Fig. 48.—How long did it take you to find out what these pictures mean?
Fig. 49.—Count the figures in the first row, using your eyes alone; have some one make lines of 10, 11, 12, 13, and more repetitions of this figure spaced closely as here. Count 20 or 30 such lines, using the eye unaided by fingers, pencil, etc.
Fig. 50.—Can you answer the question without measuring? Could a child of seven or eight?
Fig. 51.—What are these drawings intended to show? Why do they show the facts only obscurely and dubiously?