Column doesn't work any better without more numbers. From what I can tell, all we really have is the number 7 and that string of letters; that's what made me think Caesar, you just need one number to encrypt/decrypt that. There's a mention of a half, and circles, and the code's written vertically hence me thinking columns, but any more than that...
There are 41 entries, which is prime so there's no obvious way to divide it up, and the only code I can think of that could be solved with just one number is Caesar, which it apparently isn't.
Will have to leave it to someone else.