# The Special Fish Report

## Albert W. Small (December 1944)

### Page 25

Tony Sale's
Codes and Ciphers

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CX/MSS
TOP SECRET Special Fish Report Page 25

 Text length- 5,000 6,251 7,501 10,001 12,501 over 6,250 7,500 10,000 12,500 15,000 15,000 TOTAL # Rectangles 9 20 13 8 4 4 58 Jellyfish # Significant 0 2 0 0 1 0 3 # giving wheels out 0 0 0 0 0 0 0

 Text length- 5,000 6,251 7,501 10,001 12,501 over 6,250 7,500 10,000 12,500 15,000 15,000 TOTAL # Rectangles 0 1 5 23 16 30 85 Gurnard # Significant 0 0 1 7 5 4 17 # giving wheels out 0 0 1 3 0 4 8

Sgt. J. Levine at Arlington has gone into the accurate scoring

of rectangles as far as anyone here, and all data compiled here on accurate

scoring are already in Arlington's hands. Here they do not find accurate

scoring in converging to be worthwhile on a production basis.

After the Delta-X1 & Delta-X2 patterns are deemed to be significant(and
therefore
the rectangle is called "significant,") the rectangle and the patterns for

Delta-X1 & Delta-X2 are sent to the Colossus operator, together with the Z tape.

The Colossus operator plugs the Delta-X1 & Delta-X2 patterns on the machine.

Then he performs wheel-breaking runs.

For instance, using the Delta-X1 pattern only, as against a Delta-X2

pattern of all dots, he makes a count of resultant Delta-D 1p2 = . positions.

This is called the "Normal Score" ("NM"?) Then the last dot of the

Delta-X2 pattern is changed to a cross, and another count is made on 1p2.

positions. The last position of Delta-X2 is changed back to a dot and the

second to last position of Delta-X2 pattern is changed to a cross, and a count

made on 1p2. position. This is done for a cross in every position of Delta-X2.

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