Data from nine spacecraft are combined to study the properties of solar wind protons and the interplanetary magnetic field under the unusual conditions that proton speed, density, and temperature variations are small over periods comparable to the solar wind expansion time. From the 14 quiet intervals studied it is determined that (1) the T1/2-v relation is less steep than was calculated from long-term-averaged or 3-hour quiet data; (2) the density varies approximately as the inverse square of the velocity; however, the data scatter is large, and an alternative interpretation is that mass flux is constant for velocities over ~400 km/s, in agreement with earlier studies; (3) the magnitude of the interplanetary magnetic field is independent of solar wind speed and density; and (4) the average field direction varies with the solar wind speed as predicted by Parker's spiral model. The intercalibration of solar wind measurements by different spacecraft is discussed in an appendix.