36 The American Salmon-fisherman. 



But which will be the stiffer ? There is not a laborer 

 who ever carried a hod up a gang-plank who does not 

 know that the single stick is far stiffer than the com- 

 pound. 



And it stands to reason. The fibres of the single stick 

 must undergo a change throughout the entire depth of its 

 two inches. It therefore follows that to bend a distance 

 equal to that of the compound stick the outer fibres are 

 subjected to a greater extension and compression, and 

 that more force must be required to produce this greater 

 result. 



But with the compound stick the case is quite different. 

 The frictional contact of its two component parts one 

 upon the other ultimately becomes less than the power of 

 the fibres of each to resist change. The stress is there- 

 fore in part relieved by one stick sliding on the other in 

 the line of least resistance that is, on the line of contact. 

 Each part is in a measure beaten in detail. Here, as else- 

 where, "In union lies strength." 



But which is the more elastic? or, what is the same 

 thing, which will recover most promptly and completely 

 on the removal of the deflecting load ? Clearly the single 

 piece. The two parts of the compound piece slide one 

 on the other during the deflection caused by the w r eight. 

 But when the weight is removed, where is the power to 

 cause them to slide back to their original position ? The 

 elasticity of the parts may initiate the motion, but as the 

 fibres approach their normal state this force uniformly 

 decreases in strength, till ultimately the friction will pre- 

 dominate. Recovery then ceases, and the compound stick 

 remains bent until this friction is removed by separating 

 its parts. 



