The most important silver mines of Europe at present are those of Saxony, Hungary, and the Hartz. The annual produce of these united is about 180,000l. Within the last quarter of a century, there has been a great increase in the produce of silver from the Russian mines. The celebrated mines of Konigsberg, in Norway, once so rich in native silver, are now nearly exhausted. Silver has also been obtained from some of the lead mines in Great Britain. Bishop Watson, in his Chemical Essays, observes, that by the silver which was produced from the lead mines in Cardiganshire, Sir Hugh Middleton is said to have cleared 2000l. per month, and that this enabled him to undertake the great work of bringing the New River from Ware to London. Silver is exceedingly ductile and tenacious. It may be beat out into leaves only the one hundred and sixty thousandth part of an inch thick, and drawn into wire the thousandth part of an inch thick. It melts at 28° of Wedgwood's pyrometer; and when exposed to a temperature considerably higher, it becomes volatilized. Atmospheric air has no effect upon it, except when it contains sulphurous vapours, sulphuretted or phosphuretted hydrogen gases. It unites to phosphorus and sulphur. It slightly unites with the brittle acidifiable metals. With gold it forms what is termed green gold. Copper renders it harder without much impairing its ductility. It is oxydized and dissolved by several of the acids; and the acid solutions of silver are decomposable by the alkalies, earths, and by the greater number of the metals. Different methods are employed in different countries to extract silver from its ores. In Mexico, Peru, &c., the mineral is pounded, roasted, washed, and then triturated with mercury in vessels filled with water; and a mill being employed to keep the whole in agitation, the silver by that means combines with the mercury. The alloy thus obtained is afterwards washed, to separate any foreign matters from it, and then strained and pressed through leather. This being done, heat is applied to drive off the mercury from the silver, which is then melted and cast into bars or ingots. wwwww 1. In what countries are the silver mines most productive? 2. How many pounds of silver would it take to form a solid globe 91,206 feet in diameter ? 3. What is said of Sir Hugh Middleton ? 4. In what manner is silver extracted from its ores in Mexico, Peru, &c. ? The Dog Days. ON the third of July Dog-days begin. These days are so called from the star Canis or dog-star, which then rises and sets with the sun, and greatly increases the heat. This is the popular notion. Dr. Hutton, in his "Mathematical and Philosophical Dictionary," under the article Canicular Days, has the following observations: -"Some authors say, from Hippocrates and Pliny, that the day this star first rises in the morning, the sea boils, wine turns sour, dogs begin to grow mad, the bile increases and irritates, and all animals grow languid; also that the diseases it usually occasions in men are burning fevers, hysterics, and phrensies. The Romans, too, sacrificed a brown dog every year to Canicula at his first rising, to appease his rage. "All this, however, arose from a groundless idea that the dog-star so rising was the occasion of the extreme heat, and the diseases of that season, for the star not only varies in his rising, in every one year, as the latitude varies, but it is always later and later every year, in all latitudes; so that in time the star may, by the same rule, come to be charged with bringing frost and snow, when he comes to rise in winter." The doctor adds, "that, according to the common method of counting the dog-days, they had at length fallen considerably after the hottest time of the year; but that they are now properly placed in almanacks from July 3 to August 11." 1. From what are these days called Dog-days? 2. What did the Romans on this day? 3 Where are the dog-days now placed in the almanacks? LESSON CLXXXV.—JULY THE FOURTH. THE mocking-bird is a species of thrush not uncommon in many parts both of North and South America, and the West India islands. In size, it does not exceed the European song-bird, and perhaps is not equal to it in the beauty of its plumage; it is, however, far from being an inelegant creature, but it is better known for the peculiarity and amazing power of its voice. Although not gifted THE MOCKING-BIRD. 265 with any powerful weapons of self-defence, these birds display extraordinary courage in defence of their eggs and young, and will fearlessly attack any animal which may approach their haunts, even their greatest enemy, a species of black snake. 66 "To these qualities," says Wilson, the American author, we may add that of a voice full, strong, and musical, and capable of almost every modulation, from the clear mellow tones of the wood-thrush, to the savage scream of the bald-eagle. In measure and accent he faithfully follows his originals. In force and sweetness of expression he greatly exceeds them. "In his native groves, mounted on the top of a tall bush, or half-grown tree, in the dawn of dewy morning, while the woods are already vocal with a multitude of warblers, his admirable song rises pre-eminent over every competitor. The ear can listen to his music alone, to which that of all the others seems a mere accompaniment. Neither is this strain altogether imitative. His own native notes, which are easily distinguishable by such as are well acquainted with those of our various song-birds, are bold and full, and varied seemingly beyond all limits. His expanded wings and tail, glistening with white, and the buoyant gaiety of his action, arresting the eye as his song most irresistibly does the ear, he sweeps round with enthusiastic ecstasy. He mounts or descends as his song swells or dies away. "While thus exerting himself, a by-stander, destitute of sight, would suppose that the whole feathered tribes had assembled together on a trial of skill, each striving to produce his utmost effect; so perfect are his imitations. He many times deceives the sportsman, and sends him in search of birds that perhaps are not within miles of him, but whose notes he exactly imitates; even birds themselves are frequently imposed on by this admirable mimic, and are decoyed by the fancied calls of their mates, or dive with precipitation into the depths of thickets, at the scream of what they suppose to be the sparrow-hawk. "The mocking-bird loses little of the power and energy of his song by confinement. In his domesticated state, when he commences his career of song, it is impossible to stand by uninterested. He whistles for the dog- Cæsar starts up, wags his tail, and runs to meet his master; he squeaks out like a hurt chicken- and the hen hurries about, with hanging wings and bristled feathers, clucking to protect its injured brood. The barking of the dog, the N mewing of the cat, the creaking of a passing wheel-barrow, follow, with great truth and rapidity. He repeats the tune taught him by his master, though of considerable length, fully and faithfully. He runs over the quiverings of the canary, and the clear whistlings of the Virginia nightingale, or the red-bird, with such superior execution and effect, that the mortified songsters feel their own inferiority, and become altogether silent, while he seems to triumph in their defeat by redoubling his exertions. "Both in his native and domesticated state, during the solemn stillness of night, as soon as the moon rises in silent majesty, he begins his delightful solo; and serenades us the livelong night, with a full display of his vocal powers, making the whole neighbourhood ring with his inimitable melody." 1. Where is the mocking-bird mostly found? 2. What would a by-stander suppose if he heard the bird sing but could not see it? 3. Describe his imitative powers when domesticated. LESSON CLXXXVI.. JULY THE FIFTH. Bishop Watson. On this day, in 1816, died Dr. Watson, bishop of Llandaff, long known to the world as a theologian, a chemist, an agriculturist, and a man of letters. For many years he pursued with ardour his favourite study of chemistry; and the first volume of his "Chemical Essays" are an evidence of his success in this boundless field of science. By the influence of the Duke of Rutland, to whom this work was inscribed, he obtained a mitre. From that moment he seems to have abandoned his once favourite pursuit, as will be seen from the following quotation from the preface to his fifth and last volume. "When I was elected Professor of Divinity in 1771, I determined to abandon for ever the study of chemistry, and I did abandon it for several years; but the veteris vestigia flammæ still continued to delight me, and at length seduced me from my purpose. When I was made a bishop, in 1782, I again determined to quit my favourite pursuit; the volume which I now offer to the public is a sad proof of the imbecility of my resolution. I have on this day, however, offered a sacrifice to other people's RICHARD I. OF ENGLAND. 267 notions, I confess, rather than to my own opinion of episcopal decorum-I have destroyed all my chemical manuscripts. A prospect of returning health might have persuaded me to pursue this delightful science; but I have now certainly done with it for ever; at least, I have taken the most effectual step I could to wean myself from an attachment to it; for, with the holy zeal of the idolaters of old, who had been addicted to curious arts, I have burned my books." The author of the "Pursuits of Literature" thus notices the bishop's admirable refutation of Paine's work :— "Yet all shall read, when, bold in strength divine, And feel that joy which Watson best can feel." 1. Whose death is recorded as having happened on this day, 1816? 2. Under what character was Dr. Watson long known to the world? 3. What is meant by the veteris vestigia flammæ ? LESSON CLXXXVII. -JULY THE SIXTH. Richard I. of England. RICHARD I. began his reign on this day, in the year 1189. The most shining part of this prince's character was his military talents: no man, even in that romantic age, carried courage and intrepidity to a greater height; and this quality gained him the appellation of the lion-hearted cœur-de-lion. He passionately loved glory; and, as his conduct in the field was not inferior to his valour, he seems to have possessed every talent necessary for acquiring it; his resentments also were high, his pride unconquerable; and his subjects, as well as his neighbours, had therefore reason to apprehend from the continuance of his reign a perpetual scene of blood and violence. Of an impetuous and vehement spirit, he was distinguished by all the good as well as the bad qualities which are incident to that character. He was open, frank, generous, sincere, and brave; he was revengeful, domi |