Decades: 1170s 1180s 1190s 1200s 1210s - 1220s - 1230s 1240s 1250s 1260s 1270s
Years: 1218 1219 1220 1221 1222 - 1223 - 1224 1225 1226 1227 1228
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... to a smaller extent by the slipping friction. The device is covered by US patents 3,726,146 (1973) and 5,353,655 (1994) by L.A. Mishler and US patent ...