Single Order, 



the Echelon Spectroscope. 395 



Fig. 7. — Blue (4358) Line of Mercury. 



Double Order. 



Without Magnetism. 



si 



Viewed across the Lines of Force. 



Magnetic Field = 5000 c.G.s. units. 







I 



(I 



Magnetic Field = 12,000 c.G.s. units. 



Magnetic Field = 24,000 c.G.s. units. 





Magnetic Field = 23,800 c.G.s. units, 

 2E2 



