An electron‐beam x‐ray technique was used to obtain precise measurements of the density along the stagnation streamline of spherical models tested in aM = 4.2(nominal Mach number) nitrogen stream and aM = 3.8argon stream. Variation of the total pressure and the model radius provided a Re range (based on free‐stream properties and model radius) of 30‐500 in nitrogen, 100‐2000 in argon. The measurements were made with model surface temperatures of 300° K (equal to the total temperature of the flow) and 78° K.