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EXPERIMENTAL ILLUSTRATIONS OF THE VARIOUS 

 FORMS OF ELECTRICAL DISCHARGE. 



Bt Mr. "WITH. 



Me. President and Gentlemen, — A short discussion whicli took place at 

 our Pontrilas meeting, concerning the probable cause of the remarkable manner 

 in which certain trees are split into shreds when struck by lightning, has led me 

 to believe that the following experiments on facts concerning electrical discharge 

 may not proTe uninteresting to you. 



In Nos. 34 and 35 of that excellent periodical "Scientific Opinion," are 

 two extremely interesting papers on " Researches " made by Dr. Kichardson 

 with the large Induction CoU recently constructed by Mr. Apps, of the Strand, 

 for the London Polytechnic Institution. 



Dr. Richardson's experiments were made with a view to the determina- 

 tion of the various forms of lightning discharge, and the specific effect of each 

 f oi-m upon the animal frame. 



Being possessed of a fairly powerful Induction CoU, I have been able to 

 re-produce the forms of discharge described by Dr. Richardson, and, doubt- 

 less, had I felt justified In the experiments, could have verified his results 

 in other directions, which include destruction of animal life. 



My intention itojo is simply to illustrate, on a small scale of course, the 

 various forms which the lightning discharge assumes, and to state the ascer- 

 tained effects in Dr. Richardson's own words. 



I will, with your permission, entirely confine myself to experiment and fact, 

 leaving theory for your private consideration. 



I wish in the first place to direct your attention to the means at hand for 

 producing electric power. I have here a voltaic battery of five cells (Grove's) 

 with a coil containing 7^ miles of secondary wire. I now show you the ordinary 

 spark. 



Lightning discharges may assume four forms. To obtain that variety of 

 discharge which Dr. Richardson calls No. 1, we must place the terminals of 

 our coil about 1^ inches apart. 



J 



