Daytime measurements of electron density, ion density, electron collision frequency, and earth's magnetic field in the ionosphere were made during V-2 rocket flights at the White Sands Proving Ground, New Mexico. Two CW harmonically related frequencies were radiated from the rocket to two ground stations to obtain measurements of the ordinary and extraordinary indices of refraction in the region around the rocket. The results for one flight show an ion layer with a maximum of 5×108 ions/cc and a small electron layer with a maximum of 7,500 el/cc just below the E1-layer. On a September day the E1-layer remained dense up to the E2-layer, while on a January day the density apparently decreased above the E1-layer maximum to much lower values. It is shown that the Lorentz polarization term should not be used in the E-layer at 4 Mc.