTRO-MAGNETISM.
18 inches of the ends were left projecting, so that only 28 feet
actually surrounded the iron; the aggregate length of the coils Wange the investigations mentioned in our last lesson were was, therefore, 728 feet. Each strand was wound on a little less going on in America, Professor Moll, of Utrecht, made some than an inch; in the middle of the horse-shoe the wire formed experiments with one of Mr. Sturgeon's electro-magnets, three thicknesses, and on the ends, or near the poles, it was which he procured from Mr. Watkins of London, the object wound so as to form six thicknesses. This magnet supported of which was, to try the mechanical effect of using powerful 2,063 pounds, or nearly a ton, with a battery exposing a zinc single batteries. With a battery, presenting a zinc surface of surface of nearly five square feet. The effect of a larger bat11 square feet, the magnet lifted 75 pounds; but a battery oftery was not then tried. 17 feet, and also one of very great size, gave no increase of Another, and the largest of these magnets, constructed by magnetic power,
Professor Henry, is in the cabinet of the College of New He then sought to produce greater effects by using a horse- Jersey, and the following is his description of it:-It is formed shoe 124 inches high and 24 inches in diameter, which lifted of a bar of rounded iron, nearly four inches in diameter, 154 pounds with the same battery. But that he had no idea of weighing about 100 pounds, and surrounded with 30 strands the effect of increasing the number of spires of the magnetising of copper bell-wire, each about 40 feet long. With a calorihelix, is evident from the fact that he wound the latter magnet meter on Dr. Hare's plan, consisting of 22 plates of zinc, each with only 44 turns of uncovered wire, while the number of 9 inches by 12, alternating with plates of copper of the same similar spires on the smaller magnets was 83, or nearly twice size, it supports 3,500 pounds, or more than a ton and a half. as many.
After the connection with the battery is broken, this magnet Professor Moll, however, particularly observed the instan. supports a thousand pounds for several minutes; and from taneous destruction and reproduction of magnetism, which year to year the lifter adheres with a force which is overtakes place when the current is reversed, by changing the come only by a weight of several hundred pounds. When
connection of each end of the helix from one pole of the bat. the lifter, however, is detached, nearly all the magnetism tery to the other. This prompt action of the magnet is essen- disappears, tial to the usefulness of the electro-magnetic telegraph, and on It is evident that, by increasing the size of the iron bar, the that account the same fact has since been investigated by other number of the coils, and the power of the battery, the magphilosophers.
netic 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'e, it may here be remarked, that production of mechanical effects, is an idea which would the former employed one of Mr. Scurgeon's magneté, 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 io 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 roy; 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 ihe 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 The next person who contrived a modification of the abovewith silk, and wound 400 times round a horse-shoe of soft iron, described electro-magnetic machine, was Professor Ritchie, of rendered it more powerfully magnetic than a similar horse- the London University, who published an account of it, in shoe wrapped loosely with a few turns of an uncovered wire, 1833, in the “ Transactions of the Royal Society." and excited by a battery of 28 plates of copper and zinc, each In 1834, Mr. Davenport, an ingenious blacksmith of the eight inches square.
American State of Vermont, having seen a powerful electroHaving fully investigated the phenomena of electro-mag- magnet, contrived a machine upon the same principle, which VOL. V.
Fascia biel in the principal cities of the United States, but port, K. The current of a Bansen battery, with teh or éleva
, 4, and thene B.it - Was mail to drive a prin ing-press with it.
to the bobbins, M, whence it goes along the wire g to si, Un re rectat attempts to apply this power, we may men- descends along the wire i, again reaches the cylinder a, and the made on the Edinburgh and Glasgow Railway, by goes out at B. The two soft, iron cylinders, s and Q, which Mr. Durideon, who constructed an electro-magnetic locomo form the axes of the bobbins, are pierced with cylindrical Eve, 16 feet long, 6 feet broad, and weighing 5 tons; and apertures, to allow the luminous rays to pass through. Lazdy
, another, by Pruitssor Jacobi, of St. Petersburg, at the expense ai b and a are two Nicol prisms the former serving as polariser, on the Russian government. That of Mr. Davidson failed to the latter as analyser. The latter is made to revolte at the propel the engine alone more rapilly than 4 miles an hour; centre of a graduated circle, P. bozt Proisor Jacobi propeilei a boat 28 feet by 7 feet, These two prisms being arranged in such a manner that eating 7 feet of water, at the rate of three miles an hour their principal sections may be perpendicular to each other, 22 -3 the streain, with a party of about a dozen persons on the prism a completely extinguishes the light passed through
the prism b. If you then put a piece of fint or glass with It is evidently possible, when we possess a source of mecha- parallel surfaces at c on the axis of the two bobbins, the light Dral power, to accumulate it, either by employing one very is still extinguished as long as the current does not pass; bu large engine, or a numuer of smaller ones. The question directly the communications are established, the light red
bercer Evertro-mazuetic forces can be rendered practically pears, but coloured, and if the analyser a is turned to the right zse!ai, depends not, therefore, so much upon the amount of or the left, according to the direction of the current, the light power required, as upon considerations of economy. Water exhibits the various colours of the spectrum, as is the case with iod foel are found everywhere in nature in the greatest plates of quartz cut perpendicularly to the axis. M. E. Ber abundance, weil zinc and acids are manufactured articles of querel has shown that a great number of solid and liquid subBomparatistiy high cost. An engine which consumes such stances are thus capable of deflecting the plane of polarisation sta ances in large quantity cannot, therefore, be employed under the influence of powerful magnets. Mr. Faraday con: #nin profit in competition with steam. And this conclusion, siders that, in these experiments, the rotation of the plane of besed upon theoretical reasons, is fully confirmed by experi- polarisation is owing to an action of the magnets upon the Dents with such machines,
luminous rays. Messrs. Birt and E. Becquerel think the It should also be borne in mind, in estimating the effective phenomenon is owing to an action of the magnets upon the
witse-p;147 of an electro-magnetic engine, that the forces transparent bodies brought under their influence--an bype
2.5 25.2.1 distances, it exerts, when the con- very remarkable effects of powerful magnets. We will describe * 1112, a 36 pusbe distances, a force of only a few a few experiments which require şoft iron armatures, sande
of various forms (figs. 456, 457, 458) to be screwed on to the Intro 14,4 Trousert bere, that the armature or lifter of a bobbins. mated site est ***ng with a furce of sereral hundred 1. M. Bancalari first observed that on placing the flame of a pra v. 3465 4, quez, 2'287 rept. cerint with the battery is candle between the two magnets, it is repelled, fq. .
é'ways 27.5: tas cened to act, shows that Professor Faraday having found that oxygen, which is
Pain ... togethesis of Ampère, that netic at an ordinary temperature, becomes diamagnetic s
****, pilground the axes of the the temperature of Aame, the repulsion thus exhibited mathe
774, . planetary motions, as explained by the mere repulsion to which the air is subjected;
14.0,haen 'fallo established the an explanation analogous to that given of the repulsion of fame is, il y barnre of resistance, will by electrical machines.
Ir. 61,5 1,12671*?ate of our knowledge 2. If a small cube of red copper be hung better two moth had in 340, we save se 22.n to believe that no magnets by a twisted silk thread, ag. 457, and be allowed to *s * et se trees, a'rlate contact : and revolve rapidly by untwisting itself, it will stop direeds the * v poseba intry in their interiening spaces, is position. If instead of a cube a small rectangular bar is ** sababit hypangris, nor without substituted, it will come into a position at right segles for the
the axis of the bobbins, or in a line with it, according stis datote parful huntin-magusta. Professor Faraday, made of a diamagnetic substance, as bismuth ni mion,
soup adam 12.6* forward electromagnet exercises or a magnetic substance, as iron, nickel, or cobalt. Professor
pin mo un vesel 1194 gearent substances, that if Paraday, who first observed these phenoaens, atribetes
*** ***** *n of polarisation is deflected to influence of magnets.
in a watch-glass, fig. 155, observed that, secording to be od tamen suddy in represented in fig. distance of the bobbins, the solution for sed see or two stel Wind, sin im ******stly purworful electro-magnets, ings, as represented at A and & The euratare of the Said
***" i sluder, 9 and, which are in this case evidently depends upon the signede satire is Wanna inipe nani wote uthu by sliding on a sup. I bobbins combined with that of gravity.
second class have thought that groves and forests were swept LESSONS IN GEOLOGY.-No. LX: away by floods and inufidations, and were thus drifted out to
the ocean, where they were engulphed and became decomBr Trtoś: W. JESKYX; D.D., F.G.S.; F.R.G.S., ETC, posed ; while a third class think that the coal plants have CHAPTER T.
grown and have been imbedded on the spot where the coal
seams are now found, ON THE CLASSIFICATION OF ROCKS.
It is possible that coal may have been forined under each of
these three circumstances, and that in some places each of SECTION XI. (continued.)
these causes may have been in operation in producing a coal ON THE COAL MEASURES.
Some of the coal deposits in Yorkshire have erery
appearance of having been formed at the bottom of fresh water $111. GEOLÓGICAL PHENOMENA OF THE COAL lakes, as the associated beds have fresh-water shells. Seams PEROID.
in the coal field to the south and west of Shrewsbury, seem You have already been told that the carboniférous strata or formed in the bed of a river or estuary. Other seams were no coal-bearing rocks consist of sandstones ; clays, containing doubt tormed at the bottom of the ocean, for the associated iron, and hence called iron-stone; a slaty clay called shale; grits and limestones contain marine shells. beds of grit, limestone, and coal seams.
On these theories, Sir RODERICK MURCHÍSON, makes the The number of these beds varies in different coal-fields, but following remarks in his “Siluria," p. 279; "The supposithe thickness of the entire series is almost invariably very tion of many and successive subsidences of vast swampy great. In Durham and Northumberland the coal strata jungles beneath the level of the waters, best explains how the altogether form a mass of more than four thousand feet in different vegetable másses became covered by beds of sand and depth, l. 6. about three-quarters of a mile in thickness. This mud, so as to form the sandstone and shales of such coal deposit consists of the following number of beds :
fields. But this theory of oscillation, or of the subsidence én 32 Beds of coal seams with their corresponding shales.
massé of ancient marshes, and their re-elevation, with occasional 62 Beds of sandstone.
sand-drifts, though good in such examples as those of the 17 Beds of limestone towards the bottom.
South Wales and Newcastle coal fields in England, ás also of
the large coal fields in British North America,--can have The enumeration of the strata may be different in the coal- little application to those other seams of coal, which are interfields of Staffordshire, of South Wales, etc., but this specimen stratified with beds containing mariné shells, the animals of of the lithological structure and geological order of the series, which, such as Producti and Spirifers, must have lived in is sufficient to indicate that the various beds must have been comparatively deep sea-water. In such examples, and nearly formed under different geological influences and agencies, all the older coal-beds come into the category, we may, on the which I will endeavour to explain.
contrary, endeavour to explain the facts by the supposition; I. THE VEGETABLE ORIGIN OF COAL.
that the ancient streams, like the present Mississippi and
other large rivers, which flowed through groves or low lands The vegetable origin of coal is now almost universally and mud banks, transported great quantities of trees, leares admitted by all scientific geologists. The problem of its and roots entangled in earth, and deposited them at the origin was rendered difficult by the fact thai the vegetable bottom of adjacent estuaries, or that they were carried en masse matter, by bituminous fermentation and by the chemical and into the broad, open sea.". mechanical processes which converted it into a mineral, caused Notwithstanding this high authority for the formation of the original structure of the plants to be obliterated. Yet the coal on the theory of plants, grovės, and forests being driftea evidences of its vegetable origin are not lost.
by rivers into éstuaries, lakes, or seas, the structure of the coal 1. The experiments of Dr. Mc Culloch enabled him to trace
itself supplies us with many arguments to prove that the coal successfully the gradual passage of vegetable matter from peat; grew and decayed upon the spot.
seams are the decomposed remains of plants and trees that brown coal, lignite and jet, to pitchy coal, anthracite, graphite, subvert the theory of its having been drifted, and show that
All these arguments and plumbago or black-lead. 2. Professor Göppert, to demonstrate the vegetable origin nothing but the accidental results of the inundation by which
the instances in which plants and trees have been drifted, are of the impressions of leaves found in iron-stone, placed a the submersion of the forest was effected. common fern leaf in a lump of clay, which, after being dried, he exposed to red heat. When he broke this mass open, the
1. The UNIFORM THICKNESS OF EACÍ SÉAN OF COAL-A inside presented an exact resemblance of fossil plants in seam of coal is of equal thickness, and without any inequality iron-stone.
throughout the whole of its extent, for many, miles wide and By frequent experiments he found that, according to the some scores of miles long. Over such areas, some of them degree of heat in which such clay was placed, the plant became hundreds of square miles, no stream, flood, or inundation would brown), or shining black : or the plant became entirely lost, have formed a deposit of equal thickness everywhere. The in which case only the impression remained. The disappear only, exceptions are the cases in which they thin out. ance of the plant had caused the whole of the surrounding
2. Tue PRESERVATION OF THE COAL PLANTS.—'The coal plants clay to be stained black-a fact which indicates that the black are found in the most perfect state of preservation, with their colour of the coal shales is derived from the carbon of the soft leaves, the delicate texture of ferns, and the sharp angles of plants.
stems, all well defined. These plants were once soft, and a 3. The microscope has satisfactorily revealed in chips or little rolling would have crushed and disintegrated them; and slices of coal, duly prepared, traces of the fibrous tissue and yet all the lines, streaks, dottings and flutings of the Sigillaria, Woody structure of the plants. In the same manner traces of etc., are preserved in all their delicate textures. The fruits the spiral vessels and the cells of plants are found in the white also of some of the coal plants are found in clusters and heaps. ashes after the coal has been burnt,
If these plants had been drifted, their structure would have Sometimes the mineral coal appears to be entirely composed currents.
been destroyed, and their fruits would have been dispersed by of very small leaves, bruised and decayed, but all matted
3. THE CHEMICAL ELEMENTS OF COAL.-Coal consists of together.
carbon combined with the gases hydrogen, oxygen, and nitroII. THE DEPOSITION OF THE COAL SEAMS.
gen. These three gases are very volatile, and easily escape.
If successive masses of vegetable matter were drifted and Though all naturalists admit the vegetable origin of coal, deposited by ffoods or tides, such an agency, by allowing the the manner in which that vegetable matter was deposited is á gases to escape during decomposition, woulu Je inadequate to question of considerable dispute among geologists. From the produce coal; for without the gases being detained, there various circumstances in which the coal fields ùre found, some would be no coal. geologists have thought that the present coal seams were at 4. THE PURITY OF THE COAL. 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. Alan unmixed mineral—without a pebble, without gravel, with
out sand. If the searns of coal had been formed by drifted in the Silurian beds ; but they bear no proportion, either in
The bottom rock, then, of the coal strata consists, in maart
, in instances are very numerous, in which the workings of the some places, is the production of the coral insect. This bed coal measures expose the stems, trunks and roots of trees, exists everywhere as & cover over the old red sandstone, except which seem to have grown on the identical banks of sand or in Ireland, where it is either covered up by other rocks, or, mud where we now discover them, and whose decomposed most likely, replaced by the millstone grit. leaves and associated plants formed the coal.
The existence of this mountain limestone indicates that in Imagine that you had a garden of about a quarter of an acre our latitudes, at the time of its formation, there was a shalar of ground. You remove the soil, several feet deep,—say for sea, the bottom of which formed a fit foundation for coral brick-making. As the earth is wheeled away, you find tree- reefs, such as we have now in the Pacific. On banks in this trunk after iree-trunk exposed to view, standing some feet bottom the coral insects began to work, and as such banks high, and with their roots fixed. Would you doubt that those belonged to a land that was gradually sinking, the insects trees grew there? would you infer that some food placed them continued to work upwards until they produced those enrthere all in an upright position? The evidence would be mous masses of limestone, which now form high mountaiss in demonstrative that the trees grew on the spot. Precisely such both the Old and the New Worlds. & quarter of an acre is found at Parkfield, near Wolverhamp- 2. During the formation of this limestone in the seas tha: ton. The workmen cleared away all the rock that covered then c ered England, there was, in what is now called the the coal, and then they found throughout that area seventy-two Atlanti a large trace of land, extending from the norta and upright trees with their roots attached to the bottom soil. south of England for some hundreds of miles westward 10 this Some of these trees were more than eight feet in circumference. ocean. In the meantime, the building up of such extensive Some of the trunks were lying prostrate in different directions, coral reefs, and of such great thickness, would necessaris for they had been broken off close to the root by some power raise the level of the sea bottom. Nevertheless, the land is ful agent. This was undoubtedly the remains of a submerged still supposed to be sinking. forest. But below this bed, there was another forest of the 3. After the land continued to sink gradually for some time, game character, and five feet below that there was a third change took place, when it began to rise again. In the forest with large stumps of trees.
course of its elevation, the limestone work of the corals became These seams of coal, therefore, are the vegetable matter of covered with a very extensive and thick bed of sandstone and decomposed plants and trees that grew on the spot. The grit, now called the Millstone Grit, consisting of the detritus, spot was liable to be inundated from time to time, and was probably, of the large tract of land which we have supposed consequently raised higher and higher by the accumulation of
to be extending to the Atlantic. sediments, as is now the case in jungles and swamps near large 4. The deposition of this grit was succeeded by the formaz. rivers like the Ganges or the Mississippi. As one growth of tion of muddy and sandy beds, on which a most luxuriant trees perished, and as the soil rose higher, other trees grew up vegetation began to grow. These extensive beds appear from the new soil, now several feet higher above the level of have been first formed, especially in South Wales, in water of the first morass, as is represented in our engraving of the coal a moderate depth, during a slow and perhaps intermittent measures at St. Etienne, fig. 20.
subsidence of the ground, in a region to which rivers, fria I might quote instances of a similar character from the the supposed Atlantic land, would be bringing down a cok coal works of Capel Coelbren, near Swansea, of Balgray, near stant supply of sand and muddy sediment. Glasgow, and from a railway cutting, near Salford, on the As these muddy beds rose above the waves, the whole are: Manchester and Bolton line; but one other, from Cape Breton, I became covered with forests, such as we see now in the delies in Nova Scotia, will be sufficient. In the Sydney coal field of of large American rivers in warm climates-deltas which att that country, Sir Charles Lyell saw erect trees occurring at liable to be submerged beneath the sea, or covered by inundadifferent levels successively. In that section there are forty- tions of fresh water, should the district sink but a very one different beds of clay, with roots of Stigmaria in their few feet. natural position, and eighteen layers having upright trees at 5. The peculiar character of this coal forest has been reprelevels one above the other. The whole section, he says, fur- sented in one of our late engravings, fig. 17. This forest 13 nishes clear evidence that at least pifty-one forests, now depicted as growing in a broad sheet of water, or in a fossil, had grown and decayed on that spot, one after an- shallow lagoon, which received at intervals deposits of med other.
and silt, the detritus of neighbouring lands. Such lakes of III. THE PROGRESSIVE FORMATION OF THE COAL profusion of plants and trees, until, by the accumulation of
sheets of water would be speedily filled up by a growth of STRATA.
muddy sediment and the mixture of decayed vegetables, it 1. At the commencement of the coal epoch, or rather at the would be converted into a swamp or morass. close of the age of the old red sandstone, much of the northern On the surface of this morass or boggy ground, a fresh part of the globe appears to have been covered with the ocean. growth of plants and trees would now take place of plants But now, in that ocean, a very great change took place as to its and trees somewhat different from the preceding, and consista elementary constituents. Carbonate of lime seems to have ing of reed-like plants, called Equiseta and Calamites
, with predominated, and to have extended itself over much of its here and there a large tree.
As these plants in their turn area from the arctic regions to the equator. The gradual decayed, the decomposed matter furnished beds of peat, etc, diminution of the size of the pebbles, in the upper portions of 6. The succession of beds of coals, clays, sandstones, shales the old red sandstone, implies that the alternation with fine and limestones, implies that our lagoon or morass forest mar, submarine gravel was not very sudden.
by a repetition of subsidences and elevations, have sunk There are, indeed, limestones, and those produced by corals, beneath the level of the sea, and have rendered its basin the