The pigs of copper are not of the same size in the different piles, and it is evident that a pictured pig of copper is not intended to be the unit. If Fig. 25 is drawn on an area basis, it is almost impossible for the eye to fit the area for the right-hand pile into the area of the left-hand pile. This chart is a typical example of thousands of illustrations used by the popular magazines and even by some of the more pretentious reference books.

Fig. 26 is an even greater atrocity than Fig. 25. In Fig. 26, the observer is entirely unable to tell whether comparison is made in one, two, or three dimensions and he has an additional puzzle because of the large amount of perspective shown for the top of the pigs of tin. It would be surprising if one man in a thousand could guess anything near the ratio intended to be expressed between the largest and smallest pigs shown. In general, graphic work of this kind is much worse than the use of figures alone. There are times when an absence of knowledge is better than incorrect knowledge.

Fig. 27 is a good example of what can be done as a standard arrangement for simple comparisons. On the left there is a symbol to attract the eye and interest the observer. Note that a dollar mark is shown on top of the picture of the bale of cotton in one case and the sheaf of wheat in the other, to indicate that the value of the crop is considered rather than the number of units. After the pictures, which may be thought of as "ej^e catchers," we have the figures, and then