Mr. R. Phillips on the Theory of Thunder-storms. 511 



tured to give does not rest on vague surmise or on doubtful 

 experiments, but on many clear and independent experiments, 

 which harmonize well together. [I allude here only to the 

 new modes of electrical excitement I have discovered, and not 

 now to the magnetism of steam.] The experiments I have 

 recorded appear to me undoubtedly to demonstrate, that 

 water, rubbing against either air or steam, becomes positive. 

 For instance, in the experiment with the fountain (107.), the 

 water passes from the jet, dashes against the metal, and be- 

 comes reduced to a number of minute drops, and thus exposes 

 a large surface; much of the motion of the water is then soon 

 given up to the air through friction, and the drops are very 

 feebly charged with positive electricity in consequence. The 

 drops now come in contact with the sides of the tin pipe, and 

 running together exalt the electric tension so far that the 

 electricity becomes capable of being registered by the electro- 

 meter. 



if we consider a mass of air and drops of water moving 

 with a uniform velocity in a straight line, it is immediately 

 seen that this motion cannot disturb the relative position of 

 any particle. Suppose now the motion of the air to be de- 

 flected into a curve, and it is quite certain that curved cur- 

 rents do exist in the atmosphere, then from the great difference 

 of specific gravity between air and water, the water would 

 continue to separate from the air in lines more or less ap- 

 proaching the tangents of the curve along which the neigh- 

 bouring air is moving. Now if the condensation of vapour 

 continue to go on in the space inside the curve, the particles 

 so condensed would be whirled to, and accumulated on the 

 convex side of the curve, being by the friction positively elec- 

 trified, and leaving the air through which they passed nega- 

 tive. We may suppose this process to goon, and the electric 

 tension of the cloud consequently to rise until rain begins to 

 fall. Now the drops falling from the superior portions of the 

 cloud will increase in size in falling through it, and will there- 

 fore be larger on leaving the cloud than the drops formed at its 

 inferior portions; these larger drops, in falling towards the 

 earth, will therefore more or less overtake the smaller drops, 

 or, in other words, when the rain falls the electrified particles 

 become approximated. 



In the storm with which Dublin was some time since 

 visited*, the difference of motion between the wind and water 

 or ice was evidenced by a noise. And the remarkable ap- 

 pearances described by Mr. Clare in the last Number could, 

 I suppose, only have been an exhibition of the negative elec- 

 * Phil. Mag. vol. xxxvi. p. 396. 



