ON THE UNION OF FLEXIBLE FIBRES. 141 



his hands. When one length of the walk has been spun, it is immediately 

 reeled, to prevent its untwisting. The machines employed in continuing 

 the process of ropemaking are of simple construction, hut hoth skill and 

 attention are required in applying them so as to produce an equable 

 texture in every part of the rope. The tendency of two strands to twist, in 

 consequence of the tension arising from the original twist of the yarns, is 

 not sufficient to procure an equilibrium, because of the friction and rigidity 

 to be overcome ; hence it is necessary to employ force in order to assist this 

 tendency, and the strands or ropes afterwards retain spontaneously the 

 form which has thus been given them : the largest ropes even require 

 external force in order to make them twist at all. 



The constituent ropes of a common cable, when separate, are stronger 

 than the cable in the proportion of about 4 to 3 ; and a rope worked up 

 from yarns 180 yards in length to 135 yards, has been found to be stronger 

 than when reduced to 120 yards, in the ratio of 6 to 5. The difference 

 is owing partly to the obliquity of the fibres, and partly to the unequal 

 tension produced by twisting. Mr. Huddart's ropes of 100 yarns lose 

 but about one eighth of the whole strength of the yarns ; and his experi- 

 ments appear to show that similar ropes made in the common manner 

 retain only one half of their original strength. The tarring of ropes, 

 although sometimes necessary for their preservation from decay, is found 

 to lessen their strength, probably because it produces partial adhesions 

 between some of the fibres, which cause them to be disproportionally 

 strained. A rope is also said to be weaker when wet than when dry, 

 perhaps because the water enables the fibres to slide more readily on 

 each other, or because 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 as the square of its circumference contains 

 inches.* 



Flax is weaker than hemp, but not less extensively useful. Its growth 

 considerably exhausts the strength of the soil which produces it ; its 

 cultivation is encouraged in this country by a bounty from government, 

 and a large quantity is also imported from the north of Europe. The 

 plant, while green, is laid in water for ten days, and undergoes a chemical 

 change, which softens the pulpy part, without injuring the strength of the 

 fibres, and renders it more easy, when it has been dried and exposed to 

 the air for a fortnight, to separate the two substances in the process of 

 dressing it. This is performed by beating it with the edge of a flat piece 

 of wood, the stroke being oblique, and nearly in the direction of the fibres, 

 and afterwards combing it, in order to reduce the fibres into regular order, 

 and to prepare them for spinning. The refuse, consisting of the shorter 

 fibres, is tow. 



Cotton is a fine fibrous substance, that envelopes the seeds of a plant. 

 The best is brought from the isle of Bourbon ; but by far the greatest 

 quantity from the West Indies, although the Turkish dominions as well as 

 the East Indies furnish us with a considerable supply. It is usually 

 white, but there is a yellow kind, which is used for nankeens. It is 

 * See Duhamel, Traite de la Corderie Perfectionne"e, 4to, Paris. 



