Challenge Eight - third clue

The text consists of 2320 characters and 2320 factorises as 5*16*29, so the keyword for the transposition phase is likely to have length 4,8 or 10 (other lengths are possible but unlikely). Let's just say that you might want to think like Goldilocks. When you are trying to pair the columns remember that you are looking for the roughest distribution. In particular of the 36 possibilities you really only expect the text to use around 26 of them (maybe one or two numerals and all or most of the letters) whereas if you pair the columns wrongly you are likely to see almost all 36 possibilities appear. Keep trying!