ADVANCES IN SIGNALLING 241 



lected radio data and deductions were communicated, at suit- 

 able intervals, to the general staff and neighboring corps. 



The enemy was evidently well aware of these radio hunts 

 upon his preserves, and took pains to evade detection. Thus, 

 he changed the code names of his radio stations at very fre- 

 quent intervals. He limited the number and length of his 

 messages as much as possible, and used short wave lengths. 

 The shorter the message, and the more unusual the wave length 

 it employed, the harder it was for our radio scouts to catch the 

 message, and fix its direction of origin. On the other hand, 

 constant practice trained the observers so that they could detect 

 a new wave length, tune to it, take in and record the code 

 message, and get its radio direction, all in a few seconds of 

 time. The patrol became a strife of experts on each side with 

 invisible weapons in the ether. Some observers seemed to 

 develop a peculiar ethereal sense, or aptitude for hunting and 

 capturing radio raids. Each goniostation so manned sent out 

 invisible and ethereal feelers into space over a range of a 

 hundred kilometers or more, because all this fishing was at 

 relatively short radio distance. 



The goniostations that watched for radio signals from enemy 

 airplanes could sometimes supply captured code messages to 

 headquarters, which, when deciphered, would enable the artil- 

 lery officer there to warn by wire some particular battery on 

 which fire was impending from hostile batteries, to take shelter 

 in time. Moreover, when the radio officer in charge of a 

 " radio net " received sudden warning of an approaching hostile 

 radio-equipped airship squadron, he would notify his fighting 

 planes at the nearest hangar to take the air and order certain 

 of his goniostations to take swift radio bearings of the oncom- 

 ing raiders. The instant these bearings were reported, they 

 were laid out on a special map with a very swift geometrical 

 apparatus, and the distance as well as the direction of the hostile 

 plane from hangar read and given to the fighting pilots, who 

 took their direction upwards accordingly. In this way, many 

 raids were intercepted by fighting planes and not a few crushed. 



