.. looking at the fullness in the front of the dress. With the 1870’s style of bustle (or “tournure”), the drapery hanging over the bustle went almost completely down the front, or had the apron effect of draping. As it evolved the front drape became more a part of the skirt while the weight – visual and actual – started to pull to the back.
(Photos: extant ensembles (left) 1878 draping vs (right) 1881. Similar but subtle changes in the intent of the drape)