A “turtle of Vicksburg” is mentioned by Charles Fort (image above, hopefully) in The Book of the Damned: “Later we shall have data of things that have gone up in the air and that have stayed up – somewhere – weeks – months – but not by the sustaining power of this earth’s atmosphere. For instance, the turtle of Vicksburg. It seems to me that it would be ridiculous to think of a good-sized turtle hanging, for three or four months, upheld only by the air, over the town of Vicksburg.” 
Was this floating turtle of Vicksburg the same turtle, encased in ice, which fell in the region of Vicksburg, Mississippi on May 11, 1894?
Perhaps the floating turtle of Vicksburg was kept aloft for months due to the Biefeld-Brown effect. Something called “anti-gravity lifters” appear to show a tenuous link between electricity and gravity. A Google YouTube search on “anti-gravity lifter” returns videos of amateur experimenters successfully duplicating early experiments of Thomas Townsend Brown (1905 – 1985). (Background: Our Friend, The Ether (Part 15), Ersjdamoo’s Blog entry of November 9, 2013.)
Another mystery is the so-called “Devil’s Hoofprints” of 1855. Might these “Devil’s Footprints” have been caused by the inhabitants of Laputa, described by Jonathan Swift as a flying island which its inhabitants can maneuver in any direction using magnetic levitation? The Laputans are known to be obsessed with mathematics. They could have been leaving the strange marks, the “Devil’s Hoofprints”, periodically as markers for some sort of measurements they were doing.
(Background: Our Friend, The Ether (Part 14), Ersjdamoo’s Blog entry of November 7, 2013.)
Charles Fort (1874 – 1932), towards the end of The Book of the Damned, ponders upon the “Devil’s Hoofprints” mystery. Fort closes his first book with an item from the Illustrated London News of March 17, 1855. Regarding the “Devil’s Hoofprints” mystery, a correspondent from Heidelberg revealed that on the Piashowa-gora sand hill in “Russian Poland” such “Devil’s Hoofprints” are frequently found and “are attributed to supernatural influences.” 
But “supernatural influences” is another way of saying, “We do not definitely know.” A person or persons claimed to explain the “Devil’s Hoofprints” episode of 1855 in something called the “VARO Edition” of Morris K. Jessup’s book, The Case for the UFO. A correspondent had read Jessup’s book and wrote to him, revealing information on an alleged “Philadelphia Experiment” said to have occurred in 1943. (Background: Our Friend, The Ether (Part 9), Ersjdamoo’s Blog entry of October 29, 2013.) Around the same time, an annotated copy of Jessup’s book was sent to Admiral N. Furth of the Office of Naval Research. Some person or persons had scribbled notes in the margins of Jessup’s book. Some in the Navy became intrigued by these scribbled comments. A “limited edition for circulation among some of our top people” was authorized. This limited edition of Jessup’s book containing the scribbled comments is known as the VARO Edition. “Exactly 127 copies were produced” of the VARO Edition. (Later, this limited edition somehow leaked out and now it can be found on the Internet.) 
Regarding the “Devil’s Hoofprints”, the VARO Edition anonymous commentator(s) explained they had been caused by the “L-Ms.” Once, in 18th-century France, seventeen marching soldiers had been simultaneously struck down by an invisible agency. The unknown commentator(s) explained that one soldier had a compass on him, it fouled a “SWEEP” and made the “L-Ms” angry. As for the “Devil’s Hoofprints”, they had been caused when the “L-Ms” accidentally left a “Measure Marker” idling. Nowadays the “Measure-Markers” are not used, except by undersea explorers.
But who are the “L-Ms”? Are they Laputan Mathematicians? In Our Friend, The Ether (Part 14), I speculated upon how the “Devil’s Hoofprints” may have been caused by inhabitants of the flying island of Laputa.
Pondering “Devil’s Hoofprint” and other anomalies, Charles Fort cautiously offered speculations: Have devils visited the earth? “[F]oreign devils: human-like beings, with pointed beards: good singers; one shoe ill-fitting – but with sulphurous exhalations…”? 
“We have thought – with a low degree of acceptance – of another world that may be in secret communication with certain esoteric ones of this earth’s inhabitants – and of messages in symbols like hoof marks that are sent to some receptor, or special hill, upon this earth – and of messages that at times miscarry.” 
——- Sources ——-
 The Book of the Damned, by Charles Fort. From, The Complete Books Of Charles Fort. New York: Dover Publications, 1974
 The Philadelphia Experiment, by William L. Moore (with Charles Berlitz). New York: Fawcett Crest, 1979.