Page:Encyclopædia Britannica, Ninth Edition, v. 7.djvu/312

294 in the world has exceeded that of all the rest together. Researches into the ancient writings of Chaldrea have now shown how fully historians were justified in treating that country as the principal among the sources whence the star- gazers received their precepts (see Sayce, &quot;Astronomy and Astrology of the Babylonians,&quot; in Trans. Soc. Bill. Arch., vol. iii. ; Maury, La Magie et V Astrologie.} The rules in such comparatively modern works as Sibly s Occult Sciences and Lilly s Astrology fairly enough represent the ancient traditions, and show their still intelligible symbolism, how the stars rising at a child s birth are made in the horoscope to typify its destiny, and the planets and signs of the zodiac exercise &quot; influences &quot; often plainly drawn from their natures or names. Thus Mars has to do with soldiers, Venus with lovers, and Mercury with prattlers ; the solar man is grand and generous, the lunar man unsteadfast and inclined to change his dwelling, the sign Leo presides over places where wild beasts abound, but Aries over pastures. At the courts of Asiatic rulers, the state astrologer still nominally holds a position like that of his predecessor in the ancient empires of the world, but it is evident that the last twenty years have shaken, even in the barbaric East, the power of the occult sciences over the human mind.   DIVING. The art of diving to considerable depths underwater to bring up pearls, corals, and sponges has been practised in the Indian seas from very early times, and if we may believe the accounts that have come down to us, the feats of early divers are truly remarkable some of them, it is said, having been able to prolong their sub marine descents for periods varying from two to three minutes. It is obvious, however, that not having the aid of any artificial appliances for supplying air, the powers of these bold adventurers, both as regards the depth to which they could descend and the length of time they could remain submerged, were comparatively limited. At an early period, therefore, the attention of philo sophers and mechanics was turned to the discovery of a contrivance for aiding the diver in prosecuting his daring but useful calling, which was rendered all the more important from its being no longer confined to the acquisition of Eastern luxuries, but to the raising of treasure from sunken vessels. It is not considered expedient to occupy space by further reference to the feats of the early divers, out rather to pass at once to the history and construction of the diving apparatus of modern times, as illustrated by the Diving Bell and the Diving Dress at present in use. And here it may be stated that in addition to the sponge and coral trade of foreign lands, which has been greatly advanced by the use of modern appliances, there are the works of the naval engineer, and more particularly of the civil engineer, in which diving apparatus is so extensively employed and so essentially necessary as to place the art of diving on a wider basis, and to give it an importance only fully developed within the present century.

Diving Bell.—The most useful of ancient contrivances is the diving bell, which, introduced at an early period and gradually improved, is now the well-known apparatus used by engineers in the present day ; and it may be interesting to trace the successive improvements that have brought it to its present state of perfection and usefulness in con ducting submarine works. The conception of the diving bell is very simple. The air contained in an inverted jar sunk in a vessel of water excludes the water from the interior, and if the vessel be made of sufficient size to contain persons within it, it may be sunk without their being wetted, and they may continue to be submerged so long as the air within the bell continues pure enough to support animation. Such were the &quot; diving- chests &quot; of the first makers, whir.li, though they differed in form and details, were constructed on the same principle as the modern bell, and were generally formed of wood, girded with iron hoops, like a barrel. It will be obvious that if such a vessel were submerged in shallow water, having a depth of say one foot of water, a large supply of air would be inclosed in the bell, and the bottom on which it rested would, from the small depth of water upon it, be easily reached for any operation to be performed on it. But if we conceive the same bell to be lowered further below the surface, the air being compressible will be reduced in volume, and the water will rise ir the bell to fill its place. The result would be that at the depth of about 33 feet the air would be compressed into about one-half its original bulk, and the bell itself would be half filled with water ; and the bottom of the sea on which it rested would no longer be so conveniently reached as when the water was only a few inches above the lips of the bell. Moreover, the air by repeated inspiration becomes unfit to support life, and the ancient bells had to be raised to the surface at very short intervals of time that fresh air might be supplied to the men employed. Although, therefore, the original diving bell was a step towards the perfect appliances afterwards introduced, it will readily be seen that its use in diving operations was very limited indeed. Dr Halley, the secretary of the Royal Society, who seems to have taken an interest in diving and divers, and compassionated their want of fresh air, communicated a paper to the Royal Society in which, to use his own words, he proposes a plan “for carrying the pabulum vitæ down to the divers, who must without being supplied therewith return very soon to the surface or perish.” The following is the description of his arrangements for this purpose. After describing the bell itself, which was of wood of the form of a truncated cone, with a capacity of 60 cubic feet, and was suspended by a sprit from the mast of a ship, he says—

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