A lambrequin is a style of pelmet or cornice with long ends that extend down the side of the window, often to the sill or even to the floor. Lambrequins were popular in the early to mid 19th century and were made with stiffened buckram, paper or wood. The red, silk lambrequin above, c. 1850 is featured in the book Upholstery in America & Europe from the Seventeenth Century to World War I (1987 The Barra Foundation) where designs for lambrequins are "first being seen in The Workman's Guide in 1883, where they are praised as being 'very simple and may be cut to any shape'..."
Another interesting historical reference and a sound piece of design advice can be found in The American Woman's Home (Harriet Beecher Stowe and Catherine Beecher,1869) "...the patterns of these can be varied according to fancy, but simple designs are usually the prettiest. A tassel at the lowest point improves the appearance."