Page:Popular Science Monthly Volume 40.djvu/770

 as Fig. 5, this pervades the whole record. Here the hand moves to and fro, keeping time—not accurately at all, but in a general way—with the strokes of the metronome.



To obtain similar results for a visual impression, a silently swinging pendulum is used, the subject watching the oscillations and counting them. The result is more frequently a movement toward the pendulum, Fig. 6, but occasionally there appear periodic movements due to the pendulum. A very excellent instance of the latter appears in Fig. 7. We may more closely approximate the ordinary experiment of the muscle-reader by giving the subject some object to hide, say a knife, and then asking him to place his hand upon the automatograph and think intently of the place of concealment. As before, there is a movement of the hand, and on the basis of the general direction of this movement one may venture a prediction of the direction in which the knife lies. The results will show all grades of success, from complete failure to an accurate localizing of the object, but as good a record as Fig. 8 is not infrequent. In this case the eyes are closed, and we have not the aid of the senses



in maintaining a concentrated attention; moreover, the position of the subject may not be suited to a ready movement in the direction of the hidden object.

A further interesting mode of concentrating the attention