﻿550 Dr. H. TV. Malcolm on Double Refraction in 



came a bine spot and a varied and irregular mass o£ yellow 

 and blue, simplest in the case of soaked tubes. The displace- 

 ment of: the line parallel to the tube axis and the transversal 

 wave-motion both grew slower as the line got further into 

 the tube ; it spread out. lost its sharpness and grew blurred ; 

 the wave-motion gave way to an intermittent one. One 

 could see the displacement of the central line in the com- 

 pensator slowly rise to a maximum and suddenly fall to 

 zero. Table I. gives the displacements over the yellow lin& 



Table I. 



Voltage 



Age of 



Time : 



Displace- 



Current 



applied. 



tube : 

 days 



miu. 



sec. 



ment 

 A. 



amp. ( 

 X 10~ 6 . 



10-9 



21 



9 







018 



14 







11 



45 



016 



12 







16 







015 



9 







20 



15 



016 



8 







26 







015 



7 







43 







0-14 



4 



120 



16 



18 







020 



14 







44 







020 



11 







78 







021 



10 



24-5 



15 



]0 







022 



28 







41 



15 



0-26 



20 







103 







0-27 



12 



50 



10 



18 







o-io 



30 







44 







041 



20 



50 



10 



15 



30 



0-09 



19 



50 



27 



16 







0-31 



98 







44 







0-30 



64 







73 



30 



0-29 



48 







100 







0-29 



30 



100 



23 



5 



45 



0-18 



60 







16 







0-20 



34 







34 







0-20 



22 







59 







Max. 0-29 



IS 







81 







„ 0-22 



16 



200 



22 



1 







0-14 



240 







2 







048 



125 







3 



30 



20 



98 







7 







0-18 



6i 







14 







042 



45 







28 







024 



32 



220 



37 



17 







Max. 0-30 



108 







38 







„ 0-27 



16 



! 



220 



14 



12 



30 



0-18 



126 







35 







0-18 



40 



