EXTENSION OF THE TELEPHONE SYSTEM TO SHIPS 



[73 



as during the best times at night. These enormous day to 

 night fluctuations are now familiar to broadcast listeners. 

 This curve shows the impossibility of giving continuous ship- 

 to-shore telephone service at these relatively short wave lengths 

 for distances as great as 1,000 miles (1,600 km.). For such 

 distances much longer wave lengths will be required, as well 

 as more sending power. 



Distance to b.S America 



Fig. 20 



(2) The wide fluctuations which occur thruout the night period. 

 Altho smaller than the day to night fluctuations, their effect 

 upon transmission is still very large. The fluctuations during 

 the third night out, for example, are as much as 10:1 in field 

 strength or 100:1 in power, or about 20 of the power ratio units 

 we have used above. In view of the rapidity with which these 

 fluctuations occur — within a very few minutes — it is practically 

 impossible to maintain a circuit under these conditions satis- 

 factory lor regular telephone service. 



£3) The most interesting thing to observe is that the fluctuations 

 tend to fall within the two curves A and B. The day trans- 



