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 
jaid 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- 
raphy. 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 waye 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 cf 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 
