XXII Ringing Bells and Lighting Lamps by Electric Waves
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 been connected with the binding posts d and e of the relay.
The chandelier over the dining-room table had a pendant push button A (Fig. 191), with which the regular electric lights could be turned on and off. This I had removed and extended the wires down upon the table. It was only necessary to connect these to the binding posts d and e of the relay, and the next wave from the spark coil lighted the chandelier.
The flexible wires underneath the dining-room table with which the maid is usually summoned from the kitchen were next extended up and connected with d and e of the relay, and the maid was called in by an ether wave. She brought with her a tray in the centre of which stood an earthenware cup, such as is used for baking custard. This had been filled with a mixture of granulated sugar and powdered potassium chlorate. Four dry battery cells stood around this upon the tray connected in series (Fig. 192). A very small iron wire connecting two of these cells dipped into the sugar mixture. Two wires from the battery were connected to d and e of the relay. At the proper signal an ether wave was sent out by the spark coil. The coherer closed the relay and the relay acted as a push button to close the circuit of the four cells upon the tray. The fine wire dipping into the sugar and potassium chlorate got red hot. This caused the mixture to flash up and burn in most beautiful coloured flames. (Fig. 193).
On this occasion Harold’s friends gave him, with due formalities, the degree of E. E., which they said meant electrical expert, and ever since that night he has been called “the expert.” I inquired of the young folks, as their party was breaking up, if they understood Harold’s explanations of all these things, and he replied that he at any rate understood them better having attempted to explain them.