A glass rod seems to bend as it passes from one liquid to other. Light bends in this way. A light shining through the liquids bends at the meeting point. Same is true in air layers.
Related photos
A sensor display, possibly infrared, showing a crosshair reticle with a numerical scale and a timestamp at the bottom left.
A collage of newspaper clippings and a convention schedule from the 'Flying Saucers International' magazine. The main headline is 'Tracked by Radar' from The London Free Press.
A collage of newspaper clippings from the 'Flying Saucers International' magazine, with headlines such as 'Would You Believe--"Saucer" Visits Wichita?' and 'Boy Is 'Burned' By 'Flying Ship'.
A collage of newspaper clippings and UFO photographs from the 'Flying Saucers International' magazine. Headlines include 'New 'Fireball' Raises An Old Question: Do Flying Saucers Exist?' and '100 Watch UFO'.
A collage of newspaper clippings from the 'Flying Saucers International' magazine, with a large headline from the Oakland Tribune: 'Flying Saucers Are Poppin' Up All Over'.
A collage of newspaper clippings from the 'Flying Saucers International' magazine, with headlines such as 'Civil Defense Director Watches 'Flying Saucer'' and 'Who's In All Those Saucers?'.
A promotional card for the Amalgamated Flying Saucer Clubs of America, featuring an illustration of a flying saucer.
UPI Telephoto DR. CONDON Saucer-watcher