The spin and orbital decays of the Paddlewheel Satellite, Explorer VI, have been used in conjunction with several models of surface-particle interaction to calculate drag coefficients and absolute densities at altitudes near 270 km in August of 1959. The absolute densities are estimated to be accurate within 10 per cent. Because of the accuracies inherent in spin measurements, it has been possible to determine the relative densities within 1 or 2 per cent for the 5-min time interval around each perigee passage. The measured densities have been compared with several model atmospheres. The fine time resolution of the data reveals the smoothing effect of the atmosphere on the correlation with the geomagnetic planetary amplitude, d p .