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Select Books on Music (continued.)

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As the practical treatises on this science, which are usually sold under the title of "Books of Instruction,' are very worthless, it may not be amiss to notice a few publications which are really works of merit. The Books of Instruction published by the following authors may be depended on :-For the Piano, those by Clementi, Gunn, and Williams-For the Violoncello, those by Gunn and Macdonald-For the Violin, those by Philpot and Geminiani and for the Flute, those by Monzani, Wragg, and Devienne.

Rousseau, Dictionnaire de Musique, 8vo. There is a translation of this book, but it cannot be recommended. Dr. Crotch's Elements of Musical Composition, 4to. Shield on Harmony. Smith's Harmo nics, 8vo. Dr. Burney's History of Music, 4 vols. 4to. and Musical Travels, s vols., 8vo.

PART VII.-Physics.

Natural History.

1. WHILE we contemplate the infinitely varied forms

in the field of nature, and trace their gradations or connexions, we possess the peculiar advantage of uniting amusement with instruction, and our minds are impressed with a train of the most pleasing ideas. It is no unimportant object, to be able to secure to ourselves some species of study, which, in its progress, may continue to afford a rational delight, and in the pursuit of which there can be no fear of soon exhausting the subject. The celebrated RAY, speaking of the study of natural history, says, "No knowledge can be more pleasant to the soul than this; none so satisfying, or that doth so feed the mind; in comparison of which, the study of words and phrases seemeth insipid and jejune; for words being but the images of things, to be given up wholly to their study, what is it but to verify the folly of Pygmalion, to fall in love with a statue, and neglect the reality! The treasures of nature are inexhaustible: there is enough for the most indefatigable industry, the happiest opportunities, the most prolix and undisturbed vacancies."

2. The study of natural history consists in the collection, arrangement, and exhibition of the various productions of the earth. These are divided into the three grand kingdoms of nature, the mineral, the vegetable, and the animal. (1.) Minerals inhabit the interior parts of the earth. They are concrete bodies, without life and sensation. (2.) Vegetables clothe the surface with verdure, imbibe nourishment through bibulous roots, breathe by leaves, and continue their kind by the dispersion of seed within prescribed limits. They are organized bodies, and have life, but not sensation. (3.) Animals inhabit the exterior parts of the earth, respire, and generate eggs,

impelled to action by hunger, affections, and pain; and by preying on other animals and vegetables, restrain within proper bounds and proportions the numbers of both. They have organized bodies, life, sensation, and the power of locomotion.

3. Dust and earth are the principle and matter of the composition of all solid bodies. Therefore these are found in all bodies decomposed by human art. From the union

of earth with salts, oils, sulphurs, &c. result different kinds of earths, more or less compound, light, or compact. These lead us insensibly to the mineral kingdom. There is a great variety of stones; and their form, colour, size, and hardness, are very different. In them we find all sorts of saline and metallic particles; whence minerals and precious stones proceed. In the latter class of stones, some are found which are fibrous, and have laminæ, or a kind of leaves, as slate, talc, lythophytes, or stony marine plants: the amianthus, or stony flower of mines; and these lead us from the mineral to the vegetable, kingdom. The plant which appears to occupy the lowest part of vegetable gradation is the truffle. Next come the numerous species of mushrooms and mosses, between which, mould on paste, &c. seems to form the connecting medium. All these plants are imperfect, and properly constitute only the limits of the vegetable kingdom.

4. The polypus seems to unite the vegetable and animal kingdoms. From its outward appearance, this singular production might be taken for nothing more. than a mere plant, were it not seen to perform real animal functions. This zoophyte seems to form the counecting link between plants and animals. Worms, which are at the commencement of the animal kingdom, lead us to insects. Those worms whose bodies are inclosed in a stony or scaly shell, seem to unite insects and shell-fish. Between them, or rather next to them, are found reptiles; these by means of the water-snake, are united to fish. The flying-fish leads us to fowls. The ostrich, whose feet very nearly resemble those of the goat, and who runs rather than flies, seems to connect birds with quadrupeds. And the ape joins hands with quadrupeds and men.

CHAP. I.-MINERAL KINGDOM.

1. THE name of mineral, in the strict sense of the word, denotes only such substances as are found in mines, but the term is generally applied, in a more extended sense, to characterize that class of inorganic and inanimate bodies, which form the solid mass, or rather, the external covering, of the globe we inhabit,-so far at least as the labour of man has hitherto penetrated. To the whole of these substances is given the appellation of MINERAL KINGDOM, in opposition to the two other grand divisions of nature of 'which we shall afterwards treat.

2. Minerals, like organized bodies, have a certain origin, progressively increase, and are subject to dissolution, or decomposition of parts. But they arise merely by an accumulation of homogeneous, or similar particles from without; either by substances combining in consequence of their attractive power, which is called cohesion; or by the solid particles being separated from the fluid ones, when the former attract each other, according to certain ławs, constituting together a solid body; and this is termed crystallization, a form of which only certain minerals are susceptible. Mineralogy is that department of the science of nature which makes us acquainted with the characters of ninerals. It teaches the art of distinguishing them by accurate and well defined characters; the mode of describing them with so much precision, as is sufficient to recognize them with facility whenever they occur, and the art of arranging or classing them in a certain order or system.

3. The characters of minerals in their most striking properties, may be thus illustrated. (1.) Fusibility means the power of being melted. The most ready way to ascertain the fusibility of a mineral substance, is, by exposing a small particle of it to the flame of a candle or lamp concentrated by the instrument called a blow-pipe; and, if the heat thus excited is sufficient to liquefy the mineral, it is said to be fused. (2.) The hardness of minerals is ascertained either by a comparison with each other, or by their power of scratching glass, or the effect of the file upon them: those which resist the file being the

hardest. (3.) The phosphorescence of minerals means the faint light which they emit, either by exposure to simple heat, or in consequence of friction. (4.) The electricity of a mineral is that property which, being excited either by simple heat or by friction, shows itself in the attraction or repulsion of other substances, with which the mineral is brought nearly in contact. (5.) By the specific gravity of a mineral, is understood the amount of its weight, when compared with the weight of a quantity of water of the same bulk with itself. (6.) The crystalline forms under which minerals occur, are various, and may be considered as one of their most important characters, being, with some few exceptions, resolved into six principal forms.

4. Minerals are usually arranged under four classes; earthy, saline, inflammable, and metallic.

1. Earthy. This class is distinguished by its being in general brittle, not remarkably heavy, as usually possessing white or light colours, disposed to crystallize, uninflammable in a low temperature, insipid, and inodorous. The earthy minerals are either SILICEOUS, in the form of pebbles, gravel, sand, sand-stones, pudding stones, &c.; or are CALCAREOUS, as limestone, chalk, spar-marble, ala baster, &c.; or ARGILLACEOUS, as clay, fullers' earth, lithomarga, boles, slute, &c.; or MAGNESIAN, as steatites, asbestus, serpentines, &c. ; or BARYTIC, as the baroselenite or ponderous spar, &c. In these compounds, in which more than one of the earths are found, the earth from which each substance derives its genuine distinction is most abundant, so there are also others in which the earths STRONTIA, YTTRIA, and JARGONIA are most predominant. Most of the PRECIOUS STONES are compounds, in which different combinations of one or more of the other earths, lime, alumine, magnesia, and sometimes a small portion of iron, are united to a large portion of pure quartz, or silex, in a crystalline form, hence result the opal, garnet, catseye, onyx, sardonyx, &c.

The ruby has been found to be formed of alumine and magnesia, with chromic acid, and the emerald is supposed to be the same compound with the acid in a different degree of oxidizement. The chrysolite appears to be composed of lime and the phosphoric acid.

II. The class of saline minerals is characterized by

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