PART iv. OCCASIONAL PHENOMENA. 43 



assisted or stimulated by the sun warming up the tropical 

 seas ; but to be prevented from escaping thence by the 

 aerial atmosphere pressing upon its surface, and forming 

 one of the worst of conductors, whenever its state is 

 verging on the dry. But transfuse those dry gases of 

 which the atmosphere is mainly composed, with watery 

 vapour, and its molecules immediately become means 

 for conducting the electricity from the ocean surface up 

 to the cloud level. The vesicles, of which clouds are 

 composed, then become a further carriage for such earth- 

 central derived electricity ; which, after supplying the 

 thunder and lightning, or disruptive discharges, of the 

 tropics, then travels with the anti-trades spirally over the 

 temperate regions of the earth, and reaching at last the 

 circumpolar air, full of frozen particles of moisture, gives 

 out there silent " brush discharges," or in fact aurorae 

 the auroral spectroscope line alone excepted. 



Arrived at that point, M. Plante seems nearly at one 

 with Professor Stokes. But many persons may ask, has 

 even M. Plante any practical proof of this escape exist- 

 ing and going on actively in the tropics, of his supposed 

 original charge of the earth's interior electricity ? He 

 does not dogmatise on the point ; but rather invites 

 inquiry and observation. Wherefore it would be rather 

 culpable in me, who had the privilege of witnessing that 

 remarkable series of Madeiran clouds anchored above the 

 island for twelve hours, not to try how far his hypothesis 

 suits the case. Madeira is certainly not within the 



