General Report on Tunny
24B Page 115
The 32nd place will clearly be in the cell (32,1): similarly whenever a side of the rectangle is reached.
The first 1271 places will just fill the rectangle.
Evidently the first cell will contain not only the first place but also the (1271 + 1)th, (2 x 1271 + 1)th, etc. places, and similarly for every cell.
(b) The methods for entering have been used:
(i) Find the score for all places spaced at interval 1271 beginning with the 1st place of Z, then for all places spaced at interval 1271 beginning with the 2nd place of the cipher, and so on; afterwards enter diagonally.
(ii) Look for the scores in the various cells of the rectangle arranged by rows and columns, entering directly in the correct position.
Method (i) was normally used for Garbo, Thurlow and Robinson rectangles.
Method (ii) was used normally for Colossus rectangles.
The mechanical difficulty in method (ii) is the irregular stepping at the end of the row: this was found to make it not worth while except on Colossus, which can stop irregularly (38 C N): even Colossus requires a gadget to do this properly (Colossus rectangling gadgets do much more besides); with the gadgets this method is preferred.
Note: prior to the introduction of the gadget, Colossus rectangling used method (i). Method (ii) was attempted on Super-Robinson, but abandoned (R5 p 81).
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