This section is from the book "Elementary Banking", by John Franklin Ebersole. Also available from Amazon: Elementary Banking.
Early in this chapter it was stated that bank cash bookkeeping was different from that of commercial or industrial enterprises where debits and credits to cash are handled like those for any other account. In banking, in order that the teller or department maintaining the cash proof may close his day's work with equal debits and credits, which is the primary test of proof, it is necessary that the closing cash of the previous day be entered as a credit to cash on the opening of business the following day. This follows from the rule that the closing cash figure of the current day must be the total cash on hand; otherwise the day's transactions of debit and credit would reflect simply the receipts and issues of the day in question. To illustrate the condition where the closing cash of the previous day is not used in the figures: Suppose the bank receives $5,000 during the day and pays out $4,000. Then the closing cash figure would be $1,000. That, however, would not be the entire supply of cash at the bank. If the desire is that the entire closing supply of the bank be shown to the left of cash, the teller must obviously start his day's work with cash credited for the closing figure of the previous day. That automatically permits using the entire closing supply on the left. Pursuing our illustration, $5,000 receipts and $4,000 issues leaving a net increase of $1,000, if the closing cash of the night before were $74,000 and that were placed to the right of the cash on the current day, obviously $75,000 would be the closing figure under that arrangement.