The amount of suspended solid material transported by a stream is usually determined by making measurements of sediment-content and of velocity at many points in the cross-section and integrating the results. The number of sampling points required will depend upon the degree of accuracy necessary, and, according to O'Brien [see 1 of “References” at end of paper], upon our knowledge of turbulent flow and its relation to sediment-transportation.The suspended-load samplers used for these measurements may be divided into two classifications, depending upon the length of the sampling period. One might be called the integrating or continuous sampler, and the other the instantaneous or grab sampler. Turbulent fluctuations cause the sediment-content at any point in a stream to be continually-varying; therefore, only an integrated sample, taken over a period of time long enough to get an average concentration, can truly represent the sediment-content. This integration may be made with a continuous sampler of the suction-nozzle type, which maintains the same velocity at the entrance as the undisturbed velocity of the stream at that point. (Continuous suction-nozzle samplers are now being used in the Cooperative Laboratory of the Soil Conservation Service at the California Institute of Technology.) The mean concentration may also be obtained by combining a number of small grab-samples which show the true instantaneous sediment-content.