XIV, € King: Philippine Bast-fiher Ropes 569 
Table I. — Relaiionshij) between the mean calculated and the true mean 
area of the ropes tested — Continued. 
ROPES MADE OF MISCELLANEOUS FIBERS. 
Fiber. 
Calcu- 
lated 
area. 
True 
mean 
area. 
True 
mean 
area-r 
calcu- 
lated 
area. 
sq. fuin. 
sq. 
Musa icxtilis: “F" fiber » 
76.5 
76.9 
1.00 
Do - 
18.0 
15.5 
0.86 
Musa textilis; srSLiie “G” fiber® . 
54.1 
53.5 
0. 99 
Do 
20.4 
14.1 
0.69 
Acrave canfaZa; Cebu No. 2, maguey 
54.1 
43.6 
0.81 
Cocos nucijera; salt-water retted, from Caoayan, IIocos Sur 
198.6 
159.8 
0.80 
Cocos nucifera: machine cleaned, from Laguna husks.. 
153. 9 
131.0 
0.85 
Do - 
45.8 
38.9 
0.85 
Corypha elata; leaf 
174.4 
173.7 
0.99 
Corypha elata; vascular fibers from petioles; buntal 
38.5 
34.7 
0. 90 
31.9 
25.7 
0.79 i 
Dendrocalamus merrillianus b 
168.6 
159.5 
0. 94 ' 
Anamirta cocculus; entire stem of vine twisted into three-strand 
153.9 
128.7 
0. 84 
0. 87 
- 
Machine-made rope, the test specimens of which were kindly furnished by Johnson-Pickett 
Rope Company, of Manila ; all other ropes are handmade. 
^ Two-strand rope ; all other ropes have three strands. 
Twist and girth . — The maximum tensile strength of fibers is 
obtained when they are tested in their untwisted condition, but 
it is not practicable to make a long rope except by overlapping 
and twisting the fibers so that they are held in place by mutual 
friction. Short ropes without any twist were tested by Du- 
hamel ® over one hundred years ago. He found such ropes to 
be much stronger and more pliable than twisted ones, but less 
durable because the rope opened when bent, thereby allowing 
free entry of water into the interior where the fibers were soon 
decomposed. Hooke,^® as far back as 1669, gives data showing 
the diminished strength of twisted fiber. Experiments per- 
formed by Reaumur show that vegetable fibers lose anywhere 
from 14 to 39 per cent of their original strength after being 
twisted into rope. Investigations made by Duhamel at the 
“ Duhamel-Dumonceau, Henri-Louis, cited by Forbes Royle, page 20, 
data evidently taken from Traite de la Fabrique des Manoeuvres pour les 
Vaisseaux, ou I’Art de la Cordsrie perfectionee. Paris (1747). 
” Cited by Royle, page 22. 
” Quoted by Royle, page 22. 
“ Op. cit. 23. Royle gives the detailed results of several of Duhamel’s 
experiments. 
