What is a Wardian case?
Wardian cases are basically fancy terrariums. 'Fancy' in the sense that they are made from cut glass panels of various shapes and put together like a stained glass window; usually with leading or the copper foil and solder technique. Some even have stained glass in them.
The original Wardian cases were for all kinds of plants -- mainly tropicals (including orchids). They are basically mini greenhouses or conservatories.
They may come in a variety of sizes from ones small enough to sit on a window sill to those large enough to require their own stand [like aquariums do]. Some even include in their design ways to exert some control on the environment [lighting, and air circulation, etc].