# The Special Fish Report

## Albert W. Small (December 1944)

### Page 26

Tony Sale's
Codes and Ciphers

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CX/MSS
TOP SECRET Special Fish Report Page 26

The excesses of these resultant scores over the normal score are exactly
but opposite in sign
equivalent / to the excesses of dots over crosses that would be obtained

for the Delta-X2 pattern in a crude convergence of the given rectangle by

hand, with the given Delta-X1 pattern. A quick way of checking this

is as follows:

Assume a Delta-X ipj rectangle of the following proportions:

If we change the last sign of Delta-Xj to a cross we get:

6 dots in Delta-D ipj

18 dots in Delta-D ipj

19 dots in Delta-D ipj

43 = TOTAL
with regard to sign of Delta-Xi
43 - 29 = 14 = value for excess of dots/ in last row opposite to what would

be given by crude convergence had we written the Delta-Z ipj rectangle as follows in

terms of excess of dots over crosses:

**Resultant Delta-D i+j crosses are not counted, nor is excess of dots considered,
since Colossus is set to count only dots.

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