No end of fantastic schemes had been proposed, of course; of varying degrees of fantasy. Some of them sounded almost practical. Some of them had been tried; some of them were still being tried. Some, such as the perennially-appearing one of building a huge hemispherical hull in the ground under and around the vortex, installing an inertialess drive, and shooting the whole neighborhood out into space, were perhaps feasible from an engineering standpoint. They were, however, potentially so capable of making things worse that they would not be tried save as last-ditch measures. In short, the control of loose vortices was very much an unsolved problem.
Number One vortex, the oldest and worst upon Tellus, had been pushed out into the Badlands; and there, at eight o'clock on the tenth, Cloud st
