ROM:MAKING is a highly important and useful art, by which a great number of delicate fibres are com bined together.
The fibres most commonly used in the manufacture of ropes, are those of hemp, the best kinds of which come from the south of Russia, and are imported into England from Riga and St. Petersburgh.
The fibres of hemp which compose a rope, seldom exceed in length three feet and a half at an average. They must therefore be twined together so as to unite them into one, and this union is effected by the mu tual compression of the two fibres. If this compres sion is too great, the strength of the fibres at the part where they join will be diminished, so that it becomes a matter of great consequence to give them only that degree of twist which is essential to their union.
The first part of the process of ropemaking, is that of spinning the yarns or threads, which is done in a manner analogous to that of ordinary spinning. The spinner carries a bundle of dressed hemp round his waist. The two ends of the bundle unite in front. Having drawn out a proper number of fibres with his hand, he twists them with his fingers, and fixing this twisted part to the hook of a whirl, which is driven by a wheel put in motion by an assistant, he walks backward down the ropewalk, the twisted part always drawing out of the bundle round his waist more fibres as in the common spinning wheel. The spinner takes care that these fibres are properly supplied, and that they always enter the twisted part with their ends, and never by their middle. As soon as he has reach ed the end of the walk, another spinner takes the yarn off the whirl, and gives it to another person to put upon a reel, while he himself attaches his own hemp to the whirl hook, and proceeds clown the walk. When the person at the reel begins to turn, the first spinner who has completed his yarn holds it firmly at the end, and advances slowly up the walk while the reel is turning, keeping it equally tight all the way, till he reaches the reel, where he waits till the second spinner takes his yarn off the whirl hook, and joins it to the end of that of the first spinner, in order that it may follow it on the reel.
The common size of rope yarns is from one-twelfth of an inch in diameter, to a little more than one-ninth of an inch, about 160 fathoms of them weighing from two and a half to four pounds, as in the following table, the first column showing the sizes of the yarns.
Sizes. lbs. oz. drs. Sizes. lbs. oz. drs.
16 4 0 0 21 3 0 4 17 3 12 4 22 2 14 7 18 3 8 14 23 2 12 8 19 3 5 14 24 2 10 10 20 3 3 3 25 2 8 15 The next part of the process is that of Warping the yarns, or stretching them all to one given length, pre vious to their in tarred, which is about two hun dred fathoms n full length rope grounds, and also in putting a slight turn or twist into them.
The third process in ropemaking is the tarring of the yarn. Sometimes the yarns are made to wind off one reel, and having passed through a vessel of hot tar, are wound up on another; the superfluous tar be ing removed by causing the yarn to pass through a hole surrounded with spongy oakum; hut the general method is to tar it in skeins or hanks, which are drawn by a capstan with a uniform motion through the tar kettle. In this process great care must be taken that the tar is boiling neither too fast nor too slow. Yarn for cables requires more tar than for hawser laid ropes, and for standing and running rig ging it requires only to be well covered. Tarred cordage has been found to be weaker than'what is un tarred when it is new, but the tarred rope acquires strength by keeping.
The last part of the process of ropemaking is to lay the cordage. For this purpose two or more yarns are attached at one end to a hook. The hook is then turned the contrary way from the twist of the indivi dual yarn, and thus forms what is called a strand. Three strands, sometimes four, besides a central one, are then stretched at length, and attached at one end to three contiguous but separate hooks, and at the other end to a single hOok, and the process of com bining them together, which is effected by turning the single hook in a direction contrary to that of the other three, consists in so regulating the progress of the twists of the strands round their common axis, that the three strands receive separately at their opposite ends just as much twist as is taken out of them by their twisting the contrary way in the process of com bination. In this way is formed what is technically called a shroud laid rope.