the stone. From these and other instances we find that solids, liquids, and aëriform bodies are impenetrable; that is to say, it is impossible for two solids, for a solid and a liquid, for two liquids, or for a liquid and air, to occupy the same space at the same instant of time.

There are cases, however, in which a condensation takes place, when two solids, two liquids, or two gases, are mixed together, so that less space is occupied by the two united than was occupied by them separately. For example, an alloy of copper and tin contracts a fifteenth part of their former bulk; and a mixture of water and alcohol is attended by a similar result. We are not, however, to infer from these instances, that there are any cases in which two bodies or portions of two bodies can occupy the same space at the same time, the diminution in bulk being thus explained :-Every body in nature is composed of an infinite number of small particles, at a certain distance from each other, so that, when a mixture is made between two substances, the particles of the one sometimes interpose themselves between the particles of the other; and thus two bodies, when mixed together, may occupy less space than they did before the mixture took place.

2. Write a short explanation of the following Natural Phenomena.

MODEL.-The Tides.

The tides of the ocean, one of the most striking of natural phenomena, are caused by the attractive power of the sun and moon upon its waters.

Let us, for the sake of illustration, suppose that the whole surface of the earth were covered with water,

and that no external influence were brought into operation. In that case, the water would necessarily remain everywhere at a uniform level. Let us bear in mind, however, that, by the universal law of gravitation, all bodies attract each other in a degree regulated by the distance between them, and we shall then see what effect such a body as the moon, situated as she is in respect to the earth, must have upon this supposed uniformity of level. While she absolutely attracts the whole mass of the earth, the waters lying immediately under her, being operated upon with greater intensity ́ than those that are more remote, rise in a heap, and thus form what is termed high water, or full tide. Again, the waters at the corresponding point of the opposite hemisphere, being evidently that part of the whole mass which is least subject to her attractive influence, are consequently drawn forward with less energy than the intervening portions; and, being thus left behind, accumulate in such a manner as to form a tide at the same time as that produced by the direct attraction of the moon. It is evident that low water must lie on both sides of the earth between the two elevations. It is also evident that we must have two tides in the course of the earth's revolution round its axis. This is accomplished in twenty-four hours; but, as the moon is in the meantime proceeding in her course, it is nearly an hour more before the earth returns to the same relative position. We have thus two tides in about twenty-five hours.

The sun, on account of its immense distance, affects the tides less than the moon does. When these two bodies attract the waters in unison, as at new and full moon, the tides are highest, and are thence named spring tides. When, on the other hand, their attraction is in opposition, that is to say, when the moon is in her first and third quarters, the tides are lowest, and are therefore denominated neap tides.

Write a short analytical illustration of the following Passages of Poetry.

MODEL.

Evening in Paradise.

"Now came still evening on, and twilight gray
Had in her sober livery all things clad;
Silence accompanied; for beast and bird,
They to their grassy couch, these to their nests
Were slunk, all but the wakeful nightingale,
She all night long her amorous descant sung;
Silence was pleased: now glow'd the firmament
With living sapphires: Hesperus, that led
The starry host, rode brightest, till the moon,
Rising in clouded majesty, at length,
Apparent queen, unveil'd her peerless light,
And o'er the dark her silver mantle threw."

In this passage, descriptive of night in Paradise, the poet appropriately represents the duskiness of twilight under the metaphor of a garment, whose subdued and uniform colour readily suggests a contrast to the brilliant and diversified hues of the gaudy day. The deep

and holy stillness of evening in that happy abode is next finely indicated rather than fully described. Beast and bird have retired to rest-the nightingale,` with her " amorous descant," alone remaining, not to disturb, but to charm the silence, which, by personification, is invested with the attributes of life.

The firmament, by a fine metaphor, is said to glow with "living sapphires," a figure strikingly expressive of the life-like motion and cerulean beauty of the stars. In the remainder of the passage, the metaphors cluster and sparkle like the objects they represent. Hesperus, the evening star, first displays his lustre, and, like the leader of a mighty army, rides with pre-eminent brightness among the heavenly host. The moon then rises, and, emerging from the clouds which at first shrouded her effulgence, shines forth in queenly majesty the unrivalled orb of night, and, throwing her radiance like a silver mantle over the darkness, the scene closes in a flood of splendour.

EXERCISES.

I.

Spring.

Come, gentle Spring! ethereal mildness! come!
And from the bosom of yon dropping cloud,
While music wakes around, veil'd in a shower
Of shadowing roses, on our plains descend!
And see where surly Winter passes off,
Far to the north, and calls his ruffian blasts!
His blasts obey, and quit the howling hill,
The shattered forest, and the ravag'd vale;
While softer gales succeed, at whose kind touch
Dissolving snows in livid torrents lost,
The mountains lift their green heads to the sky.
As yet the trembling year is unconfirm'd,
And Winter oft at eve resumes the breeze,
Chills the pale morn, and bids his driving sleets
Deform the day delightless; so that scarce
The bittern knows his time, with bill engulph'd
To shake the sounding marsh; or from the shore
The plovers when to scatter o'er the heath,
And sing their wild notes to the listening waste.

II.

The Evening Cloud.

A cloud lay cradled near the setting sun,
A gleam of crimson tinged its braided snow :
Long had I watched the glory moving on

O'er the still radiance of the lake below.
Tranquil its spirit seemed, and floated slow!
Even in its very motion there was rest;
While every breath of eve that chanced to blow,
Wafted the traveller to the beauteous west.
Emblem, methought, of the departed soul!

To whose white robe the gleam of bliss is given; And by the breath of mercy made to roll

Right onward to the golden gates of heaven, Where, to the eye of Faith, it peaceful lies, And tells to man his glorious destinies.

III.

A Comparison.

The lapse of time and rivers is the same.
Both speed their journey with a restless stream;
The silent pace with which they steal away,
No wealth can bribe, no prayers persuade to stay;
Alike irrecoverable both when past,

And a wide ocean swallows both at last.
Though each resemble each in every part,

A difference strikes at length the musing heart:
Streams never flow in vain; where streams abound,
How laughs the land with various plenty crowned!
But time, that should enrich the nobler mind,
Neglected leaves a dreary waste behind.

IV.

The Virtues.

O Thou! by whose Almighty nod, the scale
Of empire rises, or alternate falls,

Send forth the saving Virtues round the land,
In bright patrol; white Peace and social Love;
The tender looking Charity, intent