440 



THE CHEMISTRY OF THE SUN. 



[CHAP. 



or that the light itself is poor in blue rays. So considerable was 

 this extension, amounting to six or seven diameters of the dark 

 moon, that Prof. Newcomb was inclined to ascribe it to the 

 zodiacal light. While this observation was being made by 

 Prof. Newcomb at a height of about 7,000 feet, other observers 

 were viewing the eclipse from Pike's Peak, some few hundred 

 miles away, at a height of 13,000 feet. We can imagine the 

 purity of the air at that height ; there was not too much of it 



Fio. 133. The equatorial extension and polar tracery observed at tlie minimum 



of 1867. 



so little in fact that some observers had to go down. These 

 saw the corona very well indeed ; and one or two without taking 

 the precaution of putting up a screen, saw an extension compar- 

 able with that recorded by Prof. Newcomb. 



That, then, we must take to be the undoubted result arrived 

 at during the eclipse of 1878, which happened at the last sun- 



