While that makes for a great pulp novel title, it's actually referring to the "great airship flap" of the late 19th century. Starting in 1880, anomalous airships were seen over Poland, Germany, Russia, and especially the U.S. The majority of the sightings appear to be of the same or at least similar objects; cigar-shaped, a shiny hull like aluminum, a fishlike tail, and numerous lights and searchlights on the craft's underside. Doubtless if these things were seen today, we'd call them UFOs.
What makes these sightings unique is that they were said to hover and to move against the wind. No aircraft at the time, such as they were, were capable of such actions. At the time, the leading explanation for these sightings was that they were marvelous, Jules Verne-like inventions, born of the mind of an unknown genius. Multiple accounts arose in newspapers of people claiming to represent a reclusive scientific mind, wishing not to make himself known to the world just yet, but continuing to test fly his new airship. These invariably turned out to be hoaxes.
In the 1890s, the idea of extraterrestrial visitation began to be entertained. The town of Aurora, Texas claimed that an airship crashed on a local ranch and its sole occupant, a Martian, was buried in the town cemetery. This turned out to be a complete and utter fabrication of course, but it hasn't stopped plenty of UFOlogists from showing up in the town, wanting to excavate sections of the cemetery in search of the "Martian."
The wave of sightings continued into the early years of the 20th Century, spreading even to nations like Britain and Australia. Again these objects were said to be cigar-shaped and without any visible kind of wings. A few, however, were said to have small propellers. What began to make headlines was the fact that these "air torpedoes" moved at "remarkable speeds." Sometimes the sightings only amounted to strange, fast moving lights in the sky, long before any powered flight or certainly any navigation lights. Then as most of these flaps usually do, the sightings ended around 1912 for the most part.
So what were they? Were these "airships" the 19th Century version of black military projects being test flown over various stretches of the world? Maybe. Was there really a mad steampunk genius out there? That would be cool. But what truly interests me is how our sightings throughout the years mirror what our perception of what an advanced aircraft should look like. In the late 19th Century, someone's concept, if they even had one, of what a futuristic aircraft should look like would probably be dirigible airship of some kind.
Fast forward to 1947. Contrary to popular belief, Kenneth Arnold, the man is credited with the first UFO sighting of the modern era, never claimed to have seen "flying saucers." He described their movements as "saucers skipping over water." The craft themselves were actually more wedge-shaped. But once newspapers and radio got a hold of the story, saucers were the ship design de jour for many many years. Into the 1980s, speculation ran wild as to what form the super-secret stealth fighter had. The prevailing concepts were rather triangular in shape. As if on cue, many UFOs sighted at the time were said to be triangles, most notable among them the 1990 sightings in Belgium, one the best documented UFO cases to date. To this day, triangles are among the most commonly sighted anomalous craft.
I doubt aliens would alter their spacecraft according to our fickle aesthetics, so what was the 19th Century flap? Experimental airships? Psychological perception? Who knows. But it shows to go you that people have been seeing strange things in the sky for a very long time.
Much research for this came from Unexplained! by Jerome Clark
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