208 Commendatnre G. Marconi [June 2, 



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. Not- 

 withstanding this multiplicity of stations and their almost constant 

 operation, I can;sayfrom practical experience that mutual interference 

 between properly equipped and efficiently tuned instruments has so 

 far been almost entirely absent. Some interference does without 

 doubt take place between ships, in consequence of the fact that the 

 two wave lengths adopted in accordance with the rules laid down by 

 the International Convention, are not sufficient for the proper handling 

 of the very large amount of messages transmitted from the ever in- 

 creasing number of ships fitted with wireless telegraphy. A consider- 

 able advantage would be obtained by the utilisation of a third and 

 longer wave 'to be employed exclusively for comnmnication over long 

 distances. 



In regard to the high-power transatlantic stations, the facility 

 with which interference has been prevented has to some extent ex- 

 ceeded my expectations. At the receiving station situated at a dis- 

 tance of only eight miles from the powerful sender at Clifden. during 

 a recent demonstration arranged for the Admiralty, messages could 

 be received from Glace Bay without any interference from Clifden 

 when this latter station was transmitting at full power on a wave 

 length differing only 25 per cent, from the wave radiated from Glace 

 Bay, the ratio between the maximum recorded range of Clifden and 

 8 miles being in the proportion of 750 to 1. 



Arrangements are being made to permanently send and receive 

 simultaneously at these stations, which, when completed, will consti- 

 tute in effect the duplexing of radiotelegraphic communication between 

 Ireland and Canada. 



The result which I have last referred to also goes to show that 

 it would be practicable to operate at one time, on slightly different 

 wave lengths, a great number of long-distance stations situated in 

 England and Ireland without danger of mutual interference. 



The extended use of.lwireless telegraphy is principally dependent 

 on the ease with which a number of stations can be efficiently worked 

 in the vicinity of each other. 



Considering that the wave lengths at present in use range from 



