140 Method of increasing Shocks, ^c. 



Again, solder the copper tube of the left hand to the neg. con., 

 put the pos. con. and right hand into cnp 1. When the end of the 

 neg. con. is raised from cup 4, no shock is felt, but when the other 

 end is raised from the cup on the battery, a shock is felt. Other 

 things remaining the same, carry the right hand from cup 1, out of 

 the direct circuit into cup 6. Nearly the reverse of the last named 

 phenomena takes place. A strong shock is felt when the end of the 

 neg. con. is raised from cup 4, and a weaker one when the other end 

 is raised from the cup on the battery. This experiment appears still 

 more striking, when the right hand is carried into the same cup with 

 the neg. con., cup 4 ; a shock is felt, although the distance by the 

 direct circuit from hand to hand, is only about eight inches. Hav- 

 ing detached the copper tube from the connector, put the pos. con. 

 in cup 1, the neg. con. in cup 4, the right hand in cup 4, and the 

 left hand in the neg. cup on the battery. It is immaterial now which 

 end of the neg. con. is raised, both producing a shock. If the right 

 hand is now carried to cup 6, the shock is a maximum. 



A direct shock cannot be obtained from this instrument. To test 

 this, I passed fine needles deep into the thumb and fore finger of the 

 left hand, and immersed them in cup 6 and the neg. cup on the bat- 

 tery, the pos. con. being in cup 1 ; no shock was felt on making or 

 breaking the circuit. 



If a file or rasp be inserted into either of the cups and the con- 

 nector drawn across it, the shocks become insupportable from their 

 rapidity of succession. The scintillations from the file in this case 

 are very beautiful, being by far the most brilliant and copious in cup 

 4. Very pleasing effects are produced by breaking the circuit with 

 a revolving spur wheel. A little spur wheel of copper is so made, 

 that in revolving, one spur shall leave the mercury before the next 

 touches. In this way a rapid series of sparks and detonations are 

 obtained. If bits of silver leaf are hung upon the spurs as the wheel 

 revolves, the combustion of the silver leaf is very vivid, burning 

 with its peculiar emerald light. The shocks produced while the 

 wheel is revolving, are very disagreeable. 



The decomposition of water was easily effected by breaking the 

 circuit under its surface with two clean strips of copper. On using 

 two small platinum wires, they adhered as with a deflagrator. 



The coil was tried with a two quart Leyden jar, and shocks were 

 obtained from cups entirely without the direct circuit. I refrain from 

 stating other results with the Leyden jar, as they must be rendered 

 somewhat equivocal, by the imperfect insulation of the coils. 



