Prof. W. A. Norton on the Physical Constitution of the Sun. 57 



Zollner's theory of the physical constitution of the sun, viz. 

 that the masses which burst out iuto protuberances are local 

 collections in bubble-like caverns which form in the superfi- 

 cial layers of a liquid glowing mass, does not derive any support 

 from analogical facts. It must be regarded as a pure hypothe- 

 sis, unsustained by any inherent probability, or by any known 

 fact other than that which it is framed to explain. Besides, an 

 hypothesis which brings the hydrogen in eruptive or streaming- 

 masses to the sun's surface does not suffice. Another arbi- 

 trary hypothesis is required to dispose of the hydrogen which 

 has thus been accumulating above the sun's photosphere for 

 an indefinite period of time. 



Such being the state of the case with regard to the recent 

 attempts to discover the secret of the sun's physical consti- 

 tution, in the light of the late remarkable discoveries, we seem 

 to be in this dilemma : whatever conception is formed of the 

 condition of the sun's photosphere, whether liquid or gaseous, 

 it appears to be contradicted by received principles, or con- 

 troverted by established facts. We are thus naturally led to 

 suspect that either some physical cause has been hitherto left 

 out of account which plays an important part in solar phe- 

 nomena, or else the conception adopted of the mechanical con- 

 dition of the solar vapours is radically at fault. It appears 

 to me that good and sufficient reasons may be urged that will 

 justify both these grounds of suspicion, and that anew point of 

 view may be gained from which we may obtain a deeper insight 

 into the physical processes in operation on the sun. 



It is a little remarkable that it should have been hitherto as- 

 sumed that the facts and laws of terrestrial physics can alone 

 furnish a true philosophical ground for a theory of solar phy- 

 sics, and that no serious attempt should have been made to ob- 

 tain additional light from known processes in operation on a 

 cosmical scale in the regions of space. There is a class of 

 bodies, some of which in their periodical excursions through the 

 fields of space approach quite near the sun, and which are in 

 general conspicuously subject to influences of a powerful nature 

 exerted by the sun, besides the force of gravitation. It certainly 

 seems natural to expect that these cosmical bodies might give 

 us some insight into the nature of the forces in operation at 

 the sun's surface. It is assuredly too late to urge that the 

 transformations which they undergo under the sun's influence 

 are wholly involved in mystery : for it has certainly been satis- 

 factorily established that a portion of the cometary matter be- 

 comes subject to a solar repulsion, and is urged away by this 

 force with a high velocity and to great distances from the sun, 

 and that this repulsion augments in intensity as the comet ap- 



