THE GROWTH OF OUR KNOWLEDGE OF HELIUM. 281 



In the tables, under "sun," C, followed by a number, 

 indicates the frequency as given by Young ; E indicates the 

 lines photographed during the eclipse of 1893. Under 

 "star or nebula" the references are to the tables given in 

 my memoir on the nebula of Orion {Phil. Trans., vol. 

 clxxxvi., 1895, P- 86 et seq. N = Nebula of Orion). 



* Means that these lines are out of the range of my observations. 



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