Umbriel is an industrial planet used to refine phlogisten and other products associated with Æther whaling. The atmosphere of Umbriel hangs with industrial pollutants and hazardous wastes. Ferenshi and O'Ryan traders pilot large convoys of tankers to and from Umbriel but hesitate to make planet fall due to the horrid conditions on the planet's surface. The owners of the factories and refineries are located elsewhere in the system. As whaling industrial tycoons they can afford to live in luxury.