152 



SHALLOW -WATER TRANSMISSION 



1000 



2000 

 RANGE IN YARDS 



3000 



Figure 10. Transmission over MUD with NAN pattern. 



One hundred thirty-five runs were carried out over 

 ROCK bottom at fairly constant depth. In Table 3 

 are listed the number of runs made at each wind 

 force and the median and quartile values of i?4o. 

 Figure 12 shows the complete distribution. 



One hundred seventy-four runs were carried out 

 1 ,750 over SAND bottoms in water of more than 6 fathoms. 

 2,300 2,100 Table 4 shows the same data for these runs as 

 Table 3 does for runs over ROCK. 



