By using the lantern, the president could show facts relating to the business much more rapidly, much more clearly, and with greater accuracy than would be possible with any spoken words. The showing of curves would give the directors a chance to check the president's statements so that there would be less danger than at present of a corporation president so choosing his words that, though the words might be strictly truthful in themselves, they would be over-optimistic because they did not tell all the truth. The presence of the whole file of curve cards immediately beside the lantern would enable any director to call for facts relating to any phase of the business on which he might desire information. The use of these curve cards, and a lantern, would permit a properly educated set of directors really to direct the business for which they are responsible to the stockholders.

306 GEAPHIC METHODS

It is sometimes desirable to have the chief facts relating to a business plotted on wall charts which are instantly visible in a conference room. Fig. 219 was photographed in the record room which adjoins the directors' room of Day and Zimmermann, of Philadelphia. On the swinging-leaf fixtures a series of curves are plotted giving all the salient facts relating to a group of public-service corporations. Though this type of wall chart is in many cases desirable, there are limitations to the use of wall charts because the number of charts cannot be sufficiently increased to give all the detailed information which is usually necessary. Wall charts are suitable chiefly to furnish summarized information to directors or other men whose time is limited or who come to an office only at rare intervals.