bell glass

from The Century Dictionary.

• noun A bell-shaped glass vessel used to cover objects which require protection from variations of the atmosphere, dust, and influences of like character, as delicate plants, bric-à-brac, small works of art, clocks, etc., or to hold gases in chemical operations.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a bell-shaped glass cover used to protect and display delicate objects or to cover scientific apparatus or to contain gases