"On December 7, 1883, the astronomer Richard Belgin arrives at Gare du Nord in Paris.
He is received by Bentram Delacroix, imperial geologist and esotericist. They hire a cab and drive to an undisclosed location, where they hold a quiet conversation with the German ambassador, Baron von Bismarck.
This conversation was recorded and stored on a magnetic reel. The conversation was allegedly about the so-called “Wormholes”.

These “Wormholes” were first described by Bessel & Croll in the book “The Esoteric Membranes of the Heavens” (1878). Belgin is said to have demonstrated the existence of the Bessel-Croll Codensate in 1881.
After the meeting, which lasts for 4 hours and 25 seconds, von Bismarck flies towards Berlin with the magnetic reel. However, the airship “Der Zauber” never reaches Berlin.
No one knows where “Der Zauber” disappeared. No wreckage was found.

In 1914, the French-German Aerial Defense attempted to find the wreckage using a radar transmitter mounted on a new prototype aircraft powered by compressed hydrogen, but they found nothing.
Richard Belgin and Bentram Delacroix never told anyone about the meeting. But both have noted the appointment with von Bismarck in their diaries, which are found in The Bessel-Croll Archive in London."

Excerpt from "The Disappearance of Der Zauber"
by N. J. Nicholson