_Motion_--The saucer displays a wide variety of motions. It may travel very slowly; very fast, approaching the speed of light; at jet speed; at meteoric speed; may hover motionless over one place. At any speed it can instantaneously change velocity and direction of motion--can move horizontally, vertically, toward the observer, away from the observer, in a straight path, a zigzag, a spiral. Like the Cheshire cat, it can vanish instantly or slowly fade away. _Means of propulsion_--Unknown. Some saucers move in complete silence; others produce noises: a hiss, a whistle, a roar, a thunderclap, or a detonation like a sonic boom. [Illustration: _Figure 1._ Shapes of various reported UFOs.] _Incidence_--Saucers may appear at any hour of the day or night, but they appear most frequently in the hours before and after sunset, and before and after sunrise. Their numbers may suddenly increase at certain places and certain times. The objects can appear singly, in random groups, in groups showing a geometrical pattern. A single object may split and multiply into a group, or a group may merge into one. Saucers almost always appear in the air, rarely on the earth’s surface or in bodies of water. They almost never come within touching distance of the observer. The length of their stay varies greatly, from about two seconds to two or three hours. _Structure_--Unknown. A saucer may be visible or invisible to the observer; visible to the human eye but not to the camera or radar; visible to the camera or radar but not to the eye. Some obey the laws of gravity and inertia, others do not. _Purpose_--Unknown. No officials in the government, the press, the churches, or the universities have received any attempt at communication. No saucer has produced intelligible visible, audible, or radio signals. Long before finishing this tabulation the investigator realizes that he is not dealing with one thing but with many. No single phenomenon could possibly display such infinite variety. However, before he starts trying to classify the descriptions and to explain them, he takes a look at the second class of material--the conclusions offered by saucer enthusiasts. Leaving the realm of observation for that of interpretation, he is suddenly catapulted into a world of fantasy. _A “Baedeker’s Guide” to Saucerdom_