Another simple method is to place the thumbs close together in such a manner that the nail of one overlaps the other a trifle. Then while the thumbs are pressed hard on the table if one nail is slipped up or down distinct raps are produced which seem to come from the top of the table. Some mediums produce raps by slipping a knee up and down against a table leg. Others have been known to fasten blocks of wood to the knee under the skirt and rap on the table leg with a sidewise motion of the knee. Still others strike the table leg with the heel of the shoe or press the side of the heel against the table leg and by moving the heel up and down the friction of the leather against the wood produces raps. [Illustration: TUBE AND PISTON ARRANGEMENT FOR MAKING RAPS.] Many mediums will not depend on these methods but use more complicated ones which produce the raps by means of mechanical devices which they conceal about their person. One of these consists of a small hollow metal tube in which a long, heavy burlap needle is arranged to move up and down like a piston, and attached to it to operate it a stout black thread. The tube is fastened to the inner side of a trouser leg. The free end of the thread is brought out through a seam and an inconspicuous little hook attached. After being seated at the seance table the medium attaches the little hook to the opposite trouser leg and draws on it until the needle point comes through the cloth. He then watches an opportunity to press on to the point of the needle a cork to which has been attached a piece of lead. This accomplished, all he has to do is to place the knee in the proper relation to the table and by moving the other back and forth the piston is made to work up and down, causing the leaded cork to rap out all sorts of messages. [Illustration: RAPPING MECHANISM IN HEEL OF MEDIUM’S SHOE.] Another ingenious mechanical contrivance is built into the heel of the medium’s shoe and operated electrically by running a wire from it up through the sole of the shoe and passing it between the back of the shoe and the foot and so on up the leg to batteries concealed in a pocket. By placing this heel against a table leg the raps can be made to sound as though coming from the middle of the table and with a proper amount of “suggestion” the sitters can be made to believe that the mysterious taps are produced in turn under each pair of hands on the table.