40 AKT. 6.— S. KUSAKABE: 



kinds. Specimens : No. 3 2 ; 8j ; u L , ; Gj ; 6 2 ; 10j ; 9 X ; 81 ; 7-_>; 31 2 ; 

 1 8j ; 17 2 . These are to be compared with the theoretical curves in 

 PL XV. 

 PI. XIX. 



Fig. 47. This shows that the modulus of rigidity increases when the specimen 

 is in a strained state. No. t % 

 PL XX. 



Fin. 48. Neutralization of a non-virgin piece. No. I61. 

 PL XXI. 



Fifl. 49. Gradual diminution of rigidity, from rigid substance to perfect 

 fluid. Axes of abscissa and ordinate correspond to rigid substance 

 and perfect fluid respectively. Specimens: soft iron; No. 7 X ; No. 

 17, ; No. 14 x ; No. 2j ; No. 1G X ; No. 3 X ; No. 42 x . 

 PL XX11. 



Figs. 50-52. In each figure, the upper curve shows the variation of tempera- 

 ture with time, while the lower that of twist, the couple being c-on 

 stant. Specimen No. i x . 

 Fig. 53. Relation between the temperature and the amount of twist. 



