Maria Dorothea
Her Wikipedia article is here.
Posted to the Alexander Palace Time Machine Discussion Forum by Svetabel on 24 May 2011; lightness added to being out detail by gogm.
Maria Dorothea shows off an S-curve silhouette perfectly suited to the curvaceous mature figure in this photo.
Keywords: Archduchess Maria Dorothea, Habsburg family, Orléans family, Archduchess, Duchess, curly coiffure, tiara, bun, cap sleeves, full skirt, bustle, necklace, bracelets, fan