seal. The Klonne dry seal gas holder was circular: it used a grease seal. The dry-seal Wiggins gasholder was patented in 1952: it used a flexible curtain that was suspended from the piston. The largest low-pressure gas Holder built was the Klonne gas holder built in 1938 in Gelsenkirchen. It was high and in diameter, which gave it a capacity of . There was a MAN type, built in 1934 in Chicago with a capacity of . By location Europe The pollution associated with gasworks and gas storage makes the land difficult to reclaim for other purposes, but some gas holders, such as the Vienna Gasometers, have been converted into other uses such as living space and a shopping mall and historical archives for the city. Many sites, however, were never used for the production of 'town gas', therefore the land contamination is relatively low. Gas holders have been a major part of the skylines of low-rise British cities for up to 200 years, due to their large distinctive shape and central location. They were originally used for balancing daily demand and generation of town gas. With the move to natural gas and construction of the national grid pipework, their use steadily diminished as the pipe network could both store gas under pressure, and eventually satisfy peak demand directly. London, Manchester, Sheffield, Birmingham, Leeds, Newcastle, Salisbury and Glasgow (which has the largest gasometers in the UK) are noted for having many gas holders. Some of these gas holders have become listed buildings. The gas holders behind King's Cross station in London were specially dismantled when the new Channel Tunnel Rail Link was being created, with Gas holder No 8 being re-erected on a nearby site behind St Pancras station as part of a housing development. It has been fashioned into a park. Most gas holders are no longer used, and a program of dismantling is underway to release the land for reuse. One of the largest remaining groups of gasholders is at Bromley-by-Bow in East London, believed to be the largest in Europe. A gasworks in South Lotts, Dublin, Ireland, was converted into apartments. In the past, holder stations would have an operator living on site controlling their movement. However, with the process control systems now used on these sites, such an operator is obsolete. The tallest gasometer in Europe is tall and is located in Oberhausen. In the UK