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 cup 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 intocup 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 —_— or 
breaking the circuit. 
Ifa 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 
’ 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 —*. 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 
equivocal, by the imperfect insulation of the coils. 
‘ 
