(3 ART. 10:— K. HONDA & S. SHIMIZU. 



that these two results nearly coincided with each other. The liquid 

 air was then gently poured into the Dewar's tube, until this tube was 

 tilled with the liquid, and the exposed parts above the magnetizing 

 coil were carefully protected with cotton. 



Owing to the boiling of the liquid, a small oscillation of the 

 image in the field of the telescope was first observed ; but after about 

 10 minutes, the image became somewhat steady. The magnetic change 

 of length was then measured in the usual way. 



The experiment at high temperatures were undertaken in the 

 following order. The magnetic change of length at the temperature 

 of the room was first determined. Then an electric current from a 

 dynamo was passed through the heating coil for one or two hours, till 

 the temperature of the core became nearly constant ; then the current 

 from the dynamo was replaced by one from an accumulator in order to 

 get rid of the fluctuation of temperature due to that of the dynamo- 

 current. Twenty or thirty minutes passed before the observations 

 were taken, when the temperature had become very steady. The 

 change of temperature caused a deflection of more than 6 cm per 

 degree in the field of the observing telescope, whereas the deflection 

 due to magnetization was utmost 5 cm in nickel and 1.5 cm in soft 

 iron ; hence it can be easily conjectured how great difficulty is ex- 

 perienced in obtaining a constant temperature. Since the de- 

 magnetization was carefully effected before each observation and then 

 an instantaneous deflection was noted, a slow displacement of the 

 image, such as 1 mm in several minutes, could not cause any sensible 

 error in the results. In our experiments, during the whole set of 

 observations which usually required 10 or 15 minutes, the displace- 

 ment of the zero point was only 2 or 3 mm except in a few cases. 



If one set of observations was taken, a current of increased 

 strength was again supplied" by the dynamo for about an hour or 



