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long the flat, the rocky bottom, shoals, reefs, and islands. Rocks are those stony masses which form a portion of the substance of the globe, and are generally disposed in ranges, like mountains, but in some few instances are found to exist in large and separate masses. Rocks are divided into five classes which are called formations ; as, primitive, transition, fletz, alluvial, and volcanic. (1.) Primitive are the class of rocks on which all others rest, whose texture is more or less crystalline, a quality denoting previous chemical solution. They comprehend granite, gneiss, mica-slate, talc-slate, hornblende slate, syenite, porphyry, serpentine, and lime-stone. (2) Transition rocks are principally composed of chemical productions. Lime-stone occurs more frequently in this, than in the preceding class. These rocks were formed during the transition of the earth into a habitable state ; they differ from the primitive in the variety of their colour, and by containing the remains of marine animals. (3.) Fletz rocks disposed in flat, or horizontal strata, after the creation of animals and vegetables, the remains of which are often found in the substance of these rocks. (4.) Alluvial rocks are formed by the component parts of previously existing rock, separated by the influence of air, water, and change of temperature, and deposited in beds.
Sand, gravel, loam, and petrifactions of animals and vegetables, are often found in this class. (5.) Volcanic formations are pseudo-volcanic, or such minerals as are altered in consequence of the burning of beds of coal in the nigh bourhood; and true-volcanic or such as are actually thrown from the crater of the volcano. The volcanic productions are: (1.) Pumice-stone, a kind of glass, in the form of small greyish, white, and exceedingly brilliant filaments. It is often lighter than water. (2.) Lava, the burning matter which runs down, in such prodigious quantities, from volcanos, when in a state of eruption, and often extends to a great distance. This matter is a semi-vitrified substance, and appears of a blackish cast. (3.) Basaltes is blackish and opaque, and may by the action of heat, be converted into glass, of a very beautiful black colour. Of some kinds, such as that known under the name of touchstone, the grain is exceedingly fine.
10. Decomposition of Rocks. The expansion of water
in the pores or tissures 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 maiter, 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.
11. The decomposition of rocks tends to the renovation of soils, as well as their cultivation. Finely divided matter iş carried by rivers from the higher districts to the low countries, and alluvial lands are usually extremely fertile. The qnantity 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.
12. The science of geology, independently of the healthy employment it affords, is of great importance in a practical point of view. It very nearly concerns the miner, engineer, and drainer, and even the fariner and architect; and discloses a variety of indications highly useful in their respective pursuits: to the miner, the rocks containing metallic veins and coals; to the engineer, the association of hard rocks with soft; to the drainer, the intersection of a country by hard dykes, or veins inpermeable to water; to the farmer, the best places for finding lime-stone, marle, and clay; and to the architect, the most durable stones for buildings.' The person who is attached to geological inquiries, can scarcely ever want objects of employment and of interest. The ground on which he treads—the country which surrounds him-and even the rocks and stones removed from their natural position by art, are all capable of affording some degree of amusement. 'Every new mine or quarry that is opened, every new surface of the earth that is laid bare, and every new country that is discovered, offers to him novel sources of information. In travelling, he is interested in a pursuit which must constantly preserve the mind awake to the scenes presented to it; and the beauty, the majesty, and the sublimity of the great forms of nature, must necessarily be enbanced by the contemplation of their order, their mutual dependence, and their connexion as a whole.
13. Oryctology, is the science which teaches the natural history of those animal and vegetable substances, which are dug out of the earth in a mineralised state. By this science, we obtain not only a knowledge of the peculiar beings which dwelt on this planet in its antediluvian state, but we also acquire a more correct knowledge of the structure of the globe itself. : Among these we find the remains of several animals not known to exist : such as the BELEMNÍTE, part of a chambered shell, but formerly thought to be a thunderbolt ; the ENCRINITE, an animal, formerly termed a stone lily; the Cornu 'AMMONIS, a shell, formerly considered as a peir fied snake ; the MaMMOTH, an aniinal resembling the elephant, but possessing grinders much like to those of carnivorous animals, with ntimerous others yielding additional proofs of the wisdom and power of the great Creator of all things.
Select Books on the Mineral Kingdom. Kirwan's Mineralogy, svo. Accum's Analytical Mineralogy, 2 vols. 12mo. Kirwan's Geological Essays, svo. Parkinson's Organic Remains of a former World, 3 vols. 4to. Martin on Fossils, 8vo De Luc's Geological Travels, including England, 3 vols. 8vo. Transactions of the Geological Society, 4to. Scwer by's Mineralogy, 8v0.
CHAP. II.–VEGETABLE KINGDOM. 1.
VEGETABLES are organized, supported by air and food, endowed with life, and subject to death, as well as animals. They have in some instances, spontaneous, though we know not that they have voluntary, motion. They are sensible to the action of nourishment, air, and light, and either thrive or languish, according to the wholesome or hurtful application of these stimulants. This is evident to all who have ever seen a plant growing in a climate, soil, or situation, not suitable to it. Those who have ever gaihered, a rose, know but too well how soon it withers; and the familiar application of its fate to that of human life and beauty, is not more striking to the jinagination, than philosophically and literaliy true.
The history of the vegetable kingdom is termed BOTÁNY, a study which includes the practical discrimination, methodical arrangement, and systematic nomenclature of vegetables.
2. The external covering of plants, the epidermis or cuticle, is commonly transpareni and smooth; sometimes it is hairy or downy; and sometimes of so hard a nature, that even flint has been detected in its composition. The eyrisetum hyemale or Dutch rush, serves as a file to polish wood, ivory, and even brass. Under the cuticle, is found the celluliir integument which is analogous to the rete, mucosum of animals; it is like that, of a pulpy texture, and the seat of colour. It is commonly green in the leaves and stems, and is dependent for its hue on the action of light. When the cellular integument is removed, the bark presents itself, which in plants and branches only one year old, consists of a simple layer. In the branches and stems of trees it consists of as many layers as they are years old. The uses of bark are familiar to us. The Peruvian bark affords a cooling draught to the fevered lip ;' while that of the cinnamon yields a rich cordial; and that which it stripped from the oak, is used for the purposes of tanning. Immediately under the baik is situated the wood, which forins the great bulk of trees and shrubs. This also consists of numerous layers, as may be observed in
the fir, and many other trees; and from these concentric circles, or rings, the age of a tree may be determined. Within the centre of the wood is the medulla or pith, which is a cellular substance, juicy when young, extending from the roots to the summits of the branches. In some plants, as in grasses, it is hollow, merely lining the stem, The truuk evlarges by the formation of the new liber, or inner bark, every year, the whole of the liber, excepting its outermost layer, which is transformed into cortex or outer bark, becoming the alburnum or soft wood of the next, and the alburnum becoming the lignum or hard wood.
In describing the characters of plants, we shall treat of their roots, buds, trunk, leaves, props, inflorescence, fructification, and classification,
1. Roots are necessary to plants, to fix and hold them. in the earth, from which they imbibe nourishment. Roots are either annual, or living for one season, as in barley ; bienniul, which survive one winter and after perfecting their seed, perish at the end of the following summer, as wheat; or perennial, which remain and produce blossoms for an indefinite nun ber of years, as those of trees and shrubs in general. The root consists of two parts, the caudex and the radiculu. The caudex or stump is the body or knob of the root, from which the trunk and branches ascend, and the fibrous roots descend. The rudiculu is the fibrous part of the root branching from the caudex, Roots are : 1. Fibrous, or consisting entirely of fibres, as in many grasses and herbaceous plants. 2. Creeping, or having a subterraneous stem, spreading horizontally in the ground, throwing out numerous fibres, as in mint and couch-grass. 3. Špindle-shaped, as in the radish and carrot, which produce numerous fibres for the absorption of nutriment. 4. Stumped, or apparently bitten off, as in the priinrose. 5. Tuberous or knobbed, as in the potato, which consists of fleshy knobs, connected by common stalks or fibres. 6. Bulbous, as in the crocus. 7. Granulated, or having a cluster of little bulbs or scales connected by a common as in the saxifrage.
II. Buds. These are, in most instances, guarded by scales, and furnished with gum or woolliness, as an additional defence. Buds are various in their forms, but very,