Hydraulic Belt.

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Chap. 16.]

spun wool or horse hair, and. stretched on two pulleys like the endlesschain of pots. These pulleys have grooves formed on their surfaces forthe reception of the ropes. One of them is placed over the mouth of awell, and the other suspended in or secured to the bottom. A rapid rno-tion is communicated to the upper pulley, by a multiplying wheel, andthe ascending side of each rope then carries up the water absorbed by it;and which is separated from it when passing over the upper pulley, partlyby centrifugal force, and partly by being squeezed in the deep groove, orby passing through a tube as shown in the figure. In the beginning ofthe motion, the column of water adhering to the rope, is always less thanwhen it has been worked for some time, and continues to increase tili thesurrounding air partakes of its motion. By the utmost efforts of a man,nine gallons of water were raised by one of these machines from a well,ninety-five feet deep, in one minute. Adam’s Philos. Vol. iii, 494.

The hydraulic belt is a similar contrivance. It is an endless doubleband of woolen cloth, passing over two rollers, as in figure 57. It is drivenwith a velocity of not less than a thousand feet per minute ; when the watercontained between the two surfaces is carried up and discharged as it passesover the upper roller, by the pressure of the band. Some machines ofthis kind are stated to have produced an effect equalto seventy-five percent. of the power expended, while that of ordinary pumps seldom ex-ceeds sixty per cent. See Lon. Mechan. Mag. Vol. xxix, page 431.

CHAPTER XVI.

The Screw —An original device—Various modes of constructing it—Roman Screw—Often re-invented*—Introduced into England from Germany —Combination of several to raise water to great elevations—Marquis of Worcester’s proposition relating to it, exemplified by M, Patlu—Ascent of water in itformerly considered inexplicable—Its history—Not invented by Archimedes —Supposed to have been inearly use in Egypt —Vitruvius silent respecting its author —Conon its inventor or re-inventor—This phi-iosopher famous for his flattery of Ptolemy and Berenice—Dinocrates the architect—Suspension of metal-lic substances without support—The screw not attributed to Archimedes tili after his death—Invention?often given to others than their authors—Screws used as ship pumps by the Greeks—Flatterers likeConon too often found among men of Science—Dedications of European writers often blasphemous—Hereditary titles and distinctions—Their acceptance unworthy of philosophers—Evil influence of scien-tific men in accepting them—Their denunciation a proof of the wisdom and virtue of the framers of theÜ. S. Constitution—Their extinction in Europe desirable—Plato , Solon, and Socrates —George III —George IV —James Watt —Arago—Description of the * Syracusan, ’ a ship built by Archimedes , inwhich the Screw Pump was used,

The Cochleon or Egyptian Screw, the machine next described byVitruvius , is, in every respect, the most original one of which he has giv-en an account. Unlike the preceding, which appear to have been in agreat measure deduced from each other, it forms a species of itself; andwhoever was its inventor, he has left in it a proof of his genius, and alasting monument of his skill. If it be not the earliest hydraulic enginethat was composed of tubes, or in the construction of which they were in-troduced, it certainly is the oldest one known of that description'; and inits mode of Operation it differs essentially from all other ancient tube machines; in the latter the tubes merely serve as conduits for the ascendingwater, and as such are at rest; while in the screw itis the tubes themselvesin motion that raises the liquid.

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