xxvm.] CURRENTS. 433 



An outer current carrying condensed and condensing material 

 from the poles thus suggested, and partly confirmed by observa- 

 tion, necessitates an inner current towards the poles carrying 

 the lower incandescent vapours to feed it. Here again the in- 

 formation to hand is meagre, but such as it is it gives no 

 uncertain sound. 



First, in the observations of prominences of no great height, 

 strong indications of currents have been observed. So . far, 

 sufficient attention has not been given to record the direction 

 of the drift, but this point is now engaging the attention of the 

 Rev. S. J. Perry at Stonyhurst. The illustrations from Young's 

 work given on p. 115 will show the way in which these lower 

 currents act upon the prominences. 



Another way of throwing light upon this still obscure question 

 is to observe the proper motions of spots. I have done this for 

 the years 1878 9, and find in many cases exactly what I should 

 have expected ; namely that the spots drift polewards, the lower 

 current being opposite in direction to that which brings the 

 falling materials. In many of these spots we can trace the paying- 

 out of the materials, and the formation of spots in gradually 

 lower latitudes along the same meridian, and the subsequent 

 drift of the vapours back on their paths at a lower level. 



14. By the hypothesis, the falls when they have once begun should 

 increase their intensity very rapidly. 



As it is the falls which increase the temperature of the lower 

 atmosphere, the more falls there are, the stronger will those 

 currents become, which carry the dissociated material polewards, 

 and the more material there will be to be condensed and 

 carried by the return upper current towards the equator. 



It is very evident that once such a machinery as this is set 

 going on the solar scale, the action will go on with a rapidly 

 increasing velocity and energy. This is in accordance with 

 the facts. 



F F 



