1886.] Sun-spot Spectra Observations at Kensington, 35£ 



incandescence over large areas and extending to great heights ; and, 

 besides these, the production of streamers. See fig. 4. 



Fig. 4. 1\ years from maximum, 1858. Tracing of drawing by Liais, showing "cones. : 



Two results follow : — 



1. In consequence of the increased temperature of the lower 

 regions, the velocity of the lower currents towards the poles, and 

 therefore of the upper currents from the poles, is enormously increased. 

 The disturbance of the ring will therefore be increased. 



2. Violent uprushes of the heated photospheric gases, mounting 

 with an initial velocity of a million miles an hour, can also disturb 

 the ring directly. 



In this way the sudden rise to maximum in the sun-spot curve, and 

 the lowering of the latitude of the spots, follow as a matter of course. 

 And the part of the ring nearest the sun, its base, so to speak, is, it 

 would appear, thrown out of all shape, and we get falls over broad 

 belts of latitude N. and S. 



Does this hypothesis explain then the slow descent to minimum and 

 the still decreasing latitude ? It does more, it demands it. For now 

 the atmosphere over those regions where the spots have hitherto 

 been formed is so highly heated, and its height is so increased, that any 

 disturbed material descending through it will be volatilised before it 

 can reach the photosphere. 



The best chance that descending particles have now to form spots, 

 is, if they fall from points in lower latitudes. The final period, there- 



