—that is, a form in which the materials are arranged in regular layers or strata. On account of this diversity in texture, the igneous are called Unstratified, and the aqueous Stratified rocks.

The theory that the earth's crust was formed, not all at once, but in successive portions and at successive periods, would seem to be verified, or at least supported, by the regular order in which the rocks overlie one another, as well as by the distinctive structure and composition of each group in the series.

The undermost part of the earth's crust often consists of granite and other unstratified rocks, all of which indicate, by their agglutinated texture and their unworn and angular crystals, that they were originally in a state of fusion. Immediately above this granitic mass are the metamorphic rocks, which likewise have a crystalline texture. The granitic and metamorphic rocks further resemble each other, in being what is called unfossiliferous—that is, in containing no fossils, no organic remains; a fact which also accords with the idea of fusion by heat.

Above this hard granitic and metamorphic basis the stratified rocks rise in an ascending series, comprehending three groups, which have the names of the Palæozoic, the Secondary, and the Tertiary rocks. The Paleozoic group, which is supposed to be next in age to the metamorphic, comprises the silurian rocks, the old red-sandstone, and the coal-measures. Here the crystalline texture, characteristic of the previous rocks, disappears, and a stratified texture takes its place, showing the operation, not of igneous, but of aqueous influences. Here also, as the name Paleozoic implies, we find the first traces of organic being. Fossils are abundant in the old red-sandstone; and in the coalmeasures, vegetable remains form the chief and peculiar ingredient. The Secondary rocks, like the Paleozoic, comprehend three systems-the new red-sandstone, the oolite, and the chalk. All these systems are fossiliferous; and it is in the oolite that we find the remains of those gigantic reptiles whose strange forms at once amaze the ignorant and interest the curious. The Tertiary group

presents us with organic remains not very dissimilar from the living creatures of our own era; for though the animals are often distinct from any with which we are now familiar, yet in structure they are allied to existing species. Judging from the rocks and their contents, the physical condition of the earth during the tertiary period cannot have very widely differed from its present condition.

The preceding description may help to convey some idea of the order in which the series of rocks which compose the crust of the earth were originally formed and arranged. The actual structure of the earth's crust, however, is something very different from that now described. The earth's crust is no longer "a granite nucleus surrounded by entire concentric coverings of stratified rocks like the coats of an onion." A great change has taken place in the position of many of the rocks. The earliest rocks are not always found lowest, nor the latest rocks highest. Some igneous rocks are found at the summit, instead of the bottom of the crust; and some aqueous rocks, in place of lying horizontally as at first, run obliquely in every direction. The fact would seem to be, that the igneous agencies concerned in the production of the unstratified rocks, did not cease to operate when these rocks had been formed, but continued at work during the gradual and successive depositions of the stratified rocks, breaking up and dislocating the superincumbent strata, and forcing upwards large portions of the granitic mass. Under the action of such disturbing forces, it was inevitable that the igneous rocks should, to some extent, be lifted from their original position at the base of the crust, and thrown up, in the shape of mountains and hills, through and above the stratified rocks; and it was equally inevitable that the stratified rocks, acted upon by volcanic agencies from below, should lose their horizontal position, and, in some instances, suffer disruption.

a, Unstratified rocks.

b, Stratified rocks.

c, Superficial deposits.

But it must not be supposed that the crust of the earth, though thus in various parts disrupted and disarranged, is now a scene of disorder. Though the stratified rocks no longer retain their horizontal position, but range in almost every direction, yet they are never found tossed hither and thither at random. They are always found in the order in which they were progressively formed. Everywhere, for example, the silurian rocks rest on the metamorphic and the old red-sandstone on the silurian. We never find the coalmeasures above the new red-sandstone, nor the chalk below the oolite. An orderly arrangement is everywhere discernible. Nor is it any disadvantage to the earth, considered as an abode for man, that the granitic rocks have been made to upheave and pierce the stratified rocks, so as to place both themselves and the latter, either on the earth's surface, or nearer it than before. It is, on the contrary, a great advantage. Apart from such upheaval and dislocation, the hard rocks, so valuable for architectural purposes, would have been beyond our reach; the metals would have remained for ever concealed in their native crypts; coal would have lain at an inaccessible depth; there would have been no hollows to contain the ocean, and no mountain-tops to attract the clouds. And where would have been our beautiful variety of hill and valley, of glen and stream? The earth's surface would have been a mere uniform level, without life or picturesqueness; its rivers mere sluggish canals; its whole aspect destitute of that mingled sweetness and grandeur which now makes it so glorious a mirror of Power, and Wisdom, and Goodness. Compiled.

THE LONG LIFE OF BOOKS.

THERE are two aspects under which we may regard language as a channel for communicating instruction and pleasure. One is Speech. How astonishing is it that a man may stand in the crowd of learned or ignorant, thoughtful or reckless hearers, and knock at the door of each heart in succession! Think how this wonder has been wrought already ;-by

Demosthenes waving the stormy democracy into a calm, from a sunny hillside; by Plato enchaining the souls of his disciples, under the boughs of a dim plane-tree; by Cicero in the stern silence of the Forum; by our own Chatham in the chapel of St. Stephen. They knocked and entered; wandered through the bosoms of their hearers; and aroused the passions in their lone concealment. The Athenian populace started up with one accord and one cry to march upon Philip; the Senate throbbed with indignation at Cataline; and the British Parliament was dissolved for a few hours, that it might recover from the wand of the enchanter.

But it is in the second manifestation of language that the most marvellous faculty resides. The Written outlives and outdazzles the spoken word. The life of rhetoric perishes with the rhetorician; it darkens with his eye, stiffens with his hand, freezes with his tongue. The bows of eloquence are buried with the archers. But literature is the immortality of speech. It embalms for all ages the departed kings of learning, and watches over their repose in the eternal pyramids of Fame. The sumptuous cities which have lighted the world since the beginning of time are now beheld only in the pictures of the historian or the poet. Homer rebuilds Troy, and Thucydides renews the war of the Peloponnesus. The dart that pierced the Persian breastplate moulders in the dust of Marathon; but the arrow of Pindar quivers, at this hour, with the life of his bow.

We look with grateful eyes upon this preservative power of literature, When the Gothic night descended over Europe, Virgil and Livy were nearly forgotten and unknown; but far away, in lone corners of the earth amid silence and shadow, the ritual of genius continued to be solemnized. Without, were barbarian, storm, and darkness; within, light, fragrance, and music. So the sacred fire of Learning burnt upon its scattered shrines, until torch after torch carried the flame over the world.

Art has been less happy in its self-protection. Fifty years ago, observers complained that the colour was gone from the "Cornaro Family" of Titian. The Helen of Homer

and the Faëry Queen of Spenser are safe from such a catastrophe. The coarsest rubbings of critical pens have left the features, and even the bloom of expression, unimpaired.

It is not pretended that the genius of the pen is safe from all casualties that beset his brother of the pencil. I have not forgotten Hume's letter to Robertson about the gentleman who, sending for a pound of raisins, received them wrapped up in the Doctor's highly-drawn character of Queen Elizabeth. Literature has its complaint as well as its pæan. The splendid libraries of Rome are consumed by fire, and the unknown treasures of Greece perish in the sack of Constantinople. Still the poet and the historian maintain their supremacy over the artist and the sculptor. A mob shatters into dust that statue of Minerva whose limbs seem to breathe under the flowing robe, and her lips to move; but the fierceness of the Goth, the ignorance of the Crusader, and the frenzy of the polemic, have not destroyed or mutilated Penelope and Electra. Apelles dies; Eschylus lives.

WILLMOTT.

THE SAXON AND THE GAEL.

So toilsome was the road to trace,
The guide, abating of his pace,
Led slowly through the pass's jaws,

And asked Fitz-James, by what strange cause
He sought these wilds, traversed by few,
Without a pass from Roderick Dhu?

"Brave Gael, my pass, in danger tried,
Hangs in my belt, and by my side:
Yet, sooth to tell," the Saxon said,
"I dreamt not now to claim its aid.

When here, but three days since, I came,
Bewildered in pursuit of game,