A further method of reducing wind-wave effects on the record inside 

 the well is to put the orifice as deep as possible. As depth increases 

 wave dynamic pressure attenuation increases and the wind waves become less 

 noticeable. However, the orifice should not be put too close to the bottom 

 where clogging may occur. 



The recorder for this system was a digital recorder with a sampling 

 interval of 5 minutes and a sampling height resolution of 0.01 foot. The 

 float was 5 inches in diameter. 



Figures 7 and 8 are examples of records and spectral analysis of 

 records of water levels obtained at Pentwater, using this well. Note that 

 several long waves are present simultaneously in the harbor at various 

 periods of about 1 hour or longer. From Figure 6, 85 percent or more of 

 the wave amplitudes are recorded and the particular percentages at each 

 period can be used to obtain final amplitude values of the spectral com- 

 ponents of interest. 



V. CONCLUSION 



A linear stilling well is recommended where accurate measurements of 

 water level fluctuations are required and short -period noise must be 

 dampened. 



