344 On the Flax of New Zealand. 



stiff, but very strong fibres, are often capable of less resist- 

 ance, when employed to make ropes, than other kinds, the 

 fibres of which are weaker, but softer and more flexible. It 

 is besides known, that stiff fibres break by a weak degree 

 of torsion, which is resisted by those that have more 

 flexibility. 



To ascertain the tensibilitv of the fibres of the flax of 

 New Zealand, I took six of -^'^ millimetre, or 0'0i43 line 

 in diameter, and suspended to lengths of 14 centimetres, or 

 5 inches 2-062 lines, a weight which I gradually increased, 

 examming bv what quantity they were extended before they 

 broke. The sum of these quantities, divided by the num- 

 ber of the filaments subjected to trial, gave for quotient the 

 mean term of the tensibility of each. Having subjected 

 to the same trial the filaments of the aloe, of hemp, of 

 flax, and of silk, the results which I obtained were: for 

 the flax 1-1279 mili. metres; for the hemp ^2558; for the 

 flax of New Zealand 3-3837 ; for the aloe 5-6393 ; and for 

 the silk 1 1 -2790 : so that the tensibility of flax being equal 

 to half that of hemp will be expressed by 1 ; that of the 

 Phormium tenax by U ; that of the filaments of the aloe by 

 2i ; and that of silk by 5. It is thence seen what prodigious 

 power of resistance is exhibited by a few threads of silk, 

 carefully spun, as their very great tensibility causes them 

 all to make an effort nearly equal before they yield to the 

 effort made to break them. 



It may not be improper here to remark, that the Chinese, 

 who make great use of silk strings for their musical instru- 

 ments, have no doubt found that twisting them for that 

 purpose hurts their strength, and also the justness of the 

 sound, for they arc manufactured without twisting; the 

 threads of which they are composed being merely united by 

 means of an elastic resin : on this account they are, on die 

 ffrst view, taken for catgut. I have no doubt that if our 

 artists would attempt this new manufacture, tlieir labours 

 •would be attended with success, especially as they employ 

 ■*-ith great dexterity various kinds of elastic resin ; but that 

 extracted from the Vahc of Madagascar {Vahea elastica), 

 u'ould be preferable to caoutchouc, which comes from 

 Guyana, because the latter has a very dark tint, while the 

 ©ther inclines very much to a white colour. It readily dis- 

 solvcji, as is well known, in ether. Besides gum clastic 

 extracted from several other vegetables might also be em- 

 ployed for the same purpose. 



The Pkarrnhnn tcuax is far from being the only plant of 

 the divit^ion of tVu' monocotyledons, capable of hirnishmg 



filamcntp 



