t42 ROCHESTER ACADEMY OF SCIENCE. [May 9, 



petent to produce such effect. That it is the reflux of magnetic 

 induction that creates the spots upon the sun is shown by the fact that 

 they haunt the locaUties where the eruptive forces concerned in the 

 production of the aurora are most active. Spots not unfrequently 

 increase in size as they reach some particular part of the visible 

 ■disc as though there were something in that vicinity independent 

 of the sun or at least not moving with it capable of originating them. 

 This something certainly cannot be heat from an external source and 

 the manner of its action is such that it is very unlikely that it is gravi- 

 tation, or in other words tidal stress, but it is very probable meteoric 

 or planetary matter that has become specially charged as the result 

 of some preceding outbreak which has occurred with such abruptness 

 and force as to have left its impress upon the sub-permanent magnet- 

 ism of particles in some one direction from the sun, causing a reaction- 

 ary effect upon the other sections as they pass that point. 



The relation of what is known as the eleven year period of sun 

 spots to the perihelions of Jupiter illustrates very clearly the manner 

 in which magnetic induction is originated in the sun and propagated 

 back and forth throughout the solar system in the manner described 

 in the preceding paragraph, It is found that in cycles of one hundred 

 and sixty-six years the perihelions of Jupiter make one complete round 

 of coincidences with all phases of sun-spot activity from maximum to 

 minimum and back again. It follows from this that the perihelion 

 position of Jupiter cannot determine the times of recurrence of any 

 particular phase or degree of solar activity inasmuch as it is coincident 

 in regular order with them all. Just now the perihelions coincide with 

 sun-spot maxima but going backward they gradually recede until 

 about eighty-three years ago they fell almost precisely midway 

 between such maxima and did not again coincide as at present until 

 one hundred and sixty-six years ago. Thus the average sun-spot 

 period is shorter than a revolution of Jupiter in the ratio of fourteen 

 to fifteen. Nor is it possible to explain this shortening by bringing 

 into the account the perihelions of the other planets or their alignments 

 with each other at conjunction or opposition. There is no configur- 

 ation of planetary positions that coincides with any particular phase 

 of the eleven year period. The proof is very positive that variation 

 in gravitational or tidal stresses is not the cause of the manifest periodi- 

 city at this interval. Nor have we evidence of the existence of any- 

 thing else external to the sun itself capable of producing recurring 

 solar convulsions on so vast a scale. Certainly there is no periodic 

 intrusion into the solar system of meteoric matter adequate to produce 



