A round wooden blase that supports a thick, round glass platform from a brass pillar that also functions as a tube and has a stopcock. On the glass platform is a flat brass ring with three securing clamps made of an insulating material. The ring connects to the outside through the platform.
Has "ES" painted on it, which means "electrostatic". This inscription is usually found on instruments from the Department of physics at Harvard.
For an example of what the whole assembly would look like, see the following
website.