19. The daily variant seems to be the wheel order and the message
variant is the initial setting of the 10 wheels. These are given by QEP
numbers. It seems, however, that the settings corresponding to a given
QEP do not change daily, and possibly not even monthly. Messages of 9
July and 3 August with the same QEP's have the name initial settings but
since they were practice messages this may not be too significant.
The asterisks indicate the respective motor elements which correspond to
the first enciphering elements. The statement about the 69 wheel in
paragraph 17.is meaningless because it never acts as a motor wheel.
21. The machine was broken through reading a depth (5 for part of
its length, 4 for the remainder). A depth of 4 seems about the absolute
minimum. Catalogues were prepared to assist in reading. These show the
possible alphabets which result from any assumption of a plain-cipher
pair of letters. Another method tried involved masks and inverse prob-
ability calculations. The permuting mechanism can produce only 30 out of
the 120 possible permutations. 32 seem possible but / and Z produce
identical permutations and so do T and E. A substantial amount of research
is being done on this problem at the moment. Solution through depths
cannot be relied on for the future because of tbe apparent introduction