In a field program conducted during the summer of 1963, sonic anemometers were operated at four levels on a 1400-ft tower to obtain measurements of the vertical velocity fluctuations under different stability conditions. This report provides a detailed description of the instrumentation, data reduction and analysis technique, and a complete listing of the processed spectral data. The results for four runs representing different but typical conditions are analyzed and interpreted. The main conclusion drawn from this study is that simplified concepts used for describing the vertical structure of turbulence near the ground do not apply to heights above 150 ft. (Author).