T.M. No. 6 - October 1948 



An Ocean Wave Measuring Instrument by Joseph M. Caldwel I 



Methods for measuring height and period of water waves and their 

 relative advantages and disadvantages are discussed. The development 

 of a step-resistance staff gage for measuring fluctuations of the sea 

 surface is described in detail; it is concluded to be a satisfactory 

 and accurate instrument. The gage is suitable for use only where a 

 suitable supporting structure is available. 



T.M. No. 7 - September 1944 



Shore Currents and Sand Movement on a Model Beach by W. C. Krumbein 



Uniform waves were run at an angle to a sloping sand beach in a 

 laboratory wave tank, and the alongshore current and sand movement 

 measured. Relation of alongshore current velocity, rate of sand move- 

 ment, and wave characteristics were studied on a small scale basis, 

 using dimension less parameters. Relations of beach slope and sand 

 sorting to wave characteristics were also studied. 



T.M. No. 8 - July 1945 



Depths of Offshore Bars by G. ti. Keulegan 



A method is outlined for predicting depths over crests and in 

 troughs of offshore bars. Information from existing literature and 

 laboratory tests on the position and size of bars is briefly discussed 

 and summarized. 



T.M. No. 9 - July 1948 



Proof Test of Water Transparency Method of Depth Determination 

 by J. V. Hal I, Jr. 



A report on field tests made to determine practicability of a 

 method developed by the British Army during World War II to determine 

 water depths from aerial photographs. Conclusions reached indicate 

 the method to be unsuitable for either military or civil application 

 due to extreme difficulties encountered In obtaining suitable photo- 

 graphs and controlling results through strict laboratory procedure. 

 Strict criteria for meteorological and oceanographlc conditions are 

 necessary to obtain usable photographs. 



