A History of Inventions, Discoveries, and Origins, Volume I (of 2). Johann Beckmann

Чтение книги онлайн.

СКАЧАТЬ href="#n136" type="note">136 rightly conjectures, neutral salts of arsenic. Loss of appetite, faintness, gnawing pains in the stomach, loss of strength without any visible cause, a continual indisposition, followed by a wasting of the viscera, a slow fever, &c., are all symptoms which seem to announce that dangerous metallic oxide. The opinion, however, that it was composed of opium and cantharides has, in latter times, received so many confirmations, that one is almost induced to believe that there are more kinds than one of this Stygian water. The information given by the abbé Gagliani, seems to carry too much weight with it to be denied137. It is confirmed also by M. Archenholz138; but what he says of the use made of Spanish flies, by the Chinese, to invigorate the sixth sense, gives reason to suspect that his voucher is L’Espion Dévalisé, to whom the abbé Gagliani ascribes the same words. It appears to me, however, if I may be allowed to judge from probabilities, that the poison known in the East Indies under the name of powst is also water which has stood a night over the juice of poppies. It is given in the morning fasting to those persons, and particularly princes, whom people wish to despatch privately, and without much violence. It consumes them slowly, so that they at length lose all their strength and understanding, and in the end die torpid and insensible139.

      [Chemical science has made such rapid progress of late years, that there are but few, if any, poisonous substances which cannot be detected with certainty. The improved state of our medical knowledge, and the institution of coroners’ inquests in all cases where any suspicion of the cause of death occurs, fortunately renders secret poisoning almost, if not quite impossible, at least in this country.]

      WOODEN BELLOWS

      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

      Accipiunt redduntque140…

      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.”

      Strabo141 tells us, from an old historian, that Anacharsis, the Scythian philosopher, who lived in the time of Solon, invented the bellows, the anchor, and the potter’s wheel: but this account is very doubtful, as Pliny, Seneca142, Diogenes Laërtius143, and Suidas, who likewise speak of the inventions ascribed to that philosopher, mention only the last two, and not the bellows: besides, Strabo himself remarks that the potter’s wheel is noticed in Homer, and this poet is certainly older than Anacharsis. The latter, perhaps, became acquainted with that useful instrument during the course of his travels, and on his return, made his countrymen first acquainted with it. However this may be, it is well known that the person who introduces a foreign invention among a people, is often considered as the author of it.

      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.

      In wooden bellows these inconveniences are partly lessened, and partly remedied. As these bellows, except the pipe, consist entirely of wood, many, who are not acquainted with the construction of them, can hardly conceive the possibility of making such a machine. Though they cannot be properly described without a figure, I shall endeavour to give the reader some idea of them by the following short sketch. The whole machine consists of two boxes placed the one upon the other, the uppermost of which can be moved up and down upon the lower one, in the same manner as the lid of a snuff-box, which has a hinge, moves up and down when it is opened or shut; but the sides of the uppermost box are so broad as to contain the lower one between them, when it is raised to its utmost extent. Both boxes are bound together, at the smallest end, where the pipe is, by a strong iron bolt. It may be readily comprehended, that when both boxes fit each other exactly, and the upper one is raised over the under one, which is in a state of rest, the space contained by both will be increased; and consequently more air will rush in through the valve in the bottom of the lower one; and when the upper box is again forced down, this air will be expelled through the pipe. The only difficulty is to prevent the air, which forces its way in, from escaping anywhere else than through the pipe; for it is not to be expected that the boxes will fit each other so closely as to prevent entirely the air from making its way between them. This difficulty, however, is obviated by the following simple and ingenious method. On the inner sides of the uppermost box there are placed moveable slips of wood, which, by means of metal springs, are pressed to the sides of the other box, and fill up the space between them. As these long slips of wood might not be sufficiently pliable to suffer themselves to be pressed close enough, and as, though planed perfectly straight at first, they would in time become warped in various directions, incisions are made in them across through their whole length, at the distance of from fifteen to eighteen inches from each other, so as to leave only a small space in their thickness, by which means they acquire sufficient pliability to be everywhere pressed close enough to the sides144.

      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.

      That the invention of these wooden bellows belongs to the Germans, is certain. Grignon145 expressly affirms so; and in Becher’s146 time they were to be found in Germany, but not in England. Genssane, who ascribes the invention to the Swiss, is certainly mistaken; and perhaps he was led into this error, because these bellows were first made known in France by a Swiss. I cannot, however, ascertain the name of the real inventor. In the middle of the sixteenth century lived at Nuremberg СКАЧАТЬ