Manhole

—1. In an underground conduit system, a vault built under the street, having a circular opening at the street surface covered by a cast iron cover, and large enough to conveniently admit a man, so that acce may be had to the conduit ducts and the cables. 2. An opening by which to enter a steam boiler, tank, sewer, aqueduct, or the like, for cleaning, repairing, or inspecting. 3. A side excavation or refuge in tunnels,