The #5500 Salinity Bridge is a special purpose, alternating current bridge designed specifically for use with the #5000-A and #5100-A Soil Salinity Sensors. The Bridge makes it possible to read out soil solution conductivity in millimhos/cm at 25ºC directly from the sensors. The Bridge also provides a separate scale for resistance readings. Three resistance ranges are available: 0-1,000 ohms, 0-10,000 ohms, and 0-100,000 ohms. The selector switch on the panel selects one of the three conventional resistance-measuring circuits or the special direct reading conductivity circuit. A receptacle on the panel accepts the polarized plug from the salinity sensor. Two small dials on the panel are used to set the two characteristic values of the individual sensor that are permanently marked on the plug of each sensor. The conductivity at 25ºC is read out directly on the conductivity scale of the large center read-out dial that is graduated 1-1/2 to 40 millimhos.