must be determined locally for each gage. Reversing the two electrical 

 leads connected to the wave staff will reverse the polarity of the voltage 

 to the staff, and may aid in changing the electrolytic action, and extend 

 the periods of operation between cleanings. 



The lead sensing tips of the epoxy gage sections are extended from 

 the main body of the section to increase the insulating distance provided 

 by the epoxy resin between the sensing tip and the metal gage mount. This 

 increased distance helps to increase the resistance value of the water 

 film remaining on the epoxy resin after a wave crest has passed, thus 

 providing the desired stepped resistance change by the rising and falling 

 action of the water during wave action. 



The penmotor will move in proportion to the stepped resistance changes 

 in the wave staff, and will provide a profile of the water surface against 

 time on the moving strip- chart on the recorder. 



The series-resistance gage will operate most accurately in locations 

 where small changes occur in the mineral content of the water. If the 

 gage is operated during conditions where great changes in mineral content 

 occur, such as during periods of large snow runoff, the gage calibration 

 should be checked during such conditions, and the recordings corrected 

 as necessary. 



2. Fabrication of Series-Type, Step-Resistance Gage 



Most of the parts needed for fabrication are listed in Table III. 

 The desired number of epoxy gage sections are molded as shown on Figure 8. 

 Cables for each section should be long enough to allow submerging all gage 

 sections at one time while working from the top of the gage mount. This 

 will allow operating personnel to calibrate the gage at regular intervals. 

 The top gage section has the lowest resistor value between the top plug 

 and the second plug. Resistors increase in value from the top of the 

 gage toward the bottom, the highest value of resistance being between the 

 bottom plug and the connecting conductor molded into the gage. 



The power supply requires the small aluminum chassis and the parts 

 indicated on Figure 9. Layout of the power supply is not critical, use 

 of good shop practice' is all that is required. The voltage-adjust control 

 on the constant voltage power module must be available for adjustment. 



Three 115-volt receptacle plugs, one line cord and one toggle switch 

 are installed in the sides of the timer. These items are installed and 

 wired as shown in Figure 10. 



The strip-chart recorder listed in the parts list (Table III) for 

 this gage has a minimum chart speed of about 12 inches per minute. To 

 save chart paper, the recorder can be modified for a chart speed of 6 

 inches per minute. This modification is recommended and is outlined in 

 Section VIII. A connecting cable to this recorder from its input signal 

 connector is made in the desired length using 2-conductor No. 18 cable 

 as shown on Figure 11. 



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