ROPE 



which they revolve, in opposite 

 directions and at equal speed. The 

 casing has an inlet and an outlet 

 for the air. Various forms have 

 been given to the arms. Their 

 essential features are that they 

 make the tightest practicable air 

 joint with the casing, and are them- 

 selves always in contact, or just 

 clearing, so as to avoid too much 

 friction. They act as pistons and 

 divide the casing into two com- 

 partments, one of which receives 

 air, while in the other the air is 

 compressed and forced out of the 

 casing. The machine is largely 

 used to 1 supply blast to cupolas, 

 and in gas and chemical works. 



Rope. Cordage of a certain 

 circumference, usually one inch 

 or over. There is, however, no 

 definite standard. 



Rope-making is a very old in- 

 dustry. Constant references to it 

 are made by ancient writers, and 

 pictorial diagrams of the industry 

 are found in early Egypt. Until the 

 19th century, however, ropes were 

 laboriously made by hand, though 

 the first rope-making machine was 

 actually brought out by Cartwright 

 in 1792. In the old hand manufac- 

 ture of rope, a ropeway, often a 

 quarter of a mile in length, was 

 essential, two workmen working 

 together. One carried a bundle of 

 hemp, or other material, and the 

 other looked after a wheel on which 

 were a series of hooks to which the 

 hemp was fastened. This wheel 

 was turned as the rope spinner 

 walked down the ropeway making 

 his yarn. The latter was after- 

 wards twisted into strands, and 

 the strands into ropes. Three 

 strands twisted together formed 

 what is known as a hawser laid 

 rope, and three hawsers twisted 

 became a cable. 



Machinery for Spinning Yarn 



In modern rope-making the 

 hemp, jute, coir, or other material 

 used is spun into yarn in a similar 

 way to that in which cotton is 

 spun. The yarns are wound on 

 large bobbins, and for making 

 strands are threaded through holes 

 in a vertical iron plate, passed 

 through a fixed iron tube, and then 

 attached to a hook on the twisting 

 machine. The latter runs on rails 

 laid along the rope-walk, and as it 

 moves the yarn is twisted into 

 strands, several strands at a time 

 being fashioned, according to the 

 number of hooks on the twister. 



The strands are fashioned into 

 ropes by the machine, one form of 

 which acts as follows : On the fore 

 end of the machine are a number 

 of hooks which revolve in the same 

 direction, to which are attached 

 the strands. At the other end of 

 the rope-walk is a device known as 



6697 



Rope. Stages in the manufacture of ropes. Top, preparing the hard fibre 

 below, twisting the strands to form a rope 



By courtesy of the ltd fait Ropework Co., Ltd. 



the traveller, which has one or two a fey days before being formed 



large hooks on it, according to 

 whether one or two ropes are being 

 made. In between the traveller 

 and the fore end, running on the 

 rails of the rope-walk, is the top 

 machine. The strands attached to 

 the fore end are passed through 

 grooves of the conical wooden 

 block of the top, and are then fas- 

 tened to the hooks of the traveller. 



The hooks of the latter and those 

 on the fore end revolve in opposite 

 directions, and as the twisting of 

 the strands takes place the top 

 machine is moved along the rails by 

 the pressure which is caused by 

 the closing strands on the wooden 

 block. 



In the making of tarred ropes 

 the yarns are first passed through 

 tanks of heated tar, then through 

 rollers to squeeze out the super- 

 fluous tar, and allowed to dry for 



into "ropes. In the manufacture ot 

 cord for fishing lines and nets, the 

 yarn is passed through hot starch 

 and drying and polishing rollers to 

 impart the necessary polish. Hemp, 

 flax, cotton, manila, sisal, and jute 

 are the chief vegetable fibres used 

 in the manufacture of ropes other 

 than wire ropes. For the manufac- 

 ture, etc., of the latter, see under 

 Wire Rope. See Spinning. 



Roper. River of the Northern 

 Territory, Australia. Formed from 

 the rivers Strangewaya and the 

 Chambers, it flows E. to the Gulf of 

 Carpentaria. Navigation is some- 

 what impeded by the bar at the 

 mouth, but is possible for boats of 

 12 ft. draught for 90 m. to Leich- 

 ardt's Bar. Stores for the Overland 

 Telegraph were landed at the 

 Roper, and conveyed by the valley 

 route 200 m. to Bitter Springs. 



