448 



SCIENCE 



[N. S. Vol. LI. No. 1323 



oped. The coil is in the form of a long 

 helix wound with a large number of turns 

 on which stationary waves are produced 

 by the incoming radio signals. An elec- 

 tron tube is used as the detector, the grid 

 being connected to the point of maximum 

 potential on the coil. The wave coil may 

 be used either as a part of the usual 

 antenna system or a part of a line wire, or 

 it may act itself as the antenna for pick- 

 ing up the energy of the signals. In the 

 latter case the coil may be either free at 

 both ends or grounded at one end. Good 

 results have been obtained in either case. 

 It has been ateo found that the open coil 

 has directional properties and can be used 

 as a goniometer not only for horizontal 

 measurements but for vertical measure- 

 ments as well. This form of radio goniom- 

 eter has the great advantage that it per- 

 mits not only of determining the plane 

 where the signals are strongest but also 

 the direction from which such signals 

 proceed. 



Telegraph and telephone communication 

 luas been also esta;blished between two sta- 

 tions at the Signal Corps Research Lab- 

 oratories at Camp Alfred Vail, Little 

 Silver, New Jersey, using a bare No. 16 

 copper wire buried in the earth to a depth 

 of about eight incihes to connect the sta- 

 tions. The distance between the two sta- 

 tions was three quairters of a mile. Fre- 

 quencies as high as one million cycles a 

 second were used. Similar communica- 

 tion has been carried on over a bare wire 

 one and three quarter miles long laid on 

 the surface of moist earth. The current 

 at the transmitting station in these instal- 

 lations was about 100 milliaanperes. It 

 has been shown that a bare wire buried in 

 moist earth with the distant end open can 

 be tuned both at the transmitting end and 

 at the receiving end. 



SUGGESTIONS 



1. In the older art of ocean telegraphy, 

 the elaborateness of line construction has 

 already reached a practical limit. The 

 best Atlantic ca'ble of the present day is 

 limited in operation to electric waves of 

 frequency of the order of magnitude of 10 

 per second. The electrical construction is 

 such as to limit the voltage employed on 

 any long caWe to from 50 to 80. The rela- 

 tive values of the line constants in any 

 ocean cable preclude the possibility of 

 ocean telephony. 



The most promising hope of improving 

 the line construction for ocean cables is 

 believed to 'be, to abandon the present 

 method of design and construction and to 

 start with the simple ease of bare wires in 

 water using high frequency currents and 

 study the necessary changes to produce 

 optimum transmission. 



The use of a high frequency "carrier" 

 has the iniherent advantage that the dis- 

 tortion phenomena accompanying present 

 methods of long distance transmission are 

 eliminated, and we are principally con- 

 cerned with the problem of reducing at- 

 tenuation. The most suitable voltage may 

 be employed and present multiplex meth- 

 ods may be utilized. The electron tube is 

 available for both the generation and the 

 reception of the waves. 



2. During the last few years an inten- 

 sive study has 'been made of the surface 

 conditions of wires necessary to produce 

 the emission of electrons, and to this in- 

 tensive study, both by universities and in- 

 dustrial research laboratories, is due the 

 high state of efficiency of the present elec- 

 tron tube. Nothing short of a similar 

 study of the surface conditions of wires 

 for preventing the emission of electrons 

 instead of producing them, will finally 

 give us the wire conductor of the future. 



3. The development of types of reson- 



