I love old steamer trunks (which this is not. This is a Carriage trunk. The curved lid is to shed water while riding atop a coach or carriage. Steamer trunks have flat tops for easy packing in a ship's hull.
Wardrobe style steamer trunks like this could carry a traveler's clothing selections for the voyage itself, and be checked to the stateroom. The clothes for the trip could then be packed into more capacious regular trunks and checked to the hold.