Half of the furnace for the glass-melting tank was intact, buried beneath the Grade II* listed 1887 Jubilee Cone building where the Pilkington family once produced its glass. Lancaster University archaeologists said yesterday that they had chanced upon it while excavating a 700-metre labyrinth of tunnels, through which gas and air once heated the furnace to temperatures of more than 1,000C.
"The furnace is a very rare survivor. So many of these things get demolished," said Mick Krupa, one of the archaeologists who found it. The St Helens model of the Siemens regenerative furnace was built in 1887, to transform molten glass into brilliant fire-finished sheet glass. The furnace could draw as many as 150,000 visitors every year to see the restoration that will form the centrepiece of St Helens' The World of Glass museum. The new museum is costing pounds 14.2m to create, pounds 8.3m of which is from the National Lottery.
Visitors to The World of Glass, which opens next March, will also see the remains of the brick `swing pit', where balls of molten glass were swung until they became elongated into tubes that were cut and rolled flat into window glass. The pit is also within the distinctive brick cone, an East Lancashire trademark and glass industry standard, built to cover glass workers and provide an outlet for the furnace's heat, which was generated by the area's coal.
The museum has also constructed a new 18-metre high cone - the first built in Britain for more than a century - that includes exhibition areas, and a Glass Magic area for kaleidoscopes and periscopes.