In December 1952, _True_ magazine published a sensational article that attacked the Air Force findings, insisted that the radar echoes had been caused by strange machines and, in effect, accused the official investigators of releasing an explanation they knew to be at variance with the facts shown by radar[VIII-8]. Dr. Vernon G. Plank, now at the Aerophysics Laboratory of the Air Force Cambridge Research Center, was at that time Radar Meteorologist at Walpole, Massachusetts. A specialist in the science of radar, Dr. Plank had made a detailed study of the refractive conditions prevailing over Washington for July 20 and 21, 1952. In a letter (which was never published) to the editor of _True_, he pointed out that the saucer theory of the Washington radar returns had no basis in fact. The material given in the letter merits quotation: “The regular Washington radiosonde observations, when converted into refractive index terms, reveal that a very marked superrefractive condition (a condition favorable to earthward bending of radar rays) prevailed in the lower atmosphere during this period. The cause of this superrefractive condition was primarily the rapid decrease of water vapor with altitude. “Although this superrefractive layer was not quite intense enough to cause the radar rays to be bent completely back to earth, the rays would be very markedly bent downward from their normal position. From past experience with other situations of this type it is to be expected that certain regions in this layer might be considerably more superrefractive than others, or that particular terrain features, such as rivers or small bodies of water, might create local, transitory conditions favorable to extreme superrefraction or even reflection. Another factor to consider is that whereas such local anomalies are usually due to moisture, localized temperature effects may also create or help create such intense superrefractive regions. Therefore, it would not be at all surprising that such local anomalies, when superimposed on the generally superrefractive layer already existing over Washington, could create a situation conducive to radar echoes of the type observed. “Under such conditions the general ground clutter referred to in the Keyhoe article would not be present and the radarscope would only show echoes whenever and ‘wherever’ (qualified below) a favorable superrefractive region occurred. As the radar ray has to travel from the radar set to the particular region of refraction and thence onward to the ground, the scope echoes created by such disturbances would occur at an indicated range of roughly twice the disturbance range. “Even slow air movements within a localized disturbance (one sufficiently intense to bend the ray into the ground) would be translated into enormous movements of the echo over the scope face. Both lateral and radial movements could be expected and disappearance of echo between sweeps would not be surprising.