ELECTRICITY. 519 



Violent effects of lightning. We have already men- 

 tioned the light and the heat evolved by the electric fluid 

 from the clouds, but the mechanical effects of its violence 

 are, if possible, still more striking. In passing down 

 through a floor, it sometimes perforates it in many places. 

 It knocks down walls, breaks panes of glass, and tears 

 and splits the largest trees. A case is described in Silli- 

 man's Journal of Science, in which the clothes of a man 

 standing at the door of his house, were torn into utter 

 fragments. He was rendered senseless by the shock but 

 soon recovered. 



8. EJfcct of electricity upon the animal system. 



If the knuckle of the operator is brought to the prime 

 conductor, when it is charged, the spark is received, 

 and a slight pricking sensation is felt. If the spaik is 

 very large, a sudden and very peculiar sensation is felt 

 through the joint. It is very slightly painful. 



When, however, the Ley den jar is used, and the per- 

 former grasps the outside with one hand and touches the 

 knob with the other, a very peculiar, and if the charge is 

 large, a very painful sensation, called the electric shock, 

 is felt through the arms and chest. If several individ- 

 uals unite by joining hands, and at one end of the line a 

 connexion is formed with the outside, and at the other 

 end with the inside of the jar, they will all perceive the 

 shock at the same instant. It produces a painful feeling 

 at the joints, attended by a convulsive twitch, which 

 causes an involuntary start. Some persons arc much 

 more easily affected than others. In many cases young 

 persons are fond of taking the shocks, to others they 

 are highly disagreeable. 



When this singular effect of electricity was originally 

 discovered, the philosophers who first experienced the 

 hock in their own persons, were ' so impressed with 

 wonder and with terror by this novel sensation, that they 

 wrote the most ridiculous and exaggerated account of 

 their feelings on the occasion. Muschenbroek states, 

 that he received so dreadful a concussion in his arms, 

 shoulder, and heart, that he lost his breath, and that it 

 was two days before he could recover from its effects ; he 



