be used, the power will balance three times as much, and so on. In this machine the advantage is greatly diminished by the friction of the axles and the want of pliancy in the ropes. It may be regarded, as to principle, either as a modification of the lever, or as a distinct mechanical power.

The Inclined Plane is used for the purpose of facilitating the raising of great weights. It is evidently much easier to roll a cask along a plank into a waggon, than to raise it from the ground. In the inclined plane an equilibrium is produced when the power is to the weight as the height of the plane is to the length of its sloping side; but as the friction in the use of this machine is very great, a much less power than that found by calculation will keep a body in equilibrium, and a much greater power will be requisite to draw it upwards.

The Wedge is a well-known mechanical power. The law of its equilibrium is that the power should be to the weight as half the length of the back is to the length of one of the sides; but, on account of friction and other causes, no law can be stated as universally accurate. In real practice all that we can say is, that the less the breadth of the back in proportion to the length of the side, the greater is the advantage. Nature, whose works uniformly display the utmost wisdom in their design, has formed the beaks of birds wedge-shaped for the purpose of enabling them to dig into the ground, &c. The figure of a bird, too, is similarly fitted for cleaving the air, as is also that of the breast-bones of waterfowl. May not the shape of boats and ships have been first suggested by the shape of these animals? A grand military evolution of the ancients was that of forming a battalion into the shape of a wedge; and many instances occur in history of an enemy's line having been broken by this contrivance.

The principle of the Screw is the same as that of the inclined plane. The weight, instead of proceeding straight forward, moves in a spiral form, gradually ascending to the top; and the equilibrium is calculated in the same manner as in the inclined plane.

GREECE.

BYRON.

Clime of the unforgotten brave!

Whose land from plain to mountain-cave
Was Freedom's home or Glory's grave-
Shrine of the mighty! can it be,
'That this is all remains of thee!
Approach, thou craven crouching slave-
Say, is not this Thermopyla ?
These waters blue that round you lave,
Oh, servile offspring of the free-
Pronounce what sea, what shore is this!—
The gulf, the rock of Salamis !

These scenes their story not unknown-
Arise, and make again your own ;
Snatch from the ashes of your sires
The embers of their former fires !
And he who in the strife expires,
Will add to theirs a name of fear,
That tyranny shall quake to hear,
And leave his sons a hope, a fame,
They too will rather die than shame :
For Freedom's battle once begun,
Bequeathed by bleeding sire to son,
Though baffled oft, is ever won.
Bear witness, Greece, thy living page!
Attest it many a deathless age!
While kings in dusty darkness hid
Have left a nameless pyramid,

Thy heroes-though the general doom
Hath swept the column from their tomb,
A mightier monument command-
The mountains of their native land!
There points thy Muse to stranger's eye
The graves of those that cannot die!

"Twere long to tell, and sad to trace,
Each step from splendour to disgrace;
Enough, no foreign foe could quell
Thy soul, till from itself it fell;
Yes! self-abasement paved the way
To villain-bonds and despot-sway.

POMPEII.

The shroud of years thrown back, thou dost revive,
Half-raised, half-buried, dead, yet still alive!
Gathering the world around thee, to admire
Thy disinterment, and with hearts on fire,
To catch the form and fashion of the time
When Pliny lived, and thou wert in thy prime ;
So strange thy resurrection, it may seem
Less waking life than a distressful dream.

Hushed is this once-gay scene, nor murmurs more
The city's din, the crowd's tumultuous roar,
The laugh convivial, and the chiming sound
Of golden goblets with Falernian crowned;
The mellow breathings of the Lydian flute,
And the sweet drip of fountains as they shoot
From marble basements-these, all these are mute.
Closed are her springs, unnumbered fathoms deep,
Her splendid domes are one dismantled heap,
Her temples soiled, her statues in the dust,
Her tarnished medals long devoured by rust;
Its rainbow-pavements broken from the bath,
The once-thronged Forum-an untrodden path;
The fanes of love-forgotten cells; the shrines
Of vaunted gods-inurned in sulphur-mines;
The abodes of art, of luxury, and taste—
Tombs of their once-glad residents-a waste,
O'er which compassionate years have gradual thrown
The trailing vine, and bade the myrtle moan.

The invention of optical instruments is one of the most valuable contributions which individual ingenuity has made to the general welfare. Not to mention spectacles (invented, it is said, by a Florentine of the name of Salvino, in the beginning of the 14th century), one of the most beneficial discoveries ever made for a large portion of mankind—let us consider the telescope and the microscope. The son of a spectacle-maker of Middleburg, in Holland, happening to amuse himself in his father's shop, by holding two glasses between his finger and his thumb, and varying their distance, perceived the weathercock of the church-spire opposite to him much larger than ordinary, and apparently much nearer, and turned upside down. This new wonder excited the amazement of the father. He adjusted two glasses on a board, rendering them moveable at pleasure; and thus formed the first rude imitation of a perspective-glass, by which distant objects are brought near to view. Galileo, a philosopher of Tuscany, hearing of the invention, set his mind to work in

order to bring it to perfection. He fixed his glasses at the end of long organ-pipes, and constructed a telescope, which he soon directed to different parts of the surrounding heavens. He discovered four moons revolving round the planet Jupiter-spots on the surface of the sun, and the rotation of that globe around its axis-mountains and valleys in the moon-and numbers of fixed stars where scarcely one was visible to the naked eye. These discoveries were made about the year 1610, a short time after the first invention of the telescope. Since that period this instrument has passed through various degrees of improvement, and, by means of it, celestial wonders have been explored in the distant spaces of the universe, which, in former times, were altogether concealed from mortal view.

The telescope may be considered as a vehicle for conveying us to the distant regions of space. By the aid of Dr. Herschel's telescope, which magnifies 6,000 times, we can view the magnificent system of the planet Saturn as well as if we had performed a journey 800,000,000 miles in the direction of that globe, which, at the rate of 50 miles an hour, it would require a period of 1,800 years to accomplish; by the same instrument we can contemplate the regions of the fixed stars, their arrangement into systems, and their immense numbers, with the same amplitude of view as if we had actually taken a flight of 4,000,000,000,000 miles into these unexplored regions, which could not be accomplished in several millions of years, though our motion was as rapid as that of a ball projected from a cannon. This instrument has, therefore, been justly described, when it has been called "a providential gift bestowed upon mankind, to serve as a temporary substitute for those powers of rapid flight with which Seraphim are endowed, and with which man himself may be invested when he arrives at the summit of moral perfection."

Not less wonderful are the discoveries of the microscope, an instrument constructed on similar principles, for the purpose of examining minute objects. When and by whom this