318 OPINION OF BACON. 



this subtile agent is greatly concentrated on quit- 

 ting a mass of vapour in the form of light- 

 ning, is proved by the fact, that a single spark 

 or flash, causes a precipitation of rain over se- 

 veral thousand acres and that it is a material 

 agent, is demonstrated by its mechanical force 

 in rending rocks, buildings, ships, trees, &c. as 

 effectually as if it were a ball of iron discharged 

 from a cannon. 



Lord Bacon supposed, that the greatest heat 

 in nature was that of lightning, from its instan- 

 taneous power of fusing metals, and of igniting 

 other combustibles. As an additional proof that 

 it is a concentrated exhibition of the igneous 

 principle, it may be observed, that when solar 

 caloric is greatly concentrated by a large burn- 

 ing-glass, it fuses, ignites, and volatilizes the 

 hardest gems in a few moments, thus approxi- 

 mating the character of lightning. But since 



how the electricity of a Leyden battery is condensed on present- 

 ing a metallic knob. Perhaps it is owing to all its particles 

 being attracted to the centre of the knob or that the igneous 

 matter of vapour is attracted to the centre of whatever object 

 excites it. It is worthy of notice, that when a metallic point is 

 presented to the knob of a Leyden bottle charged with electricity, 

 the igneous fluid is drawn off gradually, and no visible spark is 

 produced : but when a larger mass of matter is presented, as a 

 knob of brass, or the knuckle, it is all withdrawn at once. Thus 

 mountains, clouds, buildings, &c. attract a large portion of the 

 electric fluid at the same moment, producing a concentrated 

 spark many hundred thousand times larger than one from a 

 Leyden jar. 



