I couldn't help but repost this beauty from @marchesafashion

Petticoats have been used to add fullness/volume to skirts from time immemorial.
A good petticoat adds volume without necessarily adding "weight".

Petticoats help to create the illusion of a narrow waist and are designed for the dress they would be worn with. In other words, you can't wear one petticoat with different dresses. The silhouette has to be the same.

Who else spotted the horsehair braid? I sure did! Horsehair helps to stiffen the petticoat thus retaining the desired structure.