We propose to point out here a certain number of such artifices and to describe a few of the experiments, utilizing for this purpose the data furnished by Mr. Perry, as well as those resulting from our own observations. One of the experiments consists in having a man or several men hold a cane or a billiard cue horizontally above the head, as shown in Fig. 1. On pushing with one hand, the girl forces back two or three men, who, in unstable equilibrium and under the oblique action of the thrust exerted, are obliged to fall back. This first experiment is so elementary and infantile that it is not necessary to dwell upon it. In order to show the relative sizes of the persons, the artist has supposed the little girl to be standing on a platform in the first experiment, but in the experiment that we witnessed this platform was rendered useless by the fact that the girl who performed them was of sufficient height to reach the cue by extending her arms and standing on tiptoes. Next we have a second and more complex experiment, less easily explained at first sight. Two men (Fig. 2) take a stick about three feet in length, and are asked to hold it firmly in a vertical position. The girl places her hand against the lower end of the stick, in the position shown, and the two men are invited to make the latter slide vertically in the girl's hand, which they are unable to do, in spite of their conscientious and oft-repeated attempts. Mr. Perry explains this exercise as follows: The men are requested to place themselves parallel to each other, and the girl, who stands opposite them, places the palm of her hand against the stick and turned toward her. She takes care to place her hand as far as possible from the hands of the two men, so as to give herself a certain leverage. She then begins to slide her hand along the stick, gently at first, and then with an increasing pressure, as if she wished to better the contact between the stick and her hand. She thus moves it from the perpendicular and asks the two men to hold it in a vertical position. This they do under very disadvantageous conditions, seeing the difference in the length of the arms of the lever. The stress exerted by the girl is very feeble, because, on the one hand, she has the lever arm to herself, and, on the other, the action upon her lever arm is a simple traction. When she feels that the pressure exerted is great enough, she directs the two men to exert a vertical stress strong enough to cause the stick to descend. They then imagine that they are exerting a VERTICAL stress, while in reality their stresses are HORIZONTAL and tend to keep the stick in a vertical position in order to react against the pressure exerted at the lower end of the stick.