Comprised of two or more brass blocks fitted with brass terminals and mounted on a black bakelite base.
Tapered plugs with bakelite moulded tops fit into the tapered holes between the blocks providing low resistance contact With rubber feet.
For demonstrating expansion of solids by heating and contraction by cooling. Comprising a metal bar mounted on rod with insulated handle, and U-shaped metal gauge also mounted on insulated handle. with GO / NO GO hole.