DESERT SAND-DUNES 



37 



tract of loose sand, the twenty-fourth wave being 

 succeeded by hard ground. The size of the waves 

 was as follows : — 



Length 



33 



52 

 36 

 54 

 30 



25 

 22 

 21 



35 

 27 

 40 

 29 



19 



35 



30 



18 



30 

 29 

 30 

 15 

 16 



34i 

 37i 

 31* 



Height of Wave. 



n. 



t. 6 in. 



t. 6 in. 



t. 6 in. 



t. 6 in. 



2 ft. \\\ 

 2 ft. 

 2 ft. 

 I ft. 



1 ft. 



2 ft. 



6i 

 2 



2* 



6 



3 



8i 



I 



9 

 o 



5 

 7 

 9 



5 



4 



— II 



— 7 



— 6i 



1 ft. 9i 



2 ft. II 

 I ft. 2 



— II 



2 ft. 



2 ft. 



3 ft. 

 2 ft. 

 I ft. 

 I ft. 



I ft. 

 I ft. 



Thus the average length of the waves was 30 feet 



6 inches and the average height i foot 8 inches. 



The ratio of length to height obtained by 



3 



