12 W. A. Nor^n on the Corona in Eclipses of the Sun. 



on either side of this plane, and in consequence the corona 

 should appear to extend farther in the plane of the equator, 

 than in other directions. The convergence of individual rays 

 or lines of emanation, we have ali-eady seen, was actually 

 noticed by Professor Eastman. It of course may happen that 

 inequalities in the amount of outstreaming on opposite sides 

 of the equator, may throw the more prominent and conspicu- 

 ous parts of the corona to the one side or the other of the plane 

 of the equator. It will be observed that from our present 

 point of view, the extension of the corona in the plane of the 

 sun's equator is a phenomenon kindred to the much greater 

 lummous extension seen in the zodiacal light ; the only differ- 

 ence between them being, that in the former the auroral emana- 

 tions proceed from lower heliographic latitudes, and intersect 

 nearer the sun. 



But it may be asked how are we to explain, on the present 

 theory, the "star points " of the corona over the polar regions 

 of the sun. For these, two reasons may be assigned. (1) If 

 we admit a distribution of magnetism on the sun similar to 

 that which prevails on the earth, the auroral streamers should 

 diverge from each other less rapidly in the high than in the 

 low latitudes. (2) Upon opposite sides of a line of no declina- 

 tion traversing the sun's surface, analogous to that which tiav- 

 erses Kussia, the natural directions of the streamers prolonged 

 upward would be such as to occasion the convergence and 

 intersections of those proceeding from the opposite sides of this 



We may say then that the more extended portions of the 

 corona, m the eclipse of 1869, were over those regions of the 

 sun s surface, and those only, where upon the present theory 

 the intersections of streamers might be expected to occur. 



In some eclipses distinct luminous curves having the appear- 

 ance of luminous jets issuing tangentially to the sun's limb, or 

 obliquely inclined to it, and pursuing a course either convex or 

 concave to the limb, have been seen. According to M. Liais 

 these peculianties were conspicously obsei-vable in the eclipse 

 of Sept. 7, 1858. While it is possible that such curves may 

 be the result of the intersections of a mass of straight streamers, 

 It IS not improbable that they may be actual luminous jets ; for 

 It from any cause any portion of "the auroral matter should be 

 projected from the sun in a direction oblique to the surface, it 

 would proceed in a convex hyperbolic curve if repelled by the 

 sun, and m a concave curve if attracted. Now I have shown 

 m a former No. of this Jounial (July, 1861), that the portion of 

 cometary matter posited on the convex side of the tail of 

 Uonatis Comet was actually repelled by the sun, while that on 

 the concave side had become detached from the head of the 



