﻿282 Prof. W. A. Norton on the Corona seen 



sphere on the light of the corona, and especially on the faint light 

 at its outer boundary. 



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

 able report of observations on the eclipse, states that the four 

 angles of the trapezoidal outline, of the corona were in the middle 

 heliographic latitudes — relying upon the report of another ob- 

 server ; but on a direct examination of the question of the loca- 

 tion of these angles, or " star-points " of the corona, made since 

 the publication of the report, he has satisfied himself that their 

 actual position was such as I have above reported it from my 

 own observations*. 



In the delineations of the corona given by the observers of 

 previous eclipses, two or more conspicuous outward extensions 

 are generally shown, but the positions of these more projecting 

 parts are seldom given with respect to the equator or poles of 

 the sun. The figure of the eclipse accompanying 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 outstreaming of the corona — two lying very nearly in 

 the plane of the sun's equator, and nearly diametrically opposite 

 to each other, and a third near one of the poles of the sun. 

 In the eclipses of 1858, 1860, and 1868, four such points were 

 seen, distributed at about a quadrant's distance from each other. 

 In the eclipse of 1842 but two were noticed, which were diame- 

 trically opposite to each other. In that of 1851 there appears 

 to have been no marked deviation from a general uniformity of 

 radiation. 



Relying, then, upon the only definite knowledge we have of 

 the location of the more conspicuous portions of the corona, 

 viz. that obtained in the eclipses of 1865 and 1869, we may 

 say that the corona is brighter and more extended in about the 

 direction of the plane of the sun's equator than in any other 

 direction. This striking fact lends a powerful support to the 

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

 streamers proceeding from the lower latitudes on the sun, on 

 opposite sides of the equator, should converge and intersect in 

 the plane of the equator, and for a certain distance on either 

 side of this plane, and in consequence the corona should appear 

 to extend further in the plane of the equator than in other direc- 

 tions. The convergence of individual rays or lines of emanation, 



* Professor Winlock, in his report of observations on the eclipse, says, 

 *' The photograph of the corona taken at Shelby ville shows a flattening at 

 the extremities of the sun's axis, and an elevation about the equatorial 

 region." The photographic impressions obtained of the eclipse at the dif- 

 ferent stations show, however, but a small portion of the outward extent 

 of the corona visible to the naked eye. 



