In the 1780s and early 1790s, skirts were full and round and slightly puffed out at the back, although the wide panniers had gone. Generous fichus covered the bosom. As France’s Republican and classical styles spread across the Channel, however, the bulk of the skirt gradually diminished; it took ten yards to make a dress in 1796, but only seven yards in in 1801. The number of petticoats diminished too, until some women wore only one or even none at all. (To the scandal and shock of moralists and the secret delight of the male population.) Petticoats in the past had been highly decorative and visible – a prominent part of the dress itself. Now, if it showed at all, it was an ornamental band at the bottom of a dress.
A ball gown found in 1801 Gallery of Fashion is a ‘robe’, a descendant of the open-fronted gown that exposed the petticoat, in the style of the 18th Century.
Like the robe, the frock or gown could be adapted with equal ease to morning or evening wear. One 1807 example of an evening frock, has a square neckline, short sleeves and a relatively smooth front of sprigged muslin; all the fullness is gathered at the back and allowed to cascade down as a train. An 1808 walking frock, however, has no train and is worn with long gloves, a jacketlike vest, a shawl, and a straw bonnet. This careful covering of almost all exposed skin would have met with the approval of the author of The Mirror of Graces, who advised the cautious woman that:
"Morning robes should be of a length sufficiently circumscribed as not to impede her walking, but on no account must they be too short; for ... [when] showing the foot or ankle the idea of beauty is lost..."
In addition to the petticoat, many women now took to wearing drawers. These were quite long – long enough that Lady de Clifford pointed out to Princess Charlotte that hers were visible every time she got into or out of a carriage. Unimpressed, the princess replied, “the Duchess of Bedford’s are much longer, and they are bordered with Brussels lace.” There was, as the princess implied, little effort taken to hide the drawers, which came into fashion around 1806.
Above the petticoat, a chemise was worn. This was a knee-length linen or cotton shirt, often with a frill of some kind at the neckline and short sleeves. It was usually, but not always, worn beneath a dress. If it were worn, part of it, for example, the decorative neckline, often peeked from underneath the dress.
As the silhouette slimmed, the waistline rose, until it ended just under the breasts. The dress itself was rather loose and pulled into classical folds of drapery, often by drawstrings at the neckline. Beneath this apparent ease and lightness, many women retained the stays they had worn for centuries. These were corsets made of heavy cotton fabric or silk and stiffened with whalebone. They were sometimes assisted in front with a “divorce,” at triangular piece of padded metal that separated the breasts.
Necklines were very low and revealed a great deal of the bosom, so many women retained the modesty pieces of earlier decades, tucking a gauzy piece of fabric around the back of the neck and into the top of the gown, sometimes crossing at the front. During the day women wore the morning or walking dress with long sleeves, gloves and bonnets, which covered all of the skin. Morning gowns were often white.
Evening gowns were exclusively short-sleeved until about 1814. The anonymous author of The Mirror of Graces (1811) suggested white above all for evening gowns, as “White is becoming to all characters,” but if a large woman "(A lady of majestic deportment),” chose to wear colors, she should adhere to “the fuller shades of yellow, purple, crimson, scarlet, black and grey.”
After 1814 fichus were discarded and women displayed their low necklines to full advantage.
Resource: ALL THINGS AUSTEN An Encyclopedia of Austen’s World Volume I A-L, Kirstin Olsen.