If expenses had increased the manager could refer to the departmental or account-number cards and see just which departments or accounts were responsible for an increase or decrease in the curve giving the total. The cards in a large business would be filed by expense-account numbers, with the total card referring to any expense account for the whole business filed at the front of each group of cards giving the figures for that expense account by departments. Thus, in a manufacturing plant, the card showing the loss

292 GRAPHIC METHODS

from spoiled work as a percentage of the total payroll could have filed back of it cards showing the percentage loss in each department. If the spoiled-work curve for the whole business should go up in any month, the manager could see instantly in which departments the percentage of loss had increased and in which the percentage had decreased. Letters could be sent to the foremen of the departments having bad records, calling their attention to the bad showing made.

The cross-index of curves, obtained by filing the cards according to function or by expense-account number instead of by department, is of tremendous importance to the busy executive. This feature alone may save a large amount of his time by making necessary information more accessible, and by afi^ording information which may show leaks in his business that he would otherwise never know to exist. In a business of any size the cost of making one blue print each month from each original curve card is almost insignificant. The guide cards showing functions or account numbers remain useful year after year, and it is necessary only to discard a blue print for each card each month and to substitute the latest blue print made from the original curve card after a new point has been added.