quite unlike log reading of today. After Dunkerque, Towser went
into the War Office with a small group including Blair-Cunynghame,
and Lithgow went into the Foreign Office at B.P.
Sometime in 1940-41 Enigma began to be broken on something like
a current practical scale. The group under Lithgow devoted itself
to correlating order of battle identities from source with call-signs
and frequencies and the application of signals information from
source to problems of interception. Thus, the present Source Bureau
had its beginnings. Nothing like log reading or fusion as they have
come to be known was undertaken. However, an occassional re-enciper-
ment was found even without a systematic search.
Independently of the group at B.P. but during the same period,
Towser and Blair-Cunynghame in the War Office were developing the
processes of systemativ log reading. Training then required only
an acquaintance with the "Q" code. Because of the London blitz, this
group moved in the early spring of 1941 to Harpenden. There, "log
reading" began to come to grips with the problem of continuity.
Tracing station continuities without knowledge of call-sign system
was the art of log reading. Diaframs of networks began to appear
in log reader's notebooks. Another problem presented itself when
other intercept stations (Chicksands and Harpenden) in addition to
Chatham became operative. This was known as the problem of "recon-
ciliation", that is, comparing and combining logs from two
different intercept stations to form a single picture. During the
summer of 1941 considerable competition, not always friendly, developed