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hornblende takes the place of mica. Bunker Hill Monument, the Astor House in New York City, and the dry docks at the Charlestown and Gosport Navy-yards, are constructed of this rock. Granite is also found abundantly, and of the finest quality, in Virginia, Georgia, and other states.

3. There is an unstratified igneous rock, called porphyry, which is of a reddish color, and contains crystals of feldspar. Another compound rock is called pudding-stone. It is a conglomerate of rounded pebbles cemented together by finegrained sandy paste. When cut and polished, it resembles in appearance a slice of plum-pudding, and is much used for ornamental purposes.

4. Amygdaloid is a rock containing almond-shaped cavities. These cavities have been formed by the escape of gases as the rock cooled down from a melted state. The rock itself is evidently a kind of solidified lava, and the cavities have been subsequently filled with some mineral matter, as quartz, lime, or agate.

5. Breccia is composed of angular fragments which once constituted other rocks. It differs from pudding-stone in not having the fragments worn into the form of pebbles. The Potomac marble, of which fine specimens are seen in the old national Capitol at Washington, is a kind of breccia.1 Brecciated2 marble from Vermont and Tennessee have been extensively used in the interior of the new United States Capitol.

The composition of these rocks has been presented in the following recipes for GEOLOGICAL COOKERY:

6.

7.

8.

To make Granite.

Of feldspar and quartz a large quantity take,
Then pepper with mica, and mix up and bake.
This granite for common occasions is good;

But on saint's days and Sundays, be it understood,

If with bishops and lords in the state-room you dine,
Then sprinkle with topaz, or else tourmaline.

To make Porphyry.

Let silex and argil be well kneaded down,
Then color at pleasure, red, gray, green, or brown
When the paste is all ready, stick in here and there
Small crystals of feldspar, both oblong and square.
To make Pudding-stone.

To vary your dishes, and shun any waste,
Should you have any left of the very same paste,
You may make a plum-pudding; but, then, do not stint
The quantum of pebbles-chert, jasper, or flint.

9.

10.

11.

To make Amygdaloid.

Take a mountain of trap, somewhat softish and green,
In which bladder-shaped holes may be every where seen;
Choose a part where these holes are decidedly void all,
Pour silex in these, to form agates spheroidal,

And the mass in a trice will be amygdaloidal.

To make a good Breccia.

Break your rocks in sharp fragments, preserving the angles;
Of mica or quartz you may add a few spangles;

Then let your white batter be well filtered through,
Till the parts stick as firm as if fastened by glue.
To make a coarser Breccia.

For a breccia more coarse you may vary your matter;
Pound clay, quartz, and iron-stone, moistened with water:
Pour these on your fragments, and then wait a while,
Till the oxyd of iron is red as a tile.

1 BREC'-CIA (pronounced Brek'-sha).

2 BREC'-CIA-TED (pronounced Brek'-she-at-ed).

LESSON XVII.—BRIEF EXTRACTS.

1. "GEOLOGY, in the magnitude and sublimity of the objects of which it treats, undoubtedly ranks next to astronomy in the scale of the sciences."—SIR J. F. W. HERSCHEL.

2. "Every rock in the desert, every boulder on the plain, every pebble by the brook side, every grain of sand on the sea-shore, is replete with lessons of wisdom to the mind that is fitted to receive and comprehend their sublime import.'

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3. "The very ground on which we tread, and the mountains which surround us, may be regarded as vast tumuli, in which the organic remains of a former world are enshrined.” -PARKINSON.

4. "To the natural philosopher the rocks and the mountains are the grand monuments of nature, on which is inscribed the history of the physical revolutions of the globe, which took place in periods incalculably remote, and long antecedent to the creation of the human race. They present to his mind a succession of events, each so vast as to be beyond his finite comprehension; ages of tranquillity, with lands and seas teeming with life and happiness, succeeded by periods in which the earthquake and the volcano spread universal ruin and destruction; and they teach him that all these awful changes bear the impress of the ALMIGHTY hand, and were subservient to the eternal purpose of rendering this planet the fit abode of MAN during his mortal pilgrimage."-MANTELL.

LESSON XVIII.—CONCLUDING REMARKS.

[From the conclusion of MANTELL's Wonders of Geology.]

1. WITH these remarks, I conclude this attempt to combine a general view of geological phenomena with a familiar exposition of the inductions by which the leading principles of the science have been established. And if I have succeeded in explaining in a satisfactory manner how, by laborious and patient investigation, and the successful application of other branches of natural philosophy, the wonders of geology have been revealed-if I have removed but from one intelligent mind any prejudice against scientific inquiries which may have been excited by those who have neither the relish nor the capacity for philosophical pursuits-if I have been so fortunate as to kindle in the hearts of others that intense and enduring love and admiration of natural knowledge which I feel in my own, or have illuminated the mental vision with that intellectual light which, once kindled, can never be extinguished, and which reveals to the soul the beauty, and wisdom, and harmony of the works of the Eternal, I shall indeed rejoice, for then my exertions will not have been in vain. And although my humble name may be soon forgotten, and all record of my labors be effaced, yet the influence of that knowledge, however feeble it may be, which has emanated from my researches, will remain forever, and, by conducting to new and inexhaustible fields of inquiry, prove a never-failing source of the most pure and elevated gratification. 2. It is indeed the peculiar charm and privilege of natural philosophy that it

Can so inform

The mind that is within us so impress

With quietness and beauty, and so feed
With lofty thoughts, that neither evil tongues,
Rash judgments, nor the sneers of selfish men,

Nor greetings where no kindness is, nor all

The dreary intercourse of common life,

Can e'er prevail against us, or disturb

Our cheerful faith, that all which we behold

Is full of blessings!-WORDSWORTH.

For to one imbued with a taste for natural science, Nature unfolds "her hoarded poetry and her hidden spells;" for him there is a voice in the winds and a language in the waves, and he is

Even as one

Who, by some secret gift of soul or eye,

In every spot beneath the smiling sun,

See where the springs of living waters lie!-HEMANS.

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EDGAR A. POE. 1. ONCE upon a midnight dreary, while I pondered weak and weary, Over many a quaint and curious volume of forgotten loreWhile I nodded, nearly napping, suddenly there came a tapping, As of some one gently rapping, rapping at my chamber door. ""Tis some visitor," I muttered, "tapping at my chamber door-Only this and nothing more."

2. Ah! distinctly I remember it was in the bleak December,
And each separate dying ember wrought its ghost upon the floor.
Eagerly I wished the morrow; vainly I had sought to borrow
From my books surcease of sorrow-sorrow for the lost Lenore-

For the rare and radiant maiden whom the angels name Lenore-
Nameless here for evermore.

3. And the silken sad uncertain rustling of each purple curtain
Thrilled me-
-filled me with fantastic terrors never felt before;
So that now, to still the beating of my heart, I stood repeating,
""Tis some visitor entreating entrance at my chamber door-
Some late visitor entreating entrance at my chamber door;

This it is and nothing more.

4. Presently my soul grew stronger; hesitating then no longer,
"Sir," said I, "or madam, truly your forgiveness I implore;
But the fact is I was napping, and so gently you came rapping,
And so faintly you came tapping, tapping at my chamber door,
That I scarce was sure I heard you"-here I opened wide the door-
Darkness there and nothing more.

5. Deep into that darkness peering, long I stood there wondering, fearing,
Doubting, dreaming dreams no mortal ever dared to dream before;
But the silence was unbroken, and the stillness gave no token,
And the only word there spoken was the whispered word "Lenore?"
This I whispered, and an echo murmured back the word "Lenore !”—
Merely this and nothing more.

6. Back into the chamber turning, all my soul within me burning,
Soon again I heard a tapping something louder than before.
"Surely," said I, "surely that is something at my window lattice;
Let me see, then, what thereat is and this mystery explore-
Let my heart be still a moment and this mystery explore-

"Tis the wind and nothing more.

7. Open here I flung the shutter, when, with many a flirt and flutter,
In there stepped a stately raven of the saintly days of yore.
Not the least obeisance made he; not a minute stopped or stayed he;
But, with mien of lord or lady, perched above my chamber door-
Perched upon a bust of Pallas just above my chamber door-

Perched, and sat, and nothing more.

8. Then this ebony bird beguiling my sad fancy into smiling, By the grave and stern decorum of the countenance it wore, "Though thy crest be shorn and shaven, thou," I said, "art sure no craven,

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Ghastly grim and ancient raven wandering from the nightly shore—
Tell me what thy lordly name is on the night's Plutonian shore!"
Quoth the raven, "Nevermore.”
9. Much I marveled this ungainly fowl to hear discourse so plainly,
Though its answer little meaning-little relevancy bore;
For we can not help agreeing that no living human being
Ever yet was blessed with seeing bird above his chamber door-
Bird or beast upon the sculptured bust above his chamber door,
With such name as 66 Nevermore."

10. But the raven, sitting lonely on that placid bust, spoke only
That one word, as if his soul in that one word he did outpour.
Nothing farther then he uttered-not a feather then he fluttered—
Till I scarcely more than muttered, "Other friends have flown before-
On the morrow he will leave me, as my hopes have flown before."

Then the bird said "Nevermore."

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