In the hands of the style-conscious French, who were setting the bar in Europe for beautiful and versatile seating forms, the once regal armchair grew more democratic, with prettier, smaller proportions for portability and plump upholstery for greater comfort.

One of these upholstered seats with arms, known as the bergère, has not relinquished the popularity that its tublike accommodation afforded through the ages. Today, the form is known simply as the tub chair.

"The term 'tub' was probably initially recorded by Thomas Sheraton in his 'Cabinet Dictionary' of 1804," says Robert Trent, an independent consultant in American furniture. He explains that rounded-back chairs built on the D-shaped plan were unknown before the period of Louis XV, when references appeared in French publications, such as Diderot's encyclopedia.

"English- and French-made upholstered chairs brought to Philadelphia, New York, and Boston in the late 18th century had the rounded side and seat rails that Sheraton called the 'tub,'" Trent says. Whereas the high-back tub model evolved into the easy chair, its low-back variant was less common in the United States than it was in France and England. Sheraton pictures one in his "Cabinet Dictionary" and labels it "a cabriole armchair stuffed all over." In France, the shape of the chair back determined its type: à la reine carried a flat back; en cabriolet had a rounded, concave back.

George Bright, a cabinetmaker in Boston, made 30 snug, low-back tub chairs for Boston's new state house in 1797. The chairs were only about 3 feet high and, with a depth of 2 feet, they were deeper than they were wide. Charles F. Montgomery, in his book American Furniture -- The Federal Period 1788-1825, said it was "one of the neatest surviving chairs of its type ... originally derived from the French by the English."

How did this mite of a chair from the American Republic hold its own throughout the Victorian age? Cheryl Robertson, an independent scholar and museum consultant in decorative arts from Cambridge, Massachusetts, explains, "The Victorian era loved curved forms, such as the tub shape, which advances in the lamination process facilitated. In fact, the curving backs were central to the rococo revival aesthetic of Victorian parlor suites." The curvaceous chair resurfaced, particularly in France, in the Art Deco period of the early 20th century.

Tub chairs continue to thrive even in the 21st century. Gregory Pitts, director of design at David-Edward Furniture in Baltimore, has fabricated designs for Alan Greenspan's conference rooms and for hotels designed by Philippe Starck. "This is a form that functions well in corners and tight spaces," he says.

"Its graceful shape hugs your body," remarks Sherri Donghia, of Donghia Furniture and Textiles. "They don't take up as much space as an angular chair does. They look great from all sides and float beautifully in a room."

When designer John Saladino launched Saladino Furniture in New York in 1987, he introduced six variants of the tub chair that have never been out of production. His sensuous 26 1/2-inch-wide circular Calla chair is a favorite of Santa Rosa, Florida, designer Phillip Sides. "It is such a pretty shape against more boxy upholstered furniture," Sides says.

Throughout all its permutations through the centuries, the tub chair has been a perennial favorite for functional comfort and beauty.