operating on structure A, ad one was installed on structure B. Mechanical 
difficulty of the boat prevented the installation of the third recorder. 
Structure A is in a depth of water about 12 feet. Structure B is 
located 250 yards southwest of structure A and is in a depth of water of 
about 18 feet. The bottom slopes gently from A to B and consists of a 
gelatinous mud, particle size range between .00]1 mm and ,00) mm with a means 
particle diameter of .002 mm. The waves approached from the southwest, a 
direct line between structures A and B. 
Ze A tripod was built for mounting the third pressure head in the 
vicinity of an old abandonded lighthouse off point Au Fer Reef (depth 
of water about 7 feet). However, it has been decided that this installation 
was impracticable, since it would require an excessive length of cable to 
reach the pressure head installed outside the influence of the reefs. In- 
stead, since the waves are unusually low in this vicinity, plans have been 
made tO operate the wave recorder from the boat in conjunction with the 
pressure head mounted on the tripod. If this proves feasible, the range of 
operation will be increased. 
Plans for Third Quarter - 1 October to 31 December 1952 
1. The wave records obtained during the second quarter will be 
analyzed. 
2. Several extensive field trips will be made to the Atchafalaya 
Bay region to accumulate additional wave data on friction and percolation 
losses. 
3. One wave recorder will be installed permanently on structure B. 
Structure B is conveniently accessible from structure A without having to 
rent a boat. 
he The third wave recorder will be installed at temporary sites shore= 
ward and seaward of structures A and B respectively. This will necessitate 
the renting of a boat, as was done during the second quarter. At the shore- 
ward site of structure A the tripod for the pressure head will be used, and 
the recorder will be operated from the boat. At the seaward site of structure 
B, a structure in deeper water, where sandy bottom exists, will be used. 
ABH Waterways Experiment Station, Vicksbur Mississi 
Report for Quarter ending 30 September 1952. 
alt Model Study of the Effects of Tidal Inlets on Adjacent Beaches - 
Three tests involving stability of the unbroken beach for a tide range of 
0.1 feet, a tidal cycle of 20 min.. a wave height of 0.1 feet, and a wave 
H/L ratio of 0.025 were completed. An inlet having a bottom width of 2.0 
feet and a depth cf 0.2 feet at mean tide level was cut through the beach 
following stability for each test, and the cycle of operation repeated. 
The inlet closed completely during the second phase of each test, in~ 
dicating that the rate of littoral drift produced by the test 
43 
Quarterly 
