re made of every substance that is sufficiently fibrous, flexible, and tenacious, but chiefly of the barks of plants. The Chinese and other orientals even make them of the ligneous parts of several plants, such as certain bamboos and reeds, the stems of the aloes, the fibrous covering of the cocoa nut, the filament of the cotton pod, and the leaves of some grasses such as the sparte (Liggeum, Linn.). The aloe (Agave, Linn.) and the sparte exceed all others in strength. But the barks of plants are the most productive of fibrous matter fit for this manufacture. Those of the linden tree (Tilia), of the willow, the bramble, the nettle, are frequently used; but hemp and flax are of all others the best; and of these the hemp is preferred, and employed in all cordage exceeding the size of a line, and even in many of this denomination.

Hemp is very various in its useful qualities. These are great strength, and the length and fineness of the fibre. Being a plant of very greedy growth, it sucks up much of the unaltered juices of the soil, and therefore differs greatly according to its soil, climate, and culture. The best in Europe comes to us through Riga, to which port it is brought from very distant places to the southward. It is known by the name of Riga rein (that is, clean) hemp. Its fibre is not the longest (at least in the dressed state in which we get it) of all others, but it is the finest, most flexible, and strongest. The next to this is supposed to be the Peterburgh braak hemp. Other hems are cited nearly in the following order:—Riga outshot, Peterburgh outshot, hemp from Koningsburg, Archangel, Sweden, Memel. Chucking is a name given to a hemp that comes from various places, long in the fibre, but coarse and harsh, and its strength is inferior to hems which one would think weaker. Its texture is such, that it does not admit splitting with the hatchet so as to be more completely dressed. It is therefore kept in its coarse form, and used for inferior cordage. It is, however, a good and strong hemp, but will not make fine work. There are doubtless many good hems in the southern parts of Europe, but little of them is brought to our market. Codilla, half clean, &c. are portions of the above-mentioned hems, separated by the dressing, and may be considered as broken fibres of those hems.

Only the first qualities are manufactured for the rigging of the royal navy and for the ships of the East India Company.

ROPE-MAKING is an art of very great importance, 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 finesws and muscles of a ship; and every improvement which can be made in its preparation, either in respect to strength or pliancy, must be of immense service to the mariner, and to the commerce and the defence of nations.

We shall give a very short account of the manufacture, which will not indeed fully instruct the artificers, but will give such a view of the process as shall enable the reader to judge, from principles, of the propriety of the different parts of the manipulation, and perceive its defects, and the means for removing them.

The aim of the rope-maker is to unite the strength of a great number of fibres. This would be done in the completest manner by laying the fibres parallel to each other, and fastening the bundle at the two ends; numerous but this would be of very limited use, because the fibres are short, not exceeding three feet and a half at an average. They must therefore be entangled together, in such a manner that the strength of a fibre shall not be able to draw it out from among the rest of the bundle. This is done by twisting or twining them together, which causes them mutually to compress each other. When the fibres are so disposed in a long skein, that their ends succeed each other along its length, without many of them meeting in one place, and this skein is twisted round and round, we may cause them to compress each other to any degree we please, and the friction on a fibre which we attempt to pull out may be more than its cohesion can overcome. It will therefore break. Consequently, if we pull at this twisted skein, we will not separate it by drawing one parcel out from among the rest, but the whole fibres will break; and if the distribution of the fibres has been very equable, the skein will be nearly of the same strength in every part. If there is any part where many ends of fibres meet, the skein will break in that part.

We know very well that we can twist a skein of fibres so very hard, that it will break with any attempt to. to twist it harder. In this state all the fibres are already strained to the utmost of their strength. Such a skein of fibres can have no strength. It cannot carry a weight, because each fibre is already strained in the same manner as if loaded with as much weight as it is able to bear. What we have said of this extreme case is true in a certain extent of every degree of twist that we give the fibres. Whatever force is actually exerted by a twisted fibre, in order that it may sufficiently compress the rest to hinder them from being drawn out, must be considered as a weight hanging on that fibre, and must be deducted from its absolute strength of cohesion, before we can estimate the strength of the skein. The strength of the skein is the remainder of the absolute strength of the fibres, after we have deducted the force employed in twisting them together.

From this observation may be deduced a fundamental principle in rope-making, that all twisting, beyond what is necessary for preventing the fibres from being drawn out without breaking, diminishes the strength of the cordage, and should be avoided when in our power. It is of importance to keep this in mind.

It is necessary then to twist the fibres of hemp together, in order to make a rope; but we should make a very bad rope if we contented ourselves with twisting together a bunch of hemp sufficiently large to withstand the strains to which the rope is to be exposed. As soon as we let it go out of our hands, it would untwist itself, and be again a loose bundle of hemp; for the fibres are strained, and they are in a considerable degree elastic; they contract again, and thus untwist the rope or skein. It is necessary to continue the twist in such a manner, that the tendency to untwist in one part may act against the same tendency in another and balance it. The process, therefore, of rope-making is more complicated.

The first part of this process is spinning of rope-yarns. 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 included for the purpose, about 200 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, of a form resembling that in fig. 1. The band of this wheel goes over several rollers called whirles, 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 whirles. The spinner has a bundle of dressed hemp round his waist, with the two 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 a 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. The greatest fault that can be committed in spinning is to allow a small thread to be twisted off from one side of the hemp, and then to cover this with hemp supplied from the other side: for it is evident that the fibres of the central thread make very long spirals, and the skein of fibres which covers them must be much more oblique. This covering has but little connection with what is below it, and will easily be detached. But even while it remains, the yarn cannot be strong; for, on pulling it, the middle part, which lies the straightest, must bear all the strain, while the outer fibres, that are lying obliquely, are only drawn a little more parallel to the axis. This defect will always happen if the hemp be supplied in a considerable body to a yarn that is then spinning small. Into whatever part of the yarn it is made to enter, it becomes a sort of loosely connected wrapper. Such a yarn, when untwisted a little, will have the appearance of fig. 2; while a good yarn looks like fig. 3. A good spinner therefore 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 would instantly untwist, and become little better than loose hemp. He waits, therefore, till he sees the receler 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 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.

Rope-yarns, for the greatest part of the large rigging, are from a quarter of an inch to somewhat more than a third of an inch in circumference, or of such size that 160 fathoms weigh from three and a half to four four pounds when white. The different sizes of yarns are named from the number of them contained in a strand of a rope of three inches in circumference. Few are so coarse that 16 will make a strand of British cordage; 18 is not unfrequent for cable yarns, or yarns spun from harsh and coarse hemp; 25 is, we believe, the finest size which is worked up for the rigging of a ship. Much finer are indeed spun for founding lines, fishing lines, and many other marine uses, and for the other demands of society. Ten good spinners will work up above 600 weight of hemp in a day; but this depends on the weather. In very dry weather the hemp is very elastic, and requires great attention to make smooth work. In the warmer climates, the spinner is permitted to moisten the rag with which he grasps the yarn in his right hand for each yarn. No work can be done in an open spinning walk in rainy weather, because the yarns would not take on the tar, if immediately tarred, and would rot if kept on the reel for a long time.

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 begin with the simplest possible case, the union of two yarns into one line. This is not a very usual fabric for rigging, but we select it for its simplicity.

When hemp has been split into very fine fibres by the hatchet, it becomes exceedingly soft and pliant, and after it has lain for some time in the form of fine yarn, it may be unreeled and thrown loose, without 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 sailmaker's 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 has twisted a packthread very hard with his fingers between his two hands, if he slackens the thread by bringing his hands nearer together, the packthread will immediately curl up, running into loops or kinks, and will even twist itself into a neat and firm cord. Familiar as this fact is, it would puzzle any person not accustomed to these subjects to explain it with definiteness. We shall consider it with some care, not as a piece of mechanical curiosity, but as a fundamental principle in this manufacture, which will give us clear instructions to direct us in the most delicate part of the whole process. And we beg the attention of the

Let \( m \), \( n \) (fig. 4.) be two yarns fixed to one point \( d \), and let both of them be twisted, each round its own axis, in the direction \( a b c \), which will cause the fibres to lie in a screw form, as represented in the figure. If the end \( d \) of the yarn \( m \) were at liberty to turn round the point \( d \), it would turn accordingly, as often as the end \( m \) is turned round, and the yarn would acquire no twist; but being attached to some solid body, it cannot turn without turning this body. It has, however, this tendency, and the body must be forcibly prevented from turning. If it be held fast for a time, and then let go, it will be turned round, and it will not stop till it has turned as often as the end \( m \) has been twisted, and now all the twist will be undone. Thus it is the tendency of the yarn \( m \) to untwist at the end \( d \) (because it is kept fast at \( m \)), which produces this motion of the body attached to it at \( d \). What we have said of the yarn \( m \) is equally true of the yarn \( n \). Both tend to turn, and will turn, the body attached at \( d \) round the common axis, in the same direction in which they are twisted. Let fig. 5. be supposed Fig. 5. a cross section of the two yarns touching each other at \( d \), and there glued to a board. The fibres of each pull obliquely, that is, they both pull away from the board, and pull laterally. The direction of this lateral pull of the fibres in the circumference of each yarn is represented by the little darts drawn round the circumferences. These actions directly oppose and balance each other at \( d \); but in the semicircles \( o e t \), \( t f o \), they evidently conspire to turn the board round in the same direction. The same may be said of the outer halves of any circles described within these. In the inner halves of these inner circles the actions of some fibres oppose each other; but in every circle there are many more conspiring actions than opposing ones, and the conspiring actions exert themselves by longer levers, so that their joint momentum greatly exceeds that of the opposing forces. It may be demonstrated, that if all the fibres exert equal forces, the force which tends to turn the board round the common axis is two-thirds of the force employed to twist both the yarns.

Suppose then that the solid body to which the yarns are attached is at liberty to turn round the common axis; it cannot do this without carrying the yarns round with it. They must, therefore, turn round each other, and thus compose a rope or cord \( k l \), having its component yarns (now called strands) lying in a direction opposite to that of the fibres in each strand. The rope will take this twist, while each of the strands is really untwisting, and the motion will not stop till all is again in equilibrium. If the yarns had no diameter and no rigidity, their elastic contraction would not be balanced till the cord had made half the number of turns which had been given to that part of the yarn which is thus doubled up. But, as the yarns have a sensible diameter, the same ultimate contraction of the fibres will be expended by the twisting of the cord in fewer turns, even if the yarns had no rigidity. The turns necessary for this purpose will be so much fewer, in proportion to the twist of the yarns, as the fibres of the yarn lie more obliquely, that is, as the yarns are more twisted. But further, this contractile force has to overcome the rigidity or stiffness of the yarns. This requires force merely to bend it into the desired form; and therefore, when all is again at rest, the fibres are in a state of strain, and the rope is not so much clothed by doubling as it would have been had the yarns been softer. If any thing can be done to it in this state which will soften the yarns, it will twist itself more up. It has therefore a tendency to twist more up; and if this be aided by an external force which will bend the strands, this will happen. Beating it with a soft mallet will have this effect; or, if it be forcibly twisted till the fibres are allowed to contract as much as they would have done had the yarn been perfectly soft, the cord will keep this twist without any effort; and this must be considered as its most perfect state, in relation to the degree of twist originally given to the yarns. It will have no tendency to run into kinks, which is both troublesome and dangerous, and the fibres will not be exerting any useless effort.

To attain this state should therefore be the aim of every part of this second process; and this principle should be kept in view through the whole of it.

The component parts of a rope are called strands, as has been already observed; 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.

Lines and cordage less than 1½ inches circumference are laid at the spinning-wheel. The workman fastens the ends of each of two or three yarns to separate whirl-hooks. The remote ends are united in a knot. This is put on one of the hooks of a swivel called the loper, represented in fig. 6, and care is taken that the yarns are of equal lengths and twist. A piece of soft cord is put on the other hook of the loper; and, being put over a pulley several feet from the ground, a weight is hung on it, which stretches the yarn. When the workmen feel that they are equally stretched, he orders the wheel to be turned in the same direction as when twining the yarns. This would twine them harder; but the swivel of the loper gives way to the strain, and the yarns immediately twist around each other, and form a line or cord. In doing this the yarns lose their twist. This is restored by the wheel. But this simple operation would make a very bad line, which would be slack, and would not hold its twist; for, by the turning of the loper, the strands twist immediately together, to a great distance from the loper. By this turning of the loper the yarns are untwisted. The wheel restores their twist only to that part of the yarns that remains separate from the others, but cannot do it in that part where they are already twined round each other, because their mutual pressure prevents the twist from advancing. It is, therefore, necessary to retard this tendency to twine, by keeping the yarns apart. This is done by a little tool called the top, represented in fig. 7.

It is a truncated cone, having three or more notches along its sides, and a handle called the staff. This is put between the strands, the small end next the loper, and it is pressed gently into the angle formed by the yarns which lie in the notches. The wheel being now turned, the yarns are more twisted, or hardened up, and their pressure on the top gives it a strong tendency to come out of the angle, and also to turn round. The workman does not allow this till he thinks the yarns sufficiently hardened. Then he yields to the pressure, and the top comes away from the swivel, which immediately turns round, and the line begins to lay.—Gradually yielding to this pressure, the workman slowly comes up towards the wheel, and the laying goes on, till the top is at last close to the wheel, and the work is done. In the mean time, the yarns are shortened, both by the twining of each and the laying of the cord. The weight, therefore, gradually rises. The use of this weight is evidently to oblige the yarn to take a proper degree of twist, and not run into kinks.

A cord or line made in this way has always some tendency to twist a little more. However little friction there may be in the loper, there is some, so that the turns which the cord has made in the laying are not enough to balance completely the elasticity of the yarns; and the weight being appended causes the strands to be more nearly in the direction of the axis, in the same manner as it would stretch and untwist a little any rope to which it is hung. On the whole, however, the twist of a laid line is permanent, and not like that upon thread doubled or thrown in a mill, which remains only in consequence of the great softness and flexibility of the yarn.

The process for laying or closing large cordage is large or considerably different from this. The strands of which heavier the rope is composed consist of many yarns, and require a considerable degree of hardening. This cannot generally be done by a whirl driven by a wheel band; it requires formed, 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-machine board, fig. 8. This consists of a strong oaken plank and mode called a breasting-board, having three or more holes in it, of filing such as A, B, C, fitted with bars or iron plates. Into these there are put iron cranks, called heavers, which have Fig. 8. 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 breasting-board is fixed to the top of strong posts well secured by struts or braces facing the lower end of the walk. At the lower end is another breasting-board fixed to the upright posts of a ledge, which may be loaded with stones or other weights. Similar cranks are placed in the holes of this breasting-board. The whole goes by the name of the ledge; (see fig. 9.) The top necessary for closing Fig. 9. 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, as shown in fig. 10, where it must lie very steady, and need no 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. The 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. bound down. This is shown at W, and it greatly affiits the laying of the rope by its friction. This 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 fledge, and the foreman comes back along the stack of yarns, to see that none are hanging flacker than the rest. He takes up in his hand such as are flack, 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 all together 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 stack 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 their lower ends are fastened to the cranks in the fledge. The fledge 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 fledge 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 fledge is dragged up the walk. When the foreman thinks the strands sufficiently hardened, which he estimates by the motion of the fledge, he orders the heavers at the cranks to stop. The middle strand at the fledge is taken off from the crank. This crank is taken out, and a stronger one put in its place at D, fig. 9. The other strands are taken off from their cranks, and all are joined on the hook which is now in the middle hole. The top is then placed between 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 fledge. 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 fledge turn in the opposite direction to the former motion, so that the cranks at both ends are now turning one way. By the motion of the fledge crank the top is forced away from the knot, and the rope begins to close. The heaving at the upper end restores to the strands 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 fledge 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 fledge has moved several fathoms from the place where it was when the laying began.

These motions of the fledge and top must be exactly adjusted to each other. The rope must be of a certain length. Therefore the fledge 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 flacker 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 regulate 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 strips 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, as is shown in the figure. 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. This is sometimes very difficult, especially in ropes composed of more than three strands. It will greatly improve the laying the rope, if the top have 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 fledge 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 fledge. By this the top is forced up the walk, and the laying of the rope accelerates, while the fledge remains in the same place, because the strands are losing 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 fledge has got to its proper place, he makes the men heave briskly on the strands, and the heavers at the fledge crank to work softly. This quickens the motion of the fledge by shortening the strands; and by thus compensating what has been overdone, the fledge and top come to their places at once, and the work appears to answer the intention.

But this is a bad manner of proceeding. It is evident, that if the strands be kept to one degree of hardness throughout, and the heaving at the fledge be uniform, the rope will be uniform. It may be pointed out, and the laying may be too hard in proportion to the twist of the rope. the strands, in which case it will not keep it; or it may be too slack, and the rope will tend to twist more. Either of these faults is discoverable by slackening the rope before it come off the hooks, and it may then be corrected. But if the error in one place be compensated by that in another, this will not be easily seen before taking off the hooks; and if it is a large and stiff rope, it will hardly ever come to an equable state in its different parts, but will be apt to run into loops during service.

It is, therefore, of importance to preserve the uniformity throughout the whole. M. Du Hamel, in his great work on rope-making, proposes a method which is very exact, but requires an apparatus which is cumbersome, and which would be much in the way of the workmen. We think that the following method would be extremely easy, embarrass no one, and is perfectly exact. Having determined the proportion between the velocity of the top and fledge, let the diameter of the truck of the top carriage be to that of another truck fixed to the fledge, in the proportion of the velocity of the top to that of the fledge. Let a mark be made on the rim of each; let the man at the fledge make a signal every time that the mark on the fledge truck is uppermost. The mark on the carriage truck should be uppermost at the same instant; and in this way the foreman knows the state of the rope at all times without quitting his station. Thus, in making a cable of 120 fathoms, it is usual to warp the yarns 180 fathoms, and to harden them up to 140 before closing. Therefore, in the closing, the top must have 140 fathoms, and the fledge only 20. The diameter of the carriage truck should therefore be seven times the diameter of the fledge truck.

We have hitherto proceeded on the supposition, that the twist produced by the cranks is propagated freely along the strands and along the closing rope. But this is not the case. It is almost unavoidable that the twist is greater in the neighbourhood of the crank which produces it. The strands are frequently of very considerable weight, and lie heavy on the flukes. Force is therefore necessary to overcome their friction, and it is only the overplus that is propagated beyond the fluke. It is proper to lift them up from time to time, and let them fall down again, as the sawer does with his marking line. This helps the twist to run along the strand. But this is not enough for the closed rope, which is of much greater weight, and much stiffer.—When the top approaches the tackle-board, the heaving at the fledge 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 crank must therefore be assisted by men stationed along the rope, each furnished with a tool called a woddler. This is a stout oak 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 woddlers 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 fledge.

It is usual before taking the rope from the hooks to heave a while at the fledge end, in order to harden the rope a little. They do this so as to take it up about \( \frac{1}{6} \). The propriety or impropriety of this practice depends entirely on the proportion which has been previously observed between the hardening of the strands and the twisting of the closing rope. It is, in all cases, better to adjust these precisely, and then nothing remains to be done when the top has arrived at the upper end of the walk. The making of two strand and three strand line pointed out the principle which should be attended to in this case; namely, that the twist given to the rope in laying should be precisely what a perfectly soft rope would give to itself. We do not see any reason for thinking that the proportion between the number of turns given to the strands and the number of turns given to the laid line by its own elasticity, will vary by any difference of diameter. We would therefore recommend to the artists to settle this proportion by experiment. The line should be made of the finest, smallest, and softest threads or yarn. These should be made into strands, and the strands should be hardened up in the direction contrary to the spinning twist. The rope should then be laid, hanging perpendicularly, with a small weight on the top to keep it down, and a very small weight at the end of the rope. The number of turns given to the strands should be carefully noticed, and the number of turns which the rope takes of itself in closing. The weight should then be taken off, and the rope will make a few turns more. This whole number will never exceed what is necessary for the equilibrium; and we imagine it will not fall much short of it. We are clearly of opinion that an exact adjustment of this particular will tend greatly to improve the art of rope-making, and that experiments on good principles for ascertaining this proportion would be highly valuable, because there is no point about which the artists themselves differ more in their opinions and practice.

The cordage, of which we have been describing the manufacture, is said to be hawser laid. It is not uncommon to make ropes of four strands. These are threelaid used for throats, and this cordage is therefore called shroud-laid cordage. A rope of the same size and weight must be smoother when it has four strands, because the strands are smaller; but it is more difficult to lay close. When three cylindrical strands are simply laid together, they leave a vacancy at the axis amounting to \( \frac{1}{8} \) of the section of a strand. This is to be filled up by compressing the strands by twisting them. Each must fill up \( \frac{1}{4} \) of it by changing its shape; and \( \frac{1}{4} \) of this change is made on each side of the strand. The greatest change of shape therefore made on any one part of a strand amounts only to \( \frac{1}{8} \) of the section of the strand. The vacancy between four cylinders is \( \frac{3}{8} \) of one of them. This being divided into eight parts, is \( \frac{3}{8} \) of a strand, and is the greatest compression which any part of it has to undergo. This is nearly five times greater than the former, and must be more difficult to produce. Indeed it may be seen by looking at the figures 11. and 12. that it will be easier to compress a strand into the obtuse angle of 120 degrees than into 90; and without reasoning more about the matter, it appears that the difficulty will increase. creafe with the number of strands. Six strands must touch each other, and form an arch leaving a hollow in the middle, into which one of the strands will slip, and then the rest will not completely surround it. Such a rope would be uneven on the surface. It would be weak; because the central strand would be slack in comparison of the rest, and would not be exerting its whole force when they are just ready to break. We see then that a four strand rope must be more difficult to lay well than a hawser-laid rope. With care, however, they may be laid well and close, and are much used in the royal navy.

Ropes are made of four strands, with a heart or strand in the middle. This gives no additional strength, for the reason just now given. Its only use is to make the work better and more easy, and to support all the strands at the same distance from the axis of the rope. This is of great consequence; because when they are at unequal distances from the axis, some must be more sloping than others, and they will not resist alike. This heart is made of inferior stuff, flax laid, and of a size just equal to the space it is to fill. When a rope of this fabric has been long used and become unserviceable, and is opened out, the heart is always found cut and chaffed to pieces, like very short oakum. This happens as follows: When the rope is violently strained, it stretches greatly; because the strands surround the axis obliquely, and the strain draws them into a position more parallel to the axis. But the heart has not the obliquity of parts, and cannot stretch so much; at the same time, its yarns are firmly grasped by the hard strands which surround them; they must therefore be torn into short pieces.

The process for laying a rope with a heart is not very different from that already described. The top has a hole pierced through it, in the direction of the axis. The skain or strand intended for the heart passes through this hole, and is stretched along the walk. A boy attends it, holding it tight as it is taken into the coiling rope. But a little attention to what has been said will show this method to be defective. The wick will have no more turns than the laid rope; and as it lies in the very axis, its yarns will be much straighter than the strands. Therefore when the rope is strained and stretched, the wick cannot stretch as much as the laid strands; and being firmly grasped by them, it must break into short pieces, and the strands, having lost their support in those places, will sink in, and the cordage grow loose. We should endeavour to enable all to stretch alike. The wick therefore should be twisted in the same manner as the strands, perhaps even a little more. It will thus communicate part of its strength to the rope. Indeed it will not be so uniformly laid, and may chance to have three spiral vacuities. But that this does no harm, is quite evident from the superior strength of cable-laid cordage, to be described presently, which has the same vacuities. In this way are the main and fore stays made for ships of the line. They are thought stronger than hawser-laid ropes; but unfit for running rigging, because their strands are apt to get out of their places when the rope is drawn into loops. It is also thought that the heart retains water, rots, and communicates its putrefaction to the surrounding strands.

Such is the general and essential process of rope making. The fibres of hemp are twisted into yarns, that they may make a line of any length, and stick among each other with a force equal to their own cohesion. Recapitulating them; and, that we may have a rope of any degree of strength, many yarns are united in one strand, for the same reason that many fibres were united in one yarn; and in the course of this process it is in our power to give the rope a solidity and hardness which makes it less penetrable by water, which would rot it in a short while. Some of these purposes are inconsistent with others; and the skill of a rope-maker lies in making the best compensation; so that the rope may on the whole be the best in point of strength, pliancy, and duration, that the quantity of hemp in it can produce.

There is another species of cordage in very general mode of use. A rope of two or more strands may be used as a strand, in order to compose a still larger rope; and in this manner are cables and other ground tackle commonly made; for this reason such cordage is called cable-laid cordage.

The process of cable-laying hardly differs from that of hawser-laying. Three ropes, in their state of permanent twist, may be twisted together; but they will not hold it, like fine thread, because they are stiff and elastic. They must therefore be treated like strands for a hawser. We must give them an additional twist, which will dispose them to lay or close themselves; and this disposition must be aided by the workmen at the fledge. We say the twist should be an addition to their twist as a rope. A twist in the opposite direction will indeed give them a disposition to close behind the top; but this will be very small, and the ropes (now strands) will be exceedingly open, and will become more open in laying. The twist is therefore given in the direction of their twist as a rope, or opposite to that of the primary strands, of which the ropes are composed. These primary strands are therefore partly untwisted in cable-laying a rope, in the same manner as the yarns are untwisted in the usual process of rope-making.

We need not insist farther on this part of the manufacture. The reader must be sensible that the hawser intended for strands of a cable must not be so much twisted as those intended to remain hawsers; for the twist given to a finished hawser is presumed to be that which renders it most perfect, and it must be injured by any addition. The precise proportion, and the distribution of the working up between the hardening of the strands and coiling the cable, is a subject about which the arts are no better agreed than in the case of hawser-laid cordage. We did not enter on this subject while describing the process, because the introduction of reasons and principles would have hurt the simplicity of the description. The reader being now acquainted with the different parts of the manipulation, and knowing what can be done on any occasion, will now be able to judge of the propriety of the whole, when he learns the principle on which the strength of a rope depends.

We have already said, that a rope-yarn should be Mode of twisted till a fibre will break rather than be pulled out estimating from among the rest, and that all twisting beyond this is the strength injurious to the strength of the yarn: And we advanced of ropes. this maxim upon this plain consideration, that it is need- less to bind them closer together, for they will already break rather than come out; and because this closer binding is produced only by forcibly wrapping the out- er fibres round the inner, and drawing the outer ones tight. Thus these fibres are on the stretch, and are strained as if a weight were hung on each of them. The process of laying lines, of a permanent twist, shows that we must do a little more. We must give the yarn a degree of elastic contractility, which will make it lay itself and form a line or cord which will retain its twist. This must leave the fibres of the yarns in a state of greater compression than is necessary for just keeping them together. But more than this seems to be need- less and hurtful. The same maxim must direct us in forming a rope consisting of strands, containing more than one yarn. A needless excess of twist leaves them strained, and less able to perform their office in the rope.

It not unfrequently happens, that the workman, in order to make his rope solid and firm, hardens up the strands till they really break: and we believe that, in the general practice of making large hawsers, many of the outer yarns in the strands, especially those which chance to be outermost in the laid rope, and are there- fore most strained, are broken during the operation.

But there is another consideration which should also make us give no greater twist in any part of the opera- tion than is absolutely necessary for the firm cohesion of the parts, and this independent of the strain to which the fibres or yarns are subjected. Twisting causes all the fibres to lie obliquely with respect to the axis or general direction of the rope. It may just happen that one fibre or one yarn shall keep in the axis, and remain straight; all the rest must be oblique, and the more oblique as they are farther from the axis, and as they are more twisted. Now it is to be demonstrated, that when any strain is given to the rope in the direc- tion of its length, a strain greater than this is actually excited on the oblique fibres, and so much the greater as they are more oblique; and thus the fibres which are already the weakest are exposed to the greatest strains.

Let CF (fig. 13.) represent a fibre hanging from a hook, and loaded with a weight F, which it is just able to bear, but not more. This weight may represent the absolute force of the fibre. Let such another fibre be laid over the two pulleys A, B (fig. 14.), which are in a horizontal line AB, and let weights F and f, equal to the former, be hung on the ends of this fibre, while another weight R, less than the sum of F and f, is hung on the middle point C by a hook or thread. This weight will draw down the fibre into such a position ACB, that the three weights F, R, and f, are in equilibrium by the intervention of the fibre. We affirm that this weight R is the measure of the relative strength of the fibre in relation to the form ACB; for the fibre is equally stretched in all its parts, and therefore in every part it is strained by the force F. If therefore the weights F and f are held fast, and any addition is made to the weight R, the fibre must break, being already strained to its full strength; therefore R measures its strength in relation to its situation. Complete the parallelogram ACBD, and draw the diagonal CD; because AB is horizontal, and AC=BC, DC is vertical, and coin- cides with the direction CR, by which the weight R acts. The point C is drawn by three forces, which are in equilibrium. They are therefore proportional to the sides of a triangle, which have the same directions; or, the force acting in the direction CA is to that acting in the direction CR as CA to CD. The point R is sup- ported by the two forces CA, CB, which are equivalent to CD; and therefore the weight F is to the weight R as CA is to CD. Therefore the absolute strengths of the two fibres AC, BC, taken separately, are greater than their united strengths in relation to their position with respect to CR: and since this proportion remains the same, whatever equal weights are hung on at F and f, it follows, that when any strain DC is made to act on this fibre in the direction DC, it excites a greater strain on the fibre, because CA and CB taken together are greater than CD. Each fibre sustains a strain greater than the half of CD.

Now let the weight R be turned round the axis CR. This will cause the two parts of the fibre ACB to lap round each other, and compose a twisted line or cord CR, as in fig. 15. and the parallelogram ACBD will Fig. 15 remain of the same form, by the yielding of the weights F and f, as is evident from the equilibrium of forces. The fibre will always assume that form which makes the sides and diagonal in the proportion of the weights. While the fibres lap round each other, they are strained to the same degree, that is, to the full extent of their strength, and they remain in this degree of strain in every part of the line or cord CR. If therefore each of the fibres has the strength AB, the cord has the strength DC; and if F and f be held fast, the smallest addition to R will break the cord. The sum of the absolute strength of the two fibres of which this thread is composed is to the sum of their relative strengths, or to the strength of the thread, as AC+CB is to CD, or as AC is to EC.

If the weights F and f are not held fast, but allowed to yield, a heavier weight r may be hung on at C with- out breaking the fibre; for it will draw it into another position A c B, such that r shall be in equilibrium with F and f. Since F and f remain the same, the fibre is as much strained as before. Therefore make c a, c b equal to CA and CB, and complete the parallelogram a c b d. c d will now be the measure of the weight r, because it is the equivalent of c a and c b. It is evident that c d is greater than CD, and therefore the thread formed by the lapping of the fibre in the position a c b is stronger than the former, in the proportion of c d to CD, or c e to CE. The cord is therefore so much stronger as the fibres are more parallel to the axis, and it must be strongest of all when they are quite parallel. Bring the pulleys A, B, close to each other. It is plain that if we hang on a weight R less than the sum of F and f, it cannot take down the bight of the fibre; but if equal to them, although it cannot pull it down, it will keep it down. In this case, when the fibres are parallel to each other, the strength of the cord (improperly so called) is equal to the united absolute strengths of the fibres.

It is easy to see that the length of each of the fibres which compose any part CR of this cord is to the length of the part of the cord as AC to EC; and this is the case even although they should lap round a cylin- der of any diameter. This will appear very clearly to any person who considers the thing with attention. Let \( ac \) (fig. 16.) be an indefinitely small portion of the fibre which is lapped obliquely round the cylinder, and let HKG be a section perpendicular to the axis. Draw \( ae \) parallel to the axis, and draw \( ec \) to the centre of the circle HKG, and \( ae' \) parallel to \( ec \). It is plain that \( ec \) is the length of the axis corresponding to the small portion \( ac \), and that \( ec \) is equal to \( ae \).

Hence we derive another manner of expressing the ratio of the absolute and relative strength; and we may say that the absolute strength of a fibre, which has the same obliquity throughout, is to its relative strength as the length of the fibre to the length of the cord of which it makes a part. And we may lay, that the strength of a rope is to the united absolute strength of its yarns as the length of the cord to the length of the yarns; for although the yarns are in various states of obliquity, they contribute to the strength of the cord in as much as they contribute immediately to the strength of the strands. The strength of the yarns is to that of the strands as the length of the yarns to that of the strands, and the strength of the strands is to that of the rope as the length of the first to that of the last.

And thus we see that twisting the fibres diminishes the strength of the assemblage; because their obliquity, which is its necessary consequence, enables any external force to excite a greater strain on the fibres than it could have excited had they remained parallel; and since a greater degree of twisting necessarily produces a greater obliquity of the fibres, it must more remarkably diminish the strength of the cord. Moreover, since the greater obliquity cannot be produced without a greater strain in the operation of twisting, it follows, that immoderate twisting is doubly prejudicial to the strength of cordage.

These theoretical deductions are abundantly confirmed by experiment; and as many persons give their assent more readily to a general proposition when presented as an induction from unexceptionable particulars, than when offered as the consequence of uncontroverted principles, we shall mention some of the experiments which have been made on this subject. M. Reaumur, one of the most zealous, and at the same time judicious, observers of nature, made the following experiments. (Mem. Acad. Paris, 1711).

1. A thread, consisting of 832 fibres of silk, each of which carried at a medium 1 dram and 18 grains, would hardly support 5 pounds, and sometimes broke with 5 pounds. The sum of the absolute strengths of the fibres is 1040 drams, or upwards of 8 pounds 2 ounces.

2. A skein of white thread was examined in many places. Every part of it bore 9½ pounds, but none of it would bear 10. When twisted flax into a cord of 2 yarns it broke with 16 pounds.

3. Three threads were twisted together. Their mean strength was very nearly 8 pounds. It broke with 17½, whereas it should have carried 24.

4. Four threads were twisted. Their mean strength was 7½. It broke with 21½ instead of 30. Four threads, whose strength was nearly 9 pounds, broke with 22 instead of 36.

5. A small and very well made hempen cord broke in different places with 58, 63, 67, 72 pounds. Another part of it was untwisted into its three strands. One of them bore 29½, another 33½, and the third 35; therefore the sum of their absolute strengths was 98. In another part which broke with 72, the strands which had already borne this strain were separated. They bore 26, 28, and 30; the sum of which is 84.

Admiral Sir Charles Knowles made many experiments on cordage of size. A piece of rope 3½ inches in circumference was cut into many portions. Each of these had a fathom cut off, and it was carefully opened out. It was white, or untarred, and contained 72 yarns. They were each tried separately, and their mean strength was 90 pounds. Each corresponding piece of rope was tried apart, and the mean strength of the nine pieces was 4552 pounds. But 90 times 72 is 6480.

Nothing is more familiarly known to a seaman than further researches into the superior strength of rope-yarns made up into a skein marks on without twisting. They call such a piece of rope a twisting-salvage. It is used on board the king's ships for rolling tackles, slinging the great guns, butt-lings, nippers for holding the viol on the cable, and in every service where the utmost strength and great pliancy are wanted.

It is therefore sufficiently established, both by theory and observation, that the twisting of cordage diminishes its strength. Experiments cannot be made with sufficient precision for determining whether this diminution is in the very proportion, relative to the obliquity of the fibres, which theory points out. In a hawser the yarns lie in a great variety of angles with the axis. The very outermost yarn of a strand is not much inclined to the axis of the rope: for the inclination of this yarn to the axis of its own strand nearly compensates for the inclination of the strand. But then the opposite yarn of the same strand, the yarn that is next the axis of the rope lies with an obliquity, which is the sum of the obliquities of the strand and of the yarn. So that all the yarns which are really in the axis of the rope are exceedingly oblique, and, in general, the inside of the rope has its yarns more oblique than the outside. But in a laid rope we should not consider the strength as made up of the strengths of the yarns; it is made up of the strengths of the strands: For when the rope is violently stretched, it untwists as a rope, and the strands are a little more twisted; so that they are resisting as strands, and not as yarns. Indeed, when we consider the process of laying the rope, we see that it must be so. We know, from what has been already said, that the three strands would carry more when parallel than when twisted into a rope, although the yarns would then be much more oblique to the axis. The chief attention therefore should be turned to the making the most perfect strands.

*We are fully authorized to say that the twist given to cordage should be as moderate as possible. We are certain that it diminishes the strength, and that the appearance of strength which its superior smoothness and hardness gives is fallacious. But a certain degree of this is necessary for its duration. If the rope is laid too slack, its parts are apt to open when it happens to be caught in short loops at its going into a pulley, &c., in which case some of the strands or yarns are apt to kink and break. It also becomes too porous to water, which foaks and rots it. To prevent these and other such inconveniences, a considerable degree of firmness or hard- ropes was necessary; and in order to give the cordage this appearance of superior strength, the manufacturer is disposed to exceed.

Mr Du Hamel made many experiments in the royal dock-yards in France, with a view to ascertain what is the best degree of twist. It is usual to work up the yarns to \( \frac{3}{4} \) of their length. Mr Du Hamel thought this too much, and procured some to be worked up only to \( \frac{1}{2} \) of the length of the yarns. The strength of the first, by a mean of three experiments, was 4321, and that of the last was 5187.

He caused three ropes to be made from the same hemp, spun with all possible equability, and in such proportion of yarn that a fathom of each was of the same weight. The rope which was worked up to \( \frac{3}{4} \) bore 4998 pounds; that which was worked up to \( \frac{1}{2} \) bore 4850; and the one worked up to \( \frac{1}{4} \) bore 6205. In another trial the strengths were 4250, 6753, and 7397. These ropes were of different sizes.

He had influence enough, in consequence of these experiments, to get a considerable quantity of rigging made of yarns worked up only to \( \frac{1}{2} \) of their length, and had them used during a whole campaign. The officers of the ships reported that this cordage was about \( \frac{1}{2} \) lighter than the ordinary kind; nearly \( \frac{1}{2} \) flenderer, so as to give less hold to the wind, was therefore more simple and pliant, and run easier through the blocks, and did not run into kinks; that it required fewer hands to work it, in the proportion of two to three; and that it was at least \( \frac{1}{2} \) stronger. And they said that it did not appear to have suffered more by using than the ordinary cordage, and was fit for another campaign.

Mr Du Hamel also made experiments on other fabrics of cordage, which made all twisting unnecessary, such as simply laying the yarn in skeins, and then covering it with a wrapping of small line. This he found greatly superior in strength, but it had no duration, because the covering opened in every short bending, and was soon fretted off. He also covered them with a woven coat in the manner practised for house-furniture. But this could not be put on with sufficient tightness, without an enormous expense, after the manner of a horse whip. Small ropes were woven solid, and were prodigiously strong. But all these fabrics were found too soft and pervious to water, and were soon rendered unserviceable. The ordinary process of rope-making therefore must be adhered to; and we must endeavour to improve it by diminishing the twist as far as is compatible with the necessary solidity.

In pursuance of this principle, it is surely advisable to lay flack all such cordage as is used for standing rigging, and is never exposed to short bendings. Shrouds, stays, backstays, pendants, are in this situation, and can easily be defended from the water by tarring, serving, &c.

The same principle also directs us to make such cordage of four strands. When the strands are equally hardened, and when the degree of twist given in the laying is precisely that which is correspondent to the twist of the strands, it is demonstrable that the strands are lying less obliquely to the axis in the four-strand cordage, and should therefore exert greater force. And experience fully confirms this. Mr Du Hamel caused two very small hawsers to be made, in which the strands were equally hardened. One of them had three strands, and the other six with a heart. They were worked up to the same degree. The first broke with 865 pounds, and the other with 1325. Several comparisons were made, with the same precautions, between cordage of three and of four strands, and in them all the four-strand cordage was found greatly superior; and it appeared that a heart judiciously put in not only made the work easier and more perfect to the eye, but also increased the strength of the cordage.

It is purely unreasonable to refuse credit to such a uniform course of experiment, in which there is no motive for imposition, and which is agreeable to every clear notion that we can form on this complicated subject; and it argues a considerable presumption in the professional arts to oppose the vague notions which they have of the matter to the calm reflections, and minute examination of every particular, by a man of good understanding, who had no interest in misleading them.

The same principles will explain the superiority of superior cable-laid cordage. The general aim in rope-making or cables is to make every yarn bear an equal share of the general lateral strain, and to put every yarn in a condition to bear, dige, &c., it. But if this cannot be done, the next thing aimed at is, to put the yarn in such situations that the strains to which they are exposed in the use of the rope may be proportioned to their ability to bear it. Even this point cannot be attained, and we must content ourselves with an approach towards it.

The greatest difficulty is to place the yarns of a large strand agreeably to those maxims. Supposing them placed with perfect regularity round the yarn which is in the middle: they will lie in the circumferences of concentric circles. When this whole mass is turned equally round this yarn as an axis, it is plain that they will all keep their places, and that the middle yarn is simply twisted round its axis, while those of the surrounding circles are lapped round it in spirals, and that these spirals are so much more oblique as the yarns are farther from the axis. Suppose the fledge kept fast, so that the strand is not allowed to shorten. The yarns must all be stretched, and therefore strained; and those must be the most extended which are the farthest from the middle yarn. Now allow the fledge to approach. The strand contracts in its general length, and those yarns contract most which were most extended. The remaining extension is therefore diminished in all; but still those which are most remote from the middle are most extended, and therefore most strained, and have the smallest remainder of their absolute force. Unfortunately they are put into the most unfavourable situations, and those which are already most strained are left the most oblique, and have the greatest strain laid on them by any external force. But this is unavoidable: Their greatest hurt is the strains they sustain in the manufacture. When the strand is very large, as in a nine-inch hawser, it is almost impossible to bring the whole to a proper firmness for laying without straining the outer yarns to the utmost, and many of them are broken in the operation.

The reader will remember that a two strand line was in a direct laid or cloved merely by allowing it to twist itself up at two opposite points, the swivel of the lever; and that it was the elasticity due to this arising from the twist of the yarn which produced this effect; and he would probably be surprised when we say, said, that, in laying a larger rope, the strands are twisted in a direction opposite to that of the spinning. Since the tendency to close into a rope is nothing but the tendency of the strands to untwist, it would seem natural to twist the strands as the yarns were twisted before. This would be true if the elasticity of the fibres in a yarn produced the same tendency to untwist in the strand that it does in the yarn. But this is not the case. The contraction of one of the outer yarns of a strand tends to pull the strand backward round the axis of the strand; but the contraction of a fibre of this yarn tends to turn the yarn round its own axis, and not round the axis of the strand. It tends to untwist the yarn, but not to untwist the strand. It tends to untwist the strand only so far as it tends to contract the yarn. Let us suppose the yarn to be spun up to one-half the length of the fibres. The contracting power of this yarn will be only one half of the force exerted by the fibres; therefore, whatever is the force necessary for closing the rope properly, the fibres of the yarns must be exerting twice this force. Now let the same yarn, spun up to one-half, be made up in a strand, and let the strand be twisted in the opposite direction to the spinning till it has acquired the same elasticity fit for laying. The yarns are untwisted. Suppose to three-fourths of the lengths of the fibres. They are now exerting only four-thirds of the force necessary for laying, that is, two-thirds of what they were obliged to exert in the other case; and thus we have stronger yarns when the strands are equally strained. But they require to be more strained than the other; which, being made of more twisted yarn, sooner acquire the elasticity fit for laying. But since the elasticity which fits the strand for laying does not increase so fast as the strain on the fibres of the yarn which produces it, it is plain, that when each has acquired that elasticity which is proper for laying, the strands made of the slack-twisted yarn are the strongest; and the yarns are also the strongest; and being looser, the rope will close better.

Experience confirms all this; and cordage, whose strands are twisted in the opposite direction to the twist of spinning, are found to be stronger than the other in a proportion not less than that of seven to five.

Such being the difficulty of making a large strand, and its defects when made, we have fallen on a method of making great cordage by laying it twice. A hawser-laid rope, flax spun, little hardened in the strands, and flax laid, is made a strand of a large rope called a cable or cablet. The advantages of this fabric are evident. The strands are reduced to one-third or one-fourth of the diameter which they would have in a hawser of the same size. Such strands cannot have their yarns lying very obliquely, and the outer yarns cannot be much more strained than the inner ones. There must therefore be a much greater equality in the whole substance of cable-laid cordage, and from this we should expect superior strength.

Accordingly, their superiority is great, not less than in the proportion of 13 to 9, which is not far from the proportion of four to three. A cable is more than a fourth part, but is not a third part, stronger than a hawser of the same size or weight.

They are seldom made of more than three hawsers of three strands each, though they are sometimes made of three four-stranded hawsers, or of four three-strand- distribution of the working up a cable. When a cable has its yarns shortened to two-thirds, we believe the ordinary practice has been, 1st, To warp 180 fathoms; 2d, To harden up the strands 30 fathoms; 3d, To lay or clove up 13 fathoms; 4th, To work up the hawser nine fathoms; 5th, To clove up eight fathoms. This leaves a cable of 120. Since Mr Du Hamel's experiments have had an influence at Rochefort, the practice has been to warp 190, to harden up 38, to lay up 12, to work up the hawser 10, and then to clove up six; and when the cable is finished, to shorten it two fathoms more, which our workmen call throwing the turn well up. This leaves a cable of 122 fathoms.

As there seems little doubt of the superiority of cordage shortened one-fourth over cordage shortened one-third, the following distribution may be adopted: warp 190 fathoms, harden up 12, lay up 11, work up the hawser 12, and clove up 12 more, which will leave a cable of 143.

There is another question about which the artists are divided in their opinions, viz. the strains made use of during the operation. This is produced by the weight laid on the fledge. If this be too small, the strands will not be sufficiently tightened, and will run into kinks. The fledge will come up by starts: and a small inequality of twist in the strands will throw it askew. The top will not run well without a considerable pressure to throw it from the cloving point, and therefore the cordage will neither clove fairly nor firmly; on the other hand, it is evident, that the strain on the strands is a complete expenditure of so much of their force, and it may be so great as to break them. These are the extreme positions. And we think that it may be fairly deduced from our principles, that as great a strain should be laid on the strands as will make good work, that is, as will enable the rope to clove nearly and completely, but no more. But can any general rule be given for this purpose?

The practice at Rochefort was to load the fledge till its weight and load were double the weight of the yarns when warped 180 fathoms. A six-inch hawser will require about a ton. If we suppose the friction one-third of the weight; the strain on each strand will be about two hundred and a quarter weight. Mr Du Hamel thinks this too great a load, and proposes to put only five-fourths or three-sevenths of the weight of the cordage; and still less if a shorter piece be warped, because it does not require so much force to throw the twist from the two cranks to the middle of the strand. We shall only say, that stronger ropes are made by heavy loading the carriage, and working up moderately, than by greater shortening, and a lighter load; but all this is very vague.

The reader will naturally ask, after this account of the manufacture, what is the general rule for computing the strength of cordage? It cannot be expected to be very precise. But if ropes are made in a manner perfectly similar, we should expect the strength to be in proportion to the area of their section; that is, to the square of their diameters or circumferences, or to the number of equal threads contained in them.

Nor does it deviate far from this rule; yet Mr Du Hamel shows, from a range of experiments made on all cordage of 3½ inch circumference and under, that the strength increases a little faster than the number of equal threads. Thus he found that ropes of

| Threads | Weight (pounds) | |---------|----------------| | 9 | 1014 | | 12 | 1564 | | 18 | 2148 |

We cannot pretend to account for this. We must also observe, that the strength of cordage is greatly improved by making them of yarn spun fine. This requires finely dressed hemp; and being more simple, the fibres lie close, and do not form such oblique spirals. But all hemp will not spin equally fine. Every stalk seems to consist of a certain number of principal fibres, which split more easily into a second set, and these more difficulty into a third set, and so on. The ultimate fineness, therefore, which a reasonable degree of dressing can give to hemp, bears some proportion, not indeed very precise, to the size of the stalk. The British and Dutch use the best hemp, spin their yarn the finest, and their cordage is considerably stronger than the French, much of which is made of their own hemp, and others of a coarse and harsh quality.

The following rule for judging of the weight which a rope will bear, is not far from the truth. It supposes them rather too strong; but it is so easily remembered that it may be of use.

Multiply the circumference in inches by itself, and take the fifth part of the product, it will express the tons which the rope will carry. Thus, if the rope have six inches circumference, 6 times 6 is 36, the fifth of which is \( \frac{7}{5} \) tons; apply this to the rope of 3½, on which Sir Charles Knowles made the experiments formerly mentioned, \( \frac{3}{2} \times \frac{3}{2} = 10.25 \), \( \frac{1}{5} \) of which is 2.05 tons, or 4592 pounds. It broke with 4550.

This may suffice for an account of the mechanical part of the manufacture. But we have taken no notice and its effects on the methods practised in different rope-works are so exceedingly different, that we could hardly enumerate them, or even give a general account of them. It is evidently proper to tar in the state of twine or yarn, this being the only way that the hemp could be uniformly penetrated. The yarn is made to wind off one reel, and having passed through a vessel containing hot tar, it is wound up on another reel; and the superfluous tar is taken off by passing through a hole surrounded with spongy oakum: or it is tarred in skains or hauls, which are drawn by a capstan through the tar-kettle, and through a hole formed of two plates of metal, held together by a lever loaded with a weight.

It is established beyond a doubt, that tarred cordage when new is weaker than white, and that the difference increases by keeping. The following experiments were made by Mr Du Hamel at Rochefort on cordage of three inches (French) in circumference, made of the best Riga hemp.

August 8, 1741.

| White | Tarred | |-------|--------| | Broke with 4500 pounds. | 3400 pounds. | | 4900 | 3300 | | 4800 | 3250 |

April 25, 1743.

| White | Tarred | |-------|--------| | 4600 | 3500 | | 5000 | 3400 | | 5000 | 3400 |

September A parcel of white and tarred cordage was taken out of a quantity which had been made February 12, 1746. It was laid up in the magazines, and comparisons were made from time to time as follows:

| White bore. | Tarred bore. | Differ. | |-------------|--------------|--------| | 1746 April 14. 2645 pounds. | 2312 pounds | 333 | | 1747 May 18. 1762 | 2155 | 607 | | 1747 Oct. 21. 2710 | 2050 | 660 | | 1748 June 19. 2575 | 1752 | 823 | | 1748 Oct. 2. 2425 | 1837 | 588 | | 1749 Sep. 25. 2917 | 1865 | 1052 |

Mr Du Hamel says, that it is decided by experience, 1. That white cordage in continual service is one-third more durable than tarred. 2. That it retains its force much longer while kept in store. 3. That it resists the ordinary injuries of the weather one-fourth longer.

We know this one remarkable fact. In 1758 the shrouds and stays of the Sheer hulk at Portsmouth dockyard were overhauled, and when the worming and service were taken off, they were found to be of white cordage. On examining the storekeepers books, they were found to have been formerly the shrouds and rigging of the Royal William, 110 guns, built in 1715, and rigged in 1716. She was thought top-heavy and unfit for sea, and unrigged and her stores laid up. Some few years afterwards, her shrouds and stays were fitted on the Sheer hulk, where they remained in constant and very hard service for about 30 years, while every tarred rope about her had been repeatedly renewed. This information we received from Mr Brown, boatswain of the Royal William during the war 1758, &c.

Why then do we tar cordage? We thus render it more unpliant, weaker, and less durable. It is chiefly serviceable for cables and ground tackle, which must be continually wetted and even soaked. The result of careful observation is, 1. That white cordage, exposed to be alternately very wet and dry, is weaker than tarred cordage. 2. That cordage which is superficially tarred is constantly stronger than what is tarred throughout, and it resists better the alternatives of wet and dry.

N. B. The shrouds of the Sheer hulk were well tarred and blacked, so that it was not known that they were of white cordage.

Tar is a curious substance, miscible completely with water. Attempts were made to anoint cordage with oils and fats which do not mix with water. This was expected to defend them from its pernicious effects. But it was distinctly found that these matters made the fibres of hemp glide so easily on each other, that it was hardly possible to twist them permanently. Before they grasped each other so hard that they could not be drawn, they were strained almost to breaking.

Attempts have been made to increase the strength of cordage by tanning. But though it remains a constant practice in the manufacture of nets, it does not appear that much addition, either of strength or durability, can be given to cordage by this means. The trial has been made with great care, and by persons fully able to conduct the process with propriety. But it is found that the yarns take so long time in drying, and are so much hurt by drying slowly, that the room required for a considerable rope-work would be immense; and the improvement of the cordage is but trifling, and even equivocal. Indeed tanning is a chemical process, and its effects depend entirely on the nature of the materials to which the tan is applied. It unquestionably condenses, and even strengthens, the fibre of leather: but for anything that we know à priori, it may destroy the cohesion of hemp and flax; and experiment alone could decide the question. The result has been unfavourable; but it does not follow from this that a tan cannot be found which shall produce on the texture of vegetables effects similar to what oak-bark and other astringents produce on the animal fibre or membrane. It is well known that some dyes increase the strength of flax and cotton, notwithstanding the corrosion which we know to be produced by some of the ingredients. This is a subject highly worth the attention of the chemist and the patriot.

**ROPE-Dancer.** See **Rope-Dancer.**

**ROPE-Tarn,** among sailors, is the yarn of any rope untwisted, but commonly made up of junk; its use is to make finnet, matts, &c.

**ROQUET.** See **ROCKET.**

**RORIDULA,** a genus of plants belonging to the pentandria clas. See **BOTANY Index.**

**ROSA,** the Rose; a genus of plants belonging to the rosiflora clas; and in the natural method ranking under the 33rd order, Senticeae. See **BOTANY Index.**

The sorts of roses are very numerous; and the botanists find it very difficult to determine with accuracy which are species and which are varieties, as well as which are varieties of the respective species. On this account Linnæus, and some other eminent authors, are inclined to think that there is only one real species of rose, which is the *rosa canina,* or "dog rose of the hedges," &c., and that all the other sorts are accidental varieties of it. However, according to the present Linnæan arrangement, they stand divided into 14 supposed species, each comprehending varieties, which in some sorts are but few, in others numerous.

The supposed species and their varieties according to the arrangement of modern botanists, are as follows:

1. The canina, canine rose, wild dog-rose of the hedges, or hep-tree, grows five or six feet high, having prickly stalks and branches, pinnated five or seven-lobed leaves, with aculeated foot-stalks, smooth pedunculi, oval smooth germina, and small single flowers. There are two varieties, red-flowered and white-flowered. They grow wild in hedges abundantly all over the kingdom; and are sometimes admitted into gardens, a few to increase the variety of the shrubbery collection.

2. The alba, or common white-rose, grows five or six feet high, having a green stem and branches, armed with prickles, hispid pedunculi, oval smooth germina, and large white flowers. The varieties are,—large double white rose,—dwarf flingle white rose—maidens-blush white rose, being large, produced in clusters, of a white and blushed colour.

3. The Gallica, or Gallican rose, &c., grows from about three or four to eight or ten feet high, in different varieties, with pinnated, three, five, or seven-lobed leaves, and large red and other coloured flowers in different ferent sorts. This species is very extensive in supposed varieties, bearing the above specific distinction, several of which have been formerly considered as distinct species, but are now ranged among the varieties of the Gallican rose, consisting of the following noted varieties.

Common red officinal rose, grows erect, about three or four feet high, having small branches, with but few prickles, and large spreading half-double deep-red flowers.—Rosa mundi (rose of the world) or striped red rose, is a variety of the common red rose, growing but three or four feet high, having large spreading semi-double red flowers, beautifully striped with white—and deep red.—York and Lancaster variegated rose, grows five, six, or eight feet high, or more; bearing variegated red flowers, consisting of a mixture of red and white; also frequently stippled in elegant stripes, sometimes in half of the flower, and sometimes in some of the petals.—Monthly rose, grows about four or five feet high, with green very prickly shoots; producing middle-sized, moderately-double delicate flowers, of different colours in the varieties. The varieties are common red flowered monthly rose—blush-flowered—white-flowered—striped-flowered. All of which blow both early and late, and often produce flowers several months in the year, as May, June, and July; and frequently again in August or September, and sometimes, in fine mild seasons, continues till November or December: hence the name monthly rose.—Double virgin rose, grows five or six feet high, having greenish branches with scarce any spines; and with large double pale-red and very fragrant flowers.—Red damask rose, grows eight or ten feet high, having greenish branches, armed with short aculea; and moderately-double, fine soft-red, very fragrant flowers.—White damask rose, grows eight or ten feet high, with greenish very prickly branches, and white-red flowers, becoming gradually of a whiter colour.—Blush Belgic rose, grows three or four feet high, or more; having greenish prickly branches, five or seven-lobed leaves, and numerous, very double, blush-red flowers, with short petals, evenly arranged.—Red Belgic rose, having greenish and red footstalks and leaves, and fine double deep-red flowers.—Velvet rose, grows three or four feet high, armed with but few prickles; producing large velvet-red flowers, comprising semi-double and double varieties, all very beautiful roses.—Marbled rose, grows four or five feet high, having brownish branches, with but few prickles; and large, double, finely-marbled, red flowers.—Red and yellow Austrian rose, grows five or six feet high, having slender reddish branches, armed with short brownish aculea; and with flowers of a reddish copper colour on one side, the other side yellow. This is a curious variety, and the flowers assume a singularly agreeable appearance.—Yellow Austrian rose, grows five or six feet high, having reddish very prickly footstalks; and numerous bright-yellow flowers.—Double yellow rose, grows six or seven feet high; with brownish branches, armed with numerous large and small yellowish prickles; and large very double yellow flowers.—Frankfort rose, grows eight or ten feet high, is a vigorous grower, with brownish branches thinly armed with strong prickles; and produces largish double purplish-red flowers, that blow irregularly, and have but little fragrance.

4. The centifolia, or hundred-leaved red rose, &c., grows from about three or four to six or eight feet high, in different sorts, all of them hispid and prickly; pinnated three and five-lobed leaves; and large very double red flowers, having very numerous petals, and of different shades in the varieties. The varieties are,—common Dutch hundred-leaved rose, grows three or four feet high, with erect greenish branches, but moderately armed with prickles; and large remarkably double red flowers, with short regularly arranged petals.—Blush hundred-leaved rose, grows like the other, with large very double pale-red flowers.—Provence rose, grows five or six feet, with greenish-brown prickly branches, and very large double globular red flowers, with large petals folding over one another, more or less in the varieties.—The varieties are, common red Provence rose, and pale Provence rose; both of which having larger and somewhat looser petals than the following sort.—Cabbage Provence rose; having the petals closely folded over one another like cabbages.—Dutch cabbage rose, very large, and cabbages tolerably.—Childing Provence rose.—Great royal rose, grows six or eight feet high, producing remarkably large, somewhat loose, but very elegant flowers.—All these are large double red flowers, somewhat globular at first blowing, becoming gradually a little spreading at top, and are all very ornamental fragrant roses.—Moss Provence rose, supposed a variety of the common rose; grows erectly four or five feet high, having brownish stalks and branches, very closely armed with short prickles, and double crimson-red flowers; having the calyx and upper part of the peduncle surrounded with a rough mossy-like substance, effecting a curious singularity. This is a fine delicate rose, of a high fragrance, which together with its mossy calyx, renders it of great estimation as a curiosity.

5. The cinnamomea, or cinnamon rose, grows five or six feet high, or more, with purplish branches thinly aculeated; pinnated five or seven-lobed leaves, having almost incurved petioles, smooth pedunculi, and smooth globular germina; with small purplish-red cinnamon-scented flowers early in May. There are varieties with double flowers.

6. The Alpina, or Alpine inermous rose, grows five or six feet high, having smooth or unarmed reddish branches, pinnated seven-lobed smooth leaves, somewhat hispid pedunculi, oval germina, and deep-red single flowers; appearing in May. This species, as being free from all kinds of armature common to the other sorts of roses, is esteemed as a singularity; and from this property is often called the virgin rose.

7. The Carolina, or Carolina and Virginia rose, &c., grows six or eight feet high, or more, having smooth reddish branches, very thinly aculeated; pinnated seven-lobed smooth leaves, with prickly foot-stalks; somewhat hispid pedunculi, globose hispid germina, and single red flowers in clusters, appearing mostly in August and September. The varieties are, dwarf Pennsylvania rose, with single and double red flowers.—American pale-red rose. This species and varieties grow naturally in different parts in North America; they effect a fine variety in our gardens, and are in estimation for their late-flowering property, as they often continue in blow from August until October; and the flowers are succeeded by numerous red berry-like hips in autumn, causing a variety all winter.

8. The villofa, or villose apple-bearing rose, grows six fix or eight feet high, having strong erect brownish smooth branches; aculeated sparingly pinnated seven-lobed villosa or hairy leaves, downy underneath, with prickly foot-stalks, hispid peduncles, a globular prickly germen; and large single red flowers, succeeded by large round prickly hips, as big as little apples. This species merits admittance into every collection as a curiosity for the singularity of its fruit, both for variety and use; for it having a thick pulp of an agreeable acid relish, is often made into a tolerable good sweetmeat.

9. The pimpinelliflora, or burnet-leaved rose, grows about a yard high, aculeated sparingly; small neatly pinnated seven-lobed leaves, having obtuse folioles and rough petioles, smooth peduncles, a globular smooth germen, and small single flowers. There are varieties with red flowers—and with white flowers. They grow wild in England, &c. and are cultivated in shrubberies for variety.

10. The spinosissima, or most spinous, dwarf burnet-leaved rose, commonly called Scotch rose, grows but two or three feet high, very closely armed with spines; small neatly pinnated seven-lobed leaves, with prickly foot-stalks, prickly pedunculi, oval smooth germen, and numerous small single flowers, succeeded by round dark-purple hips. The varieties are, common white-flowered—red-flowered—striped-flowered—marbled-flowered. They grow naturally in England, Scotland, &c. The first variety rises near a yard high, the others but one or two feet, all of which are single-flowered; but the flowers being numerous all over the branches, make a pretty appearance in the collection.

11. The eglanteria, eglantine rose, or sweet-briar, grows five or six feet high, having green branches, armed with strong spines sparingly; pinnated seven-lobed odoriferous leaves, with acute folioles and rough foot-stalks, smooth pedunculi, globular smooth germen, and small pale-red flowers. The varieties are, common single-flowered—semi-double-flowered—double-flowered—blush double-flowered—yellow-flowered. This species grows naturally in some parts of England, and in Switzerland. It claims culture in every garden for the odoriferous property of its leaves; and should be planted in the borders, and other compartments contiguous to walks, or near the habitation, where the plants will impart their refreshing fragrance very profusely all around; and the young branches are excellent for improving the odour of nosegays and bow-pots.

12. The moschata, or musk-rose, supposed to be a variety only of the ever-green musk rose, hath weak smooth green stalks and branches, rising by support from six to eight or ten feet high or more, thinly armed with strong spines; pinnated seven-lobed smooth leaves, with prickly foot-stalks; hispid peduncles; oval hispid germen; and all the branches terminated by large umbellate clusters of pure-white musk-scented flowers in August, &c.

13. The sempervirens, or ever-green musk-rose, hath a somewhat trailing stalk and branches, rising by support five or six feet high or more, having a smooth bark armed with prickles; pinnated five-lobed smooth shining evergreen-leaves, with prickly petioles, hispid pedunculi, oval hispid germen; and all the branches terminated by clusters of pure-white flowers of a musky fragrance; appearing the end of July, and in August. The semper-

virent property of this elegant species renders it a curiosity among the rosy tribe; it also makes a fine appearance as a flowering shrub. There is one variety, the deciduous musk-rose above mentioned. This species and variety flowers in August, and is remarkable for producing them numerously in clusters, continuing in succession till October or November.

The above 13 species of rose, and their respective varieties, are of the shrub-kind; all deciduous, except the last fort, and of hardy growth, succeeding in any common soil and situation, and flowering annually in great abundance from May till October, in different sorts; though the general flowering season for the principal part of them is June and July; but in a full collection of the different species, the blow is continued in constant succession several months, even sometimes from May till near Christmas; producing their flowers universally on the same year's shoots, rising from those the year before, generally on long pedunculi, each terminated by one or more roses, which in their characteristic state consist each of five large petals and many stamens; but in the doubles, the petals are very numerous; and in some sorts, the flowers are succeeded by fruit ripening to a red colour in autumn and winter, from the seed of which the plants may be raised; but the most certain and eligible mode of propagating most of the sorts is by suckers and layers; and by which methods they may be increased very expeditiously in great abundance.

The white and red roses are used in medicine. The former distilled with water yields a small portion of a butyraeous oil, whose flavour exactly resembles that of the roses themselves. This oil and the distilled water are very useful and agreeable cordials. These roses also, besides the cordial and aromatic virtues which reside in their volatile parts, have a mild purgative one, which remains entire in the decoction left after distillation. The red rose, on the contrary, has an astringent and gratefully corroborating virtue.