Designer: Albert Winckler (Carlo Venturini), Ernst Hartwig Seeman (Prof. Seeman), or Otto Heinemann   
The Aga Levitation has been attributed to several individuals – Albert Winckler (Venturini) and Otto Heinemann both of Germany and Ernst Hartwig Seeman (Prof. Seeman). It is unclear which of these men used it first, but they each incorporated it into their acts. The Aga was a popular levitation in the early 1900s. Eventually, it got competition when Servais Le Roy introduced his levitation (the Asrah).
The person to be levitated lies uncovered on some sort of couch and then starts to float in mid-air. In the improved Aga, a hoop is then passed around the person, twice. The Aga effect uses a “behind the curtain” method and the improved Aga uses a “gooseneck” principle.
The improved Aga plans are available in the Great Illusions of Magic by Byron G. Wels. 
Peter Warlock’s book Walter Jeans: Illusioneer indicates in the footnote on the first page that Winkler sold the Aga levitation to Will Goldston in 1910. Will was manager of the conjuring department of A.W. Gamage, Ltd. It is said that “Aga” was formed from the initials of Gamage’s managing director (Alec) plus the first two letters of Gamage. However, John A. McKinven’s book Roltair claims that Otto Heinemann appeared with “The Mysterious Aga” about eight years prior to the Gamage version. 
 Peter Warlock, Walter Jeans Illusioneer. (Pasadena: A Magical Publication, 1986), 9.
 Byron G. Wels, The Great Illusions of Magic. (New York: Louis Tannen, Inc., 1977), 137-139.
 Warlock, 9.