142 Transactions of tee American Institute. 



former is quadrangular in shape, the latter broken into rifts ; both 

 are made up of rays. The outer corona reaches out into space to a 

 distance equal to once and a half the solar diameter, or nearly 

 1,400,000 miles ! What its composition is, is entirely unknown. Its 

 single spectrum line, though apparently coinciding with an iron line, 

 cannot be due to that metal. It must belong apparently to an element 

 as much lighter than hydrogen, as hydrogen is itself lighter than 

 the heaviest terrestrial metal. 



Such are some of the wonderful revelations which have been made 

 by the spectroscope. Such are the results which sunlight gives us 

 after traversing a prism. Such are the discoveries which show the 

 marvelous power of the human mind, and which place it one in kind 

 with that Omnipotence by which all these things were created. [The 

 lecturer closed by illuminating the interior of the Academy of Music 

 with monochromatic (yellow) light, alternating with the electric light, 

 to show what the effect of sunlight would be were there no photo- 

 sphere.] 



