244 THE NEW WORLD OF SCIENCE 



to various methods to hamper our use of it, such as sending 

 powerful dynamo currents through the ground in the neighbor- 

 hood, in order to deafen the listener and make the signals 

 unreadable. 



Experience with the system, while greatly developing it in 

 the war, seems to have indicated that the short-wave radio-loop 

 system is much more effective and advantageous; so that it is 

 doubtful whether the T. P. S. system will play much part in an- 

 other war ; whereas the use of the radio system is likely to be 

 greatly increased. 



Tree Antenna. It was discovered by the Chief Signal Officer 

 in 1904, that almost any living tree, of suitable height, could be 

 made use of as a receiving antenna for radio communication, 

 if a nail were driven into the tree trunk at a short elevation 

 above the ground, and radio apparatus connected by a wire to 

 this nail and to ground. In other words, a growing tree could 

 be made to serve for radio reception, in place of a tower, or 

 high pole and wire. Every tree is thus, in a certain sense, 

 a makeshift substitute for a radio antenna. An intensive inves- 

 tigation of this remarkable phenomenon, made during the war 

 by the Signal Corps, showed that, with modern amplifiers, 

 signals could easily be read in America from powerful European 

 stations, like Nauen in Germany, using a tree and short wire 

 instead of a mast and high wire. Moreover, such a tree 

 antenna enabled goniometric measurements to be made of the 

 direction of the incoming signals, with the aid of relatively small 

 rotatable frame coils. 



The investigation has shown that a radio observer who 

 desires to receive long distance signals, as distinguished from 

 transmitting them, need only locate a suitably high tree, and 

 connect his amplifying apparatus to it by a wire preferably 

 reaching up to about two-thirds of the total height of the tree. 

 If anyone should ask to-day what are the secrets which the 

 trees seem to whisper to one another in the woods, a scientific, 

 as well as a poetic, answer, might be that, in a certain sense, 



