624 



MOTONORI MATSUYAMA 



The amount of recovery in percentage of the deformation is 

 shown in Figures 9 and 10. For small forces the recovery is com- 

 plete. As the amount of force which has been used increases the 

 percentage of recovery decreases rapidly until the formation 

 amounts to about four degrees. After this its decrease becomes 

 slower and it approaches gradually to the zero line. Thus it is 

 seen that the transition from the stage of nearly perfect elasticity 

 to that of partial elasticity takes place very slowly in the cases 

 both when the torsion is parallel to the optic axis of the constituent 

 crystals and when it is parallel to the basal planes. 



BENDING EXPERIMENTS 



The observations on torsion of ice just presented have suggested 

 that an aggregate of parallel crystals of ice is more easily deformed 

 by a shearing force parallel to the axes of the constituent crystals 

 than parallel to their basal sections. We have also seen that 

 Young's modulus, or proportionate resistance to elongation which 

 is generally determined by the method of bending, is greatest when 

 the deforming force bending the test bar acts parallel to the basal 

 sections of the constituent parallel crystals. The next step was to 

 test the matter further by observing the behavior of bars of differ- 

 ently orientated crystals when bent beyond the limit of elasticity. 

 It was desirable to try the experiment with bars of different sizes 

 compared to the constituent crystals. But the temperature of 

 laboratory was not favorable for the use of larger bars with 

 larger deforming force. Bars of moderate size with rectangular 

 cross-sections were therefore prepared with different orientations 

 of crystals. Each bar was supported at both ends by knife-edges 

 and a weight of 100 gm. was hung from the middle point. The 

 bending was measured by the lowering of this central portion. In 

 Figure 11 some of the results of these observations are given, the 

 data for the bars being given in the following table: 



