326 The Philippine Journal of Science isis 



grams or pounds by the corresponding weight of the rope in 

 kilograms per meter or pounds per foot. The measurement and 

 the computation of difficult areas are not necessary and it is, 

 therefore, frequently used in testing fibers and fiber products. 



Testing machines for determining elongation and tensile 

 strength. — The two larger rope specimens were ruptured in a 

 direct, motor-driven, 30,000 pounds capacity, four-screw, auto- 

 matic testing machine, manufactured by Tinius Olsen, of Phila- 

 delphia, Pennsylvania. This testing machine is of the screw- 

 gear and lever type and is graduated to read five-pound inter- 

 vals. The smallest rope specimens were tested in a Riehle 

 Bros. (Philadelphia, Pa.) tension-testing machine of the elastic 

 resistor or helical spring type, having a capacity of 600 pounds, 

 graduated to read one-pound intervals. This machine is hand 

 operated by means of a fairly heavy crank-driven flywheel. 

 Both testing machines were compared and found to agree within 

 the limit of the sensibility of the larger machine. The varia- 

 tion in the strength of the rope was much greater than any 

 possible error in either of the testing machines. 



Elongation. — Each test specimen was held vertically in the 

 testing machine by smooth steel pins that passed through the 

 eyes formed at the ends of the test piece, and was subjected 

 to a small preliminaiy tension not exceeding 5 pounds. Two 

 points, 50 or 100 centimeters apart, were clearly marked on it 

 with chalk or pencil. A scale graduated in millimeters was 

 used for measuring the gauge-length. The lor.d was then ap- 

 plied at the unifoiTn rate of 1.-3 millimeters' stretch per second. 

 During the time the load was being applied, the elongation was 

 carefully noted on the scale. The total distance between the 

 index marks at the instant of rupture was noted. The difference 

 between this distance and the gauge-length gave the elongation 

 in centimeters. The elongation readings could not be measured 

 with an accuracy greater than 0.5 centimeter in 50 centimeters ; 

 therefore, the average elongations are given only in whole per- 

 centages. Table XI shows that coir rope has a slightly greater 

 average elongation than the individual coir filaments as given 

 in Tables VI and VII, whereas abaca rope has several times 

 the elongation of the individual abaca filaments as given in 

 Table VIII. 



Tensile-strength tests. — The specimens of coir and abaca were 

 tested air dry, and after exposure to fresh water, to salt water, 

 and to weather, as indicated in Tables XI, XII, XIII, and XIV, 

 respectively. The machines used in this work have already been 



