4, where it concerns the easy lifting of a very heavy person, the trick is no less simple.

Out of a hundred persons submitted to the experiment, ninety-nine, knowing that the experimenter wishes to lift them and cause them to fall forward, grasp the seat or arms of the chair, and, in endeavoring to resist, make the whole weight of their body bear upon their feet.

If they do not do so at the first instant, they do so when they are conscious of the attempts of the girl to raise the seat, and they help therein unconsciously.

The experimenter, therefore, needs only to exert a horizontal thrust, without doing any lifting, and such horizontal thrust is facilitated by taking the knees as points of support for her elbows.

As soon as a slight movement is effected, the hardest part of the work is over, for it is only necessary for the girl to cease to exert her stresses in order to have the chair fall back or move laterally in one direction or the other.