474 



Mr, W. H. Preece 



[June 4, 



sympathy with it, coherence follows, currents are excited and signals 

 made. 



In open clear spaces within sight of each other nothing more is 

 wanted, but when obstacles intervene and great distances are in 

 question height is needed — tall masts, kites and balloons have been 

 used. Excellent signals have been transmitted between Penarth and 

 Brean Down, near Weston-super-Mare, across the Bristol Clianijel, a 

 distance of nearly nine miles (Fig. 3). [The system was here shown 

 in operation] 



Mirrors also assist and intensify the effects. They were used in 

 the earlier exj^eriments, but they have been laid aside for the present, 

 for they are not only expensive to make, but they occupy much time 

 in manufacture. 



It is curious that hills and apparent obstructions fail to obstruct. 

 The reason is probably the fact that the lines of force escaj)e these 

 hills. When the ether is entangled in matter of different degrees of 

 inductivity the lines are curved as in fact they are in light. Fig. 4 



Fig. 4. — Diagram illustrating the way in which liills are bridged by the 

 electric waves. 



shows how a hill is virtually bridged over by these lines, and conse- 

 quently some electric waves fall on the relay. Weather seems to 

 have no influence : rain, fogs, snow and wind avail nothing. 



The wings shown in Fig. 2 may be removed. One pole can be 

 connected with earth, and the other extended up to the top of the 

 mast, or fastened to a balloon by means of a wire. The wire and 

 balloon or kite covered with tin foil becomes the wing. In this case 

 one pole of the transmitter must also be connected with earth. This 

 is shown by Fig. 5. 



There are some apparent anomalies that have developed them- 

 selves during the experiments. Mr. Marconi finds that his relay acts 

 even when it is placed in a perfectly closed metallic box. This is 

 the fact that has given rise to the rumour that he can blow up an 

 ironclad ship. This might be true if he could plant his properly 

 tuned receiver in the magazine of an enemy's ship. Many other 

 funny things could be done if this were possible. I remember in my 

 childhood that Capt. Warner blew up a ship at a great distance off 



