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

able 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

COMPARISONS INVOLVING TIME

INCREASE IN STUDENTS IN] CO-OPERATIVE COURSE ENGINEERING COLLEGE

INCREASE 1913 OVER ..1907 I

lassv.

available in many different colors. Some grades of the drawing ink are water-proof after drj'ing. On elaborate charts the water-proof cjuality should always be used to make certain that a few rain drops, or handling with moist hands, will not ruin the finished w^ork.