When Venus is at its greatest brilliance, it is possible to see it during daytime when one knows exactly where to look. But on January 7, 1948, Venus was less than half as bright as its peak brilliance. However, under exceptionally good atmospheric conditions, and with the eye shielded from direct rays of the sun, Venus might be seen as an exceedingly tiny bright point of light. . . . However, the chances of looking at just the right spot are very few. It has been unofficially reported that the object was a Navy cosmic-ray research balloon. If this can be established, it Is to be preferred as an explanation. However, if one accepts the assumption that reports from various other localities refer to the same object, any such device must have been a good many miles high—25 to 50—in order to have been seen clearly, almost simultaneously, from places 175 miles apart. If all reports were of a single object, in the knowledge of this investigator no man-made object could have been large enough and far enough away for the approximate simultaneous sightings. It is most unlikely, however, that so many separated persons should at that time have chanced on Venus in the daylight sky. It seems therefore much more probable that more than one object was involved. The sighting might have included two or more balloons (or aircraft) or they might have included Venus and balloons. For reasons given above, the latter explanation seems more likely. Two things stand out in his report: 1. The obvious determination to fit some explanation, no matter how farfetched, to the Mantell sighting. 2. The impossibility that Venus—a tiny point of light, seen only with difficulty—was the tremendous metallic object described by Mantell and seen by Godman Field officers. With Venus eliminated, I went to work on the balloon theory. Since I had been a balloon pilot before learning to fly planes, this was fairly familiar ground. Shallett’s alternate theory that Mantell had chased a Navy research balloon was widely repeated by readers unfamiliar with balloon operation. Few thought to check the speeds, heights, and distances involved. Cosmic-ray research balloons are not powered; they are set free to drift with the wind. This particular Navy type is released at a base near Minneapolis. The gas bag is filled with only a small per cent of its helium capacity before the take-off. In a routine flight, the balloon ascends rapidly to a very high altitude-as high as 100,000 feet. By this time the gas bag has swelled to full size, about l00 feet high and 70 feet in diameter. At a set time, a device releases the case of instruments under the balloon. The instruments descend by parachute, and the balloon, rising quickly, explodes from the sudden expansion.