it is said to be in stable equilibrium, and the stability is proportional to the rise of the centre of gravity which would thus ensue; if such motion causes the centre of gravity to fall, it is said to have unstable equilibrium; and if its centre of gravity neither rises nor falls by moving it, its equilibrium is said to be indifferent. A pyramid standing on its base has stable equilibrium; but if it is inverted, and made to rest on its apex, its equilibrium is then unstable. A sphere, resting on a horizontal plane, has indifferent equilibrium, for its centre of gravity being coincident with its centre of magnitude, it always retains the same distance from the supporting point.

The positions of tight-rope dancers are maintained by paying due regard to the position of the centre of gravity. The feet and the space between them form the supporting base of a man. Peculiarities in the gait of certain persons are owing to the necessity every one is under of keeping the vertical line from the centre of gravity of his body within the supporting base. Hence a corpulent person, or one carrying a load in his arms, throws his head backward; a porter, carrying a load on his back, leans forward; and any one carrying a load under one arm inclines to the opposite side. A person, on rising from a chair, throws the head forward to bring his centre of gravity over his feet.

If a body has great cohesion in its separate parts, a considerable portion of it may overhang the base without falling. The tower of Pisa, which is one hundred and thirty feet high, overhangs its base sixteen feet, but its centre of gravity is within the base. Such bodies, however, have an uncouth and deformed appearance; beauty of form in architecture, as well as of grace and attitude in the person, are only attainable by maintaining the centre of gravity in such a position that the vertical line from it falls, as nearly as possible, in the centre of the supporting base.

LESSON XXVIII.-WEDNESDAY.

NOAH AND THE DELUGE.

At length a reverend sire among

them came, And of their doings great dislike declared, And testified against their ways. He oft

Frequented their assemblies, whereso met,
Triumphs or festivals, and to them preach'd
Conversion and repentance, as to souls
In prison, under judgments imminent.
But all in vain: which, when he saw, he ceased
Contending, and removed his tents far off.
Then from the mountain hewing timber tall,
Began to build a vessel of huge bulk,

Measured by cubit, length, and breadth, and height,
Smear'd round with pitch; and in the side a door
Contrived; and of provisions laid in large,
For man and beast: when, lo, a wonder strange!
Of every beast, and bird, and insect small,

Came sevens, and pairs, and entered in, as taught
Their order last, the sire and his three sons,

:

With their four wives; and God made fast the door.
Meanwhile the south wind rose, and with black wings
Wide hov'ring, all the clouds together drove
From under heaven; the hills to their supply
Vapour and exhalation, dusk and moist,
Sent up amain. And now the thicken'd sky

Like a dark ceiling stood; down rushed the rain
Impetuous, and continued till the earth
No more was seen. The floating vessel swam
Uplifted, and secure with beaked prow,
Rode tilting o'er the waves: all dwellings else
Flood overwhelmed, and then, with all their pomp,
Deep under water roll'd; sea covered sea—
Sea without shore; and in their palaces,
Where luxury late reigned, sea monsters whelp'd
And stabled. Of mankind, so numerous late,

All left, in one small bottom swam embark'd.-Milton.

LESSON XXIX.—THURSDAY.

ENGLISH HISTORY-PLANTAGENET LINE.

John was nominated, by the will of his brother, heir to the throne ; but a rival appeared in the person of Arthur, the son of his elder brother Geoffrey, duke of Brittany, whose claims were supported by the king of France, and acknow

ledged by all the continental dominions of John. During the conflicts which followed, Arthur fell into the hands of his uncle, who cruelly murdered him. This atrocious deed excited just execration, and cost its cowardly perpetrator a third of his dominions. All the French provinces, with the exception of Guienne, were claimed by the king of France, and annexed to his crown.

John was next involved in a quarrel with Rome. He had appointed the bishop of Norwich to the see of Canterbury, in opposition to the wishes of the monks, who appealed to the Pope. Innocent III. declared the election void, and required them to choose Stephen Langton. John, rash as cowardly, at first refused, and braved the anger of the pontiff, who laid his kingdom under an interdict, excommunicated him, and invited the aid of Philip of France to depose him. Alarmed at the prospect of invasion, and aware of the disaffection of his people, John relented, and submitted to the most degrading conditions of peace, consenting to hold his kingdom as a vassal of Rome.

The foreign contests of John had produced nothing but disgrace and loss; and it was reserved for him to suffer equal shame at home. His vices and imbecility had made him an object alike of hatred and contempt. The arbitrary and oppressive character of his government rendered it at length insupportable. A powerful confederacy was formed against him, of all the great barons and prelates of his kingdom, who presented a statement of their grievances and wants, and prepared to support their petition by force. John, as usual, at first refused, then evaded, and finally was compelled to yield to their demands. The army of the barons contained two thousand knights, and armed men in proportion. The hostile parties met at Runnymede, on the banks of the Thames, and here was wrested from the unwilling and faithless monarch, that Charter which secured to all classes of the people liberties greater than they had ever enjoyed before, and laid the foundation of the free constitution of England. Magna Charta, as it is still called, reflects, on the otherwise ignominious reign of John, a lustre which renders it one of the brightest spots in the history of our country. The death of John occurred at a

E

very critical period. Exasperated by his perfidy, the barons offered the crown to Louis, son of the king of France, who came over to England with a fleet and army to obtain it. Great numbers of the nobility and common people flocked to his standard, and his success was only prevented by the sudden death of the tyrant at Newark, A.D. 1216.

After the death of John, his son, a child of ten years old, was crowned in 1216 by the title of Henry III., and the earl of Pembroke was appointed governor of the kingdom during his minority. The regent was a man of energy and prudence. He confirmed Magna Charta, and promised pardon to all who should return to their allegiance. Many embraced the offer and deserted Louis, who afterwards suffered a signal defeat at Lincoln, and was compelled to leave the country. The earl of Pembroke died in the following year, and was succeeded in his office by Hubert de Burgh. For several years, Hubert ruled with undivided power; but, at length, the favour of the king declined, and charges of peculation and other crimes were made against him. He fled to sanctuary, was driven from it, and imprisoned in the castle of Devizes, from which he escaped to Wales. After many reverses, he was finally restored to his estates, but took no share in public affairs. The bishop of. Winchester, who had replaced Hubert in office, was a Poitevin, and so much offended the English by the preference of his own countrymen, that the barons revolted, and the primate threatened to excommunicate the king, unless the foreigners were banished. The king yielded, the bishop was dismissed, and his countrymen sent home. The marriage of Henry, to Eleanor of Provence, in 1236, renewed the grievance. So many of the queen's relations obtained rich preferment in the Church and State, that general discontent was caused. An expedition to France, for the recovery of Normandy, ended in defeat. The Pope soon after offered the crown of Naples to Henry for one of his sons, and he embarked for Italy with an army to conquer that kingdom. The expedition was unsuccessful, and Henry returned, impoverished by the expenses of war, to meet a people alienated by his prodigality, extortion, and incapacity, and determined to obtain redress. The parliament met, a committee of govern

ment was appointed to maintain the laws, and to enforce the observance of the Great Charter. These guardians of the realm were twenty-four in number, and their administration continued for several years. Henry then attempted to escape from their restraint;-the dispute was referred to the king of France; but his decision did not satisfy the barons. A civil war ensued. Success at first fell to the side of the barons, whose leader, Simon de Montfort, introduced a memorable reform in the constitution of parliament, by summoning for the first time, in 1265, representatives of towns along with the knights and clergy. Prince Edward afterwards retrieved his father's fortunes at the battle of Evesham, in which De Montfort was slain. Henry III. died in 1272.

LESSON XXX.-FRIDAY.

MIRACLES.

The founder of Christianity, and the first preachers of it to the world at large, claim the power of working miracles; as being that special supernatural interposition, which was to accredit them to mankind in the character of messengers indeed sent from God. That the claim was made, is indisputable and, in the very nature of things, either the claim would not have been made, if the power had not been possessed; or, if it had been made unsuccessfully, the whole scheme of thus recommending the Gospel must have proved abortive. For would any man of common sense risk the failure of his entire plan, by claiming a power, which, all the while, he knew that he did not possess; or, if he were induced to act a part of such consummate folly, would not his want of success in performing a miracle involve of necessity the ruin of his project?

The persons, before whom their alleged miracles were wrought, afford another argument for the real performance of something which, at least, appeared to be out of the common course of nature. Whatever deeds they performed, they performed them before enemies, not before friends; before persons prejudiced against them, not before persons prepossessed in their favour. Would any reasonable being make such an attempt, when, if an impostor, he could scarcely.