I should have said that "city gas" comes from coal. Coal is "cooked"
and the gas stored in large chambers which ran inside large brick
cylinders, an iron vessel floating up and down on interior tracks as
the pressure was created and relieved, into the "city gas" system,
mostly for lighting. A brick "gasholder" in Troy, NY is the symbol of
the Society For Industrial Archeology" I think.

George Myers