Nikola Tesla Books
THE ALTERNATING CURRENT rests solely with the high frequency current. Perhaps the reader has seen one of these entertainers charge the body of an assistant to the point where a spark several inches in length may be drawn from the fingers, chin, elbow or even the tongue. A tuft of cotton or tissue paper held in the spark is immediately ignited, or perhaps the performer may light the tip of his cigarette with the spark taken between his finger and the body of the assistant. Possibly the performer may grasp the terminal of his machine with one hand while the other holds a wire leading to an ordinary incandescent lamp; the assistant touches the remaining terminal of the lamp and the current is turned on. The lamp filament becomes red and perhaps white hot, finally burning out completely with the current passed through the bodies of the performer and his man. The stage may be darkened and the terminal of the apparatus connected with the body; as the current is turned on, the extremities of the body are seen to glow with a weird blue light. As the hand is raised above the head, streamers of purplish fire dart from the finger tips. A vacuum tube brought to within a distance of several feet from the body lights up with its characteristic glow even though there is no connection with the performer's body or the apparatus. All of these experiments and hundreds of others may be performed with comparatively simple and inexpensive. apparatus that is well within the reach of the average amateur mechanic. If the reader aspires to greater heights, he may build apparatus with which great, long sparks may be produced. The High Frequency Current in Medicine.-The high frequency current, when applied to the human body through suitable electrodes and other appurtenances, can be made to produce the most profound physiological effects. Ap
