364 Stress and Strain and the Properties of Matter, [June 16, 



mations, considerable accuracy was attainable. The results of these 

 last experiments are given in Table III. 



Table III. 



Metal. 



Condition. 



Modulus of 

 torsional elasticity 



in grams per 

 sq. cm. obtained by 

 the statical method. 



Ditto, obtained by 

 the kinetical 

 method. 



r.u. 



rf 





Annealed . . . 



751'5xl0 6 



766-5xl0 6 



1-020 





Unannealed. 



662-2 



663-5 



1-002 





>5 



275 5 



278 -0 



1-009 



Aluminium . . 



>5 * 



267-7 



266-9 



0-997 



The general results of the whole investigation may be expressed as 

 follows : — 



1. The value of the modulus of longitudinal elasticity for hard- 

 drawn metals, as determined by the statical method of loading, accords 

 with the value obtained by the method of longitudinal vibrations, pro- 

 vided the deformations are sufficiently small. 



2. The velocity of sound in a metal wire is independent of the load 

 on the wire. 



3. The velocity of sound in a metal wire is not sensibly altered by 

 permanent extension of the wire. 



4. The value of the modulus of torsional elasticity, as determined 

 by the statical method, accords with the value obtained by the method 

 of torsional vibrations for most metals in the hard-drawn condition, 

 provided the deformations produced are small. For annealed iron 

 the value of the modulus obtained by the second method slightly 

 exceeds that obtained by the first method, and by an amount which is 

 greater than can be attributed either to the heating and cooling effects 

 of contraction and expansion, or to errors of observation. 



