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MOTONORI MATSUYAMA 



figure, the curve being steeper when the force is increased more 

 rapidly. One curve, when the force was increased by the rate of 

 1.76 gm. per minute, is exceptional and steeper than the curves 

 for the rates of 4 .4 gm. and 2 . 2 gm. per minute as is shown by the 

 broken line. The other curve for the same rate, which is not 

 given in the figure, was very close to and slightly steeper than the 

 curve for the rate of 2 . 2 gm. per minute. Since these two curves 



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Torsion in degrees 

 Fig. 7. — Torsion curves, by increasing force, of the first bar used for torsion by- 

 constant force. 



were obtained by the last observations of the present series, the 

 foregoing fact may be considered as the result of elastic fatigue. 

 The difference between these two curves for the same rate of 

 increase of force may be due to the difference of temperature 

 which was respectively — io?4 C. for the steeper and — 4?6 C. for 

 the flatter. 



Similar curves, though less numerous, were obtained with the 

 second rod, in which the crystals were parallel to the length of the 

 rod. These are shown in Figure 8. Here the deformation for 



