The invention of the blow pipe 2000 years ago vastly expanded the types of glassware that could be made. As size of objects & scale of production increased the industry developed its own types of furnaces. By mediæval times two kinds of furnace had evolved, one circular & the other rectangular. These furnaces evolved slowly but became adapted to the special needs of glass making. The only major advance up to the middle of the 19th century was use of coal as fuel instead of wood. The crucial advances were the introduction gas firing & of regenerative & recuperative heat recovery systems, then the development of the tank furnace, all largely due to the brothers Charles & Friedrich Siemens. The latter built the world's first commercially successful regenerative furnace to melt glass in Rotherham in 1860 & went on to operate the first tank furnace.
