merous. In these, petrifactions first make their appearance, and they usually consist of species of corals and zoophytes, which do not at present exist, and are therefore supposed to be extinct. Fletz rocks are disposed in flat or horizontal strata. They contain abundance of petrifactions; and these much more various in their nature than those which occur in the transition formations, consisting of shells, fish, and plants. The alluvial formations constitute the great mass of the earth's surface. They have been formed by the gradual action of rain and river water upon the other formations. They consist of the component parts of previously existing rocks, separated by the influence of air, moisture, and change of temperature, and deposited in beds. Sand, gravel, loam, and petrifactions of animals and vegetables, are often found in this class. Volcanic formations are pseudovolcanic, or such minerals as are altered in consequence of the burning of beds of coal situated in their neighbourhood; and true volcanic, or such as are actually thrown from the crater of a volcano.

The expansion of water in the pores or fissures of rocks by heat, or congelation, is a physical cause of the separation of their parts. The solvent power of moisture exerted upon alkaline or calcareous matter, in rocks, is another cause of their decomposition. Electricity, which is shown, by experiments with the voltaic apparatus, to be a most powerful agent of decomposition, seems to assist in all these changes; electrical powers being almost constantly exhibited in the atmosphere. The production of a bed for vegetation is effected by the decomposition of rocks. As soon as the rock begins to be softened, the seeds of lichens, which are constantly floating in the air, make it their resting-place. Their generations occupy it, till a finely-divided earth is formed, which becomes capable of supporting mosses and heath: acted upon by light and heat, these plants imbibe the dew, and convert constituent parts of the air into nourishment. Their death and decay afford food for a more perfect species of vegetable; and, at length, a mould is formed, in which even the trees of the forest can fix their roots, and which is capable of rewarding the labours of the cultivator, The decomposition of rocks tends to the renovation of soils, as well as their cultivation. Finely-divided matter is carried by rivers from the higher districts to the low countries, and

alluvial lands are usually extremely fertile. The quantity of habitable surface is constantly increased by these operations; precipitous cliffs are gradually made gentle slopes, lakes are filled up, and islands are formed at the mouths of great rivers. In these series of changes, connected with the beauty and fertility of the surface of the globe, small quantities of solid matter are carried into the sea; but this seems fully compensated for by the effects of vegetation in absorbing matter from the atmosphere, by the production of coral rocks and islands in the ocean, and by the operation of volcanic fires.

What does not fade? the tower, that long had stood
The crash of thunder, and the warring winds,
Shook by the slow but sure destroyer, Time,
Now hangs in doubtful ruins o'er its base;
And flinty pyramids and walls of brass.
Descend; the Babylonian spires are sunk;
Achaia, Rome, and Egypt, moulder down.
Time shakes the stable tyranny of thrones,
And tottering empires rush by their own weight.
This huge rotundity we tread grows old,
The sun himself shall die, and ancient night
Again involve the desolate abyss. ARMSTRONG.

QUESTIONS.-1. What is the basis of Werner's classification of rocks? 2. Into what five classes does he divide them? 3. What is said of primitive rocks? 4. Transition? 5. Fletz? 6. Alluvial? 7. Volcanic? 8. How does the decomposition of rocks produce a bed for vegetation? 9. Tend to the renovation of soils? [NOTE. Some knowledge of geology is daily becoming more necessary, for without it, scarce a volume of travels or topography, a review or a journal, can be read with all the interest it demands. The structure of the country and the stratification of its mountains, are now as often and as minutely described, as the plants and the animals which are found upon their acclivities.]

LESSON 86.

Biographical Sketch of Linnæus.

CHARLES LINNEUS, the founder of modern botany, was born in 1707, at a small village in Sweden, where his father

resided as a clergyman. His father was attached to his gar, den, which he had stocked with some of the rarer plants in that climate, and it is to the delight with which this spot inspired Charles, from his earliest childhood, that he himself ascribes his botanical passion. He was not distinguished for his proficiency in the ordinary studies of a lite rary education; but he made a rapid progress in the knowledge of plants, which he ardently pursued, both by frequent excursions in the fields, and by the unwearied perusal of such books on the subject as he was able to procure. When his father, who designed him for his own profession, came to the seminary, at which he was placed, for the purpose of inquiring into his improvement, he was much mortified to find his son declared utterly unfit for a learned profession by the tutors, who advised that he should be put to some manual occupation. In this perplexity he applied to the physician, Rothman, who was also lecturer in natural philosophy. This person discovered in young Linnæus, talents, which, though not fitted to make him a theologian, were not ill adapted for another profession, and he proposed that of a physician. He took the youth gratuitously into his own house, gave him private instructions, and put him into a systematic method of studying botany.

In 1727, Linnæus entered the University of Lund. He lodged in the house of Stobaeus, a physician, who possessed a good library, and a museum of natural history. He paid for his entertainment by various little services, and it was only by accident that his host came to know the extent of his studious ardour. The mother of Stobaeus having observed that the candle in his chamber was burning at unseasonable hours, was induced, through fear of fire, to complain of it to her son. Stobaeus, therefore, entered his chamber at a late hour, and found him diligently occupied with reading. Struck with this proof of his thirst after improvement, he gave Linnæus the free use of his library, and admission to his table. The advice of Rothman, however, caused him, in 1728, to quit Lund, and to remove to Upsal, for the sake of the superior advantages it afforded. His father advanced him the sum of about eight pounds sterling, which he was informed was all the paternal assistance he was to expect. Thus he was turned out upon the world while yet but a learner in the profession by which he was to obtain his bread. His

little patrimony was soon exhausted, and he was reduced to depend upon chance for a meal. Unable to pay even for the mending of his shoes, he was obliged to patch them himself with folded paper.

At length, in the autumn of 1729, as he was intently examining some plants in the garden of the university, he was accosted by Celsius, professor of divinity, and an eminent naturalist, who was then engaged in preparing a work on the plants mentioned in the scripture. A little conversation soon apprised him of the extraordinary botanical acquisitions of the student, and perceiving his necessitous circumstances, he took him to live in his own house. It was in this year that Linnæus conceived the idea of a new systematic arrangement of plants. He drew up a treatise, which was shown to Celsius, and by him to the botanical professor, who had the liberality to bestow on it his warmest approbation. As the professor's advanced age made him desirous of an assistant in the office of lecturing, Linnæus was appointed. He was afterwards invited by the Academy of Sciences at Upsal, to explore the cold regions of Lapland, and the alacrity with which this proposal was accepted, and the faithfulness with which the objects of his journey were secured, were equally creditable to his zeal and perseverance. He visited Holland, and the most richly stored gardens of England and France. The great object of his wishes had always been the professorship of botany at Upsal, and through the kindness of an eminent Swedish statesman, he at length was chosen to that station, and he entered upon the duties of his office in the autumn of 1741. His increasing fame attracted students from every quarter, among whom were several, who imbibed, and diffused throughout the civilized world, a taste for the science over which Linnæus presided.

His father who had so often grieved at the perverseness of his son's disposition for hunting after plants and insects, fortunately lived to see him, not only professor of botany, but dean of the College of Physicians at Upsal, caressed by the noblemen of Sweden, and honoured by all the learned men of Europe. His opulence was such as to enable him to purchase an estate near Upsal, which was his chief summer residence during the last fifteen years of his life. His views of nature impressed him with the most devout sentiments towards its author, and a glow of unaffected piety is conti

nually breaking forth throughout his writings. A general mourning took place at his death, in 1778, and his body was attended to the grave with every token of respect.

QUESTIONS.-1. To what circumstance does Linnæus ascribe his passion for botany? 2. What is said of his early proficiency? 3 How was his thirst for improvement discovered at the University of Lund? 4. What is said of his pecuniary means on his removal to Upsal? 5, In what manner did he come into notice at Upsal? 6 By what means was a taste for natural history diffused throughout the civilized world?

LESSON 87.

Study of Botany.

BOTANY is that branch of natural history which treats of the vegetable kingdom. The study of this science is not a trifling employment, undeserving the time and attention bestowed upon it. Can we for a moment conceive that the works of God are unworthy the attention of man ?—that those productions which bear such evident marks of the wisdom and power of the Creator, are too contemptible for the examination of his creatures? Whoever has had the curiosity to crop the humblest flower of the field, and to observe the wonderful conformation of its parts, combining the united purposes of elegance and utility, will not hastily despise the study of nature. But when these observations are extended through the immense variety of productions which compose the vegetable kingdom; when the different offices of each particular part of the plant, every one essentially contributing towards its existence and propagation, are con sidered; when we advert to the variety of modes by which these ends are effected, and the infinite contrivance which is exhibited in their accomplishment, a wide field for instruction and admiration is opened before us.

We need not labour to prove how delightful and instructive it is to

"Look through nature up to nature's God;"

neither, surely, need we attempt to show, that if any judicious or improved use is to be made of the natural bodies