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CHAPTER 10 - CURRENT METERS
Two types of wading rods are available for supporting the current meters when working in shallow and moderate-depth streams: (1) the conventional round rod and (2) the more convenient top-setting rod. Both rods use a baseplate that rests on the bottom of the flow channel.
The round rod (figure 10-13) consists of several sections of 1-ft-long, 2-in-diameter, nickel-plated round brass tubing. The rod is graduated at intervals of 0.1 ft by shallow machined lines around the rod. A single groove is used at the 0.1-ft graduations, double grooves at the 2-ft intervals, and triple grooves at the foot marks. A nickel-plated sliding support machined from a bronze casting moves up or down on the rod and is held at any desired location by a spring-actuated lock which uses a lever for release. The current meter and the vanes, if used, attach to this sliding support.
The top-setting wading rod (figure 10-15) permits all settings to be made in the dry and has a main column of 2-in hexagonal stock and a meter positioning rod of d-in-diameter stock. The main rod attaches to the baseplate and is graduated in 0.1-ft intervals so depth of flow can be measured. Interval markings are the same as those used on common wading rods. The meter is secured to the lower end of the positioning rod and guided by means of a support that slides on the main rod. The position of the meter and sliding support is set by raising or lowering the positioning rod which extends through the handle at the top of the main rod. When the elevation of the meter is set to read the depth on the vernier, it will be at the 0.6 depth position. Doubling the vernier reading puts the meter at the 0.2 depth, and halving puts it at 0.8 depth. Once set, the positioning rod, and hence, the sliding support and meter, is secured by a locking device on the handle. Thus, all adjustments are made from above water so the operator's hands and the log can remain dry.
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