He next engages in the retail coal business, investing his entire assets. He rents an office and yards at $40.00 per month, and engages a teamster who owns a team and wagon, paying him $24.00 per week. =17.= In this business there are introduced a sales book, with which the student is familiar, and a form of ledger known as _center ruled_ (p. 25). This form at first appears slightly confusing; but there is considerable advantage in having the debit and credit columns side by side, as balances can be calculated more readily. =18.= The cash book used is one having three columns. On the debit side the third column is used for cash sales. The footing is carried forward until the end of the month, or any other time when a trial balance is desired, when the amount is posted in one item. All bills are paid by check, the money received being deposited in the bank. =19.= An auxiliary book used in this business is a _scale book_, in which are recorded the weight of wagon, gross and net weights. Weighing the delivery wagons used by the business each morning is sufficient; this weight can be used on each load hauled for the day. And on deliveries made by the regular wagons, it is not necessary to record the weight of each load in the scale book; knowing the tare, the net weight can be recorded in the sales book. The principal use of the scale book is to record the weights of coal sold at the yards and hauled by the purchaser. When a wagon comes to the yard for a load of coal, it is of course necessary to obtain first the weight of the empty wagon; and it is important that both this and the gross weight be permanently recorded to prevent later disputes. The scale or weight book is usually made with sheets of from four to six weight tickets, perforated, having stubs which are exact duplicates of the tickets. The perforated ticket is given to the customer and the stub remains in the book as a permanent record. Since it is necessary to enter the weights in two places, and because this duplication of work is liable to result in errors, a better plan would be to omit the stub and make the book with carbon duplicate tickets. Even with the old style of book a sheet of carbon paper can be placed between two sheets and two copies of the ticket made at one writing; the record sheet to remain in the book. See illustration, p. 26. [Illustration: CENTER RULED LEDGER]