In Greek mythology, the river Phlegethon {"(river of) fire") was one of the five rivers of the underworld. It flowed with fire that burned but did not consume fuel.
... friction.
The device is covered by US patents 3,726,146 (1973) and 5,353,655 (1994) by L.A. Mishler and US patent 5,800,311 (1998) by P.S.Chuang.
Externa ...