ADDRESS. 13 



In a discussion in the Bakerian lecture for 1885 of what we knew up 

 to that time of the sun's corona, I was led to the conclusion that the 

 corona is essentially a phenomenon similar in the cause of its formation 

 to the tails of comets, namely, that it consists for the most part probably 

 of matter going from the sun under the action of a force, possibly electrical, 

 which varies as the surface, and can therefore in the case of highly 

 attenuated matter easily master the force of gravity even near the snn. 

 Though many of the coronal particles may return to the sun, those which 

 form the long rays or streamers do not return ; they separate and soon 

 become too diffused to be any longer visible, and may well go to furnish 

 the matter of the zodiacal light, which otherwise has not received a satis- 

 factoiy explanation. And further, if such a force exist at the sun, the 

 changes of terrestrial magnetism may be due to direct electric action, 

 as the earth moves through lines of inductive force. 



These conclusions appear to be in accordance broadly with the lines 

 along which thought has been directed by the results of subsequent 

 eclipses. Professor Schuster takes an essentially similar view, and 

 suggests that there may be a direct electric connection between the sun 

 and the planets. He asks further whether the sun may not act like a 

 magnet in consequence of its revolution about its axis. Professor Bigelow 

 has recently treated the coronal forms by the theory of spherical har- 

 monics, on the supposition that we see phenomena similar to those of free 

 electricity, the rays being lines of force, and the coronal matter discharged 

 from the sun, or at least arranged or controlled by these forces. At the 

 extremities of the streams for some reasons the repulsive power may be 

 lost, and gravitation set in, bringing the matter back to the sun. The 

 matter which does leave the sun is persistently transported to the equa- 

 torial plane of the corona ; in fact, the zodiacal light may be the accumu- 

 lation at great distances from the sun along this equator of such like 

 material. Photographs on a larger scale will be desirable for the full 

 development of the conclusions which may follow from this study of the 

 curved forms of the coronal structure. Professor Schaeberle, however, 

 considers that the coronal phenomena may be satisfactorily accounted for 

 on the supposition that the coi'ona is formed of streams of matter ejected 

 mainly from the spot zones with great initial velocities, but smaller than 

 382 miles a second. Further that the different types of the corona are 

 due to the effects of perspective on the streams from the earth's place at 

 the time relatively to the plane of the solar equator. 



Of the physical and the chemical nature of the coronal matter we know 

 very little. Schuster concludes, from an examination of the eclipses of 

 1882, 1883, and 1886, that the continuous spectrum of the corona has the 

 maximum of actinic intensity displaced considerably towards the red when 

 compared with the spectrum of the sun, which shows that it can only be 

 due in small part to solar light scattered by small particles. The lines of 

 calcium and of hydrogen do not appear to form part of the normal spectrum 



