Tunnel pit

Tunnel Tun"nel, n. [F. tonnelle a semicircular, wagon-headed vault, a tunnel net, an arbor, OF. also tonnel; dim. of tonne a tun; -- so named from its resemblance to a tun in shape. See {Ton}.] 1. A vessel with a broad mouth at one end, a pipe or tube at the other, for conveying liquor, fluids, etc., into casks, bottles, or other vessels; a funnel. [1913 Webster]

2. The opening of a chimney for the passage of smoke; a flue; a funnel. [1913 Webster]

And one great chimney, whose long tunnel thence The smoke forth threw. --Spenser. [1913 Webster]

3. An artificial passage or archway for conducting canals or railroads under elevated ground, for the formation of roads under rivers or canals, and the construction of sewers, drains, and the like. [1913 Webster]

4. (Mining) A level passage driven across the measures, or at right angles to veins which it is desired to reach; -- distinguished from the drift, or gangway, which is led along the vein when reached by the tunnel. [1913 Webster]

{Tunnel head} (Metal.), the top of a smelting furnace where the materials are put in.

{Tunnel kiln}, a limekiln in which coal is burned, as distinguished from a flame kiln, in which wood or peat is used.

{Tunnel net}, a net with a wide mouth at one end and narrow at the other.

{Tunnel pit}, {Tunnel shaft}, a pit or shaft sunk from the top of the ground to the level of a tunnel, for drawing up the earth and stones, for ventilation, lighting, and the like. [1913 Webster]