Harold was to have a birthday party, to which many of his school friends were invited. For this occasion he prepared, with my help, to perform for the girls and boys some electrical experiments, and particularly to give all who chose to try it an electric shock. For this purpose he had them all join hands, and the electric charge was sent through the whole line at once. One thing he did shocked his mother more than anything else. He instituted a mock court, at which one of the boys was tried, convicted and condemned to be executed by electricity. The whole affair was enacted with no great solemnity, but the electrical experiment was voted a great success by the executed "criminal." The following group of experiments, however, seemed to give the most satisfaction: On a table was placed the coherer connected to the relay, and in another room was placed the spark coil for sending ether waves. He had this operated by a confederate whom he chose for the purpose. He then connected two wires to the relay, one at _d_ and the other at _e_ (Fig. 189). These ran to a battery cell and a bell in a far corner of the room. At a given signal (a cough) the confederate made a spark at the spark coil in the other room; this sent ether waves through the partition between the rooms; the ether waves caused the coherer to pass electricity from the dry cell No. 1, to close the relay spring _R_. This acted like a switch to close the second circuit through the dry cell No. 2 and the bell, which rang out to the surprise of all. It continued to ring until he tapped the coherer tube and broke apart the filings. When this had been tried to the satisfaction of all, the company was invited to another room. Here they found an electric train with tracks, train sheds, stations, tunnels, bridges, switches, signals, etc., arranged upon a centre table. The electric train was to be started by ether waves. A wire from the railroad track was connected with _e_ of the relay (See Fig. 190). A wire from _d_ of the relay was connected to the third rail through a battery of sufficient strength (Battery 2). The electric train completed the circuit by connecting the tracks with the third rail. All heard the crack of the spark coil in the adjoining room, and saw the train start immediately. Ether waves had caused battery 1 to close the relay _R_. This had closed the circuit so that battery 2 might run the train, of course by means of a motor in the train. He tapped the coherer. The relay spring _R_ flew open and the train stopped. Presently another crack from the adjoining room, and the train instantly started again. When all the details of the electric train had been examined the company was invited to go to the dining room, which was dimly lighted by candles. All were seated and busily conversing when the crackling noise of the spark coil was again heard, and a group of little electric lights flashed forth upon a birthday cake. The wires from the lamps and a battery to run them had