1887.] 



On Photometry of the Glow Lamp. 



261 



Table VIII.' 



Time Scale. 









No. of exposure. 



Time. 



Readings of 

 density. 



15 



180 



••' ■ 

 7 5 



16 



160 



8-5 



17 



140 



9-5 



18 



120 



12-0 



19 



100 



17-0 



20 



90 



20-7 



21 



80 



25-1 



22 



70 . 



30-0 



23 



60 - 



375 



24 



50 



46-5 



