694 Transactions of the American Institute. 



proof of the vast accumulations which surcharge the masses or cer- 

 tain portions of the cloud, whence the lightning darts forth, followed 

 by the explosion of thunder. In order to fortify our theory, we will 

 endeavor to show, in the sequel, from the attendant circumstances, 

 that this explosion is of volumes of gas which are produced by the 

 currents of electricity passing through the watery masses, and by 

 their normal operation effecting the decomposition of the water ; and 

 that it is the detonation of volumes of gas, fired by the lightning, 

 which we recognize as thunder ; each peal of which is a single 

 report, for the most part, reverberated from the various masses of 

 vapor with the prolonged roll so often heard. If the same cause pro- 

 duces the same effect, as philosophy teaches, it would seem to be a 

 just conclusion that the application of heat to the boiler, for the raising 

 of steam, produces in the process an evolution of electricity in such 

 quantities as to decompose a portion of the water, converting it into 

 the oxygen and hydrogen gases; that these gases accumulate in 

 volumes in the upper part of the boiler, where, in their mixed condi- 

 tion, they assist by expansion the working pressure. The quantity 

 of electricity combined with the atoms in water, and of most other 

 substances, is marvelous. A single drop of water is said to have 

 been shown by Faraday to contain more than is discharged in a flash 

 of lightning. ^(Porter's Chemistry, § 252.) The change of form or 

 state of bodies is one of the most powerful methods of exciting it. 

 Water in passing into steam by artificial heat, or in evaporating by 

 the action of the sun or wind, generates large quantities of elec- 

 tricity. (Wells' Nat. Phil., 393.) So substances of the same kind 

 suddenly brought together, of different temperature, cause an abund- 

 ant evolution of electricity. Various arrangements have been devised 

 for the production and accumulation of electricity. High pressure 

 steam, escaping from a steam-boiler, carries with it minute particles 

 of water, and the friction of these against the surface of the jet from 

 which it issues produces electricity in great abundance. A steam- 

 boiler properly arranged and insulated, therefore, constitutes a most 

 powerful electrical machine. By means of an apparatus of this 

 description, constructed in London, flashes of electricity were caused 

 to emanate from prime conductors, more than twenty-two inches in 

 length. Another machine of this character has been constructed for 

 the Faulty of Science in Paris ; it is provided with eighty jets for the 

 escape of steam. The sparks form brilliant jets of fire by their rapid 

 succession, each spark being about a foot in length and several inches 

 in breadth. The quantity of electricity existing in the water and 



