The athanor was also called Piger Henricus ("Slow Henry"), because it was chiefly used in slower operations, and because when once filled with coals, it keeps burning a long time. For this reason the Greeks referred to it as "giving no trouble", as it did not need to be continually attended. It was also called the Philosophical furnace, Furnace of Arcana, or popularly, the Tower furnace.[1]