xin. A. 6 King: Philippine Coir and Coir Cordage 319 



kilograms per square centimeter has acted through a distance 

 of 2 millimeters, the work done in stretching to its elastic limit 

 a coir specimen having a sectional area of 1 square centimeter 

 and a length of 100 millimeters is equal to 154 X 0.2 = 30.8 

 kilogram-centimeters, which is the resilient energy stored in 10 

 cubic centimeters of the sample. In this form the resilience of 

 coir can be compared with that of other materials. 



When graphs have been prepared, the elastic resilience may 

 be calculated, with due regard to the scale employed, from the 

 area of the right-angled triangle ODE (fig. 2) formed by the 

 straight line of the stress-deformation graph, the abscissa, and 

 the perpendicular to the latter from the elastic limit. The com- 

 parative resilience of coir and abaca filaments is plainly shown 

 by the relative area of the two triangles ODE, and OBC, fig. 2. 



It has already been indicated that most of the coir filaments 

 tested have no definite elastic limit or elastic modulus and that, 

 except with the first application of tension when work is spent 

 in deforming the specimen, they have little shock- or jerk- 

 resisting properties. Coir has practically no elastic resilience, 

 and the greater part of the tensional deformation of the fila- 

 ments is permanent. These deductions are confirmed by the 

 results of tensile experiments recorded in Table IX. In these 

 experiments test specimens were loaded at a constant rate to 

 various degrees of stress and the load allowed to remain constant 

 for five minutes. At the end of the five minutes, each specimen 

 had elongated considerably more than its initial elongation, the 

 extehsion being represented by 5, 12, and 18, and 2, 6, and 10 

 per cent, respectively. The load was then removed and it will 

 be noted that, at the end of one minute's rest, the specimens 

 in no case recovered any of their initial elongation, as shown 

 by the permanent set of 2, 7, and 11 per cent (or millimeters), 

 respectively. 



As shown in Table IX abaca filaments, loaded to relatively 

 much higher stresses than coir, recovered completely after re- 

 moval of the load. The tests show that abaca has the property 

 of potentially storing comparatively large quantities of elastic 

 energy, these being returned in the form of useful work when 

 the load is removed. This indicates the origin of the expression 

 "give and take" which in common parlance is used to designate 

 the valuable property of resilience possessed to so high a degree 

 by the best grades of abaca cordage. The average resilience 

 stored in 10 cubic centimeters of grade "F" abaca is 1,281 kil- 

 ogram-centimeters, which is forty-one times as much as that 



