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Show THE EARTH IN MINIATURE. <br><br> Many persons have seen the somewhat clumsy apparition known as the planetarium or orrery, the purpose of which is to show the arrangement of the solar system and the motions of the planets around the sun. The best of these are rude, and from their quite apparent machinery or rods and wires are apt to be misleading to the young and untutored. "We have just seen an invention," says the London Times, "which, for want of a better name, we must call a planetarium, but which though intended to ??? the same purpose, has but little in common with the old-fashioned apparatus. This invention is the work of an Italian, Signor N. Perini, long resident in London, and whose name is, no doubt, familiar to some of our civil service and military readers as a successful teacher. The new planetarium is created in the midst of an ordinary-sized room, with a ceiling higher than usual. On entering the room one sees a high circular chamber, or box, standing on twelve wooden pillars. On entering underneath this chamber, and looking up, a dome is seen, deep blue, and sprinkled with stars, the chief northern constellations being in their proper places, and round the base of the dome the names of the signs of the zodiac. Pendant from the top of the dome by a narrow tube is an opal globe, lit inside by gas, and representing the sun. From wires, almost invisible, the planets are suspended around the sun, of sizes and at distances approximately proportionate to the real sizes and distances, and each having its proper inclination to the plane of its orbit. The various moons are in their places and Saturn has his rings. The general effect on looking up at this arrangement from below is impressive, and this effect is increased when Signor Perini, by simply turning a key, sets the system in motion, rapid or slow, as he chooses. The sun turn on his axis, and the planets in their orbits, all in time accurately proportionate, and on watching the movements for a short time one easily realizes the immense differences in length of the years of the earth and those of the outer planets. By an ingenious watch work arrangement inside the earth, which is the size of a walnut, our world is made to revolve on its axis, the latter, by a special effort of ingenuity of Signor Perini, being always made to point to the same quarter of the heavens. The same arrangement causes the moon to revolve round the earth in its own proper orbit. Perhaps the great triumph of this invention is the fact that the planets revolve round the sun in proper elliptical orbits, which are traced around the inside of the dome. The dome is 11 feet in diameter at its base and 11 feet high. In the chamber above the dome the machinery invented by Signor Perini is arranged, the details being as yet secret. The moving power is clockwork, the originality in the arrangement being, we believe, the method by which the inventor effects the elliptical motion of the planet. Not a sound is heard when the machinery is in motion, the whole working in that "solemn silence" which the hymn tells us is characteristic of the starry sky. The inventor could, we believe, make his planetarium of any size, from the dome [unreadable line] a little thing that might be used for school instruction. Signor Perini has devoted his nights and morning to this structure for seven years, and has expended upon it something like $3,500; the earth itself, we believe, has cost him $200. We believe he has been prompted to this work solely by the enthusiasm of a mechanician?, and by a desire to do something to enable those interested in astronomy to realize, as far as possible, the arrangements of the solar system. We may say that it is almost impossible to put it out of order, and it can be taken to pieces in a very short time. His address is Garrick Chambers, Garrick street. |