Petticoats of the 1840’s were…

… large, with elaborate detail, and beautiful enough to be worn as outer garments.  The one on the right might have been a “sheer gown” of the era – worn on the outside of a plain colored silk petticoat that would show through underneath.

Note the same pleating and silhouette is used for the petticoat as the main skirt in the 1840’s.