The circular canvas walls were covered with paintings, no doubt completed by some down-and-out artist turned prospector.

Ropes tied across the circular canvas reinforce the impression of confined energy on the verge of breaking free.

He loosened the Dutch painter's strict rectilinear grid with diagonals and softened it with curves, becoming the first American artist to use circular canvases.

Gimblett stepped up to the 80 inch circular canvas and while that murderous train bore down on him, he painted The Wheel in less than one minute.

Ms. Fitzgerald's circular canvases are even more atmospheric, dispensing with all but the most minimal references to tangible reality.

"Her circular canvases challenge the viewer," Mr. Craddock said, "and there is an element of spirituality and mystery, deep wonder and awe."

Goodman paints O-ist-inspired abstractions: circular canvases, like targets with brushy passages in the middle.

The circular canvas "2:00 A.M. Postcard" (1988) presents a dark narrow corridor receding into the distance, at the end of which appears a sliver of brilliant light.

The roundel (a circular canvas), the only self-portrait by the celebrated early American artist, was donated to the NPG by the Cafritz Foundation.

Karen Fitzgerald's work - tepid Turneresque abstractions on circular canvases - looks back to an earlier epoch when art was not expected to carry the burden of social commentary.