When a chart like that shown in Fig. 97 is used, no mental effort is required to get at the gist of the matter, and the facts can be obtained much more rapidly than would ever be possible by observing columns of figures alone.

A chart like that used in Fig. 97 can be prepared from tabulated figures by any ordinary draftsman in less than one hour of work. The cost of making a line cut is probably no more than the cost of setting the type if the data are to be shown by tabulated figures. The space required for a chart like Fig. 97 is very little

GRAPHIC METHODS

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more than would be required for the tabulated figures, and if there is any serious limitation on space. Fig. 97 could be much reduced in size without detracting from its clearness.

Health-department reports are not usually of interest to the layman. Yet healthdepartment reports, well presented, may be of as much popular interest as a wellaooo

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Data of the New York Edison Company

Fig. 97. Number of Telephone Messages Each Hour for One Day in a Business District in New York City as Compared with a Residence District

Solid line, the "Broad" exchange -- a tj'pical business exchange Dotted line, the "Riverside" exchange -- a typical residence exchange Note the great number of business calls after mail has been opened in