8 W. A. Norton on the Corma in Eclipses of the Sun. 



under a smaller angle, and their point of intersection will be 

 more distant from the sun's surface ; until at the heliographic 

 latitude of 30° to 35°, thej will become parallel to the plane of 

 the equator. Those emanating from still higher latitudes will 

 diverge from the plane of the equator and from each other.* 



"If these facts be attentively considered it will be seen that 

 the result should be the formation of a luminous appearance 

 extending indefinitely outward from the sun into space, and 

 elongated in the plane of his equator; and that to observers on 

 the earth it would have an apparent form more or less trian- 



The same fundamental conception which accounts for the 

 solar corona, and the physical relations known to subsist be- 

 tween the sun's spots and terrestrial auroras, as well as between 

 these spots and the varied magnetic disturbances occurring on the 

 earth, furnishes then an adequate explanation of the extent, 

 form, and position of the Zodiacal Light. In fact we see that 

 the zodiacal light is but the indefinite extension of the corona. 



We have here tacitly supposed that the solar emanations con- 

 sist of magnetic matter projected with great velocity into space, 

 in the directions of the prolongations of the auroral columns, 

 and proceeding on indefinitely in these directions ; but if, Hke 

 the cometic matter, they are exposed to a continual repulsion 

 from the sun, the paths described by the receding particles 

 would be hyperbolas convex toward the sun. The point of 

 intersection of any two streamers proceeding from correspond- 

 ing low latitudes in the two hemispheres, would in consequence 

 be tlirown to a greater distance from the sun, but the general 

 result as to the form and position of the luminous appearance 

 produced, (the zodiacal light) would be the same. 



In support of this view of the origin of the zodiacal hght 

 we may state that Cassini drew from his observations on the 

 sun's spots and the zodiacal light, made during the interval 

 from 1665 to 1688, the conclusion that a physical connection 

 subsisted between these two phenomena, and that the substance 

 of the zodiacal light was in fact some emanation from the sun's 

 spots. Again, according to Arago, it appears from the en- 

 tire series of observations at Paris and Greneva, that the 

 zodiacal light varies considerably from one year to another, 

 — ^ ^^-^ the .^ . • .. , . - . ' 



that the observed variations cannot result entirely from 

 changes m the transparency of the atmosphere. We shall soon 

 see that the form of the corona, as seen in the eclipse of 1869, 

 and previous eclipses, presented certain prominent features that 



