One of the most ingenious uses of the card system for commercial purpose is its applica tion to the keeping of ledgers, of which the loose-leaf ledger is an offshoot in the develop ing process of commercial card-indexing. The card ledger does away with the necessity of purchasing books, ledgers or binders and ac counts can be posted, checked up, trial bal ance taken off and statements mailed in ap proximately half the time required for a book ledger. Accuracy is also promoted by each card representing one account only, which can be laid on the sales sheet or other original record, thus lessening the liability to error in posting. Each account being on a separate card is easily indexed, and no separate or cross-index is required; more perfect indexing is thus en sured; as the number of accounts increase year by sets of index cards, with as many subdivisions of the alphabet as desired to facili tate quicker reference, may be substituted for the original set. Statements can be taken off promptly at the first of the month, and where necessary, several clerks can do the billing at the same time, which is impossible with the book ledger. Open accounts only are kept on the regular file; all closed accounts are removed and indexed in a separate file, the only practical method of providing for closed accounts, which can be easily referred to as open ones. The
card being removed from the files when the account is closed, and replaced when opened, also obviates the former necessity of trans ferring accounts from one ledger to another, at the end of each year. Finally the card index ledger can be profitably used for mailing and circular lists. Modern business houses no longer file their correspondence in the old letter boxes. There are various card systems, but the primal scheme is to have a cabinet in place of the separate pasteboard letter boxes. This cabinet is divided into drawers, each deep and wide enough to hold the largest business letter heads when standing in a vertical position. The drawers themselves are divided into com partments for classifying the letters and sepa rated by manila dividers, between which are folders of heavy paper. Marginal index guides on the dividers afford a mechanism for quickly finding any name or classification desired. Sup plementing this are various schemes involving different kinds of cabinets for cross-indexing cards, by which the subject matter of letters or the names of the writers as well as of the firms from which letters are received may be indexed. Consult Byles, B. B., The Card Index System' and articles in System (Febru ary 1912) and Engineering Magazine (July 1913).