and frequency of which are continuously variable while the machine is 

 in operation. This is an important featvire when stopping a particular 

 movable bed test. 



3, Range of Operation: A maximum value chart was plotted for shallow 

 water waves assuming sinusoidal profiles and indicates, for instance, the 

 range of values of wave length obtainable for a given amplitude and depth 

 within the limits of the flume geometry and the power of the generator, 



h- Baffles: Plans are presently being drawn for lightweight aluminum 

 frames to hold 6" mattresses of cinders to be used as baffles. As many 

 of these mattresses as necessary will be lowered into the entrance tank 

 behind the generator to absorb the energy of the waves generated by the 

 back of the wavemaking piston, 



5, Experimental Beach: Plans are at present being drawn for 



a hinged, adjustable slope false bottom which will support the beach 

 material. The beach will be located on the i|.0 foot steel bottom section 

 of the flume, 



6, Instrumentation 



a. Instrument Carriage: Complete plans have been drawn for a 

 general purpose instrument carriage which will ilde the length of the 

 flume on rails and will provide for more convenient mounting of any one 

 of the following instruments: 



Point gage 



Prandtl Pitot Tube 



The capacitance type turbulence gage developed at the 



Hydrodynamic laboratory 

 Construction of the all purpose carriage will probably not 



be undertaken until June 1953 * since it will not be needed 



in the preliminary test program, 



b. Photographic Equipment: It is planned to record the wave 

 profiles and the history of their transformation by photographing through 

 lucite grids on the wall of the channel. Three of those grids will be 

 required. The motion of sediment and internal wave particles may aleo be 

 recorded in this manner. 



To perform this Job, the laboratory is equipped with the following 

 standard items: 



One l6 mm. movie camera with a range of 8 to 6k exposures 



per second. 

 One U" X 5" Graphic View Camera as well as one 35 miti, camera. 

 Lighting equipment consisting of one Strobotac with a range 



of 600 to lii,liOO flashes per minute, six Strobe-Flash lamps 



with power packs and two photo flood lamps. 

 One electric timer graduated in thousandths of a second. 



-17- 



