1854.] 



ATMOSPHERICAL ELECTRICITY. 



183 



do all this, it may be difficult to calculate from such data 

 as exist how much electricity is concentrated on the aver- 

 age in the atmosphere at any one time for which an 

 accouut is to be rendered; and it may be no more easy 

 to estimate correctly the producing power of evaporation, friction, 

 and their co-operatives. There are few of the mechanical oper- 

 ations of nature which can be brought within the limits of strict 

 mathematical investigation. The precision of delicacy of finish, 

 united with great boldness of conception, which are claimed for 

 astronomy, belong only to the mechanics of the solar system, and 

 this which is called the higher mechanics is considered piece- 

 meal. It hath not yet entered into the mind of man to conceive 

 of that highest and truly celestial mechanics which metes out 

 the forces ordained to balance and move not merely planets 

 and comets, but stars, clusters, and nebulae. Here it is the 

 multiplicity of the stars which swarm in space, and the unnatural 

 and parallactic crowding in certain districts, which make the con- 

 fusion of thought. In meteorology, and indeed on many an 

 arena of nature infinitely smaller than the earth's atmosphere, 

 there is the same multitude of objects, and the same ambiguity 

 of their position ; and besides all this, there is a variety 

 of forces which cut in at various points besides the force of gravi- 

 tation, and there also exist an irregularity of figure and a 

 crowding of parts in the matter concerned, which contrast widely 

 with the almost spherical units and the ample spaces of 

 astronomy. To walk even in one of the narrowest paths of 

 meteorology, who can compare numerically the quantity of 

 electricity which diverges the tell-tale leaves of the gold-leaf 

 electroscope and that which fills the Leyden jar, and then who 

 can compare the quantity in the jar with that in the thunderbolt, 

 and afterwards say how many such thunderbolts strike upon 

 a certain assignable area of the earth's surface, and how much 

 ■electricity besides this discharges silently and steadily upon the 

 mountain-peaks, the million tree-tops, and the innumerable 

 natural lightning-rods which point ever to heaven, and preserve 

 the earth from frequent and violent electrical excitement, by 

 bringing the electricity back harmlessly to the earth ? And to 

 account for the existence of so much electricity, after its value 

 has been accurately ascertained, who can calculate, from the 

 •electricity which the evaporation of a drop of water contributes 

 to the sky, how much ascends from the earth's waters? And 

 who will undertake to calculate the friction of the winds and the 

 electricity which they grind out ? 



Beccaria, who was one of the first to follow the lead of Franklin 

 in pursuing the study of atmospherical electricity, estimated that, 

 as much electricity passed through the rods on the palace of 

 Valentino every hour as was sufficient to kill three thousand 

 men. Arago estimated that, when a cloud was present, a 

 hundred sparks would pass a break in a lightning-rod in ten 

 seconds, and this would be enough to kill a man ; enough, there- 

 fore, to kill three hundred and sixty men an hour. In respect 

 to evaporation, Leslie computes, that 52,120 million cubic feet 

 of water, each weighing about sixty-two pounds, are lifted 18,000 

 feet into the air by evaporation each minute. Now if the 

 evaporation of a drop of water develops electricity sufficient to 

 throw apart the gold leaves of the electroscope, who can say 

 that the whole fund of evaporation, which is mechanically 

 equivalent to 200,000 times the labor of the working popu- 

 lation of the globe, may not be competent for all the re- 

 quirements of electrical meteorology. 



The last general division of this article has to do with the 

 effects of atmospherical electricity. There are meteorologists 

 who, in their discussions and theories have entirely overlooked the 

 agency of electricity. There are other meteorologists, who have 



exalted the electrical forces into the first rank, and placed them in 

 the van of the great movements in the atmosphere. Both of 

 these views, in my opinion, are at variance with the truth. The 

 electrical forces are not to be despised on the one hand, nor, on 

 the other, to be enthroned above every other influence. The 

 statistics of meteorology are various, and are collected for various 

 purposes. But the most important questions of meteorology, 

 considered as a science, relate to motion. The statical aspect 

 of this science is valuable as showing when equilibrium can- 

 not exist, and where there must be motion, and how 

 much motion, there must be. The phenomena of meteorology 

 are emphatically those of change and transition. The 

 dynamical side of the problem contemplates the laws 

 of these changes and the origin and character of the forces 

 which produce them. The degree of change and its direction 

 are conveniently gauged and registered by the difference in the 

 barometric height at the same moment for two places, or for the 

 same place at two successive periods. But the cause of the 

 oscillation in the barometer and of the motions which are 

 measured by them is to be found in a disturbance of the mean 

 temperature or humidity, or both, of the air ; a disturbance 

 originating, in each case, directly or remotely, in the action of 

 the solar rays. While evaporation is going on under the provo- 

 cation of the sun, and while the winds are blowing in virtue of 

 moisture and of heat, both the winds and the evaporation pro- 

 duce electricity. This electricity, acts by its own laws of 

 attraction and repulsion, and produces motions which combine, 

 according to the established principles of mechanics, with the 

 other motions which heat immediately causes; or one of the 

 effects of heat, that is, gravitation disturbed by vapor. If we 

 take a glass-plate electrical machine, and suppose it to be turned 

 by a wind-mill instead of by manual strength, and if we apply the 

 electricity which it generates to almost any mechanical purpose, 

 we shall see that it would do much less execution than the wind 

 itself which was spent in producing the electricity. Or if 

 we examine the hydro-electric machine, the boiler of a loco- 

 motive, for example, we discover that it can generate large 

 sums of electricity, surpassing, perhaps, all that we have ever 

 seen produced artificially. Collect now the electricity which 

 this maximum of art produces, husband it careful!}', dispose it 

 so as to exert to the best advantage its mechanical power, and 

 how much work can it do compared with the locomotive which 

 generated it? If it were harnessed by any artifice, however 

 skilful to the heavy train of freight which the locomotive hardly 

 feels to press upon its Herculean shoulders, would it not be 

 utterly crushed by it? Hence we infer that in meteorology the 

 work which is done by electricity is small in comparison with that 

 which is done by the heat, acting through the wind and moisture, 

 which sets free this electricity. And if it were otherwise, if 

 heat could act with more economy through the medium of 

 electricity than through that of elasticity or gravity, or through 

 any other medium, would a thorough analysis of the phenomena 

 of meteorology be satisfied with stoping at the electrical forces ? 

 Would it not finally come to the sun's heat as the prime mover 

 and disturber? So it would appear that, although the phe- 

 nomena of meteorology are limited to this planet, the cause is 

 cosmical and not metoric. 



Without regarding electricity as the exclusive or even the 

 principal force which manifests itself in meteorology, we may 

 refer certain classes of phenomena to its more particular agency. 

 Of this description is the aurora. The great elevation of the 

 aurora, in many cases, might require us to consider it as with- 

 out the pale of meteorology, did we not expand the limits of 

 the earth's atmosphere, and therefore the limits of the science 



