fishing-line, or whip-cord, to the cable of a ROPE making, is an art of very great im portance; and there are few that better deserve the attention of the intelligent observer. Hardly any art can be carried on without the assistance of the rope-maker. Cordage makes the very sinews and muscles of a ship; and every improvement which can be made in its preparation, either in respect to strength or pliableness, must be of immense service to the mariner, and to the commerce and the defence of nations. The aim of the rope-maker is to unite the strength of a great number of fibres, and the first part of his process is spinning of rope-yarns, that is, twisting the hemp in the first instance. This is done in various ways, and with different machinery, according to the nature of the intended cordage. We shall confine our description to the manufacture of the larger kinds, such as are used for the standing and running rigging of ships. An alley, or walk, is inclosed for the purpose, about two hundred fathoms long, and of a breadth suited to the extent of the manufacture. It is sometimes covered above. At the upper end of this rope-walk is set up the spinning-wheel. The band of the wheel goes over several rollers, called whirls, turning on pivots in brass holes. The pivots at one end come through the frame, and terminate in little hooks. The wheel, being turned by a winch, gives motion in one direction to all those whirls. The spinner has a bundle of dressed hemp round his waist, with the two VOL. V. ends meeting before him. The hemp is laid in this bundle in the same way that women spread the flax on the distaff. There is great variety in this; but the general aim is to lay the fibres in such a manner, that as long as the bundle lasts, there may be an equal number of the ends at the extremity, and that a fibre may never offer itself double, or in a bight. The spinner draws out a proper number of fibres, twists them with his fingers, and having got a sufficient length detached, he fixes it to the hook of a whirl. The wheel is now turned, and the skein is twisted, becoming what is called rope yarn, and the spinner walks backwards down the rope-walk. The part already twisted, draws along with it more fibres out of the bundle. The spinner aids this with his fingers, supplying hemp in due proportion as he walks away from the wheel, and taking care that the fibres come in equally from both sides of his bundle, and that they enter always with their ends, and not by the middle, which would double them. He should also endeavour to enter every fibre at the heart of the yarn. This will cause all the fibres to mix equally in making it up, and will make the work smooth, because one end of each fibre is by this means buried among the rest, and the other end only lies outward; and this, in passing through the grasp of the spinner, who presses it tight with his thumb and palm, is also made to lie smooth. A good spinner endeavours always to supply the hemp in the form of a thin flat skein, with his left hand, while his right is employed in grasping firmly the yarn that is twining off, and in holding it tight from the whirl, that it may not run into loops or kinks. It is evident, that both the arrangement of the fibres, and the degree of twisting, depend on the skill and dexterity of the spinner, and that he must be instructed, not by a book, but by a master. The degree of twist depends on the rate of the wheel's motion, combined with the retrograde walk of the spinner. We may suppose him arrived at the lower end of the walk, or as far as is necessary for the intended length of his yarn. He calls out, and another spinner immediately detaches the yarn from the hook of the whirl, gives it to another, who carries it aside to the reel; and this second spinner attaches his own hemp to the whirl hook. In the mean time, the first spinner keeps fast hold of the end of his yarn; for the hemp, being dry, is very elastic, and if he were to let it go out of his hand, it Rr would instantly untwist, and become little better than loose hemp. He waits, therefore, till he sees the reeler begin to turn the reel, and he goes slowly up the walk, keeping the yarn of an equal tightness all the way, till he arrives at the wheel, where he waits with his yarn in his hand till another spinner has finished his yarn. The first spinner takes it off the whirl-hook, joins it to his own, that it may follow it on the reel, and begins a new yarn. The second part of the process is the conversion of the yarns into what may, with propriety, be called a rope, cord, or line. That we may have a clear conception of the principle which regulates this part of the process, we shall be gin with the simplest possible case, the union of two yarns into one line. When hemp has been split into very fine fibres by the hatchel, it becomes exceed. ingly soft and pliant, and after it has lain for some time in the form of fine yarn, it may be unreeled and thrown loose, with out losing much of its twist. Two such yarns may be put on the whirl of a spinning wheel, and thrown like flaxen yarn, so as to make sewing thread. It is in this way, indeed, that the sailmakers sewing thread is manufactured, and when it has been kept on the reel, or on balls or bobbins for some time, it retains its twist as well as its uses require. But this is by no means the case with yarns spun for great cordage. The hemp is so elastic, the number of fibres twisted together is so great, and the diameter of the yarn (which is a sort of lever on which the elasticity of the fibre exerts itself), is so considerable, that no keeping will make the fibres retain this constrained position. The end of a rope yarn being thrown loose, it will immediately untwist, and this with considerable force and speed. It would, therefore, be a fruitless attempt to twist two such yarns together; yet the ingenuity of man has contrived to make use of this very tendency to untwist not only to counteract itself, but even to produce another and a permanent twist, which requires force to undo it, and which will recover itself when this force is removed. Every person must recollect that when he had twisted a pack thread very hard with his fingers between his two hands, if he slackens the thread by bringing his hands nearer together, the pack thread will immediately curl up, running into loops or kinks, and will even twist itself into a neat and firm cord. The component parts of a rope are called strands, and the operation of uniting them with a permanent twist is called laying or closing, the latter term being chiefly appropriated to cables and other very large cordage. The process for laying or closing large cordage is this: the strands of which the rope is composed consist of many yarns, and require a considerable degree of hardening. This cannot be done by a whirl driven by a wheel-band; it requires the power of a crank turned by the hand. The strands, when properly hardened, become very stiff, and when bent round the top, are not able to transmit force enough for laying the heavy and unpliant rope which forms beyond it. The elastic twist of the hardened strands must, therefore, be assisted by an external force. All this requires a different machinery and a different process. At the upper end of the walk is fixed up the tackle board, this consisti of a strong oaken plank, called a breastboard, having three or more holes in it, fitted with brass or iron plates. Into these are put iron cranks, called heavers, which have hooks or forelocks, and keys, on the ends of their spindles. They are placed at such a distance from each other, that the workmen do not interfere with each other while turning them round. This breast board is fixed to the top of strong posts, well secured by struts, or braces, fac ing the lower end of the walk. At the lower end is another breast-board, fixed to the upright post of a sledge, which may be loaded with stones or other weights. Similar cranks are placed in the holes of this breast-board; the whole goes by the name of the sledge. The top necessary for closing large cordage is too heavy to be held in the hand; it therefore has a long staff, which has a truck on the end: this rests on the ground, but even this is not enough in laying great cables. The top must be supported on a carriage, where it must lie very steady, and it needs attendance, because the master workman has sufficient employment in attending to the manner in which the strands close behind the top, and in helping them by various methods. top is therefore fixed to the carriage, by lashing its staff to the two upright posts. A piece of soft rope, or strap, is attached to the handle of the top by the middle, and its two ends are brought back and wrapped several times tight round the rope, in the direction of its twist, and bound down. This greatly assists the laying of the rope The by its friction, which both keeps the top from flying too far from the point of union of the strands, and brings the strands more regularly into their places. The first operation is warping the yarns. At each end of the walk are frames called warping frames, which carry a great number of reels or winches, filled with rope-yarn. The foreman of the walk takes off a yarn end from each, till he has made up the number necessary for his rope or strand, and bringing the ends together, he passes the whole through an iron ring fixed to the top of a stake driven into the ground, and draws them through: then a knot is tied on the end of the bundle, and a workman pulls it through this ring till the intended length is drawn off the reels. The end is made fast at the bottom of the walk, or at the sledge, and the foreman comes back along the skein of yarns, to see that none are hang ing slacker than the rest. He takes up in his hand such as are slack, and draws them tight, keeping them so till he reaches the upper end, where he cuts the yarns to a length, again adjusts their tightness, and joins them altogether in a knot, to which he fixes the hook of a tackle, the other block of which is fixed to a firm post, called the warping post. The skein is well stretched by this tackle, and then separated into its different strands. Each of these is knotted apart at both ends. The knots at their upper ends are made fast to the hooks of the cranks in the tackle-board, and those at the lower ends are fastened to the cranks in the sledge. The sledge itself is kept in its place by a tackle, by which the strands are again stretched in their places, and every thing adjusted, so that the sledge stands square on the walk, and then a proper weight is laid on it. The tackle is now cast off, and the cranks are turned at both ends, in the contrary direction to the twist of the yarns (in some kinds of cordage the cranks are turned the same way with the spinning twist). By this the strands are twisted and hardened up, and as they contract by this operation, the sledge is dragged up the walk. When the foreman thinks the strands sufficiently hardened, which he estimates by the motion of the sledge, he orders the heavers at the cranks to stop. The middle strand at the sledge is taken off from the crank; this crank is taken out, and a stronger one put in its place. The other strands are taken off from their cranks, and are all joined on the hook which is now in the middle hole; the top is then placed be tween the strands, and being pressed home to the point of their union, the carriage is placed under it, and it is firmly fixed down: some weight is taken off the sledge. The heavers now begin to turn at both ends; those at the tackle-board continue to turn as they did before, but the heavers at the sledge turn in the opposite direction to their former motion, so that the cranks at both ends are now turning one way. By the motion of the sledge crank the top is forced away from the knot, and the rope begins to close. The heaving at the upper end restores to the strand the twist which they are constantly losing by the laying of the rope. The workmen judge of this by making a chalk mark on intermediate points of the strands, where they lie on the stakes which are set up along the walk for their support. If the twist of the strands is diminished by the motion of closing, they will lengthen, and the chalk mark will move away from the tackle-board; but if the twist increases by turning the cranks at the tackle-board, the strands will shorten, and the mark will come nearer to it. As the closing of the rope advances, the whole shortens, and the sledge is dragged up the walk. The top moves faster, and at last reaches the upper end of the walk, the rope being now laid. In the mean time, the sledge has moved several fathoms from the place where it was when the laying began. These motions of the sledge and top must be exactly adjusted to each other. The rope must be of a certain length, therefore the sledge must stop at a certain place. At that moment the rope should be laid; that is, the top should be at the tackle-board. In this consists the address of the foreman. He has his attention directed both ways. He looks at the strands, and when he sees any of them hanging slacker between the stakes than the others, he calls to the heavers at the tackle-board to heave more upon that strand. He finds it more difficult to regu late the motion of the top. It requires a considerable force to keep it in the angle of the strands, and it is always disposed to start forward. To prevent or check this, some straps of soft rope are brought round the staff of the top, and then wrapped several times round the rope behind the top, and kept firmly down by a lanyard or bandage. This both holds back the top, and greatly assists the laying of the rope, causing the strands to fall into their places, and keep close to each other, which is sometimes very difficult, espe. cially in ropes composed of more than three strands. It will greatly improve the laying the rope, if the top has a sharp, smooth, tapering pin of hard wood, pointed at the end, projecting so far from the middle of its smaller end, that it gets in between the strands which are closing. This supports them, and makes their closing more gradual and regular. The top, its notches, the pin, and the warp, or strap, which is lapped round the rope, are all smeared with grease or soap, to assist the closing. The foreman judges of the progress of closing chiefly by his acquaintance with the walk, knowing that when the sledge is abreast of a certain stake, the top should be abreast of a certain other stake. When he finds the top too far down the walk, he slackens the motion at the tackle board, and makes the men turn briskly at the sledge. By this the top is forced up the walk, and the laying of the rope accelerates, while the sledge remains in the same place, because the strands are loosing their twist, and are lengthening, while the closed rope is shortening. When, on the other hand, he thinks the top too far advanced, and fears that it will be at the head of the walk before the sledge has got to its proper place, he makes the men heave briskly on the strands, and the heavers at the sledge crank work softly. This quickens the motion of the sledge by shortening the strands; and by thus compensating what has been over-done, the sledge and top come to their places at once, and the work appears to answer the intention. When the top approaches the tackle board, the heaving at the sledge could not cause the strands immediately behind the top to close well, without having previously produced an extravagant degree of twist in the intermediate rope. The effort of the erank must therefore be assisted by men stationed along the rope, each furnished with a tool called a woolder. This is a stout oaken stick, about three feet long, having a strap of soft rope-yarn or cordage, fastened on its middle or end. The strap is wrapped round the laid rope, and the workman works with the stick as a lever, twisting the rope round in the direction of the crank's motion. The woolders should keep their eye on the men at the crank, and make their motion correspond with his. Thus they send forward the twist produced by the crank, without either increasing or diminishing it, in that part of the rope which lies between them and the sledge, Such is the general and essential process of ROPE yarn, among sailors, is the yarn of any rope untwisted, but commonly made up of junk; its use is to make sinnet, mats, &c. RORIDULA, in botany, a genus of the Pentandria Monogynia class and order. Esential character: calyx five-leaved; corolla five-petalled; anthers scrotiform at the base; capsule three-valved. There is but one species, viz. R. dentata, a native of the Cape of Good Hope. ROSA, in botany, the rose, a genus of the Icosandria Polygynia class and order. Natural order of Senticosa. Rosacea, Jussieu. Calyx pitcher-shaped, five-cleft, fleshy, contracted at the neck; petals five; seeds very many, hispid, fastened to the inner side of the calyx. There are forty species. ROSACIC acid. During certain diseases, the urine, when it cools, deposits a peculiar substance, which has been denominated, from its colour, which resembles bricks, lateritious sediment. During fevers, this appearance of the urine takes place; and in gouty persons, at the termination of the paroxysms, it is very abundant. And when this suddenly disappears, and the urine at the same time continues to deposit this sub. of ROTACEÆ, in botany, the name of the twentieth order in Linnæus's Fragments of a Natural Method, consisting of plants with one flat, wheel-shaped petal. Among the genera of this order is the gentiana, the root of which is a well-known stomachic, and makes a principal ingredient in bitters. The plant grows plentifully in the mountainous parts of Germany, from whence the roots are brought to England for medicinal purposes. The cistus, or rock-rose, and the bypincum, or St. John's wort, have been annexed also to this order, It may be observed, that gum labdanum is an odorife. rous balsam, or resin, which is found on a species of the rock-rose, viz. the cistus ladanifera, that grows naturally in the Levant. This substance is collected by the natives by means of leathern thongs, rub. bed gently over the surface of the shrub which produces it. From a species of the hypericum, an oil is extracted, that proves an excellent vulnerary. ROTALA, in botany, a genns of the Triandria Monogynia class and order. Natural order of Caryophylleæ. Essential character: calyx three-toothed; corolla none; capsule three-celled, many seeded. There is but one species, viz. R. verticillaris, a native of the East Indies. ROTATION, in geometry, a term chief. ly applied to the circumvolution of any sur face round a fixed and immoveable line, 4 d xx-xx n ; and therefore the portion of the sphere is to the portion of the circumscribed cylinder, as d- f x to d — x. ROTHIA, in botany, so named in honour of Albrecht Wilhelm Roth, physician at Bremen; a genus of the Syngenesia Polygamia Equalis class and order. Natural order of Compositæ Semiflosculosa. Cichc raceæ, Jussien. Essential character: calyx many-leaved, in a single row, equal, woolly; receptacle in the ray chaffy, in the disk villose; seeds in the ray bald, in the disk pappose. There is only one species, viz. R. andryaloides. ROTTBOELLIA, in botany, so named in memory of Christian Früs Rottboel, Professor of Botany, at Copenhagen; a genus of the Polygamia Monoecia class and order. Natural order of Gramina, Gramineæ, or Grasses. Essential character: rachis joint. ed, roundish, in most species filiform; calyx ovate, lanceolate, flat, one or two-valv. ed; florets alternate on a flexuose rachis, There are seventeen species. ROUND, in a military sense, signifies a walk which some officer, attended with a party of soldiers, takes in a fortified place around the ramparts, in the night-time, in order to see that the centries are watchful, aud every thing in good order. The centries are to challenge the rounds at a distance, and rest their arms as they pass, to let none come near them; and when the round comes near the guard, the centry calls aloud, "Who comes there?" and be ing auswered, "the rounds;" he says "stand;" and then calls the corporal of the guard, who draws his sword, and calls as "Who comes there," and when he > |