This comes from the collection at the Metropolitan Museum of Art, specifically the Heilbrunn Timeline of Art History (Nineteenth-Century Silhouette and Support), which is chock-full of awesome 19th century dresses ~ and all so beautifully photographed!
The description on this particular item reads, in part:
The 1830s silhouette was created by a corseted, raised waistline; with a bell-shaped skirt revealing the lower ankle. The wide triangle atop this dress was imposed by the stays worn underneath, which had shoulder straps to hold the shoulders down and away from the neck. The wide sleeves had at first been affixed at the top of the arm and supported with sleeve extenders made of various materials. By the late 1830s, the gigot sleeve was collapsing at the sleeve cap.
Go to the site to read more and see the amazing other dresses from throughout the century.