HARDWICKE'S SCIENCE-GOSSIP. 



121 



ON CERTAIN PHENOMENA CONNECTED WITH 

 ATMOSPHERIC ELECTRICITY. 



By WALTER G. WOOLLCOMBE, B.A., F.L.S. 



PROPOSE to offer 

 a short resume of 

 the most generally 

 received theories 

 with respect to 

 certain branches 

 of atmospheric 

 electricity. 



First, as to the 

 origin of atmos- 

 pheric electricity. 

 Though we are 

 still farfrom know- 

 ing the causes that 

 immediately pro- 

 duce it (chiefly> 

 I should say, from 

 our ignorance of 

 the nature of elec- 

 tricity and from 

 the fact that its 

 relations with other forms of energy are only just 

 beginning to develope into definite shapes), there are 

 two or three more or less plausible theories as to 

 its origin. 



1. That it arises from the effects of the thermo- 

 electric action of the sun, to which probably is due 

 the distribution of magnetic -force on the earth's 

 surface. From the analogy of electricity to nragnet- 

 ism we might allow this to be a possible cause, 

 although in our present state of incomplete know- 

 ledge the relation between dynamic electricity, so 

 produced, and the static electricity of the atmosphere 

 cannot as yet be formulated. 



2. That it arises from the chemical action of the 

 sun. This theory, as far as I am aware, is asserted 

 'by every one to be inadequate to the explanation of 

 the enormous quantity of electricity we observe at 

 times in the atmosphere, but we may reasonably 

 suppose that the various forms of this chemical action 

 liberate a certain portion. 



No. 198.— June i88i. 



3. That an enormous amount of electricity is 

 produced in the interior of the earth is shown by the 

 highly-charged vapour and ashes that are poured 

 forth from volcanoes, and doubtless a large 

 quantity of atmospheric electricity is due to their 

 eruptions. 



4. The chief source, however, is supposetl to be 

 evaporation from liquid surfaces. Now, if evapora- 

 tion were shown to liberate electricity unconditionally, 

 the oceans and seas would afford a large enough 

 evaporating surface for the production of an enormous 

 quantity. But, relying on the results of certain 

 experiments, M. Reiss states that the electricity 

 produced at the moment of evaporation is due 

 chiefly, if not wholly, to friction between drops of 

 water drawn along with the evaporating vapour, and 

 that, in order that liberation of electricity may 

 accompany the act of evaporation, the fluid must be 

 subject to limited conditions, non-existent in the case 

 of the ocean. There is every reason to suppose, 

 however, that evaporation of water, more especially 

 sea-water, is intimately connected with the production 

 of atmospheric electricity, and De la Rive seeks a 

 more ultimate cause. He says " it is due to con- 

 tinuous chemical action taking place on the interior 

 surface of the solid crust of the globe, arising, not only 

 from local actions, but also from the infiltrations of 

 sea-water, and, in accordance with the known laws of 

 electro-chemistry, this water is charged positively and 

 the solid earth negatively. Vapours arising from the 

 sea are thus cliarged with positive electricity and carry 

 it away to the upper regions. This phenomenon 

 occurs much more extensively in tropical regions, and 

 after the vapours have risen, they would be carried 

 into the two hemispheres by the tropical currents of 

 the higher regions of the atmosphere." Probably all 

 these theories as to the origin of atmospheric elec- 

 tricity are more or less true, and all the causes 

 mentioned above play a proportionately important 

 part in its formation. 



M. de la Rive's theory well accounts for the normal 



G 



