Electric currents, the same used in operating the telegraph instrument, also used in sending the wireless message from city to city and from continent to continent. It is not logical to call the spirit rap childish as it is not to call the dot and dash of the telegraph childish. As the telegraph instrument is only a toy to a child, so the rap from the spirit world seems only a toy to the uninformed mind that fails to grasp the vast import of the fact that there is no death, and that definite communication has been established between those in their physical body and those who have made their transition to the spirit world.