EXTENSION OF THE TELEPHONE SYSTEM TO SHITS 167 



Curve A shows the manner in which the distance between shore- 

 station and ship varied with time of day as on her south-bound course 

 the ship approached the shore station from the northeast and drew 

 away again to the south. The vessel in this case was on her inshore 

 course along the coast as shown in Fig. 10 above. Curve B shows 

 the manner in which the receiving amplification on shore had to be 

 changed with time of day to keep the ship-to-shore transmission 

 constant, first decreased as the ship came closer and then increased 

 as she drew away again to the south. Curve C is for reception on 

 ship and shows the manner in which the ships receiving amplification 



Fig. 14 



had to be varied to keep the shore-to-ship transmission constant. 

 Altho these are not measurements of any absolute quantity such as 

 field-strength, they are practical measurements of actual talking 

 circuits and as such include the effect thereon of apparatus adjust- 

 ments as well as the "ether" conditions and therefore are of value 

 in determining the conditions to be met in maintaining the over-all 

 system in operation. The difference between curves B and C, for 

 example, are in part the result of the difference in adjustment given 

 to the detector tubes of the two circuits. The load on the detectors 

 was kept practically constant by adjustable radio-frequency amplifica- 

 tion, so that any overloading was approximately constant thruout 



