Page:Graphic methods for presenting facts (1914).djvu/66

 effect also relieves monotony in a large exhibition which may have hundreds or even thousands of different charts and other wall exhibits.

Fig. 52 was shown in conjunction with Fig. 51 with the idea of pointing out that the number of students in the University of Cincinnati had increased just as (according to Fig. 51) the number of firms co-operating in the engineering work of the University had increased in the same time.

American Review of Reviews

Fig. 51. The Increasing Number of Business Firms Co-operating with the Engineering College of the University of Cincinnati

When the bars represent years or other divisions of time, a vertical arrangement of the bars is usually more desirable than the horizontal arrangement seen in Fig. 44. With the vertical arrangement a line may be imagined joining the tops of the bars so as to give a "curve".

Note, in this illustration of a wall chart, the popular touch given by the pictures of manufacturing plants with smoke-stacks of the same height as the first and the last vertical bars

The bars in Fig. 51 and Fig. 52 are placed vertically, each bar representing a year. This vertical arrangement of bars permits reading the chart as if a curve had been made by drawing a line through the tops of all the bars. Curves are the common language of engineers and statisticians. In order that the bars may be read as curves, it is desirable to have the bars placed in a vertical position, if they represent divisions of time, rather than entirely distinct subjects such as the separate cities compared as to the value of their output of manufactured products, in the chart reproduced in Fig. 21.

Lettering like that shown in Fig. 51 or Fig. 52 is conveniently made by using the gummed black-paper letters and figures which can be obtained in many good stationery stores. A thin pencil line as a guide at the bottom of the letters, and some judgment used in spacing, will assist greatly in getting a neat result from the gummed letters. Large bars like those shown in Fig. 51 and Fig. 52 can be made by cutting out strips of black paper and pasting them onto white cardboard. Such work, however, must be very carefully done or the bars will curl on the edges and give an unpleasant effect. It is generally better to use India ink in making the bars if a good result is to be assured. The liquid drawing ink sold at most stationery stores is