RADIOTELEGRAPHY MARCONI. 129 



attached. It therefore would seem that wireless telegraphy as at 

 present practiced is, to some extent at least, dependent on the con- 

 ductivity of the earth, and that the difference in operation across 

 long distances of sea compared to over land is sufficiently explained 

 by the fact that sea water is a much better conductor than is land. 



The importance or utility of the earth connection has been some- 

 times questioned, but in my opinion no practical system of wireless 

 telegraphy exists where the instruments are not in some manner con- 

 nected to earth. By connection to earth I do not necessarily mean 

 an ordinary metallic connection as used for wire telegraphs. The 

 earth wire may have a condenser in series with it, or it may be con- 

 nected to what is really equivalent, a capacity area placed close to 

 the surface of the ground. It is now perfectly well known that a 

 condenser, if large enough, does not prevent the passage of high- 

 frequency oscillations, and therefore in this case, when a so-called 

 balancing capacity is used, the antenna is for all practical purposes 

 connected to earth. 



I am also of opinion that there is absolutely no foundation in the 

 statement which has recently been repeated to the effect that an earth 

 connection is detrimental to good tuning, provided of course that 

 the earth is good. 



Certainly, in consequence of its resistance, what electricians call a 

 bad earth will damp out the oscillations, and in that way make tuning 

 difficult; but no such effect is noticed when employing an efficient 

 earth connection. 



In conclusion, I believe that I am not any too bold when I say that 

 wireless telegraphy is tending to revolutionize our means of communi- 

 cation from place to place on the earth's surface. For example, com- 

 mercial messages containing a total of 812,200 words were sent and 

 received between Clifden and Glace Bay from May 1, 1910, to the 

 end of April, 1911; wireless telegraphy has already furnished means 

 of communication between ships and the shore where communication 

 was before practically impossible. The fact that a system of imperial 

 wireless telegraphy is to be discussed by the imperial conference, 

 now holding its meetings in London, shows the supremely important 

 position which radiotelegraphy over long distances has assumed in 

 the short space of one decade. Its importance from a commercial, 

 naval, and military point of view has increased very greatly during the 

 last few years as a consequence of the innumerable stations which 

 have been erected, or are now in course of construction, on various 

 coasts, in inland regions, and on board ships in all parts of the world. 

 Notwithstanding this multiplicity of stations and their almost con- 

 stant operation, I can say from practical experience that mutual 

 interference between properly equipped and efficiently tuned instru- 

 38734°— sm 1911 9 



