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quantity of the heads which lie before them, and catching one at the extremity, they apply them immediately to the anvil and hammer, and by a motion or two of the foot, the top and the head are fixed together in much less time than it can be described, and with a dexterity only to be acquired by practice; the spectator being in continual apprehension for the safety of their fingers' ends. The pin is now finished as to its form, but still it is merely brass ; it is therefore thrown into a copper containing a solution of tin and the lees of wine. · Here it remains for some time, and when taken out assumes a white, though dull appearance : in order therefore to give it a polish, it is put into a tub containing a quantity of bran, which is set in motion by turning a shaft that runs through its centre, and thus by means of friction it becomes perfectly bright. The pin being complete, nothing remains but to separate it from the bran, which is perfectly similar to the winnowing of corn, the bran flying off, and leaving the pin behind it for immediate sale.

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Clouds and Rain. Conge'ries, a mass of small bodies heaped up together. A cloud is a collection of vapour, suspended in the atmosphere. In other words, it is a congeries of watery particles raised from the waters,.or watery parts of the earth, by the solar or electrical fire. These watery particles, in their first ascent, are too minute. and too much separated by their mutual repulsion, to be perceived; but as they mount higher and higher, meeting with a greater degree of cold, losing their electricity, or by some process employed by Nature for this purpose, they are in a certain degree condensed, and rendered opaque, by the re-union of their parts, so as to reflect and absorb light, and become visible as clouds.

The lowest part of the air being pressed by the weight of the upper against the surface of the water, and continually

bed upon it by its motion, attracts and dissolves those particles with which it is in contact, and separates them from the rest of the water. And since the cause of solution

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is the stronger attraction of the particles of water towards the air than towards each other, those that are already dissolved and taken up will be raised still higher, by the attraction of the dry air, which lies over them, and thus will diffuse themselves, rising gradually higher and higher, thereby leaving the lower air not so much saturated, but that it will still dissolve and take up fresh particles of water; which process is greatly promoted by the motion of the wind.

When the vapours are thus raised into the higher and colder parts of the atmosphere, some of them will coalesce into small particles, which, slightly attracting each other, and being intermixed with air, will form clouds; and these clouds will float at different heights, according to the quantity of vapour borne up, and to the degree of heat in the upper part of the atmosphere. The clouds, therefore, are generally higher in summer than in winter; in the former season they are from one mile to three miles high, and in the latter from a quarter of a mile to a mile.

When the clouds are much increased by a continual addition of vapours, and their particles are driven close together by the force of the winds, they will run into drops heavy enough to fall down in rain. If the clouds are frozen before their particles are gathered into drops, small pieces of them being condensed, and made heavier by the cold, they fall down in flakes of snow. If the particles are formed into drops before they are frozen, they become hailstones. When the air is replete with vapours, and a cold breeze springs up which checks the solution of them in the air, clouds are formed in the lower parts of the atmosphere, and these compose a mist or fog: this usually happens in a cold morning; but the mist is dispersed when the sun has warmed the air, and made it capable of dissolving the watery particles of which the mist is composed.

Southerly winds generally bring rain, because, being commonly warm, and replete with aqueous vapours, they are cooled by passing into a colder climate ; and therefore part with some of them, and suffer them to precipitate in rain: northerly winds, on the contrary, being cold, and acquiring heat by coming into a warm climate, take up or dissolve more vapour than they before contained ; and therefore are dry and parching, and usually attended with fair weather,

GREGORY.

ART OF PRINTING.

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QUESTIONS.-1. What is a cloud ? 2. Describe which the watery particles are supposed to become 3. What is the process by which other or fresh particle taken up? 4. Why are clouds generally higher in su winter? 5. When will clouds fall down in rain ?-in flakes on snow 6. When do they become hailstones ? 7. How and when is mist or. fog produced ? 8. Why do southerly winds generally bring rain? 9. Why are north winds usually attended with fair weather.

gars

LESSON 134.

Invention and Progress of Printing.

Glu'tinous, gluey, viscous, tenacious. The art of printing deserves to be considered with attention and respect. From the ingenuity of its contrivance, it has ever excited mechanical curiosity ; from its intimate connexion with learning, it has justly claimed historical notice; and from its extensive influence on morality, politics, and religion, it is now become a very important speculation. Coining, and taking impressions in wax, are of great antiquity, and the principle is precisely that of printing. The application of this principle to the multiplication of books, constituted the discovery of the art of printing. The Chinese have for many ages printed with blocks, or whole pages engraved on wood; but the application of single letters or moveable types forms the merit of the European art.

The honour of giving rise to this method has been claimed by the cities of Harlem, Mentz, and Strasburg; and to each of these it may be ascribed in some degree, as printers resident in each made successive improvements in the art.

It is recorded by a reputable author, that Laurens Koster of Harlem, walking in a wood near that city, cut some letters upon the rind of a beech-tree, which for fancy's sake, being impressed upon paper, he printed one or two lines for his grand-children ; and this having succeeded, he invented a more glutinous ink, because he found the common ink sunk and spread; and then formed whole pages of wood, with letters cut upon them, and (as nothing is complete in its first invention) the backsides of the pages were pasted together, that they might have the appearance of manuscripts written on both sides of the paper. These beechen letters

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afterwards exchanged for leaden ones, and these again or a mixture of tin and lead, as a less flexible and more solid and durable substance. He died in 1440, and by some his first attempt is supposed to have been made about 1430, but by others as early as 1423.

From this period printing made a rapid progress in most of the principal towns of Europe, superseded the trade of copying, which, till that time, was very considerable, and was in many places considered as a species of magic. In 1490 it reached Constantinople, and was extended by the middle of the following century to Africa and America.

During the period since its invention, what has not the art of printing effected ? It has blunted the edge of persës cution's sword, laid open to man his own heart, struck the sceptre from the hand of tyranny, and awakened from its slumber a spirit of knowledge, cultivation, liberty. It has gone forth like an angel scattering blessings in its path, so lacing the wounded mind, and silently pointing out the triumphs of mortality and the truths of revelation to the gaze of those whom the want of precept or good example had de. based, and whom ignorance had made skeptical.

Questions.—1. The application of what principle to the multipțication of books constitutes the discovery of the art of printing ? 2. What is said of Harlem, Mentz, and Strasburg ? 3. What is related of Laurens Koster ? 4. What is said of the progress of printing in the world? 5. Of its effects ? [Note. The fourth Centennial Anniversary of the Invention of Printing was observed at Harlem in Holland on the 10th and 11th of July, 1823, with great rejoicing and a splendid festival.

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LESSON 135.

Hope. . There is no happiness which hope cannot promise,—no difficulty which it cannot surmount, -no grief which it can not mitigate. It is the wealth of the indigent; the health of the sick, the freedom of the captive. As soon as we have learned what is agreeable, it delights us with the prospect of attaining it; as soon as we have lost it, it delights us with the prospect of its return. It is our flatterer and com

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forter in youth; it is our flatterer and comforter in years which need still more to be flattered and comforted. What it promises, indeed, is different in these different years; but the kindness and irresistible persuasion with which it inakes the promise are still the same ; and while we laugh, in advanced age, at the easy confidence of our youth in wishes which seem incapable of deceiving us now, we are still, as to other objects of desire, the same credulous, confiding beings, whom it was then so easy to make happy. Nor is it only over terrestrial things that it diffuses its delightful radiance. The power

which attends us with consolation, and with more than consolation, through the anxieties and labours of our life, does not desert us at the close of that life which it has blessed or consoled. It is present with us in our last moment. We look to scenes which are opening on us above, and we look to those around us, with an expectation still stronger than the strongest hope, that, in the world which we are about to enter, we shall not have only remembrances of what we loved and revered on earth, but that the friendships from which it is so painful to part, even in parting to Heaven, will be restored to us there, to unite us again in affection more ardent, and in still purer adoration of that Great Being, whose perfections, as far as they were then dımly seen by us, it was our delight to contemplate together on earth, when it was only on earth that we could trace them, but on that earth which seemed holier, and lovelier, and more divine, when thus joined in our thought with the Excellence that made it:

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