Due to the wayback machine failing to archive two of the three pages on the memorandum the following text is provided by the NICAP.com site.
"There have been daytime sightings which are tentatively considered to possibly resemble the exhaust of some type of jet propelled object. Night time sightings have taken the form of lights usually described as brilliant green, similar to a green traffic signal or green neon light. Some reports indicated that the light began and ended with a red or orange flash. Other reports have given the color as red, white, blue-white, and yellowish green. Trailing lights sometimes observed are said to be red. The spectrum analysis of one light indicates that it may be a copper compound of the type known to be used in rocket experiments and which completely disintegrates upon explosion, leaving no debris. It is noted that no debris has ever been known to be located anywhere resulting from the unexplained phenomena.
"Recent observations have indicated that the unidentified phenomena travel at a rate of speed estimated at a minimum of three miles per second and a maximum of twelve miles a second, or 27,000 miles an hour. Their reported course indicates that they travel on an East-West line with probability that they approach from the Northern quadrant, which would be the last stage of the great circle route if they originated in Russia. When observed they seem to be in level flight at a height of six to ten miles and thus traveling on a tangent to the earth's surface. They occasionally dip at the end of the path and on two occasions a definite vertical change in the path was indicated. These phenomena have not been known to have been sighted, however, at any intermediate point between Russia and Los Alamos, but only at the end of the flight toward the apparent "target," namely, Los Alamos.
"In every case but one the shape of the objects has been reported as round in a point of light with a definite area to the light's source. One report gives a diamond shape; another indicates that trailing lights are elongated. The size is usually compared to one-fourth the diameter of the full moon, and they have also been compared in size to a basketball with trailing lights the size of a baseball.
"On no occasion has sound been associated directly with the phenomena, but unexplained sounds have been reported from Los Alamos. On two occasions reports have been received of the sightings of multiple units.
"Some nine scientific reasons are stated to exist which indicated that the phenomena observed are not due to meteorites. The only conclusions reached thus far are that they are either hitherto unobserved natural phenomena or that they are man-made. No scientific experiments are known to exist in this country which could give rise to such phenomena."
So, while flying saucers were being dismissed publicly as misidentifications, hoaxes, and the product of Saturday night drinking parties, the Army and Air Force looked upon the matter as "Top Secret."