After the nail unlock achievement, you will head to the wasp's nest. In the corner by the stove is a pamphlet about "Spring Heeled Jack". You will then have to deciper the message. Instead of listing what each character means in lettering, it spells out like this:
NEW
COMMAND
SUBJECT
WOMAN
DELIVERY
WHARFDALE
It will expand like Wheel of Fortune. So, when you drop the first "N", all "N's" will appear.
Once you type this in, the achievement pops.
As a personal note, it would have been nice to have the chatpad work for this exercise instead of going after each individual letter.