ON THE UNION OF FLEXIBLE FIBRES.

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male and female flowers of hemp are on different plants; the male plants aresoonest ripe, and require to be first pulled. They are prepared for dressing bybeing exposed to the air, and the fibrous part is separated from the dry pulpby beating and hackling. In spinning the yarn, the hemp is fastened roundthe waist; the wheel is turned by an assistant, and the spinner, walking back-wards, draws out the fibres with his hands. When one length of the walkhas been spun, it is immediately reeled, to prevent its untwisting. The ma-rines employed in continuing the process of ropemaking are of simple con-struction, but both skill and attention are required in applying them so as toproduce an equable texture in every part of the rope. The tendency of twostrands to twist, in consequence of the tension arising from the original twist°fthe yarns, is not sufficient to procure an equilibrium, because of the frictiona nd rigidity to be overcome; hence it is necessary to employ force in order toassist this tendency, and the strands or ropes afterwards retain spontaneouslythe form which has thus been given them: the largest ropes even require ex-ternal force in order to make them twist at all.

The constituent ropes of a common cable, when separate, are stronger thanthe cable, in the proportion of about 4 to 3 ; and a rope worked up from yarns180 yards in length to 135 yards, has been found to be stronger than whenreduced to 1 ( 20 yards, in the ratio of 6' to 5. The difference is owing partlyt° the obliquity of the fibres, and partly to. the unequal tension produced bytwisting. Mr. Iluddart’s ropes of 100 yarns lose but about one eighth of the' v hole strength of the yarns; and his-experiments appear to show that similarr °pes made in the common manner retain only one half of their original streugth.-^ he tarring of ropes, although sometimes necessary for their preservation fromdecay, i s found to lessen their strength, probably because it produces partial ad-hesions between some of the fibres, which cause them to be disproportionallydrained. A rope is also said to be weaker when wet than when dry, perhapsbecause the water enables the fibres to slide more readily on each other, or be-Cai 'se the presence of water is in general favourable to separation of any kind.A good hempen rope will support, without danger, one fifth as many tons asthe square of its circumference contains inches.

hlax is weaker than hemp, but not less extensively useful. Its growthconsiderably exhausts the strength of the soil which produces it; its cultiva-