The explanation is easy. You will have taken care to put the puppets on contrary poles: a man on the positive pole, a lady on the negative pole. In this way the principle enunciated above is thoroughly proved and easily grasped. One may easily vary this experiment by replacing the gentlemen and ladies by personages of actual notoriety, or of the company, in placing them in groups which have a mutual dislike to each other, such as the schoolmaster and pupil, etc. The Bust of the Sage. Every person wonders how the sensational decapitation scene is produced. To all appearance a head is thrust through the neck opening of a guillotine, the knife descends and the head is cut off. However, in order that none of the fair sex may be alarmed, it may be varied as follows: In a cabinet a mirror is set across, sloping from the top at the back to the front. It reflects the ceiling, which is covered with the same material as that which is seen of the floor in front of the mirror. In the center of the glass is cut a hole which admits of the passing through of a man’s head. He sits or stands in under the glass at his ease. The front edge of the mirror is concealed by a few astronomical and geographical instruments, old folio books, skulls, etc. The head and shoulders are made up and draped like one of the seven wise men of Greece, and he answers questions in a grave, portentous voice. The Witchery of the Hand. In order to ascertain the existence of animal magnetism the following apparatus, very simple, and not at all difficult to construct, answers perfectly. Stick a pin in a cork, point upwards. On that pivot place horizontally a sheet of paper so that it remains in perfect equilibrium. [Illustration] If you now put your hand over the sheet of paper, a rotary movement will manifest itself, the sheet swerving from right to left. This movement is caused by the influence of the hand’s magnetism. The Perspectograph. This simple instrument, invented by Mr. Jarlot, renders the tracing of a sketch extremely easy, besides avoiding absolutely faults of perspective, which is, without doubt, the principal advantage of this instrument. Thanks to it, one obtains an easy reproduction on one plane of objects placed on different planes. Here is a description of this very simple instrument. A wooden frame A B C D, with a slot in the side, A B, in which a pane of glass can slide so as to cover the whole space of the frame, _a, b, c, d_, is fixed on a stand. [Illustration] The frame is maintained in a perfectly horizontal position by means of a water level _n n’_, placed on the lower side of the frame. At E is a small rule moving on a hinge at E, allowing the angle to be varied at the plane A B C D, by resting it on two supports E E’.