136 Rope Pump. [Book I. But was the chain of this machine formed of metal, or of ropes? Of the latter we have no doubt. They are generally made of flax or fibres of the palm tree at the present day over all the east. In great elevations, chains of rope possess important advantages over those of metal, in their superior lightness, being free from corrosion, and the facility of repairing them. But by far the most interesting problem connected with the Babylonian engine is, was the water of the Euphrates raised by it to the highest terrace at a SINGLE LIFT? If we had not been informed of one reservoir only, on the upper terrace "from whence the gardens on the others were watered," we should have supposed the water really raised as in Joseph's well, i. e. by two, or even more separate chains; and as it is, we cannot believe that so ingenious a people as the Babylonians would raise the whole of the water which the gardens required to the uppermost terrace, when the greatest portion of it was not wanted half so high. As the size of the terraces diminished as they approached the top of the walls, it is probable that full two thirds of the water was consumed within one hundred feet of the ground. We therefore conclude that this famous engine was composed of at least two, and probably more, separate chains of pots; and even then, it might with as much propriety, be noticed by ancient authors as a single machine, as that at Cairo still is, by all modern travelers. Winkelman says, the famous gardens at Babylon had canals, some of "which were supplied by pumps and other engines." And Kircher in his Turris Babel, 1679, represents fountains and jets d'eau on every terrace. There is another device that belongs to this chapter. Every person knows, that where water is dispersed over extended surfaces, and of too limited depth to allow the use of a vessel to scoop it up, various substances are employed to absorb it, as sponge and woolen rags, and from which it is separated by pressure. A housemaid, when washing a floor, thus collects in a cloth the liquid dispersed in the purifying process; and by wringing returns it to the vessel. The process is substantially the same as that adopted to raise water in Vera's Rope Pump. See No. 57. This machine consists of one or more endless ropes, formed of loosely Chap. 16.] Hydraulic Belt. 137 spun wool or horse hair, and stretched on two pulleys like the endless chain of pots. These pulleys have grooves formed on their surfaces for the reception of the ropes. One of them is placed over the mouth of a well, and the other suspended in or secured to the bottom. A rapid motion is communicated to the upper pulley, by a multiplying wheel, and the 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, partly by centrifugal force, and partly by being squeezed in the deep groove, or by passing through a tube as shown in the figure. In the beginning of the motion, the column of water adhering to the rope, is always less than when it has been worked for some time, and continues to increase till the surrounding 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 double band of woolen cloth, passing over two rollers, as in figure 57. It is driven with a velocity of not less than a thousand feet per minute; when the water contained between the two surfaces is carried up and discharged as it passes over the upper roller, by the pressure of the band. Some machines of this kind are stated to have produced an effect equal to seventy-five per cent. of the power expended, while that of ordinary pumps seldom exceeds 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 elevationsMarquis of Worcester's proposition relating to it, exemplified by M. Pattu-Ascent of water in it formerly considered inexplicable-Its history-Not invented by Archimedes-Supposed to have been in early use in Egypt-Vitruvius silent respecting its author-Conon its inventor or re-inventor-This philosopher famous for his flattery of Ptolemy and Berenice-Dinocrates the architect-Suspension of metallic substances without support-The screw not attributed to Archimedes till after his death-Invertions often given to others than their authors-Screws used as ship pumps by the Greeks-Flatterers like Conon too often found among men of science-Dedications of European writers often blasphemousHereditary titles and distinctions-Their acceptance unworthy of philosophers-Evil influence of scientific men in accepting them-Their denunciation a proof of the wisdom and virtue of the framers of the U. S. Constitution-Their extinction in Europe desirable-Plato, Solon, and Socrates-George WGeorge IV-James Watt-Arago-Description of the 'Syracusan,' a ship built by Archimedes, in which the Screw Pump was used. THE COCHLEON or EGYPTIAN SCREW, the machine next described by Vitruvius, is, in every respect, the most original one of which he has given an account. Unlike the preceding, which appear to have been in a great measure deduced from each other, it forms a species of itself; and whoever was its inventor, he has left in it a proof of his genius, and a lasting monument of his skill. If it be not the earliest hydraulic engine that was composed of tubes, or in the construction of which they were introduced, it certainly is the oldest one known of that description; and in its mode of operation it differs essentially from all other ancient tube ma chines; in the latter the tubes merely serve as conduits for the ascending water, and as such are at rest; while in the screw it is the tubes themselves in motion that raises the liquid. 138 The Screw. [Book I. This machine has been constructed in a variety of ways. Sometimes by winding, in the manner of a screw, one or more flexible tubes No. 58. Screw. (generally of lead or strong leather) round a cylinder of wood or iron. This cylinder is sustained by gudgeons in such a position, that at whatever angle with the horizon it is used, the plane of the helix must always be inclined to its axis at a greater angle; otherwise no water could be raised by it any more than by turning it in the wrong direction. The lower end being immersed in water, the liquid enters the tube and is gradually raised by each revolution until it is discharged above. These machines are commonly used at an inclination to the horizon of about 45°, although they sometimes are placed at 60°. See the figure. Instead of tubes wound round a cylinder, large grooves were sometimes formed in the latter and covered by boards or sheets of metal, closely nailed to the surfaces between the grooves-so that the latter might be considered as tubes sunk into the cylinder, instead of being folded round its exterior. No. 59. Roman Screw. Another mode was to make the threads of plank, arranged as a helix round a solid cylinder, which was fitted with journals, and made to revolve in a fixed hollow cylinder of the same length; the edges or extremities of the threads rubbing against the sides of the latter, and consequently producing the same effect as No. 58. This modification of the cochleon is known as the German Snail. It has this advantage, that it may be worked in an open channel, or half a cylinder instead of a whole one, since it is only the lower half of the latter, that is essential to the the operation of raising water. Machines of this kind of large dimensions have long been employed by the Dutch, and are generally driven Chap. 16.] The Screw. 139 by windmills. But the outer cylinder is more generally fixed to the edges of the helix, and turned with it. It was made in this manner by the ancient Romans; the outer cylinder or case was of plank, well jointed together, and nailed to the edges of the screw, and the whole cemented with pitch, and bound together by iron hoops. It was moved like the noria, &c. "by the walking of men." Vitruvius, B. x, Chap. 11. See No. 59. The screw as represented in the preceding figures, has never been lost to the world since its invention, although it has long been unknown in that country in which it was devised-Egypt. It appears early in printed books. In the first German edition of Vegetius, (1511) it is figured, and nearly in a vertical position. A laborer with a feather in his cap, and a sword at his side, is seated across the top of the frame, and turns it by a crank.a Like almost every other hydraulic engine, the screw has often been re-invented. Cardan mentions a blacksmith of Milan, who imagining himself its original inventor, "for joy, ran out of his wits," and the writer recollects when a boy, hearing of an ingenious shoemaker in much the same predicament. It appears to have been, like other machines for the same purpose, introduced into England from Germany. "The Holland ers, (says Switzer,) have long ago, as some books that I have seen of theirs of fortification intimate, us'd them in draining their morassy and fenny ground, from whence they have been brought into England; and used in the fens of Lincolnshire, Cambridgeshire and other low countries. Those of the smallest kind that are worked by men have only an iron handle, as a grindstone has; but the largest that are wrought by horses, have a wheel like the cog-wheel of a horse mill. This engine, (he continues,) which takes hold of the water, as a cork screw does a cork, will throw up water as fast as an overshot wheel, whereby in a short time, an infinite number of water may be thrown up; and I remember when the foundation of the stately bridge of Blenheim was laid, we had some of them used with great success; and they are also used in the New River Works, about Newbury, Berkshire, and said to be the contrivance of a common soldier, who brought the invention out of Flanders." Hydrostatics, 296, 298. When employed to raise water to great elevations, a series of two, three, or more, one above another, have been employed; the lower one discharging its contents into a basin, in which the inferior end of the next above is immersed, the whole being connected by cog wheels. Thus an old author observes, "you may raise water to any height in a narrow place, viz. within a tower to the top thereof, as we have known done at Augusta, in Germany; to wit, if the spiral pipes be multiplied, so that the water being raised by the lower spiral, and being poured out into some receptacle or cistern; hence, it may be raised higher again by another spiral, and so successively by more spirals, as high as you please, all which spirals may be moved by one power, viz. by the water of a river underneath, or by another animated power." Moxon. It was one of the objects of the Marquis of Worcester, and his 'unparalleled workman, Caspar Kaltoff,' to avoid the necessity of thus combin Whether sitting was the usual position of European laborers and mechanics when at work, in the middle ages, we know not; but Cambden has a remark which intimates that all English mechanics had not in his time, abandoned this oriental custom In concluding his long account of "the States and Degrees of England," from kings, princes, dukes, lords, knights, &c. he continues, "lastly, craftsmen, artizans or workmen; be they that labor for hire, and namely, such as sIT at work, mechanicke artificers, smiths, carpenters," &c. 66 [Book I. ing a number of them together, as appears from the fifty-third proposition in the century of inventions,' A way how to make hollow and cover a water screw, as "big and as long as one pleaseth, in an easy and cheap way." How, and of what materials he made this, is not known, but the fifty-fifth proposition, in the following words, has been fully and practically developed by a French engineer. "A double water screw, the innermost to mount the water, and the outermost for it to descend, more in number of threads, and consequently in quantity of water, though much shorter than the innermost screw by which the water ascendeth; a most extraordinary help for the turning the screw to make the water rise." In 1815, M. Pattu published an account of the following improvements, by which the ideas of Worcester are realized. No. 60. represents two separate screws formed on the same axis, one of which, A, is long and narrow and serves for the nucleus of C, which is much wider and shorter. This is designed to propel the former. The threads of both wind round the axis in opposite directions, so that when those on one appear to be moving upwards, those on the other seem to be going downwards. The water from the stream M, is directed into the top of the large screw, and by its weight (as on an overshot wheel) puts the whole in motion, and consequently the water at O, in which the lower end of A revolves, is raised into the cistern at B. No. 61 is merely the same machine inverted. It illustrates the applications to such locations as have a short fall above the place to which the water is to be raised. In No. 62 the small screw drives the large one, through which the water from the lowest level is raised sufficiently high to be discharged at an intermediate one, as at G. From these figures it will be perceived that the screw has been employed like the noria and the chain of pots, to transmit power. This machine was formerly considered as exhibiting a very singular paradox, viz. that the water "ascended by descending," and the mystery was, how both these operations could be performed at the same time, and yet produce so strange a result. It was remarked that when those formed of glass, were put in motion, the water ran down the under side of each turn of the tubes, and continued thus to descend until it was discharged at the top! The whole operation and the effects being visible, there seemed no room for dispute, however contrary to acknowledged principles the whole might appear. The case was apparently inexplicable, and seemed to present a parallel one to that of the asymtote; the properties of the latter being as incapable of demonstration to the senses, as the supposed operation of this machine could be reconciled to the mind. Indeed the proposition, that two geometrical lines may continue to approach each other forever, without the possibility of coming in contact, is apparently, quite as impossible, as that water should ascend an inclined plane, by the mere exercise of its own gravity. But the idea of water descending in |