W, A. Norton on the Corona in Eclipses of the Sun. 11 



tions. A similar diiference of opinion is found in the reports 

 of observations on previous eclipses. If variations m the bright- 

 ness and extent of the coronal radiations do actually occur, it 

 is favorable rather than opposed to the auroral theory of the 

 corona ■ but it is probable that the apparent changes are due 

 to inequalities in the interceptive action of the earth's atmos- 

 phere on the light of the corona, and especially on the laint 

 light at its outer boundary. . 



Professor Harkness, of the U. S. Naval Observatory, m his 

 able Report of Observations on the eclipse, states that the ioiir 

 angles of the trapezoidal outline of the corona wei-e m thr nudaie 

 heliographic latitudes — relying upon the report ot another 

 observer ; but on a direct examination of the question ot the 

 location of these angles, or "star points" of the corona made 

 since the publication of the Report, he has satished himself that 

 their actual position was such as I have above reported it irom 

 ^-' own observations.* , i i -t 



I the delineations of the corona given by the observer ot 



previous eclipses,^ two or inore fo^^spicuous 

 projecti] 





.= axo generally shown, but the positions of these more 

 ectincT parts are seldom given with respect to the equa- 

 or poles of the sun. The figure of the echpse accompa- 

 nying the Report of P. Prof. Capellotti, of observations on 

 the eclipse of April 15, 1865, made at Chili, is an exception. 

 It shows three principal points of outstreammg of the corona ; 

 two lying very nearly in the plane of the sun s equator, and 

 nearly diametrically oPP^^ite to each other, and a third near 

 one of the poles of the sun. In the eclipses of 18o8, 1860 and 

 1868, four such points were seen, distributed at ^^^^ ^^^^^iJ" 

 rant's distance from each other. In the echpse of 1842, but 



noticed, which were diametrically opposite 



that of 1851, there appears 1 



have been no marked 



deviation from a general uniformity of radiation. 



Relying then upon the only definite knowledge we have ot 

 the location of the more conspicous portions of the corona, \iz 

 that obtained in the echpses of 1865 and 1869, we may say 

 that the corona is brighter and more extended about m the 

 direction of the plane of the sun's equator than m any otner 

 direction. This striking fact lends a powerM ^^PP^^ j^ 

 the auroral theory of the corona; for, as we have already 

 seen, the streamers proceeding from the l^^^^^, j^*^*^^^^Jl^ ^^^^ 

 sun, on opposite sides of the equator should c^^.^^^^g^ ^^^ 

 intersect in the plane of the equator, and for a certain aistanc 



* Professor Winlock. in his report of observations on the ^^l^Pf ; ^^'^^J^^^® 

 photograph of the corona taken at Shell)^^!!^ shows a nattemng a 



