284 Mr G. A. Rowell on the Cause of Storms, 



stantaneously conducted away by the falling column of water, 

 the supply of water and the vacuum are thus kept up for a 

 time ; the air under the cloud rising and rushing in from all 

 parts to fill the vacuum causes a whirlwind, and as the fall- 

 ing torrent of water raises a spray in the sea, the spray being 

 taken up by the whirling air gives the whole the appearance, 

 at a distance, of water rising from the sea; water-spouts 

 being attributed to whirlwinds, is probably mistaking the 

 effect for the cause. 



The calculations above made, seem to advance the proba- 

 bility of the hypothesis brought forward by the author 

 (1839),* for explaining the causes of terrestrial magnetism 

 and the aurora, as they shew the great quantity of electri- 

 city which must be given off by every particle of vapour that 

 falls to the earth. 



The hypothesis is, that a part of the vapour which rises at 

 the equator, is, together with its electricity, carried off by 

 the superior trade-winds towards the poles, where the elec- 

 tricity, escaping through the damp air to the earth, rushes 

 along its surface towards the equator, where it is again 

 taken up by the rising vapour, and thus a circulation of 

 electricity is kept up : that the aurora is owing to this cir- 

 culation being interrupted by the intense frosts of the frigid 

 regions rendering the air between the clouds and the earth 

 so dry as to make it a perfect non-conductor, when the elec- 

 tricity accumulating over these parts flashes back towards 

 the equator through the rarer air ; and that terrestrial mag- 

 netism is owing to these currents of electricity rushing 

 along the earth and damp air from the poles to the equator 



* See the Report of the British Association for 1840. 



