a pit should be made of concrete pipe or other nonconducting material; 

 use of a metal wall would cause an inaccurate calibration of the gage. 



The procedure outlined below has been satisfactorily used for cali- 

 bration of staff-type gages. If feasible, a time of low-wave action 

 should be selected for the calibration. 



If possible, the sections that are to be removed from the water first 

 are kept inside the steel gage holder. This provides a more accurate gage 

 calibration. If the water is deep enough, place two or three of the sec- 

 tions in the holder in the order that they are used in the gage. The 

 section having the lowest value of resistors is on top, and the succeed- 

 ing sections are below it. When the section having the lowest value of 

 resistors has been removed from the holder (in the desired calibration 

 increments) , the other gage sections in the holder should be removed, and 

 a succeeding section should be put in the bottom of the mount, thus all 

 sections having the lowest resistors will be removed from inside the gage 

 holder in succession during the calibration process. 



Calibration of the gage proceeds as follows: 



If a magnetic tape recorder is used, calibrate it with 

 the strip-chart recorder as outlined in Section VII. 



Turn the strip-chart recorder "on-off" switch to "off". 



Turn the "off-on" power switch on the power supply unit 

 to "on". 



Remove all epoxy wave gage sections from the metal gage 

 holder. 



Turn on the strip-chart recorder using the switches on 

 the recorder and on the programmer. 



Using the mechanical lever on the recorder penmotor, adjust 

 the recording pen to the left side of the chart paper. 



Place the epoxy gage sections under water being careful to 

 keep the lead tips adjacent to the metal gage holder with 

 about the same spacing from the ground rod as they would 

 have been installed in the gage holder. 



Adjust the calibration resistor on the power unit to 

 provide full-scale reading on the strip-chart recorder. 



Remove all wave gage sections from the water. 



Repeat steps f, g, h, and i until zero and full scale are 

 obtained. 



Text resumes on page 27 



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