Along Gasmeterlaan in Ghent, two of the five gasholders of the former city gasworks (1883-1945) are still preserved in situ. These gasholders are of the telescopic type: in a brick tub with an earthen wall rests an outer metal ring and an inner metal bell. When filled with gas, depending on the amount, the bell will first rise along the vertical metal guide system and then also along the outer ring. The water in the vessel and the water seal between the bell and the outer ring act as a gas lock to prevent the gas from escaping.
Learn more about city gas supply and its storage at the Industry Museum's website.