Hooks such as this were screwed on the underneath side of a shelf and used for hanging clothes. In the old stand-alone wardrobes of the Victorian era, there were a few of these in each wardrobe. (They must not have had the volume of clothes that we have today. Also each season, the out-of-season clothes were boxed up or put into trunks.)
This copper-twist wired hook is somewhat attractive. It is not as hefty as some of the others pictured in this catalog, but still quite useful. The screw is 3/4 inch in length. The drop of the hook is 2 inches. A standard wardrobe might have as many as six or eight such hooks.