=14. Expense and Production Cost Ledgers.= Without digressing from our general subject, it may not be out of place at this point to call attention to a most convenient method of keeping cost records. Inasmuch as the cost of production must absorb the expense costs of manufacturing, it will be found advantageous to keep these two classes of accounts in separate binders, putting all the non─productive labor cost records in one binder, calling it _Expense Ledger No. 1_, and all the productive labor in _Production Ledger No. 2_. When the expense distribution is to be figured, it will be noted that all the entries will be made in _Ledger No. 2_, while _Ledger No. 1_ furnishes the amount and details of expense to be distributed. =15. Period for Comparisons.= Having shown that our percentages of distribution are based on the relationship of total expenses to total of productive labor, the first step in our calculation is to draw off from our ledgers a statement of each for the same period as a basis for comparison. [Illustration: Fig. 1. Private Ledger Labor Account] Inasmuch as there is generally found to be some item of extraordinary expense that appears each month, comparisons made on conditions shown by one month's operations are apt to be found abnormal, while a comparison made on results of operations extending over six months or more will give an average nearer the true condition of the plant's activities than one made on results shown by a shorter period. =16. Pay─Rolls Dissected.= For our first statement, let us examine the pay─rolls and find out what portion may be classed as non─productive labor and what as productive labor, both by departments and in totals, our examination of same to cover a period of six months as just suggested. For the sake of illustration, let us take a plant with a weekly pay─roll of about $10,000. Ordinarily there will be four pay─rolls each month, but in order to provide for thirteen rolls quarterly, it will be necessary every third month to have the labor account cover five weeks instead of four. Turning to our _Private Ledger_, we find our _labor account_ appears as shown in Fig. 1. It is now seen at a glance that the total pay─roll for six months is $266,155.00. It is now necessary to know the split─up of the above figures into productive and non─productive labor by departments, and this is easily obtained. By reverting to the pay─sheets, can be found the total pay─rolls for each department during the above period, and from _Ledger No. 1_ can be found the portion of these same rolls that were classed as non─productive labor, and the balance will be found entered in _Production Ledger No. 2_, the sum total of which will in each case balance with the totals in the _Private Ledger_. Every dollar of labor is accounted for in either one or the other of the two cost ledgers. Having done this, the labor statement resolves itself into something like the following: