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LESSONS IN ANCIENT HISTORY.-No. VI.
By ROBERT FERGUSON, LL.D.

THE Egyptians strove to throw off the Persian yoke; but when
Alexander the Great became King of Macedon, they submitted
without opposition. Nearly two centuries had been spent under
the yoke of a foreign power; and the reign of Alexander lasted
but thirteen years. When he marched into Thrace, in order to
bring into subjection those Grecian states which sought to free
themselves from the Macedonian usurpation, it is said that
Thebes took advantage of his absence and entered into a revolt;
that on his return, Alexander took that city by storm, made a
fearful slaughter of the inhabitants, and destroyed all their
buildings. His own sudden death prevented him from making
arrangements for the succession to the throne, and the kingdom
became distracted by internal quarrels. The widow of Alex-
ander gave birth to a posthumous son and heir. Perdiccas, a
Macedonian nobleman, the confidant of Alexander, to whom he
gave his ring, was appointed regent. He was far from being
popular, and a league was secretly formed against him. To
reduce the northern provinces of Asia Minor, he equipped a

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would have been invaded. About four years afterwards, he gained a decisive victory over the Egyptian fleet that came to protect the island of Cyprus; but neither he nor his father Antigonus succeeded in the reduction of Egypt.

Antigonus having been slain in the battle at Ipsus in Phrygia, more than twenty years after the death of Alexander, the kingdom of Egypt passed into the hands of PTOLEMY LAGUS, its former governor, and one of the wisest of statesmen. His entire reign extended over a period of 39 years; he was devoted to the interests of his people. He aimed at the regeneration of their social system. He revived their ancient religious and political constitution; restored the priestly caste to many of its former privileges, renewed the division of the country into separate districts; constituted Memphis the capital of the kingdom, and made the temple of Phtha the national sanctuary, in which alone the kings could be anointed and crowned. He paid great attention to trade and navigation. Under his administration, colonists from every quarter of the globe settled in Alexandria; and to

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considerable army, and sent orders to Antigonus aud Leonatus, the governors of Western Asia, to join the expedition with all their forces. Having disobeyed these commands, they were summoned to the tribunal of the regent. Antigonus, seeing his danger, entered into an alliance with Ptolemy, the satrap of Egypt, with Antipater, the governor of Macedon, and with several other noblemen, to overthrow the regency. At first, Antigonus was foiled in his attempt, and death soon removed Perdiccas beyond his reach. Through the influence of Antigonus and Seleucus, the regency was assumed by Antipater, whose possession of the supreme power was limited to three years. After a few more changes and struggles, Antigonus began openly to aim at the sovereignty of the Macedonian empire. His arms struck terror into all his enemies. He sent his son Demetrius against the Egyptian Ptolemy; but Ptolemy overthrew Demetrius near Gaza. The triumph of the Egyptians was short-lived; for at the commencement of the next campaign they were defeated, and but for the fact of Demetrius having at abat moment been engaged in a war with the Arabs, Egypt

VOL. I.

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escape the persecution of their Syrian masters, the Jews came thither in great and increasing numbers. By the conquest of the Syrian frontiers, of the ancient kingdom of Cyrene, of part of Ethiopia, and of the island of Cyprus, he rendered Egypt comparatively safe from foreign invasion, and added greatly to its external security. He was the liberal patron of literature and retreat from the storms and the conflicts which threatened every science. Philosophers and men of letters found in Egypt a quiet other part of the world.

The city of Alexandria, which was founded by Alexander the Great, owed much of its increase and magnificence to Ptolemy Lagus. According to Strabo, the celebrated Greek historian, Alexandria was four miles and a half in length, and one mile in breadth, which made the circumference of its walls nearly twelve miles. These walls, part of which are still standing, having great square towers, two hundred paces distant, with gates of Thebaic and granite marble, were washed on the south by the lake Mareotis, and on the north by the Mediterranean Sea. The one street of two thousand feet width, which began at the gate city was intersected lengthwise by straight parallel streets; and of the sea, and terminated at the gate of Campus, was adorned with the most elegant buildings, houses, temples, and obelisks; 13

and was deemed the most magnificent street in the world. The palace occupied more than one-fourth of the city, and in cluded within itself the Museum or College of Philosophy, a common rendezvous or place of meeting for the learned; academic groves, royal buildings, and a temple in which the body of Alexander was deposited in a golden coffin. In the eastern part of the city was the Gymnasium, with its splendid porticoes of more than six hundred feet in length, supported by several rows of marble pillars. It became the centre of science and civilisation -the rival of Rome in magnitude and grandeur-and the first commercial city of the world. A mole or mound, of a mile in length, divided its great harbour into two, at the entrance of which was erected the celebrated PHAROS, or lighthouse. In the height of its prosperity, it had a free population of more than 300,000 souls, and nearly an equal number of slaves. It was a place of great magnificence; it became the regal capital of Egypt, and for two centuries was the residence of the Ptolemies. The death of Ptolemy Lagus, B.C. 284, filled his subjects, who revered and honoured him as a father, with deep and universal grief. Before his decease, his son PHILADELPHUS was associated with him in the government of the kingdom. Though he possessed neither the wisdom nor the enterprise of his father, yet the empire was essentially benefited under his peaceful administration. Commerce was extended; ports were constructed for the Indian and Arabian trade; caravan roads were made to the Upper Nile, and the lower river was united to the Red Sea by a canal which communicated with the lesser harbour on the Lake Moeris; the trade with Ethiopia was revived, and even the remoter countries of Central and Southern Africa were thrown open to the enterprise of the Alexandrian merchants. The rebellion of Magus, the governor of Libya and Cyrene, was encouraged by Antiochus Theos, king of Syria. The utmost efforts of Philadelphus failed to reduce the rebel, and the affair was compromised by a marriage between the only daughter of Magus and Ptolemy's eldest son. An alliance was formed with the Roman republic, and to the Roman ambassadors who visited Egypt, the sovereign not only showed every possible mark of kindness, but explained to them those Grecian arts with which they were till then unacquainted. It was in consequence of this visit and this alliance, that a silver coinage was afterwards introduced into Rome.

Asiatic campaigns were more for plunder than territory, by his wars in the south he added a great part of Abyssinia and the Arabian peninsula to his Egyptian dominions, and he opened up new channels for trade and commerce through these more distant countries. It is said that Evergetes visited Jerusalem, there offered sacrifice to the true God, and ever afterwards showed great favour to the Jewish nation. His kingdom rapidly rose to the height of power, and promised again to take the first place among the nations. But after his death arose a succession of weak and irresolute princes, and Egypt declined to her fall From this period she makes no figure in history.

Ptolemy Evergetes died B.C. 221, and was succeeded by his son Ptolemy Philopater, a prince who gave himself up to the infiuence of flatterers and favourites, and whose life was one of debauchery and crime. He began his reign with the murder of his brother Magus, and of Cleomenes, the exiled king of Sparta. Taking advantage of Philopater's weakness and incapacity, Antiochus the Great, king of Syria, waged war against Egypt, but he was defeated. Instead of taking advantage of this temporary success, he threw his own kingdom into confusion and ruin by his cruelty. It is said that he threatened to exterminate all the Jews in his dominion; that he caused the death of his own wife and sister; that he sunk into the most beastly dissipation, and died abhorred in the prime of life, leaving only one son about five years of age.

LESSONS IN GERMAN.-No. III.

WE introduce our third lesson with a few remarks on German writing. It is plain that the students of this language will in general have neither the time nor the tact sufficient to enable them to write out their exercises in the printed letters of the language; they will, therefore, be under the usual necessity of writing them out in the written characters used by the Germans, of which we gave the alphabets, large and small, with specimens of their application, in our last number. In learning these written characters, it will be useful to observe that the leading letter of the small alphabet is m, which is written Such was the number of Jews that had settled in Alexandria, people in our own country, especially the ladies. Taking one in the usual angular style adopted by most well-educated that a temple was erected in Egypt similar to that in Jerusalem, and during the preceding and present reigns a Greek version of leg of the m, which we shall call the elementary leg, and which the Hebrew Scriptures was made expressly for their use. This consists of a black middle stroke and two hair-strokes; if you version is known by the name of THE SEPTUAGINT, or transla- add to the last hair-stroke, when you bring it up, a small turn tion of the SEVENTY. The tradition of one Aristeas, who re- or loop, you have then made an o. If now, as soon as you have lated that it was executed in seventy-two days by seventy-two made the loop of the o, you draw downwards from the very learned Jews, who had been sent for the purpose by the high short hair-stroke of the loop another black stroke, and then its priest Eleazar to Alexandria at the request of Ptolemy Phila-hair-stroke upwards, you have at last made an a. You make delphus, is a mixture of truth and fiction. This version was ab, by adding to the o a large top-loop, as we do in making our made about B.C. 280, and acquired the highest authority among own written b. You have learned to make e already, as it is the Jews of Palestine. In proof of this it may be observed that the leg of the m already described. If you take this same it was quoted in the New Testament instead of the original. Though the introduction of Coptic or pure Egyptian words, and elementary leg, and carry up its second hair-stroke, as we do the rendering of Hebrew ideas in the Egyptian manner, prove in our written d, making this hair-stroke end in a loop or cirbeyond all doubt that the translators were natives of Egypt; and clet at top, you have the letter d complete. though the difference of style evinces that the work could not be the production of one individual, but of several writers, yet it is of great importance, not only for correcting the Hebrew text, but also for ascertaining the meaning of particular modes of thought and expression which we find in the New Testament.

It was during the preceding reign that the ALEXANDRIAN LIBRARY was founded for the use of those who were devoted to letters and to science. All the Ptolemies continued to enrichm, writing it from left to right, instead of from right to left. and enlarge this library, till it numbered upwards of 700,000 volumes. This immense collection was secured by seizing all the books which were brought into Egypt by the Greeks or other foreigners, transcribing their contents, delivering the copies, and retaining the originals. This splendid library was burned by order of the Caliph Omar in the beginning of the seventh century, on the usual bigoted principle, that if they agreed with the KORAN they were useless, and if they differed they were worse than useless.

As Egypt became wealthy and prosperous, she became luxurious and corrupt. Philadelphus fell into all the effeminate dissipation of eastern monarchs; he denied the sacredness of the inarriage vow, became dissolute and profligate, and died after a reign of eight-and-thirty years, leaving an indelible spot upon his name and his memory.

His son ascended the throne B.C. 246, under the title of PTOLEMY III., surnamed EVERGETES, or THE BENEFACTOR. He was of an enterprising and warlike spirit, and carried his conquests into the remoter regions of the east and the south. He successfully extended his arms as far as Bactria; and though his

The letter e is peculiar; it is formed of the elementary leg without the second hair-stroke, to which is joined a shorter elementary leg by a hair-stroke drawn from the former very near the top of the black stroke. The letter ƒ is very like our own written f; you first make a long hair-stroke both above and below the line, terminating at the top in a loop like the letter b, and cross it in the middle by the elementary leg of the To make the letter g, first make an o, and then from the short hair-stroke of the loop draw a hair-stroke downwards, making it terminate below the line like our own written g. The letter is exactly like the longs used in writing by ourselves; it seems to have consisted of the elementary leg with a loop of hair-stroke above and another below. The letter i consists of the elementary leg with a dot above it; if you forget the dot it will be taken for a c. The letter is that part added to o which makes it a g, with a dot above it. The letter & is so like our own that it can hardly be mistaken, but it has no loop at the top. The letter is just the letter & without the loop. The letter m has been described. The letter n consists of two legs of the letter m; and the letter has been described.

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The letter p is formed of the elementary leg by turning round the second hair-stroke in a larger loop than usual, and terminating it below the line like aj; we have no letter like it. The letter g is like g with this difference, that it is pointed

below the line, and the hair-stroke is brought up from this point to the right instead of to the left. The letter r is very peculiar, and unlike any of ours. It consists first of an elementary leg; but the second hair-stroke, instead of being brought up, is looped at the bottom contrary to the usual way, and then brought up and made to terminate in an elementary leg to the right, of half the usual size. The letter & is like the letter f, with this difference, that the elementary leg instead of crossing it in the middle is placed entirely to the left at this point. Another is made by forming a loop at bottom from right to left, and terminating in a hair-stroke above the line, with a hook from left to right, somewhat like our written figure 6 made from the bottom to the top, or contrary to the usual way. Make the letter like our manuscript t, cross it with the elementary leg from left to right; or make it like without the loop. The letter u is exactly like the letter n, The letter is another peculiarly-formed letter. The first part of it is exactly like the letter r, but it terminates in a round black stroke curved towards the right, or hollow towards the first part of the letter and giving it somewhat of the appearance of an inverted a. Prefix to the letter the elementary leg so often mentioned, and you have the letter w. The letter x is formed like the letter p, with this difference, that the part below the line is turned to the right instead of to the left, and terminates in a small scroll. The letter y is like the letter with its curve to the right extended below the line, and its hair-stroke brought up like a j. The last letter z is very like our own manuscript z, and consists of the elementary leg rounded, and the second hair-stroke replaced by a curved part below the line, like the letter j. The double consonants being so manifestly formed of the simple letters which enter into their composition, it is unnecessary to make this lesson any longer by describing them. It may just be observed that double s is a combination of the two different forms of s above described; that the double f is like the doubles without the elementary leg behind it, and with a dash or flourish across it; and that in combination z is written on the line, instead of below it, and in form resembling our manuscript B. shall describe the written alphabet of capitals in our next lesson.

with a circlet or curve over it for the sake of distinction.

SECTION VII.

We

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1. Wer hat das Papier dieses Mädchens? 2. Dieses Kind hat es 3. Weffen Buch hat dieser Schüler? 4. Er hat das Buch des Lehrers 5. Von wem haben Sie dieses Leder? 6. Ich habe es von dem Schuh, macher. 7. Für wen ist dieser Apfel? 8. Er (Sect. 18. III.) ist für das Kind des Sattlers. 9. Wessen Rock hat der Sohn des Schneiders? 10. Er hat den Nock dieses Freundes. 11. Von wem hat ter Sohn dieses Hutmachers Geld? 12. Er hat Geld von dem Vater. 13. Wo ist der Wagen des Bauers? 14. Der. Freund des Lehrers hat ihn. 15. Wessen Haus und Garten hat der Lehrer? 16. Er hat das Haus und den Garten tes Bürgermeisters. 17. Von wem haben Sie diesen Hut? 18. Ich habe ihn (Sect. 18. III.) von dem Hutmacher. 19. Für wen ist er? 20. Gr ist für den Sohn des Schneiders. 21. Haben Sie Gold, Silber oder Kupfer für den Lehrer? 22. Ich habe Silber für ihn. 23. Wen liebt das Kind? 24. Es liebt den Bruder des Lehrers.

QUESTIONS. 1. How do the endings of „Diese e“ differ from those of Da8"? 2. Do the endings of Diefer" differ from those of Der"? 8. Which cases of the pronoun „es" are alike? 4. Which cases of „e 8" are like those of er"?

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1 Wo ist der Bruder des Steuermanns? 2. Er ist bei dem Capitain in dem Schiffe. 3. Ist der Sohn des Erelmanns auch bei ihm? 4. Nein, er ist in Deutschland. 5. Wo ist der Vater? 6. Er ist bei dem Gapitain in dem Zollhause. 7. Lobt der Capitain den Sohn des Edelmanns? 8. Ja, und er lobt auch den Vater. 9. Licht der Edelmann den Capitain? 10. Ja, er liebt und lobt ihn sehr. 11. Ist dieser Mann der Sohn des Capitains? 12. Nein, er ist der Sohn des Steuermanns. 13. Ist dieser Matrose reich? 14. Nein, er ist arm und fröhlich. 15. Wie alt ist dieser Mann? 16. Er ist nicht sehr alt. 17. Ist er frank? 18. Nein, er ist hungrig. 19. Was giebt dieses Mädchen dem Kinde? 20. Gs (§ 134. 2.) giebt ihm nur Zucker. 21. Was geben Sie dem Knechte? 22. Ich gebe ihm Geld. 23. Was giebt der Knecht dem Pferde? 24 Er giebt ihm Hen. 25. Liebt dieses Kind den Lehrer? 26. Ja, und der Lehrer lobt das Kind. 27. Ist der Jäger noch in dem Walde? 28. Ja, und der Sohn des Etelmanns ist bei ihm. 29. Der Jäger geht nach dem Walde zu dem Vater, und ich gehe zu dem Bruder.

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LESSONS IN GEOLOGY.-No. II.

By THOS. W. JENKYN, D.D., F.G.S.

ON THE CRUST OF THE EARTH. In reading books on Geology you will often meet with the

The definite article is less varied than the definite, having for phrase "the crust of the earth," or "the earth's crust." The the masculine and neuter nominative but one form. Ex.:

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1. Hat ein Mann, oder ein Kind den Stock dieses Freuntes? 2 Dieser Mann hat ein Schwert eines Feintes, und dieses Kind hat den Stock eines Freuntes. 3. Was hat der Jäger? 4. Er hat einen Hund und ein Gewehr. 5. Wer hat den Pflug des Bauers?

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6. Der Vater dieses Rintes hat den Pflug. 7. Hat tiefer Schmied das Geld des Kaufmanns? 8. Nein, er hat nur Eisen von einem Kaufmanne. 9. Haben Sie den Wagen des Backers? 10. Nein, ich habe diesen Wagen von einem Wag. 11. Haben Sie das Vand dieses Märchens? 12. Nein, ich habe Luch von einem Luchhändler. 13. Haben Sie den Rock dieses Freundes? 14. Nein, ich habe diesen Rock von einem Schneiter. 15. Haben Sie das Papier des Lehrers? 16. Nein, ich habe dieses Papier von einem Papier Händler und einen Empfehlungsbrief von dem Lehrer. 17. Ist das Pferd 'n Bugthier? 18. Ja, und es ist auch ein Lastthier. 19. Ist das Kameel ach ein Zugthier ? 20. Nein, es ist nur ein Lastthier? 21. Wessen Besetzbuch hat der Sohn des Edelmanns? 22. Er hat das Gesetzbuch des Oberhofrichters.

QUESTIONS. 1. What is said of the indefinite article compared with the definite? 2. Can you give any examples? 3. Are nouns more frequently compounded in German than in English? 4. And how is it often necessary to translate them? What are some examples?

phrase involves in itself many important principles in theoretical geology. The very word “crust" implies a surface that has undergone some process of hardening, and that retains beneath it some materials in a condition different from itself.

You must not imagine that the hypothesis of a "crust of the earth" excludes the ideas of a Creation and a Creator. Suppose that Science could demonstrate to you that this great globe once existed in a gaseous form, and that, by the gases entering into combination and evolving heat, a glowing and fusing mass would whirl round in space, and that this was the first genesis by which our world was made visible and palpable. You would then ask, how came these gases to exist? And You would learn from chemistry that all gases combine acyou would learn that they must have been made by a Creator. cording to regular and established laws. The gases did not make these laws, but received them from a living and intelligent Lawgiver.

The phrase "crust of the earth" may possibly recall to your mind the idea of either the crust of a loaf, or, perchance, that of a pie. Both these ideas will mislead you. In these cases the crust has been hardened, not by cooling, but by the influence of external heat upon the outward surface. In geology, on the contrary, the phrase implies that the body of the earth was once in a state of fusion,-that is, it was once all in a melted state, glowing, burning, and flaming; and that it gradually cooled until it became covered with a hardened surface.

If you have ever been in a large iron-foundry, where there are blast furnaces for melting ores, you will at once understand the geological meaning of the word "crust." Near the bottom of the blast furnace there is a flue, or tap, for allowing the fluid cinder, or scoria, which floats on the surface of the metal within, to flow out in burning streams. As this stream recedes from the flue, it becomes cooler; and a little lower down, it is covered with a blackened surface which is so hard as that the workmen can safely walk upon it, though underneath it is still in a melted state. It is this kind of surface, hardened by cooling influence from above, but still kindling and burning beneath, that geologists call “crust.”

You can, with a little effort, conceive of the propriety of applying the word "crust" in this sense to the surface of the globe. You have seen a red-hot coal, burning and flaming on all its sides, fall from the fire in your own grate. In a short time the outside of it became cooler and cooler, while the inside and centre, according to its size, were still red-hot. In this case, the outside, in cooling, became covered with irregular white flakes, or pellicles, called ashes.

You can also imagine a round mass of iron, say a small cannon-ball, heated in a blacksmith's furnace, and then thrown out suddenly and left to cool. As it cooled, all its surface would be covered with pellicles, or flakes of rust, which chemists call the oxide of iron; and which, if examined under a good microscope, would appear as if it had been put together by joints and angles.

that, while you were at the blast furnace in the iron-foundry, a Your conception will be assisted better still, if you imagine Herculean workman took up a large iron ladleful of the fluid cinder, and hurled his ladleful of the burning matter into the air; or you can suppose that mount Etna, or Vesuvius, were a Titanic workman, throwing out such a mass high up for some miles in the air, and, perhaps, beyond the circle of our atmosphere, or even of the attraction of our earth. If this mass would continue to whirl and roll round without falling again to our earth, it would take the form of our globe, which astronomers have demonstrated to be, necessarily, an ellipsoid, that is, orange-shape, or a round ball flattened at both ends. Whenever you break to pieces a large mass of cinder, or scoria, that has cooled, you find that its inside has streaks and veins of different materials, and that it has many cavities or holes, called by the foundry-men "honeycomb." These cavities were in the cinder while yet in the red-hot stats,

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and they were formed within it either by air or by gases. Imagine that, at the bottom of these cavities, there was once floating a diminutive drop of melted matter, moving whenever the mass was shaken. Now, OBSERVE, you have before you the cinder, the cavity, and the melted drop floating.

To these three facts, direct the magnifying-glass of your imagination, but let it be kept in the firm hand of your reason; and then apply your mind and your logic to "the great globe itself, and all that it inherits." Let the cool cinder be magnified into our planet; the cavities, into subterranean caverns of many hundred square miles; and the melted globule into an immense lake, or large sea, burning, boiling, heaving to the top of the cavity, melting parts of the crust nearest to it, or forcing the crust to swell upwards, or cracking it and forming crevices through which some of it comes up to the open air, and there hardens again to form an additional crust.

Fig. 1 will give you a rough idea of the formation of the earth's crust. Fig. 1.

B

D

THE FIRST HARDENING OF THE CRUST OF THE EARTH.

swell. In consequence of this swelling, the earth will be raised up into a hillock, sulphurous vapours will make their way through the cracks and crevices made by the force pushing upward, and sometimes flames will appear. Now, suppose that this mixture of sulphur and iron could be introduce into the cavity which we have imagined, and that the crust above it was so thick and hard and heavy, that the heat could not push it up. Still there would be heat in the cavity, or in the globule.

You see, then, that it is possible for elements or gases to exist in the cavity, which will continue the heat and keep the molten drop burning and floating. As it continues to burn, it will consume the sides of the cavity, and wear away the roof. It will, in time, enlarge the cavern, till the drop has become an immense molten lake. This molten lake or sea will, by growth of heat, acquire also intensity of power for action, until it crack the roof, and swell up the ground or crust till it burst asunder, and thus form fissures for the escape of smoke, flames, and melted matter. That there are such immense caverns in the crust of the earth, has been argued mathematically by appealing to the irregularities, which have been observed in the vibrations of the pendulum in different countries.

Your disciplined imagination must now be directed to the thickness of the crust of the earth. It is computed that our globe is in diameter-that is, from its upper surface to its lower one, or from A to D-in round numbers, about 8,000 miles. The crust of the earth from A to B, has been mathematically shown to be at least four hundred miles in thickness. Were it even twice this thickness, its thickness would be consistent with the actual phenomena observed, and with che theory of universal fluidity at one time. It is, therefore easy to imagine that, in a crust of four hundred miles thick, it would be very practicable for deep and immense lakes, or larg seas, of melted matter to exist, and be widely distributed, in subterranean caverns, provided that they be so enclosed in the crust as to move with it in the daily rotation of the earth.

Mr. Hopkins, of Cambridge, the present President of the Geological Society, has endeavoured, by profound mathematical calculations on the nutation of the earth's axes, and on the precession of the equinoxes, to fix this thickness at 800 miles. This thickness may scarcely be admissible, since we do not know the condensing power of high pressure, and the expanding power of very intense heat. As this thickness is supposed to be extreme, geologists generally estimate the thickness of the crust, as inferred from experiments on the pendulum, &c., to be, in different countries, at from two to four hundred miles.

I have said that the comparisons which I have introduced might probably assist your conceptions of the geological crust; but they, like most analogies, do not represent the whole case. In the examples mentioned, the process of cooling goes on from the surface to the centre, until the whole mass, cinder, cavity, and drop, are all perfectly cooled down. This is not the geological theory about the earth's crust; for, if the process of cooling continued, the earth would become refrigerated or cooled to its very centre: and then there would be no heat under its crust. This process of cooling to the centre would take myriads of ages. Some geological chemists have en-voirs, forming a kind of lakes or seas. This hypothesis has deavoured to calculate that, from the known laws of radiation of heat, the complete cooling of the globe would take about two hundred millions of years.

Though the above instances of incrustations be imperfect, I want you to keep in mind the ideas of the cinder, the cavity, and the molten globule. Examine them; find any objections you can against them; but keep them in your mind. The principal difficulty in the above illustrations is that they will not account for the continuance of the heat under the crust. You must, therefore, try to imagine that the molten globule has some power of perpetuating its burning heat, though the crust above the cavity continues hard and cool. How can this be done? You must suppose that solid, fluid, or gaseous, elements form compound bodies, and that when these different elements pass into new combinations, the process is always accompanied with heat, and that the heat becomes intense, in proportion to the rapidity with which the combination is formed. Take an instance. Chemists inform us that if you take clean iron filings, and mix them with a larger quantity of sulphur, and with as much water as will form the whole into a kind of paste; and then bury the paste in the earth, and press the earth firmly on it; in a few hours the whole mass will

The argument of Mr. Hopkins, however, is only intended to show that, if the fusible nucleus, or kernel, of the earth be now in a state of fluidity, it must be at the depth of from 400 to 500 miles beneath the surface, and that, consequently, such a thickness is far too deep to account for volcanoes and earthquakes. Hence we are led to the inference, that the fluid matter which supplies actual volcanoes is not a molten ocean all round the centre of the earth, but large subterranean reserthe double advantage of accounting chemically for the fluid supplies of volcanoes, and mechanically for the phenomena of the elevation of mountains in past geological time, and for the laws which such elevations follow.

From the appearance of the engraving, in fig. 1, you are not to imagine that the globe is hollow from в to c. Various observations, and various experiments with the pendulum, have proved that our planet is not an empty sphere; but that its interior, whether fluid or solid, has a higher specific gravity than the materials of the crust. From the same experiments, it has been inferred, that there is a gradual and regular increase in its density from the surface down to the centre.

You are now concerned to know whether it can be proved that there is any heat under the crust of the earth. You wil. learn, in the course of these lessons, that the action of volcanoes, and the rise of hot springs, or thermal springs, to the surface, prove that there are subterranean sources of heat active somewhere. I will now only notice that it is well known that the temperature of the crust of the earth increases the deeper you descend into it. In the Northumberland coalpits, the heat of the rocks increases by one degree of Fahrenheit's thermometer for every 44 feet in descent.

In the lead

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