weren’t airplanes or birds. They had arrived at this conclusion by making a frame-by-frame study of the motion of the lights and the changes in the lights’ intensity.
When the Navy people had finished with their presentation, the scientists had questions. None of the panel members were trying to find fault with the work the Navy people had done, but they weren’t going to accept the study until they had meticulously searched for every loophole. Then they found one.
In measuring the brilliance of the lights, the photo analysts had used an instrument called a densitometer. The astronomer on the panel knew all about measuring the density of an extremely small photographic image with a densitometer because he did it all the time in his studies of the stars. And the astronomer didn’t think that the Navy analysts had used the correct technique in making their measurements. This didn’t necessarily mean that their data were all wrong, but it did mean that they should recheck their work.
When the discussion of the Navy’s report ended, one of the scientists asked to see the Tremonton Movie again; so I had the projectionists run it several more times. The man said that he thought the UFO’s could be sea gulls soaring on a thermal current. He lived in Berkeley and said that he’d seen gulls high in the air over San Francisco Bay. We had thought of this possibility several months before because the area around the Great Salt Lake is inhabited by large white gulls. But the speed of the lone UFO as it left the main group had eliminated the gulls. I pointed this out to the physicist. His answer was that the Navy warrant officer might have thought he had held the camera steady, but he could have “panned with the action” unconsciously. This would throw all of our computations ’way off. I agreed with this, but I couldn’t agree that they were sea gulls.
But several months later I was in San Francisco waiting for an airliner to Los Angeles and I watched gulls soaring in a cloudless sky. They were “riding a thermal,” and they were so high that you couldn’t see them until they banked just a certain way; then they appeared to be a bright white flash, much larger than one would expect from sea gulls. There was a strong resemblance to the UFO’s in the Tremonton Movie. But I’m not sure that this is the answer.