XIV, 6 King: Philippine Bast-fiber Ropes 569 
TABLE I.—Relationship between the mean calculated and the true mean 
area of the ropes tested—Continued. 
ROPES MADE OF MISCELLANEOUS FIBERS, 
True 
Caleu- mean | 
Fiber. pe | Ean pote | 
area. lated 
area, 
Sq. mim. sq. mm. 
wauee Cégtiis grade fuer 6. oe eae 76.5 76.9 1.00 
eo es ee eee oe 18.0 15.5 0. 86 
Ditae tevtilia; wrade: GO Tiber 6 2 eS 54.1 58.5 0. 99 
es ce a eg 20. 4 14.1 0.69 
Agave cantala; Cebu No. 2, maguey 8..._._....-. ......--.--.------- 54.1 43.6 0.81 
Cocos nucifera; salt-water retted, from Caoayan, Ilocos Sur_-____-- 198.6 159.8 0.80 
Cocos nucifera; machine cleaned, from Laguna husks-_----_-..--- 153.9 131.0 0.85 
32 are ree anc Do a ee ee 45.8] 889! 0.85 
Corypha elata; leaf...........------- NGL OL ysBomy Ae ae a 174.4| 178.7] 0.99 | 
Corypha elata; vascular fibers from petioles; buntal..._..._...---- 38.5 $4.7 0.90 | 
Fr Ee 2 alee REE sa SG PEIN E toa 81.9 25.7 0.79 | 
Dendrocalamus merrillianus b.........---------------------------- 168.6} 159.5| 0.94 | 
Anamirta cocculus; entire stem of vine twisted into three-strand 
PODC 2 ooo - se caneeeetietn odie don gat ites soe oye 153. 9 128.7 0.84 
Average a le eee 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 Réaumur™ 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 Traité de la Fabrique des Manoeuvres pour les 
Vaisseaux, ou l’Art de la Corderie perfectionée. 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. 
