Frederick S. Oliver
The Waters of Light
Promenade Deck: Some vailxi have an open promenade deck.
Most vailxi were provided with an arrangement allowing, when desired, an open promenade deck at one end.
Frederick S. Oliver
1905 – A Dweller on Two Planets
The Atlanteans possessed machinery and devices far beyond what was known at the time of writing, including flying machines called "vailxi" and other forms of advanced transportation and communication.
The Poseidii have mastered aerial travel, using advanced aircraft called Vailxi.