W. A. Ncyrion on the Corona in Eclipses of the Sun. 9 



It is proper to state here, that in what precedes we have really 

 been contemplating but different sides of one comprehensive 

 theory, which embraces a connected series of solar phenomena, 

 of which the corona is but one term. The outline of this 

 theory is given in the author's Treatise on Astronomy, revised 

 edition (1867). It is that a portion of the matter of the sun"s 

 photosphere is in the habitual condition of auroral magnetic 

 columns ; that by electric discharges along these columns, their 

 substance becomes dispersed and in part projected into space ; 

 and that this process, wherever occurring, may by a continued 

 dissipation of a portion of the photospheric matter at that locality, 

 eventuate in the formation of a visible spot on the disc ; that 

 the photospheric matter thus discharged into space, is in that 

 peculiar condition recognized in cometic matter in which it 

 becomes subject to a repulsive action from the sun (or else to a 

 diminished attractive action, as occurred to a certain extent in 

 the case of Donati's comet, and in that of 1861), and in the act of 

 flowing away is visible in solar eclipses as the streamers of the 

 corona, and at more remote distances as the zodiacal light ; that 

 these solar emanations furnish the matter of terrestrial auroras, 

 and when descending in copious showers into the earth's atmos- 

 phere, and developing electric currents and disturbing the 

 magnetic condition of the earth, are the determining cause of 

 all the phenomena of " magnetic storms." The apparent struc- 

 ture, and variability of the corona, and, as we shall soon see, the 

 most characteristic features of its form, the form, position, and 

 variability of the zodiacal light, the coincidence of the periods 

 of the sun's spots with the periods of terrestrial auroras, and 

 with those of the perturbations of the magnetic needle, all 

 accord with this general theory. I have also endeavored to 

 show in my papers on the variations of the magnetic elements, 

 that these variations are such as should naturally result from 

 the electric currents in the upper atmosphere, (or^what may be 

 called the photosphere of the earth), that would ensue from the 

 reception of the supposed impulsive waves, and material emana- 

 tions proceeding from the sun. (See this Journal, II, vol. xix, 

 March and July, 1855). 



If it indeed be true, that from the fundamental conception 

 of material emanations from the sun similar to those which we 

 know to take place from the head of a comet under the in- 

 fluence of the sun, a connected series of phenomena may be 

 theoretically deduced which have their actual counterparts in 

 Nature, it must be conceded that there is a high probability 

 that this conception is founded in truth, and furnishes the true 

 explanation of the varied phenomena observed. 



