ATMOSPHERIC ELECTRICITY. 391 



"Water, in passing into steam by artificial heat, or in evaporating by the ac- 

 tion of the sun or wind, generates large quantities of electricity. The crystal- 

 lization of solids from hquids, all changes of temperature, the growth and de- 

 cay of vegetables, are also instrumental in producing electrical phenomena. 



Does vital and Recent investigations have shown that vital 

 tto^TxcUeeiec" action and all muscular movements in man 

 tricitj? ^Q(j animals, develop or produce electricity;- it 



may also be shown by direct experiment that a person 

 can not even contract the muscles of the arm without ex- 

 citing an electrical action. 



Certain animals are gifted with the extraordinary power of producing at 

 pleasure considerable quantities of electricity in their system, and of commu- 

 nicating it to other animals, or substances. Among these the electrical eel 

 and the torpedo are most remarkable, the former of which can send out a 

 charge sufficient to knock down and stun a man, or a horse. The electricity 

 generated by these animals appears to be the same in character as that pro- 

 duced by the electrical machine. 



762. It has of late become the habit with many to regard 

 Is there any ... , /. „ , . , , , , 



reason in as- electricity as the agent oi all phenomena in the natural world, 



cnbing un- ^Y\q cause of whlch may not be apparent. For this there is no 

 known pheno- ■' ^^ 



niena to elec- good reason. Electricity is diffused through all matter, and 

 tncity . jg g^gj. active, and many of its phenomena can not be satisfac- 



torily explained ; but it is governed, like all other forces of nature, by cer- 

 tain fixed laws, and it is by no means a necessary agent in all the operations 

 of nature. It therefore argues great ignorance to refer without examination 

 every mysterious phenomenon to the influence of electricity. 



SECTION I. 



ATMOSPHERIC ELECTRICITY. 



Does electricity 763. Elcctricity is always found in the air, 

 mofiilre? "^ and appears to increase in strength and quan- 

 tity with the altitude. 

 What kind of It is somctimes difterent in the lower re- 

 diffuiS"'^ " gions from what it is in the upper, being posi- 

 mosph^rl'?^''** tive in one and negative in the other ; but in 

 the ordinary state of the atmosphere, its elec- 

 tricity is invariably positive. 



When the sky is overcast, and the clouds are moving 

 in different directions, the atmosphere is subject to great 

 and sudden variations, rapidly changing from positive 



