358 F. H. Bigelow — Further Study of the Solar Corona. 



energy outwards and the rate of change in its volumetric 

 dimensions, as derived from theory. 



3. The location of the coronal poles at successive eclipses 

 will afford a means of determining the period of the rotation 

 of the sun on its axis, in consequence of the large number of 

 revolutions occurring between such epochs. It would be 

 necessary to assume that the axis of polarization of the sphere 

 remains the same, as is probably the case. 



4. The accelerated angular velocity of the equatorial belts 

 as compared with the polar regions, would result from the 

 descent of cool matter from high altitudes above the surface 

 of the sun, each particle being considered as a satellite ap- 

 proaching its center of gravity. The motion of the spot belts 

 in latitude synchronously with the display of energy as re- 

 corded by the maxima and minima, may be due to a corres- 

 ponding motion of the maximum zone towards and from the 

 poles, with the accompanying elevation of the ends of the 

 coronal stream lines ; or to changes in the relative energies of 

 propulsion, as a function of the time. It is possible that a 

 picture of the corona may be sometime taken which will show 

 these streamers distributed in two parallel belts a few- degrees 

 apart. It is a most interesting question in physics as to the 

 reason of the location of this coronal zone at the computed 

 distance from the poles, since it suggests also a problem similar 

 to that of the terrestrial auroras. At this place the linear dis- 

 tance across the greatest number of equipotential surfaces, is 

 apparently the shortest, hence it may be the path of least re- 

 sistance. There should also be a connection between the dis- 

 tribution of the actinic light of the corona and the equipotential 

 surfaces, and it is not unlikely that the light is simply propor- 

 tional to the potential. 



This discussion suggests the importance of securing photo- 

 graphs of the corona sufficiently large to admit of accurate 

 measurements ; the necessity of studying the relation between 

 the position of the streamers and the spots at the moment of 

 the eclipse ; and the possibility of deriving the period of the 

 sun's axial rotation from the coronas of successive eclipses. 



