130 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



ments 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 increasing number of ships fitted with wireless teleg- 

 raplry. A considerable advantage would be obtained by the utiliza- 

 tion of a third and longer wave to be employed exclusively for com- 

 munication 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 8 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 be- 

 tween 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 wireless 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 

 200 to 23,000 feet, and moreover that wave group tuning and direc- 

 tive systems are now available, it is not difficult to foresee that this 

 comparatively new method of communication is destined to fill a 

 position of the greatest importance in facilitating communication 

 throughout the world. 



Apart from long-distance work, the practical value of wireless 

 telegraphy may perhaps be divided into two parts, (1) when used 

 for transmission over sea and (2) when used over land. 



Many countries, including Italy, Canada, and Spain, have already 

 supplemented their ordinary telegraph systems by wireless-telegraphy 

 installations, but some time must pass before this method of commu- 

 nication will be very largely used for inland purposes in Europe 

 generally, owing to the efficient network of land lines already existing 

 which render further means of communication unnecessary; and 



