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116 moves to the right, and if I heat the other it moves to the left. We now place this one, which causes a deflection to the right when it becomes hot, in connection with a muscle to which a weight is attached, and we place the nerve of the muscle over the two wires from the secondary coil of our induction

machine. To keep off all radiant heat as much as possible, we shall enclose the whole apparatus in a square chamber, the walls and roof of which are made of plate glass one inch in thickness. Notice the position of the spot of light. I now open the key so as to tetanise the muscle, and you notice that at once the