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revolve a definite number of times per each foot of travel of the former; in this way a regular amount of turn is put into the strand. The turn varies with the size of the strand, more turn being required in the small than in the large sizes. The length of the track limits the travel of the former and also the length of the strand; six strands are generally made . at one time. As many strands as are required for the rope are stretched at full length along the walk and attached at each end to hooks on the laying machine. The hooks are set revolving continuing the fore-turn placed in the strand by the former. At one of the laying machines each strand is in turn removed from its hook and laid in one of three equi- distant concentric grooves of a cone-shaped block called the "top," and then fastened together on the center hook of the machine. The hooks on the two laying machines are now set revolving, the direction of the turn at one end being the opposite to that at the other end; as a consequence being fastened at one end to one hook and at the other end to three hooks; the strands turn or twist on themselves at the end where there is one hook. As the twist or turn is communicated to the strand between the single hook and the "top," the latter is pushed forward, leaving the laid rope behind it. : Great care must be exercised in guiding the block, for on its uniform motion depends the firmness of the rope, as well as the uniform character of its lay. The essential object of spinning hemp is to twist the fibers together, so that by the mutual friction among the fibers composing a thread the strength of the thread is made equal to the strain necessary to break it at its smallest section; hence the right amount of twist is a matter of considerable importance. Too much twist injures the individual fiber and causes the thread to kink and bunch, while too small an amount of turn would allow the fibers to slip and part from one another. The same reason applies to the twisting of threads together to form a strand and the strands to form a rope. The turn which forms the strand is the reverse of the turn placed in the yarn in spinning, and again, the twist which laid the rope is the opposite of the twist or turn in the strand, and hence simi- lar to that of the yarn. These operations may appear at first sight strange and contradictory as well as unnecessary, but every effect must have a cause. Were the strand to have the same twist'as the thread which is spun with its full share, more twist would be added to the thread, causing it at the first opportunity to kink, and by destroying the parallelism of the fibers, weaken the thread. The strand and thread, both having the same turn, each would assist the other to unravel, while with opposite turn each assists the other in pre- serving the unity and uniformity of the strand. Some of the turn in the thread is taken out by the formation of the strand; to compensate for the loss of turn in the strand when laying the rope, an excess of turn is put in the strands while they are fastened to the laying machines. The excess so put in equals the amount taken out by the laying, so that the strand made into rope possesses a normal amount of turn. The turn in the yarn and rope is generally right-handed, while that in the strand is left-handed. If the same turn were put in the strand as in the rope, the rope while under tension would preserve its uniformity and appear well laid, but imme- diately upon the release of the tension each strand would unwind 'and separate and the rope would part. If the strands are tied together at the ends they would close up, shortening the rope. If while in this condition the ropes were again subjected to tension, the strands would stretch, but the lay would not be uniform. The independent stretch of each strand as well as its unequal lay would cause each strand, in assuming its share of the load, to slide and saw upon its neighbors, injuring the fibers and eventually cutting the rope. . The fibers of the prepared manila are composed of elongated cells, roughly resembling a bundle of pipes. They are extremely tenacious longitudinally, but considerably less so transversely, not being very strongly cemented together. Bearing these facts in mind, it will be seen that a loosely twisted, or "'long-laid" rope affords a greater resistance, in- asmuch as the fibers are in the line of their greatest strength. Yet inas- much as the friction between the fibers is an.essential factor in the perfect rope, it is clear that this friction is greater, the harder the rope is twisted. These two elements, working against each other, require for their ad- justment the nicest judgment, coupled with experience. To invest in a eaiey of rope made hap-hazard, or by guess-work, is short-sighted policy. The quality of the oil necessarily used in laying up the rope is another element which enters into the cost. Some "cheap" rope is so heavily saturated with cheap grease as to be absolutely offensive. Since manila rope is universally sold by weight, the temptation to "load" it is great. On the other hand it is more readily detected than the adulteration with red hemp and sisal. . In estimating the difference in value between first and second-class rope, it must always be borne in mind that this difference increases with time of service. Thus a new second-class rope may withstand a breaking strain very nearly equal to that of a new first-class rope, yet after a few months' wear the difference will be vastly greater. This is peculiarly true of sisal rope, where a difference of more than 50 per cent. has been noted. Durability, as well as tensile strength, is thus seen to be an important factor in buying rope. : : Almost the entire product of a rope mill is shipped out in coils, although smaller size ropes are put up in either coils or reels. Some of the product, however, of a rope mill is shipped in balls, and especially is this the case with binder twine. When yarn is spun for this purpose the bobbins are taken direct from the jenney room, where the yarn is spun, to the balling room. The bobbins are here placed on the balling machine, where they are made up into balls of four pounds each, and packed into oe ally made bags, weighing when completed and ready for shipment, 9 S. gross. é : In buying rope, the custom in Great Britain, and formerly in_ this country, was to designate the sizes by the circumference. Thus, a line 1 in. in diameter, was formerly, and by sailors still is, denominated "3 in. or "3% in.," according to the desire of the skipper, "Since no one has succeeded in squaring the circle, any more than in discovering perpetual motion, it is obvious that some confusion was likely to ensue, particularly in the case of such sizes as "2 in.," which might be either 2 in, diameter, or ¥% in. diameter. Our advice to our customers is to order by diameter solely, thus avoiding all uncertainty. : Manufacturers vary somewhat as to the sizes of their.ropes. A hard twisted line may have the same amount and weight of fiber in it as a more MARINE REVIEW. -- loosely twisted one, and yet not measure quite as much in diameter. A tightly twisted rope is apt to "kink" as it comes out of the coil. This may be counteracted by coiling it one or more times through itself. Most of our lines are laid up in coils of 1,200 ft., or half coils of 600 ft. But rope _ of 3% in. diameter and less is kept only in full coils. Following is a table of weights and strength of manila rope based on our experience of upwards of thirty years. It may be regarded as sub- stantially correct, though there is sure to be some variation, even in ropes made at the same time at the same factory: WEIGHT AND STRENGTH OF MANILA ROPE. & ae A -- «a a 33 eo aS 8 33 Eeouo we Sg 32 0 BRE abel bg GE SB oe ce gg) SSE FEE 6g) ce) BBE Be a of som Bae 24 Bo Ona Fas a Zi =S DD a Ai FS @ 4 48 5 450) 1 4 5/16 8 87 i NBO Nod Yel Ber oO de % 50 900] 19/16 1--4 900 16,700 TG TT 75 1,250 1 54 1 Bs) OO Rane > 18 100° 1,700: fd = $40 Won 00 aang 9/16, 100) 9 180 Bee 8 --10in. 1,440 26,900 % tT 6in. 160 3000]| 2 % -- 8% 1,680 31,500 Mou B 200 3,900 || 2 % -- 7% 1,960 36,600 18/16 25 250 4,700 || 2 ¥% -- 614 2,240 42,000 ico 300 5,600 || 2 5% --5% 2560 47,800 1 3--3 360 6,750 ]/ 2 % --5 2,880 54,000 11/16 2-9 420 7850|| 3 -- 434 3,240 60,500 1% 24 A800 1eOG 34, -- 3% 4,400 82,500 1% 2--1.: 560 10,600 |) 4 -- 22/3 5,380 108,000 15/16. 1-10 = 640-:11,950 The above weights are approximate only and apply to sisal as well as to manila rope. THE ORIGIN OF WIRE ROPE. Like many other useful inventions, the origin of wire rope is in dis- pute. Some authorities claim that this apparently intractable material was first made into rope among the Hartz mountains, about the year 1832. It is more certain that in the year 1835, a London engineer named Andrew Smith patented a machine for its manufacture in England. There is a tradition that this vast industry owes its origin to the persistency of a humble rodent. The aforesaid Smith, so the story goes, was making some sort of Venetian blind that was to be moved by a cat-gut cord. Whether through a desire to even up matters with their ancient enemy or otherwise, the cord was eaten by rats as fast as Mr. Andrew Smith could replace it. Something more had to be done. The Smith family reputation for success was at stake. So Andrew bethought himself and began to twist a small cord of fine wires, which, if they tried to gnaw it, must have worn out the incisors of the Muride. The first introduction of wire rope into this country is in dispute between the Morris and Essex canal and the Allegheny Portage railroad. The number of applications in this country: at present is enormous. It is difficult to conceive by what means the elevator service of our modern high buildings could be operated without use of this material. Thus the wire rope has played no inconsiderable part in the growth and development of our great cities. The materials used in making wire rope vary from a cheap grade of iron to the finest steel. Experience has demonstrated that a soft grade of wire is the most durable when constantly bending over a small sheave on drum, but a stiff rope, such as is in demand for rigging or bridge work, calls for a high breaking strain. To get this high tensile strength some- thing of pliability must be sacrificed. Crystallization takes place rapidly in a quick bending steel wire rope. Thus it will be readily seen that in ordering a wire rope it is well to mention the use to which it is to be put. The art of fitting wire rope is a special trade, requiring experience and skill. Mistakes due to inexperience are too costly to be weighed in the balance against the cost of expert service. One of the most modern applications of wire ropes is that of galvan- ized steel hawsers, for towing the vessels in the service of the great lakes. After spending a large amount of money in experimentation, so as to learn the kind 'best adapted for use through the winding, shallow, and rocky rivers through which the lake steamers are obliged to pass with their consorts, our company has settled upon a form of construction and quality of material which we recommend with great confidence. Wire rope, in this country, is universally sold by the foot, while ropes made of vegetable fiber are invariably sold by the pound. To describe the various processes of wire rope manufacture would be interesting, but would require space beyond the reasonable limits of the present work. Three leading types of machines are in use, the principle in each being a "sun and planet" motion. A jute or other hempen core is wrought into the interior of most metal ropes, and this serves aS a cushion to equalize the tension of the various wires and strands, as well as to secure greater pliability. In the case of hawser laid, or tiller rope, this core is found in each individual strand, as well as in the center of the rope itself. The result is a rope of extreme pliability, though of modi- fied strength. Ropes made of fine wires, laid up nineteen to the strand, are preferred for hoisting purposes, whether made of iron or of steel. For all applica- tions of hoisting rope, a main essential is a large bending arc, whether of drum or sheave. A short bend, and particularly a bend in different direc- tions, rapidly destroys the life of a wire rope. Iron wire ropes are used for rapid passenger elevators, and will outwear a stronger steel rope in many places. Where wire ropes are subject to abrasion, as in mining tramway plants, they are made with only seven wires to the strand. Wherever any bright wire rope is exposed to the weather, it is important to preserve it from rust by means of a coating of some kind of lubricant, such as Dixon's wire rope grease. Wire rope should be oiled as regularly as.a piece of machinery. Galvanized ropes are used for standing rigging and for guys, but not for running lines, for which they are-not adapted. The ends are secured by means of eyes spliced around wrought, iron thimbles. Not.eyvery old salt knows how to splice a wire rope. To-do it well requires a skilled artisan with modern tools.