A pit or tunnel under a glass furnace for collecting ashes or raking the fire.

A natural, hollow chamber or series of chambers and galleries beneath the earth's surface, or in the side of a mountain or hill, with an opening to the surface.

1. Fragmented rock materials, derived from the sidewalls of a borehole, that obstruct the hole or hinder drilling progress. Also known as cavings.

2. The partial or complete failure of borehole sidewalls or mine workings. Also known as cave-in.

A heavily shielded compartment in which highly radioactive material can be handled, generally by remote control. Also known as hot cell.