Page:The American Cyclopædia (1879) Volume XIV.djvu/444

 424 ROPE practice of water-rotting it. American hemp is dew-rotted. Manila hemp comes chiefly from the Philippine islands, taking its name from Manila, the principal town. The best brand is the Cebu, named from the island on which it is grown ; Quilot is another good brand ; the Leyte is of inferior quality, while Lupis is very fine, white and silky, and of too high a grade for rope making. Hemp purchased for gov- ernment use is first tested by inspection. It should present a fair appearance to the eye, be clear, dry, and free from a niusty smell. If the appearance is satisfactory, a sample is selected at random from the cargo or lot and sent to the ropewalk to be more thoroughly examined. A lot containing about 140 Ibs. is given to the hackler, and divided into two parts of 70 Ibs. each. One part is hackled sufficiently fine for the smallest yarn or that used for bolt rope ; the other part for larger yarn or the size used for cables. After hackling the hemp is again weighed to ascertain the quantity of dressed hemp produced and the percentage of tow and waste taken from it; this should not exceed 20 per cent. The dressed hemp is then passed through the spreaders and drawing machine and taken to the spinners, where it is spun into yarns of 20 s. and 40 s. The yarns are then weighed to ascertain the waste in spinning and the quantity of yarn produced. Half of 'the yarn is taken to the "laying" ground, where it is laid up into rope 1} in. in circumference. The other half is first tarred and then laid up into ropes of each sized yarn, making in ail four ropes : tarred and untarred of 20 s., tarred and untarred of 40 s. The ropes are then carefully weighed to ascertain the weight per fathom and the percentage of tar absorbed. The strength of the rope is then found by securing short pieces, cut in lengths of 6 ft. for con- venience, in a testing machine. The dry or white rope should sustain a strain of 4,200 Ibs. ; the tarred, 3,200 Ibs. The weight should be from - 5 to '6 of a pound per fathom for the dry, and from '6 to *7 for the tarred. The hemp having passed the required inspection, the first step in the process of preparing it for the manufacture of rope is to hackle or hatchel it. The hackle or hatchel consists of a strong board in which are inserted long steel prongs sharply pointed and polished. The hackler, taking a wisp of hemp in his hand by one end, throws the other over the prongs and combs it out, cleaning it of dirt and tow and straight- ening out the fibres. Having combed it out to where it was held, he reverses the wisp and combs out the other end. Much of the tow that is thus combed out is again hackled and spun into yarn for inferior kinds of rope. Af- ter hackling, the hemp is passed through the spreading and drawing machines, care being taken to regulate the supply so that the " sli- ver" or "roping "for the spinning machines shall be of suitable size ; if too small, the yarn is liable to break in spinning; if too large, the spinning machine will clog up. The first of the " preparation machines " is the " spread- er," which is in fact a finer method of hackling. Its office is to comb out and straighten the fibres. The largest one now in use at the gov- ernment ropewalk is intended especially for the very long manila fibres, being 17 ft. long by 6 ft. wide. It will run off a bale of 270 Ibs. of manila in nine minutes, or 60 bales in 10 working hours, taking it direct from the bale, or rather with the intermediate step of oiling. From this machine the manila passes to a smaller and finer one, where the fibres in the sliver are still further straightened, and the sliver itself evened and drawn down. Thence it passes to a third, called the drawing frame, a machine built on precisely the same principle, but with one chain instead of two and with finer teeth, through which it is usual to pass it twice, the sliver at each successive step being reduced in volume, straightened and evened more thoroughly, to prepare it for the spin- ners. The course of preparation for the hemp is the same, though if the machines are prop- erly geared and the draught correct, it will be found sufficient to run the hemp through the spreader only once, and through the drawing frame twice. From the preparation machines the hemp passes to the spinner, where it is spun into yarn and at the same time wound on a bobbin containing about 300 fathoms. In making rope, a three-inch rope is the key to the sizing of the yarn. Yarns of 20 s. are of such a size as to require 20 to make one strand for a three-inch rope, or to fill a tube half an inch in diameter ; yarns of 26 s. require 26 threads to fill the same sized tube, and so on. If manila or white rope is to be made, the bobbins pass from the spinning room to the laying ground ; if tarred rope, the next step is tarring. The bobbins containing the yarn are taken from the spinners to the tar house, where they are placed on horizontal rods con- tained in a framework conveniently arranged with reference to the tar box ; 160 bobbins is about the capacity of the frame. The end of each yarn is passed through a board or gauge perforated with holes sufficiently large to al- low the yarns to run freely, thence through three or more similar gauges so arranged over the tar box that when all is ready they can be lowered to the bottom. The tar box should be about 30 ft. long, 2 ft. wide, and 8 ft. deep. Steam, admitted to copper steam pipes at the bottom, keeps the tar at the desired tempera- ture. A thermometer is so arranged that the bulb is always immersed in the tar, which, after the evaporation of the watery parts, should be maintained at 220 F., and should never be allowed to get below 212 while tar- ring. The machinery is so regulated that the yarn is drawn through the tar at the rate of about 15 ft. a minute. After leaving the tar the yarn passes between two metal rollers at- tached to the further end of the box, the up- per one carrying a heavy weight to press out the superfluous tar. Thence the yarn passes