324 The Philippine Journal of Science wis 



per cent larger than the true transverse area of the rope re- 

 presented in fig. 4 by the cross-hatched ai'ea.=** The latter area 

 is a close approximation of the actual solid fiber area, but still 

 does not take into consideration the void spaces between the in- 

 dividual filaments constituting each strand. These smaller void 

 spaces depend upon the size and shape of the fiber; its clean- 

 ness; the method of manufacture; the degree of twist; the 

 presence or absence of grease, fat, oil, or adulterant, etc. No 

 attempt was made in this work to determine the actual void 

 space within the strands. 



In order to determine the true transverse cross section of the 

 rope specimens, pieces of rope about 15 centimeters long were 

 soaked for about five minutes in melted paraffin heated to about 

 90° C, until most of the bubbles of entrapped air had escaped, 

 when the pieces were placed in test tubes which were then filled 

 with paraffin. Efl^ort was made to avoid swelling the rope. 

 When the paraffin was solidified the tubes were cooled in tap 

 water and the glass broken off. The rope, which was now firmly 

 embedded in paraffin, was carefully cut by hand at right angles 

 to the longitudinal axis into sections 2 centimeters long by 

 means of a heavy razor. Each 2-centimeter section gave 

 two very clear profiles, which were brought into sharp contrast 

 by marking the boundary of the strands with India ink. Each 

 profile was then copied on tracing paper ; a few of these profiles 

 are illustrated in fig. 4. The tracings of the outlines were care- 

 fully and accurately cut out giving three irregular pieces of 

 paper showing the exact contours of the three rope strands, 

 and necessarily having the same areas as the rope sections. 

 The paper profiles were then weighed on a Heusser button 

 balance, sensitive to 0.002 milligram, and compared with the 

 weight of 1-centimeter paper disks, obtained adjacent to the 

 profiles, having an area of 78.54 square millimeters. For cutting 

 the disks, a bow compass with a keen tool-steel cutter was used 

 in place of the usual graphite style. From the averages of these 

 data the areas of the irregular rope sections were calculated. 

 In order to show the accuracy that may be attained by this 

 method the data for the 50-millimeter coir rope from Ilocos 

 Sur are given in Table X. 



** The relative magnitude of areas computed by the two methods is 

 being further studied in conjunction with the mechanical properties of 

 Philippine bast-fiber cordage. 



