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

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СКАЧАТЬ He is of opinion that the invention is scarcely a century old; and that these water-clocks, which are now common, were first made for sale and brought into use among the people in the country, by a pewterer at Sens in Burgundy. What this artist affirms, that they can be constructed of no metal so easily, so accurately, and to last so long as of tin, is perfectly true. I have however in my possession one of brass, which is well constructed; but it suffers a little from acids. Among the newest improvements to this machine may be reckoned an alarum, which consists of a bell and small wheels, like those of a clock that strikes the hours, screwed to the top of the frame in which the cylinder is suspended. The axis of the cylinder, at the hour when one is desirous of being wakened, pushes down a small crank, which, by letting fall a weight, puts the alarum in motion. A dial-plate with a handle is also placed sometimes over the frame.

      [A very ingenious application of the principle of the clepsydra, for the purpose of measuring accurately very small intervals of time, is due to the late Captain H. Kater. Mercury is allowed to flow from a small orifice in the bottom of a vessel, kept constantly filled to a certain height. At the moment of noting any event, the stream is interrupted and turned aside into a receiver, into which it continues to run till the moment of noting any other event, when the intercepting cause is suddenly removed. The stream then flows in its original course. The weight of mercury in the receiver, compared with the weight of that which passes through the orifice in a given time, observed by the clock, gives the interval between the events.]

      FOOTNOTES

197 [Sextus Empiricus (Adv. Math. cap. 21) says that the Chaldæans divided the zodiac into 12 equal parts, as they supposed, by allowing water to run out of a small orifice during the whole revolution of a star, and dividing the fluid into 12 equal parts, the time answering to each part being taken for that of the passage of a sign over the horizon.]

198 Lib. ix. c. 9.

199 [Some mode of measuring time by the reflux of water, however rude it might be, was used at Athens before the time of Ctesibius, as we see by various passages in Demosthenes.]

200 Auctor Dialog. de Caus. Cor. Eloq. 38.—The orators were confined to a certain time; and hence Cicero says, latrare ad clepsydram.

201 Some account of the writers who have spoken of the water-clocks of the ancients may be found in Fabricii Bibliograph. Antiquaria, p. 1011. They were formerly used for astronomical observations. The authors who treat of them in this respect are mentioned in Riccioli Almagest. Novo, i. p. 117.

202 In that year Kircher’s Ars Umbræ et Lucis was published for the first time. In the edition of 1671, several kinds of water-clocks are described, p. 698.

203 A particular account of these water-clocks is to be found in Ozanam, Recréations Math. et Physiques [republished in Hutton’s Mathematical Recreations, ii. 40]. Bion on Mathematical Instruments.

204 Muschenbroek, Philos. Natur. i. p. 143.

205 Journal des Sçavans, 1691.

206 This monk may be considered as the restorer of the clepsydra, or clock which measures time by the fall of a certain quantity of water confined in a cylindric vessel. These clocks were in use among ancient nations. They are said to have been invented at the time when the Ptolemies reigned in Egypt. Dom Vailly, who applied himself particularly to practical mathematics, having remarked the faults of these clocks, bestowed much labour in order to bring them to perfection; and by a number of experiments, combinations, and calculations, he was at length able to carry them to that which they have attained at present. At the time of their arrival they were very much in vogue in France.—Hist. Littéraire de la Congr. de St. Maur, ordre de S. Bénoit. Bruxelles, 1770, 4to, p. 478.

207 Ozanam, ii. p. 475.

208 Alexander will not admit this to be the case. “It is possible,” says he, “that two persons of penetrating genius may have discovered the same thing.”

209 Art du potier d’étain, par Salmon. Paris, 1788, fol. p. 131.

      TOURMALINE.

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The ancients, though ignorant of electricity, were acquainted with the nature of amber, and knew that when rubbed it had the power of attracting light bodies. In like manner they might have been acquainted with the tourmaline, and might have known that it also, when heated, attracted light bodies, and again repelled them; for had they only bethought themselves, in order to search out the hidden properties of this stone (which on account of its colour and hardness is very remarkable), to put it into the fire, they would have then seen it sport with the ashes. Some learned men have thought they found traces of the properties of this stone, in what the ancients tell us respecting the lyncurium, theamedes, and carbunculus. The fruit of my researches respecting this subject I shall here lay before the reader. All that we find in the ancients to enable us to characterize the lyncurium is, that it was a very hard stone, which could with difficulty be cut; that seals were formed of it; that it was transparent, and of a fiery colour, almost like that of yellow amber; that it attracted light bodies, such as chaff, shavings of wood, leaves, feathers, and bits of thin iron and copper leaf, in the same manner as amber; that the ancients procured it from Æthiopia, but that in the time of Pliny no stone was known under that name210.

      This information proves, in my opinion, that the lyncurium cannot be the belemnites, as some old commentators and Woodward have affirmed; for the latter has not the celebrated hardness and transparency of the former, neither has it the property of attracting light bodies, nor is it fit for being cut into seals. That opinion probably has arisen in the following manner:—the ancients supposed that the lyncurium was the crystallized urine of the animal which we call the lynx. As some belemnites contain bituminous particles which give them an affinity to the swine-stone, naturalists, when they have rubbed or heated yellow and somewhat transparent pieces of this fossil, have imagined that they smelt the fabulous origin of the lyncurium.

      Less ridiculous is the opinion of some old and modern writers, that the lyncurium was a species of amber. Theophrastus, however, the ablest and most accurate mineralogist of the ancients, would certainly have remarked this and not have separated the lyncurium from amber. Besides, the latter has not the hardness of the former, nor can it be said that it is difficult to be cut; for at present it is often made into various toys with much ingenuity. The opinion of Pliny is here of little weight; for it is founded, as ours must be, on the information of Theophrastus.

Epiphanius, who considered the Bible as a system of mineralogy, but could not find the lyncurium in it, supposes that it may have been the hyacinth211. However СКАЧАТЬ