OOC:
Dr Walker can make a Theoretical Sciences roll to see if he can make any sense of any of the formulae on the blackboards. You'll likely need several successes.
Professor Tichener arrives pretty much as soon as you enter his room, a short, bald man (who doesn't seem to be in any of the photos, though to be fair, several only depict parts of the body, and finding out if they matched up with the professor would be most indecorous). He smiles broadly, and immediately asks to see the coded ledger - it seems that your patron has already been in touch with him - and upon receiving it, and being told what Lillian has accomplished so far, makes "mm" and "mm-hmm" noises softly as his eyes dart over the pages.
"You've made very good progress - have you considered a career in maths? Or perhaps even for the Bureau of Investigation? he asks Lillian, quickly turning pages and making more "mmhmm" sounds. It takes him about five minutes before he starts explaining the double code and how he has solved it and mentions how close Lillian was to cracking it, just a small error here and a transcription error there that she would have noticed as she took the next steps, etc.
Once the code has been explained, it's a fairly simply job to translate, so he leaves that to you to do yourself.
OOC:
You'll need to make a Dismal Sciences roll in order to decipher what the actual accounts reveal, now that you've cracked the code, which should take the rest of the day more or less. Again, one can help the other.
"Is there anything else I can help you with while you're here?"