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Double-Walled Glass Cup

Unidentified · Physics

A glass cup resembling a wine glass. The bulb of the glass is formed of two glass hemispheres, a smaller one inside a larger one; these are connected at the upper rim. The inner sphere is only supported by the outer rim.

The outer hemisphere opens at its base into a stem which flutes outwards at the base to provide a stand. The stem is closed off underneath the base by a protruding glass plug.

Small silver bulbs, possibly mercury, sit on the interior of the glass surface between the walls.

Accession Number:

Alternative Name:

Primary Materials: Glass, Metal: Mercury?


Dimensions (cm): Height = 15.5, Diameter = 7.5


An air gap between two layers of glass can provide insulation and aid with keeping a substance at a relatively stable temperature. The purpose of this piece is otherwise unknown. It may be a glassblower’s demonstration or practice piece.


Excellent: The glass is not broken or chipped. There is a small stain mark on the interior of the glass in the stem.

Associated Instruments:

Manufacturer: Locally made?

Date of Manufacture: 20th cent.


Department of Physics, University of Toronto

Additional Information and References:

Historical Notes: