All that remains to be explained is the working of the sounder. It is very simple. In the first place, the lid and box are hinged so as to be hinge bound; that is, they will not, of their own weight, quite touch each other, possibly about an eighth of an inch, or less, apart. But by the pressure or weight of the hand they will come together. Now, the telegraph key, like all such instruments, is provided with a tension screw, which can be screwed one way or the other. When the medium desires his instrument to work, he raises this tension screw, to which is fastened the button of the key, just high enough to touch the lid on the inside of the box when it is closed of its own weight. Now, when the hand is resting on the box, he proceeds to make the sounder “speak” at will, with no perceptible movement of his hand. A simple muscular contraction of the palm of the hand, which cannot be detected, is sufficient to control the sensitive key, by pressure of the box cover on it. The whole thing is so simple, and at the same time puzzling, that it makes one laugh to think how little it takes to make a fool of a man. In the case of this medium, the head of the tension screw was brass, and left a brassy mark on the slate top. He soon observed this, and changed it for a hard rubber one, which left no telltale marks behind. Sometimes he did not raise the tension screw, but laid the folded paper the question was written on on top of it. This made up the required height. Other mediums improved on the above method by working the key through the box by an electro-magnet concealed in the table top. The current to the magnets was turned on and off, or broken, as the line is used, by means of a small button in the body of the table, pressed by the medium’s leg. This method allowed him to keep his hand off the box. The raps, or noises, are produced in various manners. Press your boot heel gently against a table leg. The slipping of the leather against the wood makes perfect spirit raps, wood being a good conductor of sound. The raps apparently come from the table top if attention is directed in that direction. Some mediums, with the tips of their fingers pressed firmly on a table top, slip them, by a dexterous movement, along the varnished surface, thus making very fair examples of raps or thuds. Some mediums, in their own homes, have tables provided with electro-magnets concealed in them, by which the knocks are accomplished. Medical experts claim that a very good result can be obtained by the mere displacement of the tendons of the muscle called _peroneus longus_, in the sheath in which it slides behind the external _malleolus_. Others again produce it by snapping the toe or knee joints. Watch a boy some day as he snaps his finger joints, and if he were to rest his elbows on the table while doing so, the sound would be intensely strengthened. CHAPTER VI. SPIRITUALISTIC TIES.