being set free by the owner (manumission), voluntarily or in accordance with laws requiring it after a certain time or in certain cases, thereby becoming freedman
... 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.
External links
www.gyrotwister.de ...