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 but it is not really necessary. In a cabinet like that shown in Fig. 217, the original curve cards would ordinarily be filed behind the guide cards showing the factory or selling-house locations, or behind guide cards showing the names of departments in any large business. All the cards for succeeding years would be filed behind the proper guide cards, with the curve card for the earlier year at the front. Having the card for the earlier year at the front instead of at the back permits comparison of curves for different years with a very slight lifting of the cards, and without any danger of the cards being put back in the drawer in mixed order.

Information cards like those shown in Fig. 216 would be filed in the same filing-cabinet. These 4-by-6-inch information cards are filed by curve serial numbers, with appropriate numbered guide cards so that any information card may be quickly located by its serial number. As the numbered information cards are needed only for occasional reference, they can be put in the back portion of a file drawer, leaving the front portion of the drawer available for the curve cards more frequently needed.

In checking up the condition of his business, the executive usually considers it department by department. For this reason the original curve cards should be filed by departments so that the complete history of any department may be had from the cards behind the guide card for that department. A large portion of the executive's work, however, involves the study of his general business not by departments but by functions. For instance, the executive may wish to know how many employees he has in his whole business, and how many employees there are in each department, if he is considering the departmental increases or decreases which affect the total payroll. It is therefore desirable that the executive should have available for instant reference a cross-index of information which will show his whole business by function instead of by department. Such a cross-index can easily be provided, when curve cards are used, by taking a blue print of each curve card and then filing the blue print by function, instead of by department. In such an arrangement, there would be a complete set of guide cards giving different headings, such as "Number of Employees", "Total Sales", "Total Expenses", etc., with guide cards having suitable subheadings placed behind each one of the main guide cards. A blue print of the curve showing the total number of employees in the corporation would be filed at the front of the division for employees. Back of