What's a bankbook?

(snip)...
A serious question?
At one time bank branches lacked computer terminals that allowed them instant access to the balance and other activity of an account. The customer's pass book simultaniously served as the customer's "statement" of the account status and proof that there was money in the account (for the purposes of withdrawals). Interest payments didn't appear in the pass book until the customer took it to the bank branch where the bank employees calculated the interest with electromechanical adding machines (the interest amounts were still calculated based on the proper dates - often the end of a quarter) and wrote the amounts in the pass book (usually with a ball point pen). Each teller had ink stamps to mark entries as legitimate and identify which teller made the entry.
All this was duplicated in the branch's accounting books. Presumably the labor necessary for maintaining the branch's records was the motivation behind the bank's limited daily lobby operateing hours (many closed at 2:00 PM - weekend hours were unheard of). All the information from the checks and deposit slips had to be copied into the cloth bound account books!
As a
modest concession to ordinary working people the banks did have short late afternoon lobby hours on Fridays. Miss that lone afternoon opportunity and you had to wait a full week or conduct your business during your lunch break (if a branch was close enough).