416 AGRICULTURE 



Principles of knot tying. Certain principles apply to 

 the tying of all knots. The efficiency of the knot does 

 not depend on the number of turns or hitches, but on the 

 position of the "nip." The bend or hitch must be so formed 

 that the part of the rope under strain nips securely some 

 portion of the knot, either against itself or the object to 

 which it is attached. The nip of each different knot should 

 be studied. 



Rope materials. While a large part of our rope and 

 cordage is made of hemp, many other materials are now 

 coming to enter into their manufacture. The coil rope is 

 made from cocoanut fiber, which is used because it is so 

 light and pliable. This rope is useful for warps, rocket 

 lines, life-buoy lines, nets, etc. Manila grass is adapted to 

 the construction of coarse ropes and hawsers requiring 

 great strength and hard wear, and where tar can not be used 

 on the rope. 



Strips of hides are used for ropes where great strength 

 and pliability with small diameter are needed. Cotton is 

 employed for ropes and cordage used for fancy work of 

 all kinds. Wire is used for rope making whenever very 

 great strength is needed, as in connection with dredging 

 machinery, suspension bridge cables and the like. 



Rope making. Yarns are formed by twisting the 

 hemp right-handed, while the "strands" are made by twist- 

 ing or laying up the yarns left-handed, and the rope by 

 laying it up in strands right-handed. Three small ropes 

 laid up left-handed form a cable-laid rope. Four-stranded 

 ropes are laid round a heart. In using hemp for rope mak- 

 ' m g> great care should be exercised not to twist the hemp 

 more than necessary, as this weakens the rope. A three- 

 stranded rope will bear a greater strain in comparison to its 

 size than any other rope of the same material. This ac- 



