670 Professor W. G. Adams [June 3, 



northward. All the arches seemed exactly bisected by the plane of 

 the mac^netic meridian. At 10 . 30 streamers appeared in the south-east, 

 runniucr to and fro from west to east. They increased in number and 

 approached the zenith, when all of a sudden the whole hemisphere 

 was covered with them, and exhibited such an appearance as baffles all 

 description. The intensity of the light, the prodigious number and 

 volatility of the beams, the grand intermixture of all the primitive 

 colours in their utmost splendour, variegating the glowing canopy 

 with the most luxuriant and enchanting scenery, afforded an awful, 

 but at the same time a most pleasing and sublime, spectacle." But 

 he adds : — " The uncommon grandeur of the scene only lasted one 

 minute ; the variety of colours disappeared, and the beams lost their 

 lateral motion, and were converted, as usual, into the flashing 

 radiations ; but even then it surpassed all other appearances of the 

 aurora, in that the whole hemisphere was covered with it." 



In his address before the British Association in 1863, Sir William 

 Armstrong speaks of the sympathy between forces operating in the 

 sun and magnetic forces on the earth, and notices a remarkable 

 phenomenon seen by independent observers on September 1, 1859 : — 

 " A sudden outburst of light, far exceeding the brightness of the sun's 

 surface, was seen to take place, and sweep like a drifting cloud over a 

 portion of the solar surface. This was attended with magnetic 

 disturbances of unusual intensity and with exhibitions of aurora of 

 extraordinary brilliaixy. The identical instant at which the effusion 

 of light was observed was recorded by an abrupt and strongly marked 

 deflection in the self-registering instruments at Kew. The magnetic 

 storm commenced before and continued after the event." 



The daily and yearly periods of the magnetic changes, the change 

 in the horizontal force depending on the sun's rotation an his axis, the 

 ac^reement of the eleven-year period of magnetic disturbances, sun- 

 spots, and auroras show that the sun plays a very important part in 

 causing or regulating both the regular and irregular magnetic 

 changes. 



The sun may be a very powerful magnet, and when his magnetism 

 is greatly altered we may see the effects of this disturbance in the 

 bright faculae and in the spots in his atmosphere. Such a change of 

 magnetism would affect the magnetism of the earth, although the 

 effect could not be very large, unless the sun is magnetised to an 

 intensity much greater even compared to his mass than the earth is 

 magnetised. Then, as there are tides in the seas around us, and 

 probably in the earth's crust, so there are certainly very large tides 

 in the ocean of air above us, and may not the sun and moon by 

 dragging this air towards them as the earth revolves cause that 

 friction between air and the earth, and also that evaporation, which 

 together may account for the presence of and keep up the supply of 

 positive electricity in the air and negative electricity in the earth ? 

 Again, these tides in the atmosphere will cause the mass of it to lag 

 behind the revolving solid earth, and at a height of 30 or 40 miles we 



