Fig. 200
In 1819 Hans Christian Oersted in Denmark (1777–1851) first noted that the region about a wire carrying an electric current has an influence upon a magnet. I will show this fact by a simple experiment. I magnetize a stout sewing needle by drawing it from end to end across the pole of a steel magnet, and by means of a triangular piece of paper and a fine thread I suspend it a few inches above the table ([Fig. 200]). I then lay upon the table a piece of wire parallel with the needle and fasten one end of it to one binding post of a dry cell. Whenever I touch the other end of the wire to the other binding post of the cell, thus sending an electric current through the wire, the magnetized needle is deflected at right angles.
This experiment, performed by Oersted, seems to have started Faraday upon that wonderful series of researches which has resulted in giving us the dynamo.
XXVII
WIRELESS TELEGRAPHY IN EARNEST
We had decided to let Harold make a trip to Europe alone. The first message from him after his departure was a brief note to his mother saying that they had had a turbulent voyage, but all had landed safely upon the other side, none the worse for their experiences.