As the commercial manufacture of glass is about to resume after many years, archaeologists have discovered the ruins of an old and rare glasshouse in Co Offaly.
Ireland's new glass industry will be based at Ballyconnell in Co Cavan where Fermanagh businessman, Mr Sean Quinn, plans to build a glass furnace.
However, archaeologists in Co Offaly have uncovered the ruins of a forest-glass wood-fired furnace dating from the 17th century.
The so-called forest-glass manufacturers used wood from nearby forests and silica extracted from sand and lime.
The glasshouse furnace, with its barrel-vaulted roof in situ, is standing in the townland of Glasshouse, near Shinrone.
It has excited archaeologists in Ireland and Britain because the main evidence for the manufacture of glass in this period comes from medieval documentary sources, and the survival rate of glass furnaces is very poor.
According to a report in Archaeology Ireland there is no surviving upstanding forest-glass wood-fire furnace of the 16thand 17th-century period in England.
But the simple rubble-stone structure with its barrel-vaulted firing chamber and central fire trench has remained undisturbed in Shinrone for centuries.
The glass industry was established in Ireland in 1586 when Queen Elizabeth I granted a Capt Woodhouse the right to make glass in Ireland.
By the early 17th century, the felling of wood to make glass was banned in England because of the depletion of woodland.
At that stage, English manufacturers had turned to using coal-fired glasshouses, and Admiral Sir Robert Mansell held a monopoly on the new technologies.
He enforced the 1615 ban on using wood to make glass, and sought the arrest of one of the families involved in forest-glass production.
In 1618 glass-making families, who had come to England from Lorraine in France, moved their activities to Ireland where the ban on using wood was not in force.
A man called Abraham Bigo rented land from Laurence Parsons to build a glasshouse, and the industry flourished in Offaly until the manufacture and export of glass were banned in 1638. There followed a prohibition on cutting wood to burn for glass-making in 1641.
The authors of the report, Mr Caimin O'Brien and Ms Jean Farrelly, found that glasshouses were still being built in Co Offaly until 1666.
The belief is that the Shinrone glasshouse may date from the period 1590-1640 and at that time the Bigo and Hensey families, associated with glass-making, were living and working throughout Co Offaly.