Americans remain loyal to timeless Windsor chairs; Both antique and new forms of this light, elegant style have a popular appeal

Thomas Jefferson sat in one while he composed the first draft of the Declaration of Independence. So did many members of the First Continental Congress when they convened in Philadelphia in 1774. And George Washington purchased 27 of them for the portico of his home at Mount Vernon.

In fact, while the leaders of the young nation might have disagreed on other issues, it seems there were few who didn't favor conducting business while comfortably ensconced in a Windsor chair.

Many other Americans of the 18th and early 19th century felt much the same way. The lightness and elegance of the simple spindle-backed chairs appealed to the wealthy, who purchased them in great quantities for both their townhouses and gardens. And the affordable price of the chairs meant that lower income Americans could enjoy them as well.

Today Windsor chairs and their myriad of descendant forms are as popular as ever. While a careful search through antique shops and flea markets will occasionally yield an early 19th-century rod-back Windsor for $75 to $100, the finest 18th-century versions of the genre are eagerly sought by collectors who are willing to pay prices in the four-figure range. Modern versions of Windsor chairs are perennial big sellers at furniture stores, ranging all the way from traditional Ethan Allen to trendy Crate and Barrel.

So it is not surprising that Charles Santore, in his recently published ''The Windsor Style in America'' (Philadelphia: Running Press), calls Windsor furniture ''the most characteristically American and the most historically significant furniture style to emerge from 18th-century America. It is a democratic style, one which appealed to and was used by all levels of American society.''

Despite the fact that the chairs were so highly regarded by early Americans, they had their origins, just as many of the revolutionists themselves did, in England. As legend has it, King George II, while journeying in the countryside on a chilly day, sought shelter in the humble home of one of his subjects. Much taken with a crude but comfortable spindle-backed chair in the household, he had his cabinetmakers make several versions of it for himself.

Whether or not the tale is true, it is true that Englishmen of lesser rank were enthusiastically purchasing chairs of this type being produced in the market town of Windsor during the early 18th century. As they did with most fashions, the American colonists soon followed suit with their own markedly different adaptations of the style. By the mid-18th century Philadelphia, New York, and New England cabinetmakers were turning out light and graceful chairs quite independent in design from the heavier, more formal prototypes of the Old World.

Although antique Windsors were produced in several important styles, most were characterized by the same basic form and construction. Nails were rarely used in the chairs. Instead, steam-bent spindles and legs were fitted into holes in seats of unseasoned wood which shrank as they dried and gripped the component parts well. The result was in the creation of a lightweight chair with a remarkable durability that few of the machine-made type can match.

Few Windsor chairs were fashioned out of only one type of wood. Instead, most had seats of pine or beech, legs from oak, hickory, or maple, and spindles and arms from hickory or ash. The diversity was not intended to show because nearly all the chairs were painted, usually green in the mid-18th century and eventually dark red, black, yellow, gray, brown, or blue. Many of the chairs in the 19th century were painted in several colors and then stenciled on top of that. Today by far the most valuable antique Windsors are those with their original paint or stenciling intact.

Most Windsor chairs were made in subtle variations of eight basic styles: comb-back, low-back, sack-back, fan-back, continuous arm, writing arm, bow-back, and rod-back. The terms are fairly self-descriptive. A comb-back chair, for example, is one in which spindles and crest rail form a back shaped just like an old-fashioned hair comb. A low-back chair has a semicircular back that is the forerunner of what would eventually be known as the captain's chair.

The back spindles on a fan-back chair tend to ''fan'' out from the chair seat in a graceful splay. Bow-backs are characterized by a gently curving, hoop-shaped crest rail into which the spindles are attached. In a continuous armchair, the arms and crest rail are one gracefully curving entity.

The sack-back chair, a combination of the low-back and bow-back styles, took its name from the fact that sometimes a sack was draped over its back to shield the sitter from drafts. The writing-arm Windsor is really a desk and chair in one unit, often consisting of a wide paddle-shaped surface attached to the right arm and a drawer handily built beneath the seat.

Chairs in the above-mentioned styles had their heydey during the 18th century when highly skilled turners and cabinetmakers carefully fashioned each one. Rod-back Windsors, chairs in which the back spindles are attached to a simple, straight crest rail, are products of the early 19th century when the chairs, although still well-made, were increasingly mass-produced. Whereas many of the earlier chairs had elaborately turned legs and arm supports, these newer chairs were made with the bamboolike markings popular in the Sheraton era of furniture design.

Although the style of the early Windsors has continued to influence chair styles up through our own era, after 1850 the grace and elegant lightness of the chairs as well as their traditional mode of construction was lost to a more mechanized age. What hasn't been lost is an appreciation for the ingenious and aesthetically pleasing bit of American history they represent