xm. A. 6 King: Philippine Coir and Coir Cordage 



325 



Table X. — Comparative weights of paper profiles of coir rope, 50 milli- 

 meters in eircumfereyice, and paper disks 1 centimeter in diameter. 



Froiiie.s. 



0.00962 

 0.00913 

 0.00932 

 0.00893 

 0.00856 

 0.00864 

 0.00888 

 0.00921 

 0.00902 

 0.00931 



0.00906 



[Weights of paper in grams.] 



Disks. 

 0.00419 



0.00436 

 0.00463 

 0.00441 

 0.00457 

 0.00433 

 0.00444 

 0.00449 

 0.00447 

 0.00444 

 0.00465 



0.00445 



The average area of the rope section is equal to 

 0.00906 



0.00445 



X 78.54 square millimeters= 159.8 square millimeters. 



The values thus obtained for the various ropes closely approx- 

 imate the actual transverse areas of the ropes. This true mean 

 area was used in making the calculations of the ultimate tensile 

 strength per unit area of the ropes as given in Table XI. 



Many commercial tests of ropes are intended to be comparable 

 only; therefore, the transverse cross section need not be the 

 actual but only the relative measurement. In the comparison of 

 ropes of the same numerical size the transverse cross sections if 

 determined by the same method are relative, w^hether the method 

 employed be the ring method, the gii'th method, the strand-area 

 method, or the absolute-aiea method. However, it must be 

 borne in mind that many published data of rope areas, while 

 accurate for the purposes they are intended to serve, are not 

 at all comparable with one another; and they should not be com- 

 pared unless the method of determining the transverse cross 

 section is given and the same method was used in obtaining the 

 results to be compared. 



Breaking length. — Due to the difficulty involved in measuring 

 the cross-sectional area of ropes, fibers, and yarns, it is more 

 convenient to compare their strength by means of the so-called 

 "breaking length" instead of the strength per unit area. The 

 breaking length of a rope is the length which a specimen must 

 have to break of its ov-IlI weight when suspended at one end. 

 It is computed by dividing the ultimate breaking load in kilo- 



