Method of increasing Shocks, &c. 139 
maximum with this apparatus. It will be seen from this, that from 
cup 4 to 6, the shock is inversely as the spark, while in the first half 
of the coil, it is in the same ratio. It may be well to mention here, 
that I found if the surface of the mercury, where the contact be brok- 
en, be covered with water, the shock is very much increased, ‘The 
rationale I am unable to give, but such is the fact. This augmenta- 
tion does not take place at every rupture of contact, but is best at- 
tained by striking the connector against the bottom of the cup and 
quickly raising it. The shock is also increased by covering the mer- 
cury with naphtha and the mercury nprawed to be oxidized, the 
naphtha soon growing turbid. 
The next results to be stated, are still more curious, wd accor- 
ding to the received theories of electromotion, difficult to explain. 
The pos. con. and right hand are still in cup 1. The neg. con. in 
cup 2, and the left hand in cup 3, the shock is now stronger than 
when the left hand was in cup 2 with the connector, and the shock 
goes on increasing as the left hand is carried into cups 4, 5 and 6 in 
succession.* Let now the pos. con. and right hand remain in cup 
1, place the neg. con. in cup 3, and the left hand in cup 4; the shock 
goes on increasing as before, and when the left hand arrives at cup 
6, the shock is as strong as that obtained from the whole coil, (220 
feet,) while the actual circuit from positive to negative, is only 80 
feet. Let the pos. con. and right hand remain in cup 1, put the 
neg. con. in cup 4 and the left hand in cup 5; the shock is now as 
strong as when the whole coil is in the circuit, and when the left hand 
is in cup 6, the shock is stronger than can be ‘obtained from the 
apparatus in any other way. ‘These last results show that the real 
maximum as indicated by the shock, is given by the direct circuit 
from positive to negative, through half the coil, with the lateral co- 
operation of the other half. 
‘Thus much being known, we might reasonably expect that while 
the connectors are in the extreme cups 1 and 6, we should obtain 
shocks from any two intermediate cups, and this I found to be the 
case; but contrary to expectation, I obtained shocks from-cups en- 
tirely without the actual circuit. For instance the pos. consin cup 
1, neg. in 3, right hand in 4, and left band in 6. In this case the 
hock was slight ; but by thrusting needles into the thumb and fore 
finger of the left hand, and immersing the needles in cups 4 and 6, 
the shock was extremely painful. 
—— 
. ‘Anassistant is necessary to make the immersion of the connectors, 
