So 



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all six recording elements due to the sound from a 15 centi- 

 meter howitzer situated very nearly equidistant from all six 

 of the listeners. The vertical lines represent tenth second 

 intervals. The hundredth second intervals which appear on 

 the actual film have been omitted from the drawing. Figure 



15-cm. Howitzer. 



10'5-cm. Howitzer. 



c. 



si 



Figure 5 



5 B is similar to A except that a wind was blowing from the 

 left flank which caused the sound to be so loud on the right 

 flank that the twitches of the lower elements are too rapid to 

 photograph. Figure 5 C is the record from a high velocity 

 gun situated towards the right flank of the sound-ranging base. 

 The portions of the record marked S are due to the bow wave 

 of the shell as it passes over the various listening instruments 

 while the portions marked G are due to the muzzle wave of 



