TWO YEARS LATER. 41 



It need hardly be said that considerations so ob- 

 vious have not escaped the attention of astronomers. I 

 have said that Halley rejected the atmospheric glare 

 theory, and that other astronomers have spoken of it 

 with but little respect. In quite recent times, com- 

 petent astronomers, who have had occasion to examine 

 it, have in like manner rejected it. Dr. Harkness, 

 who witnessed the American eclipse, and was led by 

 the study of the corona as actually seen to inquire 

 into, the physical nature of the phenomenon, remarks 

 respecting the theory that ' the moon's shadow, at the 

 point where it enters the earth's atmosphere, usually 

 has a diameter of one hundred miles or more, and if it 

 were possible for an observer placed within that shadow 

 to see the illumination of the atmosphere outside of it, 

 the appearance presented would be that of a halo having 

 an interior diameter much greater than the size of the 

 moon.' Dr. Curtis, also a skilful mathematician 

 after exhibiting precisely the same line of reasoning, 

 remarks that 'it is geometrically impossible for an 

 observer near the centre of the shadow to see any 

 portions of our atmosphere which lie beyond the cone 

 of darkness which portions alone could, of course, 

 under any circumstances be illuminated in apparent 

 contiguity with the moon's disc.' 



Thus we are brought back to the theory that the 

 corona really is a solar phenomenon, while yet we are 

 precluded from supposing that it is a solar atmosphere. 

 What, then, can it be ? 



Now astronomers hope for much, and for very 



