In the days when there were no closets, each bedroom had a stand-alone wardrobe. This tall piece of furniture had shelves and/or drawers on one side and a place to hand garments on the other. The double doors on the wardrobe were then closed and could be locked. Across the top of inside of the wardrobe, there probably was a shelf. On the garment side, screw hooks like this one were screwed on the underneath side of that shelf, and that was how the clothes were hung.
This wardrobe hook is made of heavy wire. The screw is 3/4 inch long. The drop of the hook is 2 inches. It is quite sturdy and can hold a considerable amount of weight.