The Enigma Machine — Part 2
when your finger is dry and moving. A stationary finger or
a damp finger produce no effect. Why?
Now, hold the can in your hand and place your other
hand on the top of the machine (Figure 2). Have someone
else brush the can with a dry finger. Surprise! The vibration
effect passes right through you and the can to the other
person (although reduced by roughly half). You don’t feel
a thing. See how many people you can pass the “vibration”
through. It is possible to eliminate the can and lightly brush
the back of the other person’s hand. The effect is quite
reduced, but still present.
Turn the can upside down, place it on the machine
and brush the bare aluminum bottom with your finger. The
vibration effect is greatly reduced or eliminated. Why? (If
the can is painted on the bottom, place the aluminum
plate on the machine, as shown in Figure 3, and brush
The vibration effect was first discovered by accident
when I brushed my ear against a strong electromagnet
that was being energized with a powerful, high frequency
signal (about 12,000 Hz). A sound was heard when the
ear was brushed, but not when it was stationary. Why?
Figure 3. For some experiments, a metal plate on the machine
increases the strength of the effects.
Was it vibration or some type of nerve stimulation?
Simple experiments showed that it was mechanical
There are two questions about this effect. The first is
why a finger must be brushed to feel the vibration. (A
stationary finger does not create the effect.) The second
question is why the finger must be dry. (A damp finger
Circle #34 on the Reader Service Card.