A History of Inventions, Discoveries, and Origins. Johann Beckmann
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Название: A History of Inventions, Discoveries, and Origins

Автор: Johann Beckmann

Издательство: Bookwire

Жанр: Документальная литература

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isbn: 4064066382865

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СКАЧАТЬ is taken from Fraser’s History of Nadir Shah. Aurengzebe also caused one of his sons to be put to death by this poison.

      WOODEN BELLOWS.

       Table of Contents

      After the discovery of fire, the first instrument employed to blow it and strengthen it, has undoubtedly been a hollow reed, until the art was found out of forming a stick into a pipe by boring it. Our common bellows, which consist of two boards joined together by a piece of leather, and which probably are an imitation of the lungs, appear to have been early known to the Greeks. I have, however, met with no passage in any ancient author from which I could learn the oldest construction of this machine, which in latter times has received many improvements. Had I found such information, I should have endeavoured to explain it, as it would have contributed to enlarge the knowledge we have of the metallurgy of the ancients.

      It may be remarked on the following lines of Virgil,

      … Alii taurinis follibus auras

      that bull’s leather is unfit for bellows, and that ox or cow leather only can be used for that purpose; but accuracy is not to be expected in a poet; and besides, Virgil is not the only author who employs the expression folles taurinos; for Plautus says also, “Quam folles taurini habent, cum liquescunt petræ, ferrum ubi fit.”

      In the oldest smelting-houses the bellows were worked by men. Refuse, therefore, and other remains of metal, are often found in places where until a recent period no works could be erected, on account of the want of water.

      Bellows made with leather, of which I have hitherto spoken, are attended with many inconveniences. They require careful management; are expensive in their repairs; and besides last often not more than six or seven years. If thin leather is employed, it suffers a great deal of the air to escape through it; an evil which must be guarded against by continually besmearing it with train-oil, or other fat substances; and this is even necessary when thick leather is used, to prevent it from cracking in the folds. Damage by fire and water must also be avoided; and every time they are repaired, the leather must be again softened with oil, which occasions a considerable loss of time.

      The advantages of these wooden bellows are very great. When made of clean fir-wood without knots, they will last thirty or forty years, and even longer, though continually kept in action forty-six or forty-eight weeks every year: nay, Polhem assures us, that, when properly made, they will last a century. The effect produced by them is stronger, as well as more uniform, and can be moderated according to circumstances. They are worked also with greater facility. The slips of wood on their sides are apt to become damaged; but they can soon and easily be repaired. Every three or four months, however, the outer sides only of the inner box, and the bolt which keeps the boxes together, must be smeared with oil. If we reckon up the price of such bellows, and the yearly expense, they will, according to Grignon’s account, be only a fifth part of those of the old leather bellows.