The particular order we have chosen is known as QWERTZU order.
The diagram shows the connections when the key Q is depressed and supposing
that C1 is connected to C3 through the wheels
[Diagram]
The only outlet for the positive of the battery is through the Q key
to G hence to C3 and then through the E bulb. The result is that the E
bulb lights. More generally we can say
If two contacts C, C’ of the Eintrittswalz are connected through
the wheels then the result of enciphering the letter associated with C
is the letter associated with C’.
Notice that if P is the result of enciphering G, then G is the result
of enciphering P at the same place, also that the result of enciphering
G can never be G.
....
On the wheels are rings or tyres carrying alphabets, and rotatable with
respect to the rest of the wheel; more about this under ‘turnovers’.
When the machine is being used three of the wheels are put in between
the U.K.W. and the E.W. in some prescribed order. The way that the current
might flow from the E.W. through the wheels and back is shown below
[Diagram]
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