Hats and bonnets of the Romantic Era were magnificent creations overflowing with ruffles and frills, exotic plumes, vivid flowers, and yards of colorful ribbons. Elaborate hair styles were topped by these wide-brimmed creations or the face was framed by the frills of a white ruffled cap. Bonnet trimmings were removed and replaced with ease to create a fresh look for each new dress.
By John Linnell, 1826. I looked at the picture and guessed late 1820s before I found the year. Waist is lowering, sleeves are getting big, details on the dress are more complicated, but still sporting the Regency hairstyle.