What can this word mean in english ( To Let ) in the following page ???

Number 3, Lauriston Gardens wore an ill-omened and minatory look. It was one of four which stood back some little way from the street, two being occupied and two empty. The latter looked out with three tiers of vacant melancholy windows, which were blank and dreary, save that here and there a (“To Let” ) card had developed like a cataract upon the bleared panes. A small garden sprinkled over with a tered eruption of sickly plants separated each of these houses from the street, and was traversed by a narrow pathway, yellowish in colour, and consisting apparently of a mixture of clay and of gravel.